Electronics

CONTENTS

• What is Amplitude Modulation
• Virtues, Limitations and Modifications of Amplitude Modulation
• VSBSC Modulation
• DSBSC Modulation
• SSB Modulation
• DSBSC vs SSBSC
• Advantages & disadvantages

What is Amplitude Modulation?

Define Amplitude Modulation:

“A modulation procedure where amplitude of carrier is varied with respect to the instantaneous value of modulating signal is called Amplitude Modulation”.

From the context of communications, a main motivation for the modulation would be to ease transmission of this information-carrying signal over a communication channel or radio station via a prescribed pass-band. On this basis, we might classify continuous-wave modulation to two broad category: amplitude modulation and angle modulation. Both of these modulation differentiate themselves by providing absolutely distinctive spectral features and as a result distinct functional advantages. The classification is completed on the basis of if the amplitude of the sinusoidal carrier wave, or the frequency or phase the angle of the sinusoidal carrier wave, is varied in nature with the information signal.

Concepts of Amplitude Modulation:

Consider a carrier signal is characterized by,

                                  C(t) = A_c cos (2πf_ct)

Here, A_C is the carrier signal amplitude and f_c is the carrier signal freq. The information or message signal is indicated by term m(t); An amplitude-modulated (AM) wave may thus be described as a function of time as follows:

                                          s(t) = A_c[1+K_am(t)]cos(2πf­_ct)

Where K_a is a constant termed as the amplitude sensitivity. Characteristically, the carrier amplitude, message signal are stated in volts, and amplitude sensitivity is represented in volt^-1

1. The amplitude of |K_am(t)| is generally less than unity;

                       |K_am(t)|<1, for all t

• The carrier freq. ( f­_c ) is much higher than the maximum freq. element represented by W of the message signal m(t);

                                         f_c >>W

• For +ve freq., the maximum freq. of the Amplitude modulation wave is equal to (f_c + W), and the lowest freq. element is equal to (f_c – W). The difference between these two freq. terms as the transmission bandwidth (B_T) of the amplitude modulation wave, which is precisely double the message signal bandwidth (W). So

                                     B_T = 2W

Modulation Index of Amplitude Modulation:

Modulation index indicates how much modulated variable of the carrier signal fluctuates around its unmodulated level. In Amplitude modulation, this quantity also termed as modulation depth, specifies by exactly how much the modulated variable differs around its original level.

Mathematically modulation index is, m_a, defined by,

     where, K = proportionality constant;

              V_m = amplitude of modulating signal;

              V_c = amplitude of carrier signal;

We know that,

               A = amplitude of modulated signal = V_c(1+m_asinω_mt)

So,          A_max = V_c(1+m_a) and A_min = V_c(1-m_a)

Finally, modulation index,

What is VSB-SC Modulation?

Define Vestigial Side Band System Modulation in Amplitude Modulation:

Single sideband modulation works reasonably for an info signal with an energy gap centred around ‘0’ frequency. If more information is to be broadcasted in a given time then corresponding larger B.W. is required, for example: television

• SSB can play important role in reducing the bandwidth
• We can analyse the case of video transmission for television system
• Bandwidth occupied by T.V. video signal minimum 4MHz. So, a transmitted B.W. of 9 MHz at least would be required. So SSB is used for saving the B.W.
• While using SSB, care must be taken to see at the receiver end. No problem of demodulation arises. So the carrier passed undiminished or as it is.
• As the phase response of the filter at the edges of the flat pass band is loud to have bad effect on video signals received in a T.V. receiver a part of the unwanted i.e., lower sideband also transmitted. The effect of this is to produce a vestigial transmission system also known as AGC. A typical frequency spectrum of this type is shown :

• 1.25 MHz of the lower side band gets transmitted along with the USB so that the lowest frequencies of the required USB will not be distorted in their phase by the vestigial sideband filter as only 1.25 MHz of the LSB is transmitted; a saving of nearly 3 MHz of V.H.F spectrum is produced with every T.V channel. This makes it promising to allow multiple number of channel is in the same bandwidth.
• In the above figure, it was observed that the receiver video amplifier frequency response the sound occupies a frequency band near the video amplifier frequency response. The sound occupies a frequency band near the video as it is required with the picture and in practice it is not possible to have separate receiver to receive the sound operating at distant frequency i.e., away from Video Frequency.
• In television receiver attenuation is intentionally delivered for video frequency from 0 to 1.25MHz. the reason for this is the extra power is transmitted for this part of the information of the video signal as it is transmitted in both sideband this would have produced unnecessary emphasis in the video output of the receiver if the attenuation had been absent.

What is DSB-SC Modulation?

Define Double Side Band Modulation in Amplitude Modulation:

Fundamentally, the double side band suppressed carrier (DSB-SC) modulation comprises of the product of the message signal and the carrier wave as shown in the equation

                              s(t) = c(t)m(t)

                                     = A_c cos (2πf_c t) m(t)

Consequently, the device utilized to produce the DSB-SC modulated signal is the denoted to as ‘product modulator’. It is also identified fact that not like AM, DSB-SC modulation is reduced to ‘0’ at whatever time the message signal is not present.

Thus, the apparatus used to create the DSB-SC controlled wave is termed as product modulator. In addition, we understand that unlike any amplitude modulation, DSB-SC modulation is decreased to zero if the message code is switched off.

Mostly, the signal goes into a phase change if the message signal is not zero. The packet of a DSB-SC controlled signal is so dissimilar from the message one, meaning that simple demodulation with the packet detection isn’t a feasible choice for DSB-SC modulation.

DSB-SC features:

• Only two side-band with suppressed carrier is transmitted
• With carrier suppressed power saving for m=1 is 66%
• It requires lesser bandwidth
• It has balanced modulation

What is SSB-SC Modulation?

Define Single Side Band (SSB-SC) Modulation:

In suppressing the carrier, DSB-SC modulation have a significant limit of Amplitude modulation when it is to this wastage of transmitted electricity. To look after another significant restriction of Amplitude modulation when it comes to station bandwidth, we will have to suppress one of both sidebands from the DSB-SC modulated wave. This adjustment of DSB-SC modulation is exactly what implemented in SSB modulation. In significance, SSB modulation be subject to entirely on the lower-sideband and upper-sideband to transmit the message transfer through communication channels based on which side-band is in fact is communicated.

Single Side Band can be represented mathematically as;

                    s_ssb (t) = s(t) . cos(2πf₀t) – ŝ(t) . sin(2πf₀t),

Where, s(t) is the message, ŝ(t) is its Hilbert Transform, and f­₀ is the radio carrier frequency.

SSBSC Features:

A SSBSC has the following features:

• Only one side band is transmitted
• With one side boundary for m=1 it is 83.3%
• Its bandwidth is least
• This is a phase shift method modulator.

Comparison between DSB-SC and SSB-SC:

DSB-SC	SSB-SC
Only two side-band with suppressed carrier is transmitted.   With carrier suppressed power saving for m=1 is 66%   It requires lesser bandwidth     It has balanced modulation	Only one side band is transmitted     With one side boundary for m=1 it is 83.3%   Its bandwidth is least     This is a phase shift method modulator.

Advantages and disadvantages of Amplitude Modulation:

ADVANTAGES of AM

• Small antenna size.
• Long range communication.
• Using repeater any distance communication is possible.
• Noise can be eliminated.

DISADVANTAGES of AM

• Power requirement is high.

For more Electronics related article click here

Modulation and demodulation are fundamental concepts in communication systems that play a crucial role in transmitting and receiving information. In this section, we will explore the definitions of modulation and demodulation, as well as the importance of these processes in communication systems.

Definition of Modulation

Modulation is the process of modifying a carrier signal to encode information. In simpler terms, it involves altering certain characteristics of the carrier signal, such as amplitude, frequency, or phase, in order to carry the desired information. By modulating the carrier signal, we can efficiently transmit information over long distances and through various media.

Definition of Demodulation

Demodulation, also known as detection or extraction, is the reverse process of modulation. It involves extracting the original information from the modulated carrier signal. Demodulation is necessary at the receiving end to recover the transmitted information accurately. By demodulating the received signal, we can retrieve the original data and make it usable for further processing or interpretation.

Importance of Modulation and Demodulation in Communication Systems

Modulation and demodulation are vital components of communication systems for several reasons. Let’s explore some of their key importance:

1. Efficient Transmission: Modulation allows us to transmit information efficiently over different types of communication channels. By modifying the carrier signal, we can adapt it to the specific characteristics of the transmission medium, such as bandwidth limitations or noise interference. This enables us to achieve better signal quality and maximize the utilization of available resources.

2. Compatibility: Modulation techniques enable compatibility between different communication systems. By using standardized modulation schemes, such as amplitude modulation (AM), frequency modulation (FM), or phase modulation (PM), we can ensure that different devices and systems can communicate with each other effectively. This compatibility is crucial in enabling seamless communication across various platforms and technologies.

3. Signal Integrity: Modulation helps in preserving the integrity of the transmitted signal. By modulating the carrier signal, we can make it less susceptible to noise, interference, and distortion during transmission. This ensures that the received signal retains its quality and fidelity, allowing for accurate demodulation and extraction of the original information.

4. Multiplexing: Modulation techniques enable the transmission of multiple signals simultaneously over a single communication channel. This is achieved through techniques like frequency division multiplexing (FDM) or time division multiplexing (TDM). By modulating each signal with a unique carrier frequency or time slot, multiple signals can be combined and transmitted together, significantly increasing the efficiency and capacity of the communication system.

Modulation Index

The modulation index is a crucial parameter in the field of communication systems, particularly in the context of modulation and demodulation techniques. It plays a significant role in determining the quality and efficiency of the transmitted signal. In this section, we will explore the definition of modulation index, its explanation in amplitude modulation (AM), the calculation of modulation index, and the effects it has on the transmitted signal.

Definition of Modulation Index

The modulation index, also known as the modulation depth, is a dimensionless quantity that represents the extent of modulation in a communication system. It quantifies the relationship between the amplitude of the modulating signal and the amplitude of the carrier signal. Essentially, it indicates how much the carrier signal is being varied or modulated by the information-bearing signal.

Explanation of Modulation Index in Amplitude Modulation (AM)

In amplitude modulation (AM), the modulation index determines the variation in the amplitude of the carrier signal. It is defined as the ratio of the peak amplitude of the modulating signal to the peak amplitude of the carrier signal. A higher modulation index signifies a greater variation in the amplitude of the carrier signal, resulting in a more significant modulation effect.

When the modulation index is low, the amplitude of the carrier signal remains relatively constant, and the modulating signal has minimal impact on the transmitted signal. On the other hand, a high modulation index leads to a more pronounced variation in the amplitude of the carrier signal, allowing the modulating signal to have a more significant influence on the transmitted signal.

