Question

(Minimum 100 words)

1. What are the two different transmission modes? Explain?

2.Define a DC component and its effect on digital transmission.

3. Distinguish between a signal element and a data element

Answer 1

Q1. Transmission modes

"It's mean transferring of data between two devices i.e. it tells the direction of signal flow between the  two devices ."

Two different transmission modes are-

1- Simplex mode

2- Duplex mode- (i).Half duplex mode ,(ii).Full duplex mode

1.Simplex Mode - In Simplex mode the comunication between two devices is undirectional ,Only one of the two devices on a link can transmit other can only recieve .It's performance is  worst performing mode of transmission. Example are Keyboard ,monitor etc.

2.(i). Half Duplex Mode- In this mode ,both sender and reciever each can send and recieve . but not at the same time When one device is sending ,the other can only recieve and vice versa.It's is better than simplex mode .Example is Walkie-Talkie etc.

(ii).Full Duplex Mode- In this mode ,Both station can send and recieve data at the same time simultaneously .This is best performing mode of transmission . Example is -Telephone .

Q2.Define a Dc component and its effect on digital transmission.

solution- Dc Component - "Dc" Stands for "Direct Current " ,In Digital signal when the voltage is constant for a while ,the spectrum creates very low frequencies called Dc Component .A system that cannot pass low frequecy  ,dc component creates problem for such systems .

Digital transmission- is the transmission of signals that vary descretely with time between two values ,One value representing the binary number '0' and the other representing '1'.

Effect -DS is not desirable because the dc component does not pass through some components of a communication system such as transformer .This leads to distortion of the signal and may create error. And it also results in unwanted energy loss on the line.

Q3. Distinguish between a signal element and data element.

Solution - Signal element- A signal element is the shortest unit(time wise) of a digital signal .Signal element are carriers which carries data elements.

Data element- A data element is smallest entity that can represents a piece of information that is bit,Data elements are what we need to send ,data elemens being carried .There are two types of data elements and they are known as simple and compound .Simple is used to represent individual and compound is used to represent a collection of related data elements.