A METHOD AND SYSTEM FOR SCALEABLE NEAR-END SPEECH CANCELLATION FOR TIP AND RING TONE SIGNAL DETECTORS

摘要

A method and system (10) for providing suppression of near-end speech energy for tone signal detectors (27) or FSK demodulator (28). In accordance with t he invention a system or device (100) is connected between the tip and ring on a subscriber loop (12), the subscriber loop (12) being connected to office equipment (11) and that subscriber's station set (13). The system (100) includes a receive interface that is connected to either a tone signal detector (26) or a frequency shift keying modulator (28). The system (100) achieves speech cancellation by forming a Wheatstone bridge with a mirror circuit possessing a scaled image of the loop and office equipment impedance . In one embodiment of the invention the Wheatstone bridge is formed using the combined impedance of the loop (12) and office equipment (11) as the impedan ce that is to be matched by a set of balanced networks included within the syst em.