Calculation of Modulation Index

The modulation index can be calculated using the formula:

Modulation Index = (Amplitude of Modulating Signal) / (Amplitude of Carrier Signal)

For example, if the amplitude of the modulating signal is 5 volts and the amplitude of the carrier signal is 10 volts, the modulation index would be 0.5. This indicates that the modulating signal is half the amplitude of the carrier signal.

Effects of Modulation Index on the Transmitted Signal

The modulation index has a direct impact on the characteristics of the transmitted signal. It influences the bandwidth, power efficiency, and quality of the signal. Let’s explore the effects of different modulation index values:

1. Low Modulation Index: When the modulation index is low (close to zero), the transmitted signal is primarily composed of the carrier signal. The modulating signal has minimal effect on the signal, resulting in a narrow bandwidth. However, the information carried by the modulating signal may be difficult to discern due to the low level of modulation.

2. Moderate Modulation Index: A moderate modulation index value (between 0.5 and 1) allows for a more significant variation in the amplitude of the carrier signal. This results in a wider bandwidth and improved signal quality. The information carried by the modulating signal is more easily distinguishable.

3. High Modulation Index: When the modulation index is high (greater than 1), the transmitted signal experiences a substantial variation in amplitude. This leads to an even wider bandwidth and a higher level of modulation. However, excessive modulation can cause distortion and signal degradation, affecting the quality of the transmitted signal.

Phase Modulation

Phase modulation is a modulation technique used in communication systems to transmit information by varying the phase of a carrier wave. It is closely related to frequency modulation (FM) and amplitude modulation (AM), but instead of varying the frequency or amplitude, phase modulation focuses on changing the phase of the carrier wave.

Definition of Phase Modulation

In phase modulation, the phase of the carrier wave is modified in accordance with the input signal. The input signal, also known as the modulating signal, contains the information to be transmitted. By altering the phase of the carrier wave, the modulating signal is effectively encoded onto the carrier wave.

Phase modulation can be mathematically represented as:

s(t) = A * cos(wc * t + β * m(t))

Where:
– s(t) is the modulated signal
– A is the amplitude of the carrier wave
– wc is the angular frequency of the carrier wave
– t is the time
– β is the modulation index
– m(t) is the modulating signal

Comparison of Phase Modulation with Other Modulation Techniques

Phase modulation shares similarities with frequency modulation (FM) and amplitude modulation (AM), but it also has distinct characteristics that set it apart.

Frequency Modulation (FM)

In FM, the frequency of the carrier wave is varied in proportion to the modulating signal. This means that the frequency deviation is directly related to the amplitude of the modulating signal. In contrast, phase modulation focuses on altering the phase of the carrier wave, which is not directly dependent on the amplitude of the modulating signal.

Amplitude Modulation (AM)

AM involves varying the amplitude of the carrier wave in response to the modulating signal. This modulation technique is commonly used in broadcasting, where the amplitude variations carry the audio signal. Phase modulation, on the other hand, does not directly manipulate the amplitude of the carrier wave. Instead, it encodes information by modifying the phase.

Advantages and Disadvantages of Phase Modulation

Like any modulation technique, phase modulation has its own set of advantages and disadvantages.

Advantages

1. Robustness: Phase modulation is less susceptible to noise and interference compared to amplitude modulation. This makes it a reliable choice for transmitting signals in noisy environments.

2. Bandwidth Efficiency: Phase modulation offers better bandwidth efficiency compared to amplitude modulation. It allows for the transmission of more information within the same frequency range.

3. Improved Signal Quality: Phase modulation provides improved signal quality, as it is less affected by variations in amplitude. This results in clearer and more reliable communication.

Disadvantages

1. Complexity: Phase modulation requires more complex circuitry and processing compared to amplitude modulation. This can increase the cost and complexity of the communication system.

2. Limited Range: Phase modulation is more sensitive to changes in the carrier wave’s phase. This can limit the range of the transmitted signal, especially in scenarios with high levels of interference.

Effects of Modulation Index on AM Waves

The modulation index plays a crucial role in determining the characteristics of amplitude modulation (AM) waves. It is a measure of how much the amplitude of the carrier wave is varied in response to the modulating signal. In this section, we will explore how the modulation index affects AM waves and the implications of doubling the modulation index.

Explanation of how the modulation index affects AM waves

The modulation index, also known as the modulation depth or modulation factor, is defined as the ratio of the peak amplitude of the modulating signal to the peak amplitude of the carrier wave. It quantifies the extent to which the modulating signal influences the amplitude of the carrier wave.

When the modulation index is low, the amplitude variations in the carrier wave are minimal. This results in a narrow bandwidth and a lower quality of the modulated signal. On the other hand, a high modulation index leads to significant amplitude variations in the carrier wave, resulting in a wider bandwidth and a higher quality of the modulated signal.

To better understand the effects of the modulation index, let’s consider an example. Suppose we have a carrier wave with a peak amplitude of 10 volts and a modulating signal with a peak amplitude of 5 volts. If the modulation index is 0.5, the amplitude of the carrier wave will vary between 7.5 volts and 12.5 volts. As the modulation index increases, the amplitude variations become more pronounced, resulting in a more pronounced modulation of the carrier wave.

Doubling the modulation index of an AM wave

Doubling the modulation index of an AM wave has significant implications for the modulated signal. When the modulation index is doubled, the amplitude variations in the carrier wave become more pronounced. This leads to an increase in the bandwidth of the modulated signal.

A wider bandwidth allows for the transmission of more information, as it accommodates a greater range of frequencies. However, it also requires more resources in terms of transmission power and bandwidth allocation. Therefore, doubling the modulation index should be done with caution, considering the trade-off between increased information transmission and resource utilization.

In addition to the bandwidth implications, doubling the modulation index can also affect the demodulation process. The demodulator, which extracts the original modulating signal from the modulated carrier wave, relies on the modulation index to accurately recover the modulating signal. If the modulation index is too low, the demodulator may struggle to extract the modulating signal accurately. Conversely, if the modulation index is too high, the demodulator may introduce distortion or inaccuracies in the recovered signal.

Why Modulation Index is Less Than 1

In most modulation techniques, the modulation index is typically less than 1. This value plays a crucial role in determining the quality and efficiency of the modulation process. Let’s explore the reasons behind this phenomenon, the relationship between modulation index and signal quality, and the impact it has on the efficiency of modulation.

Reasons for Modulation Index Being Less Than 1 in Most Modulation Techniques

There are several reasons why the modulation index is generally kept below 1 in most modulation techniques:

1. Avoiding Overmodulation: Overmodulation occurs when the modulation index exceeds 1. This can lead to distortion and interference in the transmitted signal. By keeping the modulation index below 1, we ensure that the signal remains within the acceptable range and avoids overmodulation.

2. Preventing Signal Interference: When the modulation index is less than 1, the sidebands produced during modulation are spaced closer together. This reduces the chances of interference with neighboring channels or frequencies, allowing for efficient use of the available bandwidth.

3. Minimizing Power Consumption: In many modulation techniques, the power required to transmit a signal increases as the modulation index approaches 1. By keeping the modulation index below 1, we can minimize power consumption while still achieving satisfactory signal quality.

Relationship Between Modulation Index and Signal Quality

The modulation index has a direct impact on the quality of the modulated signal. Here’s how it affects signal quality:

1. Signal Fidelity: The modulation index determines the extent to which the original message signal can be accurately reproduced at the receiver. A higher modulation index allows for better fidelity, as it provides a wider range of amplitudes to represent the message signal. However, if the modulation index is too high, it can lead to distortion and signal degradation.

2. Signal-to-Noise Ratio (SNR): The modulation index affects the SNR of the modulated signal. A higher modulation index generally results in a higher SNR, as it allows for a larger portion of the transmitted power to be allocated to the signal. This leads to improved signal quality and better reception.

3. Bandwidth Efficiency: The modulation index also influences the bandwidth efficiency of the modulation technique. By keeping the modulation index below 1, we can ensure that the sidebands are closely spaced, allowing for efficient use of the available bandwidth. This is particularly important in applications where bandwidth is limited or expensive.

Impact of Modulation Index on the Efficiency of the Modulation Process

The modulation index plays a crucial role in determining the efficiency of the modulation process. Here’s how it impacts efficiency:

1. Power Efficiency: By keeping the modulation index below 1, we can achieve a balance between signal quality and power consumption. Higher modulation indices require more power to transmit the same signal, leading to decreased power efficiency. By optimizing the modulation index, we can maximize power efficiency without compromising signal quality.

2. Spectral Efficiency: Spectral efficiency refers to the amount of information that can be transmitted per unit of bandwidth. By keeping the modulation index below 1, we can achieve higher spectral efficiency by closely packing the sidebands within the available bandwidth. This allows for more efficient use of the frequency spectrum.

MCQs on Modulation and Demodulation

MCQs related to modulation index

1. What is the modulation index?
2. The modulation index is a parameter that determines the extent of modulation in a signal.
3. It is defined as the ratio of the peak amplitude of the modulating signal to the peak amplitude of the carrier signal.

4. A higher modulation index indicates a higher degree of modulation.

5. What is the significance of the modulation index?

6. The modulation index determines the bandwidth occupied by the modulated signal.
7. It affects the quality of the demodulated signal and the efficiency of the modulation technique.

8. A modulation index of 1 is considered optimal for most modulation schemes.

9. How does the modulation index affect the bandwidth?

10. The bandwidth of a modulated signal is directly proportional to the modulation index.
11. A higher modulation index leads to a wider bandwidth.
12. This is because a higher modulation index introduces more sidebands around the carrier frequency.

MCQs related to modulation and demodulation techniques

1. What is Amplitude Modulation (AM)?
2. AM is a modulation technique where the amplitude of the carrier signal varies in accordance with the modulating signal.
3. It is commonly used in broadcasting and two-way communication systems.

4. AM signals can be demodulated using envelope detection or synchronous detection techniques.

5. What is Frequency Modulation (FM)?

6. FM is a modulation technique where the frequency of the carrier signal varies with the modulating signal.
7. It is widely used in FM radio broadcasting and high-fidelity audio transmission.

8. FM signals can be demodulated using frequency discriminators or phase-locked loop (PLL) circuits.

9. What is Phase Modulation (PM)?

10. PM is a modulation technique where the phase of the carrier signal is varied in accordance with the modulating signal.
11. It is commonly used in digital communication systems and satellite communication.
12. PM signals can be demodulated using phase detectors or Costas loop circuits.

MCQs on the working principles of modulation and demodulation

1. How does modulation work?
2. Modulation involves combining a low-frequency information signal (modulating signal) with a high-frequency carrier signal.
3. The modulating signal alters the characteristics of the carrier signal, such as amplitude, frequency, or phase.

4. This modulated signal is then transmitted through a communication channel.

5. How does demodulation work?

6. Demodulation is the process of extracting the original modulating signal from the modulated carrier signal.
7. The demodulator circuit or receiver reverses the modulation process to recover the original signal.

