Cordless telephone

Details Cordless telephone Cordless telephone

1984-12-10

1988-02-16

Lev, Robert

Telephonic communications

Audio message storage, retrieval, or synthesis

379 63, 455 54, H04M 100

Patent

active

047260513

ABSTRACT:
A cordless telephone is described comprising a fixed part which includes a reception section for receiving exact reception channel frequencies lying in a predetermined frequency range at equal intervals apart and a transmission section for transmitting exact transmission channel frequencies lying at a predetermined duplex interval from the reception channel frequencies. The cordless telephone further comprises a mobile part which includes a reception section for receiving frequencies lying in the range of the transmission channel frequencies of the fixed part and a transmission part for transmitting frequencies lying in the range of the reception channel frequencies of the fixed part. The mobile part includes a frequency control loop which using the transmission channel frequency transmitted by the fixed part as reference frequency holds its reception section fixedly tuned to the received transmission channel frequency. For initiating the communication setup by a call initiated by the mobile part the latter first transmits an arbitrary frequency accompanied by an identification code within the predetermined frequency range. Thereupon the fixed part transmits a transmission channel frequency accompanied by the identification code, whereupon the frequency control loop of the mobile part after reception of the transmission channel frequency and after detecting the identification code holds the reception section of the mobile part fixedly tuned to the received frequency. Furthermore, calibration methods are described with which it can be ensured that shifts of the operating frequency range of the mobile part can be compensated.

REFERENCES:
patent: 3509462 (1970-04-01), Ertman
patent: 4197498 (1980-05-01), Fukui et al.
patent: 4287599 (1981-09-01), Goncharoff et al.
patent: 4404685 (1983-09-01), Rogers
patent: 4446564 (1984-05-01), Pierce

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