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Patent US6997871B2 successfully refreshed from Google Patents.
Patent EP0004445A2 successfully refreshed from Google Patents.
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EP0004445A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Color television receiver

Assignee: RCA Licensing Corp
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Filing: 1979-03-16
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Granted: —
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Expires: 1999-03-16
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Abstract

Abstract In a receiver subject to SECAM signal reception, an FM detector responsive to the received signals has its center frequency tuning switched between one SECAM subcarrier center frequency and the other SECAM subcarrier center frequency. Control of the switching, in response to line rate burst interval pulses and to half line rate waves from a triggered flip-flop, is such that tuning is different in image portions of successive line intervals, but the same in lead-in burst portions of successive line intervals. A first sampler effects sampling of the detector output only during alternate burst occurrences, while a second sampler effects sampling of the detector output during the intervening burst occurrences. Sampler outputs are supplied to a comparator (45) which provides an output suitable for controlling disabling/enabling of flip-flop (29) to establish correct phasing of the switching of the detector tuning. Where the receiver is a dual standard receiver also subject to PAL signal reception, another output is derived from the comparator for control of the switching (35) of the receiver between PAL-reception & SECAM-reception operating modes. For decoding SECAM transmissions, these may be converted (31, 33, 23) to signals resembling PAL transmissions, for onward processing in a common PAL-decoder (0) used also for the PAL reception. However, if switching tuning happens to be in the incorrect phase, the PAL chroma filter (13) may be connected to the PAL decoder (0) as though PAL and not SECAM were being received, until such time as the tuning is being switched in the correct phase. The converted SECAM is now switched-in (35) to the PAL decoder (0).

Inventors

  • 👤 Willem Hendrik Groeneweg

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-01 23:43
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/44; H04N9/47; H04N9/64; H04N9/642

Claims Analysis

Total Claims: 3
Claim 1
Independent Claim 431 words
In a color television receiver subject to reception of composite color television signals inclusive of a chrominance component encoded in SECAM format; said SECAM-encoded chrominance component comprising, during image portions of alternate line intervals, a first subcarrier frequency modulated in accordance with a first color-difference signal, and during image portions of the intervening line intervals, a second subcarrier frequency modulated in accordance with a second color-difference signal, with a lead-in burst of oscillations at the center frequency of said first subcarrier preceding the image portion of each of said alternate line intervals, and with a lead-in burst of oscillations at the center frequency of said second subcarrier preceding the image portion of each of said intervening line intervals; apparatus comprising: an FM detector, responsive to the received signals, and subject to operation in either a first mode with center frequency tuning corresponding to the center frequency of said first subcarrier, or a second mode with center frequency tuning corresponding to the center frequency of said second subcarrier; and characterized by a triggered flip-flop circuit for providing, when enabled, a pair of half line rate wave outputs of mutually opposite phase; a source of line rate pulses timed to substantially coincide with the periods of appearance of said lead-in bursts; means, responsive to said line rate pulses and to one of said pair of half line rate wave outputs, for controlling the operating mode of said FM detector such that said FM detector operates in respectively different ones of said modes during the image portions of successive line intervals but operates in only said first mode during each period of lead-in burst appearance; first sampling means, coupled to receive an output of said FM detector, and responsive to said line rate pulses and to said one of said pair of half line rate wave outputs, for sampling the output of said FM detector only during alternate ones of said periods of appearance of lead-in bursts; second sampling means, coupled to receive said output of said FM detector, and responsive to said line rate pulses and to the other of said pair of half line rate wave outputs, for sampling the output of said FM detector only during the intervening ones of said periods of appearance of said lead-in bursts; means for comparing the output levels of said first and second sampling means; and means, responsive to an output of said comparing means, for disabling said flip-flop circuit only when the output level of a given one of said sampling means significantly exceeds the output level of the other of said sampling means.
Claim 2
Dependent Claim 431 words
In a color television receiver subject to reception of composite color television signals inclusive of a chrominance component encoded in SECAM format; said SECAM-encoded chrominance component comprising, during image portions of alternate line intervals, a first subcarrier frequency modulated in accordance with a first color-difference signal, and during image portions of the intervening line intervals, a second subcarrier frequency modulated in accordance with a second color-difference signal, with a lead-in burst of oscillations at the center frequency of said first subcarrier preceding the image portion of each of said alternate line intervals, and with a lead-in burst of oscillations at the center frequency of said second subcarrier preceding the image portion of each of said intervening line intervals; apparatus comprising: an FM detector, responsive to the received signals, and subject to operation in either a first mode with center frequency tuning corresponding to the center frequency of said first subcarrier, or a second mode with center frequency tuning corresponding to the center frequency of said second subcarrier; and characterized by a triggered flip-flop circuit for providing, when enabled, a pair of half line rate wave outputs of mutually opposite phase; a source of line rate pulses timed to substantially coincide with the periods of appearance of said lead-in bursts; means, responsive to said line rate pulses and to one of said pair of half line rate wave outputs, for controlling the operating mode of said FM detector such that said FM detector operates in respectively different ones of said modes during the image portions of successive line intervals but operates in only said first mode during each period of lead-in burst appearance; first sampling means, coupled to receive an output of said FM detector, and responsive to said line rate pulses and to said one of said pair of half line rate wave outputs, for sampling the output of said FM detector only during alternate ones of said periods of appearance of lead-in bursts; second sampling means, coupled to receive said output of said FM detector, and responsive to said line rate pulses and to the other of said pair of half line rate wave outputs, for sampling the output of said FM detector only during the intervening ones of said periods of appearance of said lead-in bursts; means for comparing the output levels of said first and second sampling means; and means, responsive to an output of said comparing means, for disabling said flip-flop circuit only when the output level of a given one of said sampling means significantly exceeds the output level of the other of said sampling means.
Claim 3
Dependent Claim 157 words
/ that 2. Apparatus of claim l,characterized in said receiver is alternatively subject to reception of composite color television signals inclusive of a chrominance component encoded in a PAL format, and includes a PAL chrominance component decoder; said apparatus also including: means, responsive to an output of said FM detector, for forming quasi-PAL chrominance component; a path for received signals bypassing said FM detector and said quasi-PAL chrominance component forming means; switching means for supplying the output of said quasi-PAL chrominance component forming means to said decoder when in a first switching state, and for supplying the output of said bypassing path to said decoder when in a second switching state; and means, responsive to an output of said comparing means, for causing said switching means to assume said first switching state only when the output level of the other of said sampling means significantly exceeds the output level of said given one of said sampling means.

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