Telephonic communications – Substation or terminal circuitry – For loudspeaking terminal
Patent
1986-06-30
1989-04-04
Ng, Jin F.
Telephonic communications
Substation or terminal circuitry
For loudspeaking terminal
379388, 381 94, H04M 908
Patent
active
048192635
ABSTRACT:
Hands-free two-way communication is achieved, without the necessity of selectively muting either the sent or received signal and without the generation of interfering acoustical feedback between the speaker and microphone at the hands-free station, by frequency offsetting the audio signal sent from the hands-free station. The audio signal is frequency offset by first modulating the audio signal at a first carrier frequency to produce modulated upper and lower sideband outputs. The modulated upper sideband output is filtered out, and the modulated lower sideband output is coupled to the input of a demodulator. The modulated lower sideband output is then demodulated at a second carrier frequency offset from the first carrier frequency by a predetermined amount. A demodulated upper sideband output and lower sideband output is thus generated. The demodulated upper sideband output is filtered out, and the demodulated lower sideband output is provided for transmission or broadcast in the two-way communication. The demodulated lower sideband output is identical to the original input audio signal with the exception that it has been frequency offset by an amount equal to the predetermined amount of frequency offset between the first and second carrier frequencies. In the event of cross-talk or any feedback within the two-way communication loop, each transmission of the information is thus frequency offset, and the establishment of interfering feedback loops is thereby avoided.
REFERENCES:
patent: 3089920 (1963-05-01), Law
patent: 3622714 (1971-11-01), Berkley et al.
patent: 3678390 (1972-07-01), Iwasaki et al.
patent: 3784747 (1974-01-01), Berkley et al.
patent: 3922488 (1975-11-01), Gabr
patent: 4019140 (1977-04-01), Swerdlow
patent: 4134069 (1979-01-01), Shiki
patent: 4400584 (1983-08-01), Vilmur
patent: 4424593 (1984-01-01), Kahn
patent: 4528656 (1985-07-01), Morais
patent: 4543665 (1985-09-01), Sotelo et al.
patent: 4554679 (1985-11-01), Schiff
patent: 4625083 (1986-11-01), Poikela
patent: 4641339 (1987-02-01), Stottlemyer
patent: 4649505 (1987-03-01), Zinser, Jr. et al.
Bethel George F.
Bethel Patience K.
Cellular Communications Corporation
Ng Jin F.
Vaas Randall S.
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