Northern Telecom Limited

William T Ross

Clifford D Read

Andre J Robert

Michel J Brisebois

Bruce H Tsuji

Kristin J Travis

William V Pezzullo

Kenneth M Orford

Joseph B Johns

J M Simard

An interactive subscriber telephone terminal, comprising: a display screen; a plurality of temporarily definable response/data entry keys; and local control means for selectively causing the display screen and/or the response/data entry keys to be controlled by one of: remote signals transmitted to the terminal from a telephone switching office, and the local control means.

Screen-based telephone set for interactive enhanced telephony service

A digital FSK demodulator used in e.g. a telephone loop produces unequal amplitudes in detected mark and space tones. The inequality or offset must be cancelled so that a proper timing signal can be recovered from the FSK signal. The demodulator includes a digital compensation circuit for offset cancellation in which peak amplitudes of digital 0 and digital 1 signals are continuously monitored. The peak amplitudes are then averaged to obtain an offset estimation which is subtracted from the output of the demodulator for offset compensation.

Digital FSK demodulator with automatic offset cancellation

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Dunrobin, Canada

William T Ross