Modulation device

Details Modulation device Modulation device

1987-08-14

1988-12-27

Groody, James J.

Facsimile and static presentation processing

Facsimile

Specific signal processing circuitry

358 23, 358189, 455197, H04N 538, H04N 540

Patent

active

047944587

ABSTRACT:
A modulation device especially suitable for use in a joint TV reception device for tuning the input video and audio signals to various TV channel frequencies. The device includes a modulator for modulating a carrier wave with the video and audio signals to provide a modulated signal, a mixer for mixing the modulated signal with a local oscillation signal to provide mixed signals, a wide band amplifier for amplifying the mixed signals and a variable low-pass filter for filtering the amplified mixed signals to provide a TV broadcasting signal of desired frequency. The device further includes a control device for controlling the frequency of the local oscillation signal and the cutoff frequency of the variable low-pass filter so as to cancel a higher harmonic component from the output signal to avoid undesirable inteference.

REFERENCES:
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patent: 4607215 (1986-08-01), Takano et al.
patent: 4726072 (1988-02-01), Yamashita et al.
patent: 4727336 (1988-02-01), Mark
patent: 4731877 (1988-03-01), Moon
Honda et al., "Future Promotion of the Cable TV System Applications", 20th Annual NCTA Convention Official Transcript, P. 542-561, Jul. 6-9, 1971.

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