Television – Receiver circuitry – Intercarrier circuits
Patent
1993-07-01
1994-08-09
Powell, Mark R.
Television
Receiver circuitry
Intercarrier circuits
348735, 348736, H04N 562
Patent
active
053370910
ABSTRACT:
In a television receiver a downconverter responding to a selected television signal respectively supplies its first and second output signals as the input signals of first and second IF amplifiers, respectively. The downconverter includes a local oscillator for generating oscillations at a frequency controlled in response to the AFT signal. The first IF amplifier includes a first adjacent-channel sound carrier trap, in consequence whereof the first-IF-amplifier response is substantially reduced for the downconverted picture carrier, and an in-channel sound carrier trap. Responsive to the first-IF-amplifier response, a video detector generates a composite video signal in which sound beats are suppressed to relatively low level by the first adjacent-channel sound carrier trap. A second IF amplifier includes a second adjacent-channel sound carrier trap The second-IF-amplifier response, from which in-channel sound carrier is not trapped, is not as much reduced for the downconverted picture carrier by the second adjacent-channel sound carrier trap as the first-IF-amplifier response is by the first adjacent-channel sound carrier trap. From the second-IF-amplifier response, intercarrier detection circuitry detects an intercarrier-sound-IF response, which is amplified by an intercarrier sound-IF amplifier and then detected by an FM sound detector. Responsive to the second-IF-amplifier response, an automatic fine tuning (AFT) detector generates the AFT signal used to control the frequency of the oscillations generated by the local oscillator that the downconverter includes.
REFERENCES:
patent: 4490743 (1984-12-01), Mycenek et al.
patent: 4599652 (1986-07-01), Carlson
patent: 5177613 (1993-01-01), Rumreich et al.
Balaban Alvin R.
Harford Jack R.
Murrell Jeffrey S.
Powell Mark R.
Samsung Electronics Co,. Ltd.
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