from
The Free On-line Dictionary of Computing (8 July 2008)
data service unit
digital service unit
<communications> (DSU or "data service unit") A device used in
digital transmission for connecting a CSU (Channel Service
Unit) to {Data Terminal Equipment} (a terminal or computer),
in the same way that a {modem} is used for connection to an
analogue medium.
A DSU provides a standard interface to a user's terminal which
is compatible with {modems} and handles such functions as
signal translation, regeneration, reformatting, and timing.
The transmitting portion of the DSU processeses the customers'
signal into bipolar pulses suitable for transmission over the
digital facility. The receiving portion of the DSU is used
both to extract timing information and to regenerate mark and
space information from the received {bipolar} signal.
(1995-01-30)