CIRCUITRY FOR INTERFACING TELECOMMUNICATIONS EQUIPMENT TO A COMMUNICATION CHANNEL

摘要

Measuring the programming resistor in a data jack by placing the resistor in an AC voltage divider circuit via a transformer. An AC voltage (preferably generated by the modem's own transmitter circuitry) is applied to the voltage divider circuit, and an AC voltage measurement (preferably made by the modem's A/D converter) provides the resistance of the programming resistor. Matching the low-pass filter impedance characteristic of a local loop with a network having a matching low-pass filter characteristic, while also compensating the received signal with a compensation network having a high-pass filter characteristic, to reduce the frequency dependent gain effects caused by the matching network and/or the local loop.