8. The demodulation technique used depends on the modulation scheme employed.

9. What are the advantages of modulation and demodulation?

10. Modulation allows multiple signals to be transmitted simultaneously over a shared medium.
11. It enables long-distance communication and reduces interference between different signals.
12. Demodulation allows the receiver to extract the original information signal accurately.

How Modulation and Demodulation Work

Modulation and demodulation are fundamental processes in communication systems that allow the transmission and reception of information over long distances. These processes involve the manipulation of a carrier signal to carry the desired information. Let’s explore how modulation and demodulation work in more detail.

Explanation of the Process of Modulation

Modulation is the process of modifying a high-frequency carrier signal with the information to be transmitted. The carrier signal acts as a “vehicle” for the information, allowing it to be efficiently transmitted over long distances. There are several types of modulation techniques, including amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM).

In amplitude modulation, the amplitude of the carrier signal is varied in proportion to the instantaneous amplitude of the modulating signal. This variation in amplitude represents the information being transmitted. For example, in AM radio broadcasting, the audio signal is used to modulate the amplitude of the carrier signal, allowing the transmission of voice or music.

Frequency modulation, on the other hand, involves varying the frequency of the carrier signal based on the instantaneous amplitude of the modulating signal. This variation in frequency represents the information being transmitted. FM is commonly used in radio broadcasting, where the frequency of the carrier signal is modulated to carry audio signals.

Phase modulation, as the name suggests, involves varying the phase of the carrier signal based on the instantaneous amplitude of the modulating signal. This variation in phase represents the information being transmitted. Phase modulation is widely used in digital communication systems, such as satellite communication and wireless networks.

Explanation of the Process of Demodulation

Demodulation, also known as detection or extraction, is the process of recovering the original information from the modulated carrier signal. It is the reverse process of modulation and is essential for receiving and decoding the transmitted signal accurately.

Demodulation involves extracting the original information from the modulated carrier signal by using a demodulator or detector circuit. The demodulator circuit is designed to detect and separate the modulating signal from the carrier signal. The demodulator circuit can be specifically designed based on the modulation technique used.

For example, in AM demodulation, a diode detector circuit can be used to rectify the modulated signal, resulting in the recovery of the original audio signal. In FM demodulation, a frequency discriminator or phase-locked loop (PLL) circuit can be employed to detect the frequency variations and recover the original modulating signal.

Overview of the Components Involved in Modulation and Demodulation

Modulation and demodulation involve several components that work together to ensure the accurate transmission and reception of information. These components include:

1. Carrier Signal: The high-frequency signal that is modulated to carry the information.

2. Modulating Signal: The information signal that is used to modulate the carrier signal. This can be an audio signal, video signal, or data signal.

3. Modulator: The circuit or device that performs the modulation process. It combines the carrier signal and the modulating signal to produce the modulated signal.

4. Demodulator: The circuit or device that performs the demodulation process. It separates the modulating signal from the modulated carrier signal, allowing the recovery of the original information.

5. Transmission Medium: The physical medium through which the modulated signal is transmitted. This can be a wired medium, such as coaxial cables or optical fibers, or a wireless medium, such as radio waves or microwaves.

By understanding the process of modulation and demodulation, we can appreciate how information is efficiently transmitted and received in various communication systems. These processes form the backbone of modern telecommunications, enabling us to communicate and exchange information over vast distances.

Modulation Index Calculation

The modulation index is a crucial parameter in modulation and demodulation techniques. It quantifies the extent of modulation applied to a carrier signal. By calculating the modulation index, we can determine the efficiency and quality of the modulation process. In this section, we will explore the step-by-step guide to calculating the modulation index and provide examples for different modulation techniques.

Step-by-step guide to calculating modulation index

To calculate the modulation index, we need to consider the peak amplitude of the modulating signal and the peak amplitude of the carrier signal. The formula for calculating the modulation index varies depending on the modulation technique used. Here is a step-by-step guide to calculating the modulation index for different modulation techniques:

1. Amplitude Modulation (AM): In AM, the modulation index represents the ratio of the peak amplitude of the modulating signal to the peak amplitude of the carrier signal. The formula for calculating the modulation index in AM is as follows:

Modulation Index (m) = (Amplitude of Modulating Signal) / (Amplitude of Carrier Signal)

For example, if the peak amplitude of the modulating signal is 10 volts and the peak amplitude of the carrier signal is 5 volts, the modulation index would be:

m = 10 V / 5 V = 2

1. Frequency Modulation (FM): In FM, the modulation index is determined by the ratio of the frequency deviation to the modulating frequency. The formula for calculating the modulation index in FM is as follows:

Modulation Index (m) = (Frequency Deviation) / (Modulating Frequency)

For instance, if the frequency deviation is 50 kHz and the modulating frequency is 10 kHz, the modulation index would be:

m = 50 kHz / 10 kHz = 5

1. Phase Modulation (PM): In PM, the modulation index is calculated by dividing the phase deviation by the modulating frequency. The formula for calculating the modulation index in PM is as follows:

Modulation Index (m) = (Phase Deviation) / (Modulating Frequency)

For example, if the phase deviation is 30 degrees and the modulating frequency is 1 kHz, the modulation index would be:

m = 30 degrees / 1 kHz = 30 degrees/kHz

Examples of modulation index calculations for different modulation techniques

Let’s consider a few examples to illustrate the calculation of the modulation index for different modulation techniques:

1. Example 1: AM Modulation

2. Amplitude of Modulating Signal: 8 V

3. Amplitude of Carrier Signal: 4 V

Modulation Index (m) = 8 V / 4 V = 2

Therefore, the modulation index for this AM modulation example is 2.

1. Example 2: FM Modulation

2. Frequency Deviation: 25 kHz

3. Modulating Frequency: 5 kHz

Modulation Index (m) = 25 kHz / 5 kHz = 5

Hence, the modulation index for this FM modulation example is 5.

1. Example 3: PM Modulation

2. Phase Deviation: 45 degrees

3. Modulating Frequency: 2 kHz

Modulation Index (m) = 45 degrees / 2 kHz = 45 degrees/kHz

Thus, the modulation index for this PM modulation example is 45 degrees/kHz.

Frequently Asked Questions

1. What is modulation index in phase modulation?

The modulation index in phase modulation refers to the ratio of the maximum phase deviation to the frequency deviation of the carrier signal.

2. What happens when the modulation index of an AM wave is doubled?

When the modulation index of an AM wave is doubled, the amplitude of the sidebands also doubles, resulting in an increase in the bandwidth of the modulated signal.

3. Why is the modulation index less than 1?

The modulation index is typically less than 1 to ensure that the modulation does not cause distortion or overmodulation of the carrier signal. It helps maintain the integrity of the transmitted signal.

4. Are there any MCQs available on modulation index?

Yes, there are multiple-choice questions (MCQs) available on modulation index that can help test your understanding of this concept.

5. Where can I find MCQs on modulation and demodulation?

You can find MCQs on modulation and demodulation in various textbooks, online learning platforms, or educational websites that cover the topic of communication systems.

6. How does modulation and demodulation work?

Modulation is the process of superimposing information signals onto a carrier signal, while demodulation is the process of extracting the original information signals from the modulated carrier signal. This is achieved using modulation and demodulation techniques such as amplitude modulation (AM), frequency modulation (FM), or phase modulation (PM).

7. What does the modulation index indicate?

The modulation index indicates the extent of modulation applied to a carrier signal. It determines the amplitude, frequency, or phase variations of the carrier signal based on the information signal.

8. How is modulation achieved?

Modulation is achieved by varying one or more characteristics of a carrier signal, such as amplitude, frequency, or phase, in accordance with the information signal. This variation allows the information to be transmitted over a communication channel.

9. What happens to the transmitted power when the modulation index of an AM wave is increased from 0.5 to 1?

When the modulation index of an AM wave is increased from 0.5 to 1, the transmitted power remains constant. However, the power distribution between the carrier and the sidebands changes, with the sidebands gaining more power.

10. How is modulation index calculated?

The modulation index can be calculated by dividing the peak amplitude of the modulating signal by the peak amplitude of the carrier signal. It represents the extent of modulation applied to the carrier signal.

Topics of Discussion

1. VHDL Process using Xilinx

2. Steps to Install Xilinx

3. Step by Step Examples for implementation of Sequential & Combinational Circuits.(VHDL Process)

Tutorial with a step-by-step guide for VHDL Process

VHDL Process Using XILINX

To implement VHDL designs, we will use Xilinx. Xilinx is one of the best providers of programming logic devices. It is a tech company based on states.

Prerequisite for using VHDL:

WHAT IS VHDL ? Check Here!

• Must have some knowledge of digital electronics. <You can check out some articles here!>
• It is good if you have an uninterrupted internet connection for downloading the files.
• Xilinx needs at least 18 GB of space in your PC. So make sure that your disk has enough space to run the application.
• Make sure you have created a free account with a valid email id in Xilinx before downloading. That will help you in future purposes.
• We are using windows.

Installation Guide for VHDL Process

• Step 1: Download the zip file according to your operating system and their versions.

The link to download Xilinx is given below.

https://www.xilinx.com/member/forms/download/xef.html?filename=Xilinx_ISE_DS_Win_14.7_1015_1.tar

It is 6.18 GB free zipped file. We will use this version to demonstrate the tutorial.

You can find other downloadable options from here –

https://www.xilinx.com/support/download/index.html/content/xilinx/en/downloadNav/vivado-design-tools/archive-ise.html

• Step 2: Unzip the file and store that in a preferred folder. The folder name should be – Xilinx_ISE_DS_Win_14.7_1015_1. Open this folder.

• Step 3:  Double click on the xsetup file (as shown in the image) and start the installing. Allow all the permissions . The installation may take up to two hours depending on the memory space available and the PC configurations. Nothing to worry, sit tight and get it installed.

Choose the ISE webpack from the list when this pop up appears before final installation. Also, keep the default storage space as it suggests and if that location has enough space.

 After the installation of the file, there will be two shortcuts appearing in the desktop, and there will be a pop-up regarding the license. Don’t click on the shortcut icons as the installation is not completed and also close the license tab for the time being.

• Step 4: Now, the software is installed inside your computer. Find out the installed folder which is of around 18 GB of size. By default, it gets stored in C drive if you have not made any changes. Open the folder.

Open Xilinx folder -> 14.7 -> ISE_DS -> lib -> nt64

Path – [C:\\Xilinx\\14.7\\ISE_DS\\ISE\\lib\ t64]

• Step 5: Now there will be a file named – “libPortability.dll”

Rename that file as – “libPortability.dll.orig”

• Step 6: Then find out the file named as – “libPortabilityNOSH.dll”. It will be just below the file we worked in step 4. Copy the file and paste it. Now rename that pasted file as – ‘libPortability.dll”. Keep the copied file in the dashboard.

The final outcome will look like the below-given figure.

