Important Short Questions and Answers: Data and Pulse Communication

DATA AND PULSE COMMUNICATION

1. Define Morse code.

It is used to send messages. A key which turned the carrier of a transmitter ON and OFFto produce the dots and dashes. These dots and dashes were detected at the receiver and it is converter back into letters and numbers makes the original message.

2. What is multipoint communication?

A multipoint line configuration is one in which more than two specific devices share a single link.

3. What is meant by point to point communication?

Point to point communication is the link between two stations A and B ie)., information is transferred between a main frame computer and a remote computer terminal.

4. What is meant by Forward Error Correction (FEC)?

FEC, a receiver can use an error correcting code, which automatically correct certain errors without any retransmissions

In FEC, bits are added to the message before the transmission Purpose of FEC code is to reduce the wasted time of retransmission

5. What is meant by data communication

Data communication can be defined as two personal computers connected through a Public Telecommunication Network (PTN)

6. What are the applications of data communication?

Used in Automatic Teller Machine (ATM) Internet

Airline and Hotel reservation system

Mass media

NEWS network

7.What are the advantages and disadvantages of Parallel communication

Advantages:

Parallel transmission is speed

Used for short distance communication

Disadvantages:

Require more lines between source and destination  & More cost

8. What are the advantages and disadvantages of series communication

Advantages:

Number of transmission lines is less Used for long distance communication Low cost

Disadvantages:

Speed is low

9. Define Pulse Amplitude modulation

The amplitude of a carrier pulse is altered in accordance to that of amplitude of message signal to make it accommodate the information signal.

10. What are the different types of error detection techniques?

a. Redundancy b. Echoplex

c. Exact count encoding d. Parity

e.  Check sum

f. Vertical Redundancy Check

g. Horizontal Redundancy Check

h.  Cyclic Redundancy Check

11. Define Pulse width modulation

In PWM system, the message signals are used to vary the duration of carrier pulse. The message signal may vary either the trailing edge or leading edge or both of the carrier pulses n order to accommodate the intelligence of information system.

12. Define sampling rate

The sampling rate fs must be atleast two times the highest frequency component of the original signal to be accurately represented fs>=2fm

13. Define Pulse position modulation

The position of a carrier pulse is altered in accordance with information contained in sampled waveform.

14. Define Pulse code modulation

Pulse code modulation refers a form of source coding. It is a form of digital modulation techniques in which the code refers a binary word that represent digital data.With PCM, the pulses are of fixed length and fixed amplitude.