Question

1) Consider the transmission of digital data 1011 0010. Each bit is transmitted during a time period of T = 1 msec. What is the data transmission rate in bit/sec? Suppose bit 1 is represented by 5 mV and bit O is represented by O mv. Sketch the baseband waveform with a rectangular pulse to show how the waveform during the transmission of the above bits will look like. Below the baseband waveform sketch (1) binary ASK waveform, (2) binary FSK waveform and (3) binary PSK waveform. The timing information with respect to changes in the waveform must be clearly depicted in your diagram. Also, assume that the number of carrier waveform cycles during a bit period is an integer. 2) Explain with the necessary mathematics and diagrams how synchronous as well as asynchronous demodulation can be used for ASK. 3) Explain with the necessary mathematics and a diagram how BPSK signals can be demodulated.

Answer 1

1) 8 bits are transmitted in T_b = 1 msec = 0.001 s

$\small \Rightarrow$ bit rate = 8/0.001 bps

= 8000 bps

= 8 kbps

5 mv Signal 1 0 0 1 ms 2 ms 3 ms 4 ms 5 ms 6 ms 7 ms 8 ms 5 mV MMMMMMMMMMM MANUAL ASK S 5 mV AMMA FSK 5 mm PSK V MA