• Step 7: After that, we have to go to another file-folders.

Open Xilinx folder -> 14.7 -> ISE_DS -> common -> lib -> nt64

Path – [C:\\Xilinx\\14.7\\ISE_DS\\common\\lib\ t64]

There will be a file named as – “libPortability.dll”.

Rename that file as – “libPortability.dll.orig”

• Step 8: Now, paste the file that we have copied in step 6 and rename that pasted file as – ‘libPortability.dll”.

The final outcome will look like the below-given figure.

• Step 9: License: Now double click on the shortcut ISE Design Suite 14.7. There will be a pop-up asking for a license. Just click Okay, and another window will be opened. There will be options for the license. From the “Acquire license”, click on the “Get My Purchased License (s)” and then NEXT.

Then, there will be another pop-up from “Xilinx License Manager”. Click on the connect now option. It will open a tab on the default web browser of your PC.

Log in with your credentials, and there will be options like the below image. You have to choose the 4^th or 5^th option from the list. Just click on the license you want.

There will be a mail in your email id, containing the license file for Xilinx. Download the license file and store it into the download folder.

• Step 10: Go back to the ISE. There you can see a window remained open. Choose the option load license and locate your license in the download folder to upload.

After uploading the license, there will be a message showing successfully. Click Ok and then click close in the previous window. Now Xilinx is ready to be used.

Creating your first project in XILINX (VHDL Process)

We will implement a simple AND gate dataflow modelling using Xilinx.  AND gate is represented as – Y= AB. The truth table is shown below.

A	B	Y =AB
0	0	0
0	1	0
1	0	0
1	1	1

• Step 1: Open the project navigator by double-clicking the icon on the desktop.
• Step 2: Go to File and then New Project. File -> New Project

• Step 3:  Give a name to your project and select the location to store the project. Never uses basic gate names. Then click on the next. Copy the name, and it will help later.

• Step 4: Now set up the values as mentioned below. Do the setup carefully. Any mistake will lead to failure.

Click on the NEXT and then click on ‘Finish’ For the next pop-up.

• Step 5: Now, in the editor section, you can see your model at the left top corner, inside the design tab and under the Hierarchy bar. Place your cursor on the folder named by you and do a right-click. Then Choose the New Source from the menu.

• Step 6: In the new window, choose the VHDL Module and paste the same name that you have copied in step 3, or you can get the name from the location tab. Click on next.

• Step 7: In the define module pop-up,
• Change the Architecture from ‘Behavioral’ to ‘Dataflow’.
• In the Port Name, Write A, B, and Y in the consecutive rows. Now for The Y marked row, Choose the direction as ‘out’ as it will be the output. You can change the direction from the down arrow associated with it.
• There will be another pop-up. Check if the porta is okay or not. Then click finish.

• Step 8: RTL SCHEMATIC CREATION

Now a code editor will be opened.

A. In the 40^th line, you can ‘begin’. From that place, you have to write the dataflow code. The Code for our program will be –

Y <= A and B;

B. Save the code using Ctrl + S.

C. Now, on the left side of the window, under the design bar, you can see a tab named ‘process < model_name>’.

D. Expand the ‘Synthesis – XST’ from there.

E. Double click on the ‘Check Syntax’. It will show a green tick, denoting success.

F. Then, Double click on the ‘Synthesis – XST’. A green tick will have appeared here too.

G. Now click on the ‘View RTL Schematic’ to view the RTL implementation. A pop up will appear. Choose the second option and click on the next.

H. A diagram segment will be opened up.

I. Double click on the box to show the inside structure.

• Step 9: TEST BENCH CREATION

1. Change the tab from Implementation to Simulation.

1. Again, right-click on the first folder and choose the new source.

1. Choose the ‘VHDL Test Bench’ and give a new file name. Click on the next.

1. After that, a window named Associate Source will be popped up to link your dataflow model with the test bench. Click on the model and click NEXT. Click on ‘Finish’ for the next window.

1. A new code editor will be opened up.

Now, for an AND gate, we don’t need clock pulses. To delete or comment all the clock signals.

The clock signals are at line no. – 60, 72 to 78 and line no. 87.

Test bench code is written in the ‘Stimulus process section’.

You can start from the 90^th line.

 The code for test bench of AND gate is –

A <= ‘0’;

               B <= ‘0’;

               wait for 100 ns;

               A <= ‘0’;

               B <= ‘1’;

               wait for 100 ns;

               A <= ‘1’;

               B <= ‘0’;

               wait for 100 ns;

               A <= ‘1’;

               B <= ‘1’;

               wait for 100 ns;

6. Now from the left side option, expand the Isim Simulator, and then double click on the ‘Behavioral Check Syntax’. A green tick will appear.

7. Now double-click on the ‘Simulate Behavioral Model’.

A window will be popped up. allow the software to access.

On the toolbar at the top, find out the option of zooming. Click on the third option to see the full view.

Click Here to Know About the VHDL CODING PROCESS!

In this VHDL Tutorial, we will discuss some of the basic concepts related to VHDL technology and few example with coding. VHDL Tutorial is segmented as follows :

TOPICS OF DISCUSSION

A. What is VHDL?

B. History and Standardization

C. VHDL Design Procedures

D. Some rules and basic information about VHDL

E. Syntaxes & Some important concepts for writing VHDL Codes

F. VHDL Simulators for VHDL Tutorial

VHDL || What is VHDL?

The full form of VHDL stands for Very High Speed Integrated Circuit Hardware Description Language (VHSIC-HDL).

As the name suggests, VHDL is a hardware description language or a special type of programming language which describes the hardware implementations of digital system and circuits.  It is a strongly typed language and points to be remembered that it is not a programming language.  

History and Standardization

US Defense Department has a significant contribution to the modern technological field. It has given birth too many great ideas and innovations. US Defense also developed VHDL in the year 1983. It was developed for documentation of behavior of the application specific integrated circuits.

Later, some ideas were implemented from Ada programming languages. VHDL got standardized for the first time in the year 1987. It was added up with several data types of several types, including strings and numeric and logical.

Standardization

VHDL or for Very High Speed Integrated Circuit Hardware Description Language (VHSIC-HDL) is standardized by IEEE 1076 standard. It is being updated from its birth and has undergone many revisions. Let us look at some of the standard revisions and major updates.

Revisions	Updates
IEEE 1076 – 1987	Revision and standardization from US Defense.
IEEE 1076 – 1993	Came up with the greatest release, and it is the most widely used version.
IEC 61691 -1 – 1- 1: 2004	IEC adopted IEEE 1076-2002 Version
IEEE 1076 -2008	Updated with some major changes like – Introduction of generics on packages and use of external names
IEC 61691 -1 – 1- 1: 2011	IEC adopted IEEE 1076-2008 Version

Design of VHDL

VHDL design has some design units. They are known as – Entity, Architecture, Configuration, and Package.

Entity: Entity defines external views of a model that is a symbol.

Architecture: Architecture defines the functionality of a model that is schematic.

Configuration: Configuration is used for associating architecture with an entity.

Package: Package is the collection of information which can be referenced by VHDL modules. A VHDL package consists of two part. They are – package declaration and package body.

Entity Declaration

The general structure of entity declaration is given below –

ENTITY < entity_name > IS

          Generic declarations

          Port declarations

END ENTITY <entity_name>;

• <entity_name> can be alphabetic/ numerical or alpha-numerical.
• Generic Declarations is for passing information into a model.
• Port Declarations is for describing the inputs and outputs pins.
• An entity can be closed in several ways.
  • END ENTITY <entity_name>;
  • END ENTITY;
  • END;

Port Declarations

A general structure for port declarations is given below –

ENTITY < entity_name > IS

          Generic declarations

          — Port Declarations:

PORT (

          SIGNAL CLK, CLR: IN BIT;

          q: OUT BIT

          — note that there is no semicolon in the last line of declarations.

          );

END ENTITY <entity_name>;

The structure of port declaration: <class> object_name : <mode> <type>;

• Class: Class is what can be done to an object. Here class is signal. A point to be remembered that the SIGNAL is not written while writing program; rather, it is assumed and not required.
• Object_name: It is the identifier.
• Mode: It specifies the direction.

IN – Input

OUT – Output

INPUT – Bidirectional

BUFFER – Output with internal feedback

• Type: Type specifies what can be contained inside an object.

Generic Declarations

A general structure of generic declarations is given below –

ENTITY <entity_name> IS

          GENERIC (

                    CONSTANT tplh, tphl : time := 5 ns;

                    tphz, tplz : TIME := 3ns;

                    default_value : INTEGER := 1;

                    cnt_dir : STRING := “UP”

                    — note that there is no semicolon in the last line of declarations.

                    );

          Port declarations

          END ENTITY <entity_name>;

• Generic values can be overwritten during compilation.
• Generic must possess the tenacity to a constant during the compilation of a program.  

Note that CONSTANT keyword is assumed and not required to write.

Architecture

• Analogy-schematic: Analogy schematic gives the description of the functionality of a model and the timing associated with it.  
• The architecture of a model should be associated with an ENTITY.
• An Entity may have many architectures associated with it.
• Architecture statements execute concurrently.
• Some styles of architecture –
• Behavioural: Behavioural model describes how designs operate.

RTL: RTL describes how designs can be implemented using registers.

Functional: It includes no timing.

• Structural: Implementation of gate level structure.
• Dataflow: Implementation of the truth table.
• Architecture is ended with –
  • END ARCHITECTURE <architecture_name>;
  • END ARCHITECTURE
  • END;

A general structure of writing an architecture:

ARCHITECTURE <identifier> OF <entity_identifier> IS

          SIGNAL signal_1 : INTEGER := 1;

          CONSTANT cnst := BOOLEAN := true;

          TYPE process IS (W, X, Y, Z);

          — Attribute declarations

          — Attribute specifications

          — Subprogram declarations

          — Subprogram body

BEGIN

          Process statements

          Concurrent procedural calls

          Signal assignment

          Generate statements

END ARCHITECTURE <identifier>;

Configuration     

As discussed, an earlier configuration is used for associating architecture with an entity. Associating or combining is necessary because An ENTITY can not work until the architecture is associated with it.  A general structure of configuration is given below.

CONFIGURATION  < identifier > OF < entity_name > IS

          FOR < architecture_name >

                    FOR < instance_name > : < component_name > USE < entity >(< architecture >)

                    END FOR;

                    FOR < instance_name > : < component_name > USE < configuration_name >

                    END FOR;

          END FOR;

END CONFIGURATION < identifier >;

Packages

VHDL packages are one whole unit of an entire system. It is the main aim of the implementation of VHDL. A package has two parts. As said earlier, package declarations and package body make a complete package.

VHDL delivers two in-built packages.

Some rules and basic information about VHDL Tutorial

Let us discuss about have a glance at some basic information before we dive to explore the VHDL tutorial.

