Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1988-03-17
1990-04-24
Chin, Tommy P.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
455229, H04N 560, H04N 116
Patent
active
049204165
ABSTRACT:
A detector indicates the presence of a desired signal when both of at least two conditions occur. The first condition requires the presence of a selected frequency in an input signal and a second condition requires the amplitude of the input signal at the selected frequency to fall within a predetermined range. A third condition requires that one or both of the first and second condition have a duration of at least a selected period of time. In one embodiment, the detector indicates the presence of a stereo audio signal in a television transmission program when (1) a pilot frequency (15.734 khz) is present in the composite baseband, (2) the signal amplitude at the pilot frequency corresponds to a frequency deviation of not more than 5.5 khz and not less than 4.5 khz from the 4.5 mhz carrier frequency, and (3) the two aforementioned conditions exist for a predetermined period of time, preferably about one millisecond. In another embodiment, the detector indicates the presence of a second audio program (SAP) in a television transmission program when (1) the SAP carrier frequency (78.67 khz) is present in the composite baseband, (2) the signal amplitude at the SAP carrier frequency corresponds to a deviation from the sound carrier signal of not more than 16.5 khz and not less than 13.5 khz, and (3) the aforementioned two conditions are present for a predetermined period of time, preferably about one millisecond.
REFERENCES:
patent: 4241495 (1980-12-01), Blatter
patent: 4527196 (1985-07-01), Hovens
patent: 4633495 (1986-12-01), Schotz
patent: 4646150 (1987-02-01), Robbins
Chin Tommy P.
Lobato Emmanuel J.
North American Philips Corp.
Rich Marianne R.
LandOfFree
Method and apparatus for detecting a desired television signal does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for detecting a desired television signal, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for detecting a desired television signal will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-38012