The switching circuit will produce triggering pulsed
waveform generated according to input signal fed from
comparator circuit which will need to produce HDB3 wave
form. According to triggering pulse, +3.3, -3.3 or 0 voltage
values are output by the HDB3 line coding circuit which in
other words regenerates the HDB3 line coded E1 data
stream which is ready to interface to the destination.