1. Reserved Keywords: VHDL has some keywords as reserved (that cannot be used for declaring a variable).

2. Parts: VHDL has two steps or parts for the creation of a model. One is Simulation, and the other is synthesis and simulation.

3. Case sensitive language: VHDL is not a case sensitive language (for the most of the part).

4. Commenting: To comment a statement in the VHDL code editor, start the sentence with –, for an example:

— This is a comment in VHDL.

5. Termination: VHDL codes and each single lines of codes are terminated using a semicolon (whenever needed). 

6. Space Sensitivity: VHDL is not white space sensitive.

Syntaxes and Some important VHDL Tutorial concepts for writing a VHDL Codes

1. Array with examples
2. Process with examples
3. IF – THEN – ELSIF implementation with examples.
4. CASE statement
5. FOR LOOP

A. Array

Array stores value. It is a user-defined data type to store value. An array may contain variables of signal, constants type.

A general structure to declare an array is given below:

TYPE array_name IS ARRAY (range) OF data_type;

For an example,

TYPE lambdageeks IS ARRAY (0 to 9) OF std_logic_vector (0 UPTO 9);

B. Process Statement

Process is a simultaneous and synchronized statement. It introduces the chronological statements. Multiple processes run parallelly if the model needed.

A process consists of two parts. They are the execution of the process and then wait for the next condition.

SYNTAX:

process sensitivity_list

          declarations

begin

          chronological_statements;

end process;

C. IF – THEN – ELSIF implementation

These statements are used for implementing a condition and for their result.

An if condition can have an infinite number of branches as per the requirement. A considerable number of elsif condition is also possible. But, in an, if loop, there can be only one else condition. An if loop is terminated by the end if statement. If the condition is given is true, then it will enter the loop and will execute the statement. If it fails, then go for else or elsif statement.

The syntax of the statements is given below.

SYNTAX

          if conditional_boolean_expression then

                    statement1

          elsif conditional_boolean_expression then

                    statement2

          . . .

          else

                    statement3

          end if;

D. CASE Statement

Case statement finds out which statement will be executed. A case statement can also be branched as IF-ELSE loops.

SYNTAX

[label]: case < conditional-expression > is

          when < choice> = >

                    statement1

          when <choice> = >

                    statement2

          …

          when <choice> = >

                    statement

end case [label];

E. FOR Loop

A for loop is a continuous execution of statements according to the bounding conditions.

For each FOR loop, we need an iterator which will perform the operations in the for a loop. It is also known as an identifier. It is an integer by default and no need to declare the iterator. It is one of the most commonly used loops for making complex models. It is more familiar than while loops.

SYNTAX

[label]: for iterator in range loop

          Statement1

          Statement2

          …

          Statement n

end loop [label];

VHDL Simulators for VHDL Tutorial

Some of the famous VHDL simulators used for the implementation of VHDL are listed below.

1. Xilinx Vivado: The most famous simulator for VHDL is Xilinx Vivado. Xilinx provides programmable logic devices. We will use this simulator for the next part of the VHDL Tutorial. 
2. Cadence Incisive: The previous version was known as NC-VHDL.
3. VHDL Simili: Symphony EDA develops it. It is free for consumers. 
4. GHDL: One of the famous free VHDL simulator. 
5. Boot: Freerangefactory organization developed the simulator. 
6. NVC: Nick Gasson developed the opensource VHDL compiler. 
7. EDA Playground: Another free version based on web-browser. 
8. Synopsis VCS-MX.

Make your first project using VHDL. Check out the next part of VHDL Tutorial.

For more electronics related article, Click here!

Points for Discussion

A. Application in Education

B. Application in Home Automation

C. Application in Industrial Automation

D. Pi as AI Assistant (Raspberry Pi Alexa)

E. Photography Applications

F. Raspberry pi drone and Raspberry pi drone peripherals

G. Raspberry Pi camera

H. Octoprint Raspberry Pi

Various Applications of Raspberry Pi

Raspberry pi is considered as one of the greatest inventions. It is one of the hot-selling electronics devices in today’s world. From taking images of planets in night using raspberry pi cameras to controlling the washing machine in your home , Raspberry pi drone is using in advanced drones also. Do. Raspberry pi is now literally the ‘Jack of all trade’. But the tiny computer is not trying to replace the conventional computing machines but assisting the machines like never before!

It’s versatility of shape and size and dynamic nature of operation helps to implement innovative ideas in a simple way and through shorter process. Out of in numerous numbers of applications, we will discuss about some common applications which are appreciated and adapted by tons of people (the range of people lies from – 8^th standard student to NASA scientists!). At first, we will discuss about the uses of raspberry pi by dividing its uses in separate fields then we will be more specific.

What is Raspberry Pi? How it works? Read Here

A. Education

Raspberry pi helps the students to grow interest in the modern technological domains. They come up with different innovative ideas and some of them are just mind blowing. There are various communities to teach the students the use of raspberry pi, about the workings, about the effectiveness of raspberry pi. As a result of these communities, report says there are growing interests inside students of various schools in States and Britain.

Raspberry Pi foundation has taken steps to accumulate software developers and teachers to give free training for the enthusiasts. The foundation has also started with their teacher training organizations to train the teachers in a more precise way. The course is aimed to update the teachers with the modern curriculums. It is known as ‘Picademy’.

National Aeronautics and Space Administration (NASA) has also joined the campaign by launching an open source project. It is known as JPL Open Source Project and it is the miniature version of curiosity rover placed in mars. Raspberry pi controllers control the small model and inspires and encourages students to contribute to the project. Raspberry pi sensors also got involved in the project. It is one of the best examples of raspberry pi robot.

B. Home automation

Home automation is basically smart home which is controlled by automation system. Home automation can control and monitor raspberry pi security cameras, security systems of vaults, climate inside different rooms, power supply, all the home appliances (refrigerators, washing machines, microwave ovens, etc.) present inside the household, home theatres and all the entertainment system and what not! Raspberry pi is the heart behind the automation system and it controls the whole system. The economical cost has increased the demand for raspberry pi for the automation systems. There are developers and scientists researching to make more affordable automation system using raspberry pi.

C. Industrial automation

Raspberry pi models are cheaper for making automations systems. That is why many industrial companies have started with raspberry pi for their automation systems. Implementation of IoT is quite simpler using raspberry pi models. Networking and controlling of sensors, software and hardware can be efficiently done by raspberry pi. That is how modern industrial automation is becoming more advance and more secure. On the other hand, the controlling became easier than before.

In the year 2014, Mod Berry was released. Mod berry was released by TECHBASE (a famous automation builder company of Poland). It is a computer for industrial uses and it is built using raspberry pi compute model. This device has some added advantages like- RS-485/232 serial ports, 1 wire buses, etc. The computer got popularity as soon as it came into market.

Raspberry pi has also come up with different products of great usability. Raspberry pi camera or OTTO camera is a digital camera which was made by Next Thing Co. comes with some great features. It has a raspberry pi compute module to run the camera in efficient and desired way.

There are media player or raspberry pi media player developed by Slice. The digital player uses raspberry pi module as the core of the media player.

D. AI Assistant

Raspberry pi has recently tied knot with google to come up with hardware kits that will use Google’s cloud speech API and assistant software development kit for interpreting natural language or voices. That will not only make the devices more advanced but also will help the user to do certain tasks. That is how a raspberry pi will work as intelligent assistant or it can be called as raspberry pi Alexa. 

E. Photography

Raspberry pi module can help to capture some long-desired shots of many photographers. Raspberry pi No-IR camera works as artificially intelligent camera. A good quality camera with the no-IR filter camera of raspberry pi can be used to take some snaps from the night sky. The results will be much better than normal camera. Researches are still in progress to get more clarified results.

We have discussed some field related uses of the Raspberry Pi module. Let us be more specific and continue the discussion with some fantastic and cool science projects and ideas using raspberry pi module.

F. Raspberry pi web server

Raspberry pi can be used as webserver for the customers who needs it. However, raspberry pi cannot host a website with large base and high visitor counts but it’s perfect for new websites with low visitor counts. Three are web servers such as Apache, nginx and others for hosting large extensive websites. You will need a raspberry pi monitor for sure.

G. Raspberry pi drone

Emild has come out with a special structure using raspberry pi to control flight for new a Raspberry pi drone . To make a raspberry pi drone, one need to write the framework for autopilot. The job for Raspberry pi drone is now easily done by most of the raspberry pi model. The updated model of Raspberry pi by Emild has made it easier as it does not require to recreate the model. You can implement the innovative ideas in most of the Raspberry pi drone nowadays. Now raspberry pi drone can be used for most of the drone based operations and list is increasing daily.

Raspberry pi drone equipment’s

Tools need to make a raspberry pi drone are given in the below list.

• Raspberry pi 4
• NAVIO Kit (Built by Emild)
• Motors
• RC Controller
• Raspberry pi battery
• Adaptors
• Micro SD Cards
• USB cords
• GPS system
• 1045 props
• PPM Encoders

H. Raspberry pi security camera

Earlier we have discussed home automation system using raspberry pi. Security camera is one of the most important parts of the system. This is not only for homes but also for industrial uses. A security camera is necessary for everywhere. Installing the system will allow you to watch live streams from the cameras and you can monitor the situations. It also records the video, so you can watch them latter too.

The list of tools needed for installing security camera using raspberry pi is given in the below list.

• Raspberry Pi Module version – 3 and above
• Raspberry pi camera (separately built for connecting with raspberry pi module)
• Power supply
• Micro SD card
• Wi – fi module
• Ethernet cable to connect the network

The steps for setup are as follow –

1. Install the raspberry pi operating system using the micro SD card.
2. Connect the Secure Shell or SSH (your local network).
3. Connect the raspberry pi camera.
4. Give access to Wi – Fi.
5. Set up all your hardware components.
6. Motion detection installation.
7. Set up your pc for saving the videos in a particular folder and make sure the machine has space to store.
8. Fix the motion AutoStart.
9. Fix the camera at the desired place.
10. Access the live stream.

I. Octoprint Raspberry pi

Octoprint is the web interface for 3D printers. Raspberry pi helps Octoprint to control and monitor the printing process with its own controller. Raspberry pi camera can help Octoprint in this matter.

Tools needed for the projects are –

• Raspberry pi module version – 3 and above.
• Micro Sd Cards.
• USB cables.
• Raspberry pi camera
• 3d printed camera mount.

J. Coffee machine controllers using raspberry pi

There is n need to talk about the demand and popularity of a modern coffee machine in today’s era. Using an raspberry pi just add some more control and need less human interaction with the machine. It will set up warning when resource fell short, will give warnings for too much use, will give you estimation for bulky orders etc. The equipment needed to modify the coffee machine are noted below.

• Raspberry pi module version 3 and above.
•  Ultrasonic sensor
• Cloud4Rpi software
• Coffee Machine

K. LED controllers for raspberry pi

One of the very common yet popular project using raspberry pi is LED controllers. One can control and design LEDs with raspberry pi according their choices and requirements. One can select which light will be on for how much amount of time, or which light will be blinking using a simple raspberry pi module. The needed components are listed below.

