Telephonic communications – Substation or terminal circuitry – Sidetone control or hybrid circuit
Patent
1993-03-31
1995-03-14
Dwyer, James L.
Telephonic communications
Substation or terminal circuitry
Sidetone control or hybrid circuit
379410, 379407, 379406, 379390, H04M 100
Patent
active
053982827
ABSTRACT:
Sidetone in a four-wire telephone station set that is coupled to a two-wire telephone line through a four-to-two wire hybrid circuit is automatically and cancel the phase "to a predetermined value", set by incrementally adjusting a balancing impedance connected to the circuit until an optimum impedance match between the telephone set and line is achieved. Under software control, during idle intervals between dialed digits when a call is initiated, a microcontroller mutes the telephone transmitter and receiver on the telephone side of the circuit and substitutes for these components a tone signal generator to produce a sidetone signal that is applied to a full-wave rectifier and therefrom to a peak voltage detector to generate a sidetone envelope. Individual ones of several impedance balancing networks are then sequentially connected to the telephone side of the circuit and the sidetone envelope for each balancing impedance is digitally encoded and stored. A mutual comparison of the stored data indicates a minimum sidetone value which corresponds to an optimum impedance match that is retained unless a subsequent telephone call results in a change of balancing impedance.
REFERENCES:
patent: 4996710 (1991-02-01), Takahashi et al.
patent: 5029203 (1991-07-01), Ikefuji et al.
patent: 5133007 (1992-07-01), Nishimura
patent: 5191606 (1993-03-01), Juang
Diesing Norbert J.
Forrester Christopher M.
Fortier Guy J.
McCready W. J. Leonard
Pepper David A.
Dwyer James L.
Northern Telecom Limited
Saint-Surin Jacques M.
Sakovich Michael M.
LandOfFree
Automatic sidetone selector does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Automatic sidetone selector, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Automatic sidetone selector will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-717874