AUTOMATIC LOSS CONTROL CIRCUIT FOR DIGITAL LOOP TRANSMISSION SYSTEM

摘要

A circuit is proposed for adjusting the loss provided to loops in digital loop carrier transmission systems. A constant current is supplied to the loop an d the resulting voltage is measured to determine the resistance of the loop. This valu e is fed to a microprocessor with a look-up table which controls a programmable analog/digital converter. The loss at the output of the converter is a stepwise function based on the resistance of the customer loop.