24 voice signals bandlimited to 34kHz are sampled and timedi

24 voice signals, bandlimited to 3.4kHz, are sampled and time-division multiplexed using PAM. The PAM pulses are 1us, and the multiplexing signal also provides an additional synchronizing pulse of sufficient amplitude and of the same 1us duration.

If the signals are sampled at 8kHz, what is the spacing between the successive multiplexed PAM pulses?

Solution

(a) The sampling interval is Ts = 125us. There are 24 channels and 1 sync pulse, so the time allowed to each channel is Tc=Ts/25=5us. The pulse duration is 1us. So the time between pulses is 4us.

(b) If sampled at the Nyquist rate, 6.8kHz, then Ts=147us, Tc=5.88us, and the time between pulses is 4.88u•

Ts =1/2W

TX=TS/N

BT =1/T

Time-Division Multiplexing

System Transmission bandwidth

N-channel PAM system

Each signal is band-limited to W Hz

Sampling period: Ts = 1 /2W

The time spacing between adjacent samples in the TDM waveform is: Suppose we use rectangle pulses, the transmission bandwidth should be BT=

1/T