Attenuation meter for two-wire telephone line - uses two test voltages and requires no extra test wire

摘要

The attenuation measurer, for two-wire telephone lines, needs no extra test wire and has the two-wire line (PL) connected via two-wire/four-wire interfaces (Gas, Gae) to the test units (MA), (MB) at each end of the line. To measure attenuation from the first end (MA), a second test voltage is applied at the second end (MB) at the same time as a first test voltage at the first end. The transmitter and receiver of the second end are then connected together and the second test voltage disconnected. Measurements are made both with the two voltages present and with only the first present.