Telephone range extender with gain

Abstract

A telephone Range Extender with Gain (REG) is disclosed for extending the range of loop lengths over which telephone service can be provided. This is accomplished by providing voice frequency gain, a higher voltage talking battery, and supervisory and signaling circuitry for increasing the level of supervisory and signaling currents at the central office end. The range extender requires no adjustment for loops of different lengths. A .pi. configuration negative impedance amplifier includes an adjustable gain circuit responsive to the resistance of the connected loop to automatically adjust the gain of the amplifier to the length of the loop. At the same time, an impedance matching circuit is transformer-coupled to the loop. The frequency shaping of the negative resistance amplifier and the impedance matching network, when reflected through the transformer, provides acceptable impedance matching for a wide range of loop lengths and wire gauges. For stability, the gain of the amplifier is forced to a low value when the central office termination becomes an open circuit.

Dependencies are inferred from the claim text.