Line coding demonstrator is intended to demonstrate the principles of LINE CODING. In digital transmission of data, over wire or optical fiber systems, the digital data is transmitted in binary form after proper signal conditioning. The data so transmitted must be securely received, at the intended receiving station. In order to accomplish this function, several schemes are designed and adopted. One such a scheme is called as LINE CODING. There are many methods in line-coding formats. Each one of the methods offers one or more of the following advantages over the other. For example, (a) the line coding is used in telephone line applications for spectrum shaping. (b) This is also used to recover bit clock for synchronization with the received signals. (c) To eliminate DC component, that is likely to accompany with the received signal, which otherwise introduce base line wandering. (d) To increase the bandwidth, of transmitted data, compared to other schemes. Using this trainer the student can observe waveform of a selected scheme as described below, using an oscilloscope. The schemes available on this trainer are:
a. Unipolar Non Return Zero (NRZ)
b. Unipolar Return Zero (RZ)
c. Polar Non Return Zero
d. Polar Return Zero
e. Bi-Polar Non Return Zero and
f. Bi-Polar Return Zero. In order to accomplish this the trainer has a built in sequence generator, and necessary building blocks for conducting one of the above schemes. It is necessary to connect an external square wave generator as input to the sequence generator with at-least 100KHz at TTL levels. This instrument has built-in power supply. |