• Raspberry pi module of any version
• LEDs
• Resistors.
• Breadboard
• Jumper Wires.

Topics of Discussion

• Overview Of Raspberry Pi
• Raspberry Pi Logo
• Raspberry Pi Accessories & Hardware
• Raspberry Pi Fan
• Raspberry Pi Battery
• Raspberry Pi Power Buttons
• Raspberry Pi Shut Down Command

Overview

Raspberry pi is a small digital computer which has a wide range of applications in the field of modern technologies. It is a programmable device which can work as per requirement. The hardware ( main raspberry pi accessories) is implemented in a single board, and that is why the demand for it increasing exponentially. 

Raspberry Pi in the United Kingdom develops raspberry pi, and it is one of the bestselling computers in the world.

What is Raspberry Pi Drone? Check out other Raspberry Pi Applications!

Raspberry Pi accessories and Hardware

A typical raspberry pi accessories and important hardware are combination of a RAM, A CPU, GPU, USB hub, Ethernet chip, and the input-output port.

Processor

The microprocessor is the heart of the raspberry pi. First-generation raspberry pi uses BCM2835 SoC processor which has an s-processor, a GPU and a RAM unit. It has two cache level – primary and secondary level. The primary level cache has 16 KiB memory, and the second-level cache has 128 KiB memory. The secondary cache or the level 2 cache is associated with the GPU. The operational frequency of the processor stands at 700Mhz.

The preliminary version of Raspberry Pi 2, has a quad-core ARM cortex processor with a speed of 900 MHz. The level 2 cache memory limit is increased to 256KiB. The second version of Raspberry pi is updated with 1.2 GHz and 64-bit processor. The Broadcom BCM2836 Soc was brought back. The production of BCM2836 Soc was stopped before in 2016.

The raspberry pi 3 uses Broadcom BCM2837 Soc, and raspberry pi 4 uses Broadcom BCM2711 Soc. The speed of raspberry pi 3 stands at 1.2 GHz as it uses ARM Cortex – A53 processor and the rate of raspberry pi 4 stands at 1.5 GHz as it comes with ARM Cortex A72 processor.

The specification of processors for different versions, shown in the below table.

Model & version	Processor	Broadcom Soc	Speed	Cache
Raspberry Pi	ARM1176JZF-S	BCM2835	700 MHz	L1 – 16 KiB L2 – 128 KiB
Raspberry Pi 2 V1.1	ARM CORTEX-A7 (32 bit)	BCM2836	900 MHz	L2 – 256KiB
Raspberry Pi 2 V1.2	ARM CORTEX-A53 (64 bit)	BCM2837	1.2 GHz
Raspberry Pi 3 Model – B	ARM CORTEX-A53 (64 bit)	BCM2837	1.2 GHz A+, B+ – 1.4 GHz	L2 – 512 KiB
Raspberry Pi 4	ARM CORTEX-A72 (64 bit)	BCM2711	1.5 GHz	L2 – 1 MiB

Know about microprocessors Here!

RAM

RAM is the main memory segment for raspberry pi. First generations of raspberry pi have RAM of 256 MiB- 128 MiB was for GPU and 128 MiB for CPU. The primary releases of the Raspberry pi RAM were separate able. 192 MiB memory was set for CPU. That much memory is enough for high-quality video decoding, 3D image processing. The 224 MiB was for the operating system that is Linux processing. Then another 128 MiB was for high load processing like – 3D processing.

Later there was a new model of ram size 512 MiB. It has specific split files.

The Raspberry Pi consists of 1 GiB Ram while Raspberry Pi 4 has RAM of 2, 4, 8 GiB of RAMS according to various model.

Networking

To connect with the internet, the ethernet port is there for Raspberry Pi 4 models. Previously there were no ethernet ports; instead, there were USB ethernet or Wi-Fi connectivity. Bluetooth connection is available for Raspberry Pi 3 and Pi Zero W., The version of the Bluetooth, is 4.1. The wi-Fi versions for those models are – 802.11n with 2.4 GHz bandgap.

Shape, Size & Weights

The increasing demand for Raspberry Pi is for its flexible size and small weight. It has a variety of sizes and can be easily fit into various electronics circuits. Raspberry Pi models are generally rectangular. A logo of raspberry pi is printed on the board. Weights and shapes of different Raspberry pi models are shown in the following table.

Model	R Pi 1 A	R Pi 1 A+	R Pi 3 A+	R Pi 2 B	R Pi 3 B	R Pi 4 B
Size	85.6 mm X  56.5 mm	65mm X 56.5 mm X 10 mm	65 mm X 56.5mm	85.60 mm X 56.5 mm	85.60 mm X 56.5 mm X 17 mm	85.60 mm X 56.5 mm X 17 mm
Weight	31 g	23 g	45 g	45 g	45 g	46 g

General Purpose Input- Output (GPIO) connector

One of the main features that have made Raspberry Pi so popular is the input-output pins. Almost every model of raspberry pi has the input-output pins. Raspberry Pi 1 models have 26 pins for both models A and model B. Models like A+ and B+ of version 1 have 40 pins. Raspberry pi 2 model B and all models of raspberry pi 3 has 40 pinouts. The specification table for the input-output pins is given below for further clarification.

PIN	GPIO	FUNCTION
1		+ 3.3 V
2		+ 5 V
3	2	SDA1 (I2C)
4		+5V
5	3	SCL1 (I2C)
6		GND
7	4	GCLK
8	14	TXD0 (UART)
9		GND
10	15	RXD0 (UART)
11	17	GEN0
12	18	GEN1
13	27	GEN2
14		GND
15	22	GEN3
16	23	GEN4
17		+ 3.3 V
18	24	GEN5
19	10	MOSI (SPI)
20		GND
21	9	MISO (SPI)
22	25	GND
23	11	SCLK (SPI)
24	8	CEO_N (SPI)
25		GND
26	7	CE1_N (SPI)
27	0	ID_SD (I2C)
28	1	ID_SC (I2C)
29	5	N/A
30		GND
31	6	N/A
32	12
33	13	N/A
34		GND
35	19	N/A
36	16	N/A
37	26	N/A
38	20	DIGITAL IN
39		GND
40	21	DIGITAL OUT

Raspberry pi fan

Raspberry pi model 4 comes with a case fan for its subsidiary models. It is specially designed for over clockers and other power consumers. It controls the temperature of the raspberry pi and thus made it more user friendly. The specifications of the fan are –

Input Voltage: 5V DC supplied via a general-purpose input-output header.

The fan speed is changeable.

Maximum airflow is 1.4 CFM.

Raspberry Pi battery

Raspberry pi models are fed into powers via an external cable which is connected with some power source. There is no in-built connection to place a battery inside the raspberry pi model. But now, there are several vendors for raspberry pi batteries. You just need to pick up the correct product for the model and connect it properly. It will be placed externally.

Raspberry Pi Power Buttons

There are no in-build power buttons for raspberry pi models. But there are ways to solve the problem. External power buttons can be added with the raspberry pi board to switch on and off the raspberry pi. Switching off the raspberry pi indicates that the model goes into HALT state for operation.

Note that raspberry pi accessories are necessary to build the power button externally.

Raspberry pi shutdown command

The raspberry pi model can be turned off (goes to halt state) using a specific command. If someone s using the command line or terminal windows, then type the following command –

sudo shutdown -h now.

Raspberry Pi Operating Systems

Raspberry pi runs using Linux Operating Systems. The specific version is known as ‘Raspbian’. It is a 32-bit operating system. Other types of OS can be operated using Micro or Mini SD cards.

Python and Scratch can be used as programming language though other languages have a scope too. The firmware (it is a software class which can control hardware of a specific device) is a closed structure, but there are unofficial opens sources available as well.

There are some other operating systems which are available in official websites. They include Ubuntu MATE, Windows 10 IoT Core, etc.

Some examples of Linux based OS and not Linux based OS are given in the below table.

Linux Based	Not Linux Based
Android Things	RISC OS
Arch Linux ARM	2.  FREEBSD
OpenSUSE	3. NetBSD
SUSE Linux Enterprise (Server 12 SP2)	4. Plan 9 from Bell Labs
Gentoo Linux	5. Windows 10 IoT Core
Lubuntu	6. Haiku
Xubuntu	7. Helen OS
Devuan	8. Broadcom VCOS
Kali Linux
Ark OS
Tiny Core Linux
Void Linux
Fedora
OpenWrt
RetroPie
Postmarket OS
Alpine OS

APIS

API is a software known as Application Programming Interface. It is the link between two applications. It is a computing interface.

Video Core IV GPU can be used via binary blob for Raspberry Pi. The GPU code does the main work for the driver.

The firmware used by Raspberry Pi is a binary blob, and it is free of license.

There are also different third-part application software like – Astro Print, C/C++ Interpreter Ch, Mathematica, Minecraft, Real VNC, User Gate Web Filter, Steam link, etc.

The software inside the raspberry pi can be developed using various tools and raspberry pi accessories. Some of the tools are – Arduino IDE (Arduino programming),  BlueJ (Java beginners), Lazarus (Pascal IDE), Ninja IDE (python), TensorFlow (Machine learning and Deep learning framework developed by Google). etc.

Know More About APIs, Click Here!

Raspberry Pi Accessories

To operate a raspberry pi, there are specific devices that one need to use. Some of the raspberry pi accessories for beginners are –

• DC motor,
• motor driver,
• LCD and Segment display,
• light sensor,
• temperature sensor,
• Extra general-purpose input and output pins,
• resistors,
• rheostats,
• capacitors,
• transformers,
• breadboard,
• potentiometer,
• jumper wires for connections, etc.

These raspberry pi accessories will help to use raspberry Pi to perform better in multiple real time applications.

Raspberry Pi Logo

The raspberry pi foundation organized a logo making competition for their product. On the 7^th of October 2011, they declared the result. Paul Beech got the highest numbers of votes from the judges and won the competition. He makes the current logo.

CONTENTS

• Intel 8086
• PIN diagram
• Different addressing modes
• Different Flags Register
• Pipeline architecture in 8086 microprocessor
• Advantage of pipelining
• Memory segmentation in 8086
• Difference between 8085 and 8086 microprocessor

What is Microprocessor 8086?

INTEL 8086:

• Microprocessor 8086 first invented by INTEL in 1976.
• 8086 is equipped with 16-bit, HMOS N-channel based microprocessor.
• This has two modes; minimum and maximum.
• 8086 has total twenty (20) address lines
• 8086 has sixteen (16) data lines.

PIN diagram of 8086 microprocessor:

What is Addressing Mode?

“Addressing mode is the way to specify a particular data to be operated by an instruction.”

We need different types of addressing mode because it provides flexibility to the programmer to access data.

