Q. Explain the basic architecture of digital switching systems. Explain in detail companding.

Ans:

A simple N X N time division space switch is displayed in Figure. Switch can be represented in an equivalence form as a two-stage network with N X 1 and 1 X N switching matrices for first and second stages corresponding as displayed in Figure. Network has one link interconnecting the two stages. Every inlet/outlet is a single speech circuit corresponding to a subscriber line. Speech is carried as PAManalogue samples or PCM digital samples, occurring at 125-µs intervals. When PAM samples are switched in a time division manner, switching is called analogue time division switching. If PCM binary samples switched, then switching is termed as digital time division switching. In Figure, the interconnected by a suitable control mechanism and speech sample transferred from the inlet to the outlet.