Automatic loss control circuit in a digital loop transmission system.

摘要

In a circuit for adjusting the loss provided to loops (T,R) in digital loop carrier transmission system a constant current is supplied to the loop and the resulting voltage is measured to determine the resistance of the loop. This value is fed to a microprocessor (25) with a look-up table which controls a programmable analog/digital converter (31). The loss at the output of the converter is a stepwise function (40,41) based on the resistance of the customer loop. <IMAGE>