What are the types of Addressing Mode in 8086?

The different types of Addressing Modes are explained below:

Register Addressing: 

The operand is a register.

                                     Example – MOV, AX, BX

Immediate Addressing:

The instruction itself comprises the operands.

                                     Example – MOV, AX, 5000H

Direct Addressing:

The instruction specifies the address the operand.

                                    Example – MOV, AX, 9000H

Indexed Addressing:

The operand is specified using one of SI and DI as index register, along with an optional offset. The address of operand is acquired by addition of the information of the index register with the offset, if present.

                                      Example – MOV AX, [SI] or MOV AX, [SI+1000H]

Based Addressing:

The operand is specified using one of BX and BP as base register, along with an optional offset. The address of operand is acquired by addition of the information of base register with the offset, if present.

                                     Example – MOV AX, [BX] or MOV AX, [BP+1000H]

Based-Indexed Addressing:

The operand is specified using one of SI and DI as index register and ones of BX and BP as base register, along with an optional offset. The address of the operand is acquired by addition of information of the index register with the contents of the base register and the offset, if present.

                                    Example – MOV AX, [SI+BX] or MOV AX, [DI+BP+1000H]

Different Flags in 8086 Microprocessor:

1. S (Sign Flag) – Set when answer of computation is negative.
2. Z (Zero) – Set when computation of previous instruction is zero.
3. P (Parity) – Set when lower byte contains even number of ones.
4. C (Carry) – When there have carry in computation.
5. T (Trap) – when processor enters single step instruction mode.
6. I (Interrupt) – Maskable interrupts are identified.
7. D (Direction) – In string manipulation.
8. AC (Auxiliary Carry)
9. O (Overflow) – When result is larger to accommodate in registers.

Pipeline Architecture in 8086 Microprocessor:

The fundamental idea of pipelined architecture is to sub divide the processing of a computer instructions into a series of independent stage (like “pre-fetch”, “fetch”, “decode”, “execute” etc.) with storage at the end of each step.

This permits the computer’s control to instruct the processing speed of the slowest step that is a lot quicker than the time requirement to do all steps at the same time. The pipeline signifies how every step is taking information simultaneously, and any step is linked to subsequent one.

In this, there are 2 separate units

– The “Bus Interface Unit” (BIU)

–  The “Execution Unit” (EU).

The BIU executes all bus operations for the execution unit. The data is in communication in between the CPU and memories and input output kit upon request from the EU. During this if the EU is active implementing commands, the BIU “look ahead” and brings more instruction from the memory. This way, a type of “Fetch-Execute-Pipeline” is implemented in 8086.

Write down some of the Advantages and Disadvantages of Pipelining?

The advantages of pipelining are:

• The cycle time of the chip is comparatively lesser. Pipelining does not minimize the time necessary to finish an instruction; rather it raises the quantity of instructions which may be processed concurrently and reduces the delay between complete instructions.

• The multiple no increased pipeline stages means that more commands could be processed at once and the less delay in between the commands. Every overriding simulated microprocessor manufactured today uses at least two stage pipelines around 30- 40 stages.

• When pipelining is employed, the CPU ALU designed to work fast, but with more complicated design.

• Pipelining in concept improves the performance within an un-pipelined core by a factor stage no and also the code is impeccable for pipeline implementation.

•Pipelined CPUs in general work at a much higher clock frequency than the RAM and that improves overall processor performances.

The disadvantages of pipelining are:

• This is a non-pipelined chip, simpler in design and more economical to fabricate, implements just a single instruction at a time. This avoids when sequential instructions being executed simultaneously.
• This type of processor have more instruction latency in comparison to some non-pipelining chip. The operation of a pipelined processor is a lot more difficult to predict and might vary widely for various applications.

What are the functions of BIU and EU 8086 microprocessor?

Define Execution Unit (EU):

The execution unit of the 8086 and 8088 are indistinguishable. A 16-bit ALU in the EU keep up the CPU status and control flag, and deploys the general registers and instruction operand etc. All registers and datapaths from the EU are all 16 bits length for internal communications.

The EU does not have any link to the machine BUS, the external world. This acquires directions from the BIU via queue. Similarly, as soon as an instruction needs accessing memory or peripherals, the EU asks the BIU to access or to keep the information. The BIU, however, relocate address to provides the EU entry to the entire storage.

Define Bus Interface Unit (BIU):

The BIUs are employed differently to match the arrangement, performance features of various buses. The BIU implements all the bus operation for EU.

The queue size in BIU lets it maintain the EU provided with pre-fetched Instructions under most states without monopolizing the system bus. The 8086 BIU normally gets two bytes per fetching; in case a program 1 byte in the odd address and start again fetching two-byte words in the consequent even one.

Memory Segmentation in 8086 Microprocessor:

Microprocessor 8086 has 20 address pins, so maximum numbers of memory location, which can be connected with 8086 are 2²⁰ = 1MB location or 16 blocks of 64 K locations. The memory connected with 8086 divided into following four segments:

1. Code Memory Segment:  It is used to store instructions code of a program.
2. Data Memory Statement: It is used to store data bytes/words.
3. Extra Memory Segment: It is an additional segment for storing data.
4. Stack Memory Segment: It is used to store stack of data using PUSH/POP instruction.

Microprocessor 8085 vs Microprocessor 8086:

Microprocessor 8085	Microprocessor 8086
It has 16 bit addressing bus	It has 20 bits addressing bus
8085 does not support pipelining	It supports pipelining
Instruction Queues are not supported	Instruction Queues are supported.

To know more about microprocessor click here

C o n t e n t s

• What is a microcontroller ?
• Different Addressing Modes of microcontroller
• 8051 microcontroller PIN Diagram
• 8051 microcontroller Architecture
• Memory of 8051
• Interrupts of 8051
• Features of a microcontroller
• Microprocessor vs Microcontroller
• Applications

What is a Microcontroller?

“A microcontroller is a small computer that consists of processor, internal RAM, ROM or flash, timers, interrupt handler, serial interface, ports & other application-specific devices.”

• A microcontroller is employed if the memory prerequisite for computations is small and the programs and ports are used for the control and communication purpose.
• For example i.e., 8051, PIC and ARM are the standard Microcontrollers.

Main Features of 8051 Microcontroller :

• 8-bit ALU and Accumulator, 8 bit registers, 8 bit data bus and 2×16 bit address bus/program counter/data pointer and related 8/11/16 bit operations.
• Fast interrupt with operational register.
• Power saving mode.

Addressing Mode of 8051 Microcontroller:

“An addressing mode denotes by what method addressing a particular memory location.”

There are five important addressing modes in 8051 microcontroller, they are:

Each of these addressing modes provide important flexibility.

Immediate Addressing

Immediate addressing is like the data to be stored in memory instantly as per the opcode . The instruction itself commands which value might be kept in memories specifically.

E.g., the instruction as follows:

MOV A, #20H

Here memonics utilizes immediate addressing for the reason that the accumulator is going to be filled with the value which mentioned.

In direct addressing,  the value to be loaded is time dependent, this adressing certainly not flexible.

Indirect Addressing

Indirect addressing is a really good comparatively that in most instances contributes an exceptional degree of flexibility. This is by only means to get the additional 128 bytes of internal RAM located in an 8051.  Example is like

MOV A, @R0

This instruction bases the 8051 Microcontroller to have another look at the value of the R0 register. The 8051 will then load the accumulator with the info of internal RAM that’s located at the address indicated by R0 register.

By way of instance, let us say R0 retains the value 50H and address 50H retains the value 66H. When the above-mentioned instruction is implemented the 8051 will assess the value of R0. Since R0 retains 50H, the 8051 will find the value of this internal RAM address 50H and keep it in the accumulator. Indirect addressing consistently identifies internal RAM; it refers to a SFR

External Direct

External memory is get into by means of a set of instructions uses ‘external direct’ addressing. There are two such types of commands that could be used for external direct addressing operations, those are

MOVX A, @DPTR

MOVX @DPTR, A

Here, the two controls use DPTR. In these commands, DPTR should first be loaded using the location of external memory which is to be read or write. After DPTR retains the proper external memory card, the initial command will transfer the contents of the external memory address to the accumulator. The next command is going to do the contrary; it permits to write the accumulator’s value to the external memory address which is already pointed by DPTR.

External Indirect

External memory may be acquired using a indirect addressing that is known as external indirect addressing. This kind of addressing is generally utilized in relatively minor tasks which have a rather modest number of external RAM. Such example is

MOVX @R0, A

The value of R0  has to be read and the value of the accumulator is from external RAM location. Considering that the value of R0 could simply be 00 through FFh, and is limited to 256 bytes. Employing external indirect addressing; nonetheless, it’s normally simpler to use external direct mode if the task has more than 256 bytes.

Architecture of 8051 Microcontroller:

• 8051 is equipped with an 8-bit CPU with a Boolean processor.
• 5 interrupts.  2 Externals, 2 priority levels.
• This has two sixteen bit timer/counters.
• One programmable full-duplex serial port.
• Total 32 I/O lines.
• Equipped with the 4 KB of on-chip ROM ; EPROM  is also available in some models.
• 128 bytes of on-chip RAM, just enough for many single chip.

PIN Diagram of 8051 Microcontroller:

8051 Microcontroller PIN Configuration:

PIN 1 to 8

These pins generaly utilized as I/P or O/P according to the user requirements.

PIN 9:

This is utilized as  Resetting purpose; Generally HL signal pin  halts the MCU and clear all the registers. When this pin is back to LO, new program will start.

PIN 10 – 17:

These are utilized as with the port 1, each of these pins could be employed as universal i/p or o/p.

Pin 10:

RXD- Ac as a serial I/P for the asynchronous trasfer otherwise clock output for synchronous mode of operation.

Pin 11:

TXD- Act as a serial O/P for  the asynchronous transfer otherwise clock output for synchronous mode of operation.

Pin 12:

INT0- This is for input interrupt 0

Pin 13:

INT1- This is for input interrupt 1

Pin 14:

T0- This is employed for clock input of the timer 0

Pin 15:

T1- This is dedicated for clock input of the timer 1

Pin 16:

WR- This is for write operation controlling from external RAM memory device.

Pin 17:

RD- This pin is dedicated for read operation to external RAM memory

PIN 18-19:

X2 and X1- These are for input and output  operation of the internal oscillator

PIN 20:

GND- Ground ; This is for grounding the chip.

PIN 21-28:

Port 2- provisional external memory is not present, Port 2 will work as an universal I/O operation.

PIN 29:

PSEN: MCU triggers after reading each byte from the program memory. When an external memory is employed for program storage purpose, then PSEN will be associated with the control operation.

PIN 30:

ALE: This will have important function before external memory reading, MCU will send the lower byte of the address registers to the Port-P0 and triggers the output ALE.

PIN 31:

EA: The LOW signal refer to the Port- P2 and P3 for transporting addresses irrespective of the memory status.

