Method and apparatus for sidetone optimization

Details Method and apparatus for sidetone optimization Method and apparatus for sidetone optimization

1994-05-31

1996-07-02

Hofsass, Jeffery

Telephonic communications

Substation or terminal circuitry

Sidetone control or hybrid circuit

379403, H04M 158

Patent

active

055331190

ABSTRACT:
A sidetone optimization circuit (230) provides the capability to adjust sidetone level received at a telephone handset to a desired level. A noise source (204) generates a noise signal that gets filtered by filter (206) in order to provide band limited noise to a telephone interface circuit (202). Telephone interface circuit (202) provides a sidetone signal (210), also known as a trans-hybrid loss signal. The trans-hybrid loss signal is filtered at filter (212) and transformed to a DC level at detector (214). The DC level is then compared to a predetermined threshold at comparator (224), and a variable impedance circuit (218) is adjusted until the DC level reaches the predetermined threshold in order to achieve a desired level of sidetone.

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L3000 Subscriber Line Interface Series Datasheets and Application Notes, Mar. 9, 1993, by SGS-Thomson, SLIC L3000/L3092.
Telecoms IC Handbook, Plessey Semiconductors, p. 61, Plessey Company, Plc 1988, Publication No. P.S. 1913.

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