Telecommunications – Receiver or analog modulated signal frequency converter – Signal selection based on frequency
Patent
1980-01-17
1983-01-11
Olms, Douglas W.
Telecommunications
Receiver or analog modulated signal frequency converter
Signal selection based on frequency
179 1GN, 455 71, 328138, 358144, H04H 500, H04N 700
Patent
active
043683541
ABSTRACT:
A discriminator apparatus for a television multivoice system comprises a mixer for mixing a program identifying signal with a reference signal thereby to produce a differential beat signal. A reference signal generator includes a signal source of an original frequency, and a frequency converter for converting the original frequency to the reference frequency which is close to the frequency of the program identifying signal and so selected that the frequency of the differential beat signal is lower than the lowest audible frequency. A low-pass filter is employed for extracting the differential beat signal. Need for expensive mechanical filters of a narrow fractional bandwidth is thereby eliminated.
REFERENCES:
patent: 2965717 (1960-12-01), Bell
patent: 3566036 (1971-02-01), Roche
patent: 4048654 (1977-09-01), Wegner
patent: 4281217 (1981-07-01), Dolby
Furihata Makoto
Oguino Masanori
Sakata Noboru
Hitachi , Ltd.
Olms Douglas W.
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