20 Digital Communication Interview Questions and Answers

Digital Communication is an important aspect of any business. In order to be successful, it is essential that you are able to effectively communicate with your team, customers, and clients. When interviewing for a position that requires strong digital communication skills, you can expect to be asked questions about your experience and ability to communicate effectively. In this article, we discuss some of the most common digital communication interview questions and how you should answer them.

Digital Communication Interview Questions and Answers

Here are 20 commonly asked Digital Communication interview questions and answers to prepare you for your interview:

1. What is Signal-to-Noise Ratio (SNR)?

SNR is a measure of the strength of a signal relative to the background noise. The higher the SNR, the better the quality of the signal.

2. What are the advantages and disadvantages of using digital communication instead of analog?

The main advantage of digital communication is that it is much more efficient than analog communication. This is because digital signals can be processed much faster than analog signals, and they are also much easier to store and retrieve. The main disadvantage of digital communication is that it is much more susceptible to noise and interference than analog communication.

3. Can you explain what bit error rate (BER) means in context with digital communications?

The bit error rate is the number of bits that are incorrectly transmitted in a digital communication system. This can be due to noise, interference, or other factors. The BER is usually expressed as a percentage or a ratio.

4. How can you use BER to analyze the performance of a system?

BER can be used to analyze the performance of a system by looking at the number of errors that occur during communication. The higher the BER, the more errors that are occurring, and the lower the quality of the communication.

5. Can you explain what intersymbol interference (ISI) is in context with digital communications? How can it be avoided?

ISI is a form of distortion that can occur in digital communications systems. It occurs when the signal that is being transmitted is not perfectly reconstructed at the receiving end, which can lead to errors in the data that is being transmitted. ISI can be avoided by using error-correcting codes, which can help to ensure that the data that is being transmitted is received correctly.

6. What’s the difference between amplitude shift keying (ASK) and frequency shift keying (FSK)? Which one should be used in certain situations?

ASK is a digital modulation technique that uses the amplitude of a signal to encode information, while FSK uses the frequency of a signal. In general, ASK is simpler and cheaper to implement than FSK, but FSK can transmit data at a higher rate. When choosing between the two, it is important to consider the tradeoffs in terms of complexity, cost, and data rate.

7. What is quadrature amplitude modulation (QAM) and how does it work?

QAM is a digital modulation technique that is used to transmit digital data over a carrier signal. The data is encoded in the amplitude and phase of the carrier signal, which is then used to modulate the signal. QAM is a very popular modulation technique because it is very efficient and can support a large number of data channels.

8. What is angle modulation?

Angle modulation is a type of modulation where the angle of a carrier signal is varied in order to encode information. The most common type of angle modulation is phase shift keying (PSK), where the phase of the carrier signal is shifted in order to encode information.

9. Can you explain a situation where you would want to use pulse code modulation over pulse width modulation?

Pulse code modulation is a digital communication technique that is typically used when transmitting a signal over long distances. This is because pulse code modulation is less susceptible to noise and distortion than other modulation techniques. Pulse width modulation is typically used for lower data rate applications, such as controlling the speed of a motor.

10. What do you understand about phase lock loops (PLLs), their uses, and applications?

PLLs are used in a variety of digital communication applications in order to lock the phase of a signal to a reference signal. This allows for more accurate and reliable communication between devices. PLLs can be used in applications such as frequency synthesis, demodulation, and clock recovery.

11. Can you compare FDM and TDM? Are there any differences between them? If yes, then which one would you recommend for certain situations?

FDM is a type of digital communication that uses multiplexing to send multiple signals over a single channel. This allows for more efficient use of bandwidth and can improve communication quality. TDM is a similar technique that uses time-division multiplexing to send multiple signals over a single channel. The main difference between the two is that FDM can send signals of different frequencies simultaneously, while TDM can only send signals that are evenly spaced in time. FDM is generally considered to be more efficient and is the recommended technique for most situations.

12. What is Continuous Wave Modulation (CWM)? When should it be used over other forms of modulation?

CWM is a type of modulation where a carrier wave’s amplitude, frequency, or phase is varied in order to encode information. CWM is typically used for transmitting digital data over long distances, due to its resistance to signal degradation.

13. Explain the concept of time division multiplexing (TDM).

Time division multiplexing is a digital communication technique that allows multiple signals to share a single communication channel by dividing the channel into multiple time slots. Each signal is assigned a different time slot, and the multiplexer switches between the signals in a predetermined order. This allows multiple signals to be transmitted over a single channel, without the need for multiple physical channels.

14. What do you understand about spread spectrum systems?

Spread spectrum systems are digital communication systems that use a wide range of frequencies to transmit data. This allows for more data to be transmitted in a given amount of time, and also makes the signal more resistant to interference.

15. What’s your opinion on direct sequence spreading? Is it better than frequency hopping or vice versa?

There is no one-size-fits-all answer to this question, as the best spreading method will depend on the specific application and environment. However, in general, direct sequence spreading is more resistant to interference than frequency hopping, making it a good choice for applications where reliability is paramount. However, frequency hopping can be more efficient in terms of bandwidth usage, making it a better choice in applications where bandwidth is limited.

16. What is Multiple Access?

Multiple Access is a technique used in digital communication systems to allow multiple users to share a single communication channel. There are multiple ways to achieve Multiple Access, but the most common are Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), and Code Division Multiple Access (CDMA).

17. What is Frequency Division Multiple Access (FDMA)?

Frequency Division Multiple Access (FDMA) is a digital communication technique that allows multiple users to share the same communication channel by dividing the channel into multiple frequency bands. Each user is assigned a different frequency band, and can only communicate with other users who are using the same frequency band. This allows multiple users to share the same channel without interfering with each other.

18. What are some real world examples of FDMA?

FDMA is used in many different types of digital communication systems. One example is in the GSM mobile phone standard, where each user is allocated a certain number of time slots in which to transmit data. Another example is in the DVB-T digital TV standard, where each TV channel is allocated a certain number of frequency slots.

19. What is Time Division Multiple Access (TDMA)?

Time Division Multiple Access is a digital communication method that allows multiple users to share the same time slot on a given channel. This is done by dividing the time slot into multiple smaller time slots, with each user being assigned to a specific time slot. This allows for multiple users to share the same channel without interfering with each other.

20. What are some real world examples of TDMA?

TDMA is commonly used in cellular telephone systems, where it is known as time division multiple access, and in satellite communication systems.