Telephonic communications – Repeater – With gain or attenuation control
Patent
1996-09-04
1999-10-26
Le, N.
Telephonic communications
Repeater
With gain or attenuation control
379345, 379402, 379410, H04M 100
Patent
active
059741376
ABSTRACT:
The present invention provides a two-wire line conditioning apparatus having an improved calibration and cancellation circuit and provides an improved calibration method using a multitone calibration signal. The output is monitored by an AGC circuit which controls the output, and prevents hard clipping. This is particularly important for DTMF receivers. Additionally, the apparatus automatically adjusts an electronic hybrid as part of a calibration procedure so as to eliminate undesirable echo effects when calls are placed along the line. The electronic hybrid balancing process and echo cancellation circuitry may also be utilized in a circuit for converting four-wire communications systems to two-wire communications systems. The line conditioning device of the present invention utilizes a multitone signal to simulate the voice frequency spectrum between approximately 500 Hz and 3500 Hz to probe the line side with a plurality of tones (e.g., 500, 1500 and 3500 Hz; or 500, 1000, 1500, 2000, 2500, 3000, 3500 Hz). The amplitude of the tones are weighted to reflect the transmissibility in the voice band. The value of Z.sub.var considered to be optimal is that value which minimizes the power of the echo of the weighted multitone signal. Embodiments are presented that require intervention by a technician for the calibration procedure, and embodiments that automatically perform calibration using dial tone without manual intervention.
REFERENCES:
patent: 4041252 (1977-08-01), Cowden
patent: 4278848 (1981-07-01), Rizzo et al.
patent: 4333133 (1982-06-01), Pernyeszi
patent: 4388500 (1983-06-01), Regan
patent: 4567331 (1986-01-01), Martin
patent: 4787080 (1988-11-01), Yamakido et al.
patent: 4812851 (1989-03-01), Giubardo
patent: 4918725 (1990-04-01), Takahashi
patent: 4961218 (1990-10-01), Kiko
patent: 4987569 (1991-01-01), Ling et al.
patent: 5034978 (1991-07-01), Nguyen et al.
patent: 5132963 (1992-07-01), Ungerboeck
patent: 5204854 (1993-04-01), Gregorian et al.
patent: 5249225 (1993-09-01), Williams
patent: 5253291 (1993-10-01), Naseer et al.
patent: 5280526 (1994-01-01), Laturell
patent: 5287406 (1994-02-01), Kakuishi
patent: 5333194 (1994-07-01), Ceasar
patent: 5434916 (1995-07-01), Hasegawa
patent: 5504811 (1996-04-01), Kiko et al.
patent: 5533119 (1996-07-01), Adair, et al.
Chmura Stanley
Sheets Laurence L.
Hsieh Shih-Wen
Le N.
Teltrend Inc.
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