PIN 32-39: 

Port 0: analogous to port 2, pins of port 0 could be utilized as universal I/O. The P0 performs as address O/P if ALE pin is at high state.

PIN 40:

VCC:This is for  +5V  dc power supply.

Interrupts of 8051 microcontroller:

Five interrupts are provided in 8051. Three sets automatically by internal operations and other two is  triggered by external signal linked to pins INT0 and INT1.

Automatic interrupts are:

1. Timer Flag 0
2. Timer Flag 1
3. Serial Port Interrupt (R1 or T1)

Interrupt Name                                          Interrupt Address

Timer Flag o                                                   0 0 0 B

Timer Flag 1                                                   0 0 1 B

INT0                                                                0 0 0 3

INT1                                                               0 0 1 3

Serial Input                                                     R1/ T1                             

Applications of Microcontroller:

• Microcontroller is employed in Mobile phones, camera circuitry.
• Microcontrollers are used extensively in Automobile Industry
• Computer Systems like traffic signal controlling.
• Different control operation such as heater, greezer,  liftcontrol, Micro-oven etc.

Comparison of Microprocessor vs. Microcontroller:

	MICROPROCESSOR	MICROCONTROLLER
CPU	It has 1 Central Processing Unit	It has a Central Processing Unit, Memory, Input-output pins.
USE	Microprocessor is used in personal computers.	Microcontroller has applications in embedded system.
INTERFACE	Microprocessor interface is complicated.	Simpler Interface
COST	They are expensive	They are inexpensive
REGISTER	It has less numbers of registers, operations are mostly memory based.	Greater number of registers making it easy for operations.

For more Electronics Articles and question answers related to electronics click here

1. What is the number of outputs of a full adder circuit?

1) Two

2) Three

3) Four

4) One

Solution: 2) Three

How a full adder works? Check Here!

2. What is the expression for the sum(s) of a half adder if the inputs are A & B?

1) S = A OR B

2) S = A AND B

3) S = A XNOR B

4) S = A XOR B

Solution: 4) A XOR B

3. What is the sum(S) expression of a full adder if the inputs are A, B & C?

1) S = A OR B AND C

2) S = A AND B OR C

3) S = A XNOR B XOR C

4) S = A XOR B XOR C

Solution: 4) A XOR B XOR C

4. What is the result of the binary sum?

 10101 + 1011

Do you know how to perform binary addition in digital electronics? Click to know!

1) 1 0 0 0 0

2) 1 0 1 0 1 0

3) 1 0 0 0 0 0

4) 1 1 1 1 0 0

Solution: 3) 1 0 0 0 0 0

5. Which of these following logic gates gives a high output when both the inputs are low?

1) NOR gate

2) NOT gate

3) NAND gate

4) ALL OF THE ABOVE

Solution: 4) ALL OF THE ABOVE

6. Which of these following does not include in an ALU (Arithmetic Logic Unit)?

1) Adder

2) Subtractor

3) Multiplexer

4) None of the above

Solution: 3) Multiplexer

How a multiplexer works? Find out in detail!

7. which logic gate itself is a combinational circuit?

1) XOR

2) NAND

3) NOR

4) NOT

Solution: 1) XOR

8. How many bits does the sum of the full adder consists of?

1) Four bits

2) Three bits

3) Two bits

4) Five bits

Solution: 3) Two bits

9. A combinational circuit calculates the arithmetic sum in a parallel way. What is the name of the adder?

1) Sequential Adder

2) Parallel Adder

3) Serial Adder

4) Both 1) & 2)

Solution: 2) Parallel Adder

10. What is the primary object that is needed for VLSI technology?

1)  NOR gate

2) NAND gate

3) Both 1) and 2)

4) Gate array

Solution: 4) Gate array.

11. Choose whether the below-given statement is true or false.

Statement: A binary subtractor can be made using a binary adder.

1. True
2. False

Solution: (1). True

How binary adders can make binary subtractors! Click to know!

12. A circuit takes single input but provides multiple outputs. Identify which circuit it could be.

1) Multiplexer

2) Demultiplexer

3) Encoder

4) All of them

Solution: 2) Demultiplexer

13. What does a multiplexer do?

1) It takes multiple inputs and provides a single output.

2) It takes a single output and offers multiple outputs.

3) It inverts the input.

4) None of the above.

Solution: 1) It takes multiple inputs and provides a single output.

14. A half subtractor provides how many outputs?

1) One

2) Four

3) Three

4) Two

Solution: 4) Two

15. Mark the given statement as True or false.

Statement: An Encoder can be used as a transducer. 

1. True
2. False

Solution: (1). True

16. How does a priority set?

1) The lower the subscript number, the higher the priority.

2) The higher the subscript number, the lower the priority.

3) The higher the subscript number, the higher the priority.

4) None of the above.

Solution: 3) The higher the subscript number, the higher the priority.

17. Find out the result of the BCD addition.

0110 + 0101

1) 10001

2) 11001

3) 1011

4) 1111

Solution: 1) 10001

What is BCD Adder? Know Here!

18. Find out the result of the binary subtraction?

1101 – 1011

Do you know how to perform binary subtraction in digital electronics? Click to know!

1) 10001

2) 0010

3) 1011

4) 0001

Solution: 2) 0010

19. Mark the given statement as True or false.

Statement: The logical expression for both the full adders and full subtractors are the same.

1. True
2. False

Solution: (1). True

20. Which type of complement method is used for the decimal number system?

1) 10’s compliment

2) 8’s compliment

3) 9’s compliment

4) Both 1) and 3)

Solution: 4) Both 1) and 3)

21. How many select lines will be there if the inputs of a MUX are 8?

1) One

2) Four

3) Three

4) Five

Solution: 3) Three

22. How many select lines will be there if the inputs of a DEMUX are 4?

1) One

2) Five

3) Three

4) Two

Solution: 1) Two

23. Recording a video clip is which type of operation?

1) Multiplexing

2) De Multiplexing

3) Encoding

4) Decoding

Solution: 3) Encoding

24. A half binary adder is implemented using basic gates. How many and gates will be required?

1) One

2) Two

3) Three

4) Four

Solution: 1) One

25. Mark the given statement as True or false.

Statement: Multiplexers cannot implement Boolean functions.

1. True
2. False

Solution: (2). False

26. Which circuit can perform the increment operation of an ALU?

1) Adder

2) Subtractor

3) Both 1) and 2)

4) None of them

Solution: 3) Both 1) and 2)

27. Mark the given statement as True or false.

Statement: Technologies like TDM, FDM, CDMA, etc., uses multiplexers and demultiplexers.  

1. True
2. False

Solution: (1). True

28. A decoder has an output of 2n. How many inputs does it consume?

1) n

2) 2n

3) 2n – 1

4) n-1

Solution: 1) n

29. Which type of basic gates is most necessary for Encoders?

1) OR gates

2) AND gates

3) NOT gates

4) All of the above

Solution: 1) OR gates

30. Mark the given statement as True or false.

Statement: DTMF is Diode Time Multiplexer Frequency. 

1. True
2. False

Solution: (2). False. DTMF – DUAL TONE MULTIPLE FREQUENCY.

31. What is the lowest number of NAND gates required for a half subtractors?

1) Four

2) Five

3) Six

4) Seven

Solution: 2) Five

32. A decoder has four input lines. How many output lines will be there?

1) Eight

2) One

3) Four

4) Sixteen

Solution: 4) Sixteen

33. Mark the given statement as True or false.

Statement: An encoder takes multiple data inputs and converts them into a single output with select lines. 

1. True
2. False

Solution: (2). False

34. What is min-term?

1) Product of sum

2) Sum of product

3) Product of product

4) Sum of the sum

Solution: 1) Product of sum

35. Find the application of a MUX.

1) It is used in Analog to Digital converters and Digital to analog converters in digital electronics.

2) It is used in rectifiers.

3) It is used in filters.

4) None of the above is correct.

Solution: 1) It is used in Analog to Digital converters and Digital to analog converters in digital electronics.

36. Mark the given statement as True or false.

Statement: An operation in Flip Flop is faster than an operation in the multiplexer.

1. True
2. False

Solution: (2). False

37. Which IC works as a multiplexer?

1) 74HA198

2) 74HC150

3) 74CH199

4) 74HC157

Solution: 4) 74HC157

38. Which IC works as a demultiplexer?

1) 74HC83

2) 74HC38

3) 74CH19

4) 74HC15

Solution: 1) 74HC83

39. Which IC works as Encoder?

1) HT85A

2) HT87B

3) HT12E

4) HT74F

Solution: 3) HT12E

40. What is the lowest no. of OR gate required for the given expression?

Y = A’B + B’A

1) 1

2) 2

3) 4

4) 5

Solution: 1) 1

41. What is the lowest no. of AND gate required for the given expression?

Y = A’B + B’A

1) 1

2) 2

3) 4

4) 5

Solution: 2) 2

42. What is the lowest no. of NAND gates required to make an inverter?

1) 1

2) 2

3) 3

4) 4

Solution: 1) 1

43. What is the lowest no. of NOR gates required to make an OR gate?

1) 1

2) 2

3) 3

4) 4

Solution: 2) 2

44. Which gates are known as universal gates in digital electronics ?

1) OR and AND

2) NOT and XOR

3) NOR and NAND

4) All of them

Solution: 3) NOR and NAND

45. A truth table is given below where A and B are the provided inputs, and from Y the output is taken. Identify the Logic gate.

1) XOR

2) NAND

3) XNOR

4) NOR

Solution: 3) XNOR

46. A truth table is given below where A and B are the provided inputs, and from Y the output is taken, for a digital electronics circuitry. Identify the Logic gate.

1) XOR

2) NAND

3) XNOR

4) NOR

Solution: 4) NOR

47. Find the odd one out from the digital electronics circuitry.

1) MULTIPLEXER

2) FLIP/FLOPS

3) REGISTERS

4) COUNTERS

Solution: 1) MULTIPLEXER

48. What is the lowest no. of NOT gate required for the given expression?

Y = A’B + B’C + AC

1) 1

2) 2

3) 3

4) 4

Solution: 1) 1

49. Find the odd one out.

1) DEMULTIPLEXERS

2) ENCODERS

3) HALF ADDERS

4) FULL SUBTRACTORS

Solution: 1) DEMULTIPLEXERS

50. A truth table is given below where A and B are the provided inputs, and from Y the output is taken, for a digital electronics circuitry. Identify the combinational circuit.

A	B	Y
LOW	LOW	LOW
LOW	HIGH	HIGH
HIGH	LOW	HIGH
LOW	LOW	LOW

1) SUBTRACTOR

2) MULTIPLEXER

3) ADDER

4) Both 1) and 3)

Solution: 4) Both 1) and 3)

Conclusion : With these we are done with the critical Digital Electronics MCQs and To learn more on Digital Electronics Article and Question Answers click here