In digital communications, sampling of the Analog signals is done at discrete intervals.Discrete samples of different signals are time multiplexed on a single wire.
Sampler   : a) Frequency -  2 to 20 KHz,
                  b) Pulse width - 10mS to150mSec
                 c) LED  indicator if pulse width exceeds 1/4 of time period of  sampling freq.
  I/P sockets   : 2I/P  for  sampling & multiplexing.
 Speech simulating  : a) Facility for On/Off signal
                                 b) Amplitude - 2V p-p,
                                c) Band width-upto 3KHz
 Demultiplexer      : Synchronous type  - 2 O/Ps.
 Low pass filters    : 2 Nos.,cut off in audio range,removes sampling spikes from         demultiplexer O/P

 All important signal are brought on the front panel
The instrument works on 230V + 10%,AC Single Phase