Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1987-12-17
1989-06-06
Groody, James J.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358160, 358198, H04N 5222
Patent
active
048376230
ABSTRACT:
An interrupt circuit monitors a television audio demodulator or an external video input circuit and interrupts the video signal to CRT and the audio signal to television speaker(s) whenever a lost signal condition is detected. In the preferred embodiment, a lost signal condition is detected by monitoring the voltage level of the signal from the audio demodulator or the external video input circuit and generating a detect signal whenever the voltage exceeds a predetermined threshold. When a television signal is lost, both the audio demodulator signal and the external video signal constitute a noise signal that has a voltage amplitude that is greater than the normal operating range of either of these two signals. In the preferred embodiment, when a detect signal is produced, both the video signal to the CRT and the audio signal to the television speaker(s) are interrupted and alternate video and audio signals are provided to the CRT and speaker(s) by a microprocessor. These alternate signals will announce the lost signal condition to the viewer.
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patent: 4607390 (1986-08-01), Faugeron
Groody James J.
North American Philips Corporation
Parker Michael D.
Rich Marianne R.
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