Carrier signal generating circuit in video signal recording/repr

Facsimile and static presentation processing – Facsimile – Recording apparatus

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358315, 358320, 358330, H04M 980

Patent

active

053232429

ABSTRACT:
In a video signal apparatus, a carrier signal generating circuit includes a VCO for generating a signal having a frequency at least twice that of a carrier signal necessary for conversion to a lower band with a sub-carrier in an NTSC system, a one-half divider circuit for dividing the VCO frequency signal by two, a delayed flip-flop circuit for receiving the divided signal and the sub-carrier signal to generate a difference frequency signal, a 1/40 divider circuit for dividing the Q output, a phase comparator circuit for comparing the phases of the 1/40 divided signal and the horizontal synchronizing signal to output a phase difference, a frequency discriminator circuit for comparing the phase of the flip-flop output with the frequency-divided output of the horizontal synchronizing signal to output a frequency error, and a circuit for converting the output of the phase comparator circuit and the frequency error into DC voltages and applying their sum as a control voltage for the VCO. A CR constant control circuit controls the CR constant of a four-phase signal generator for converting the output of the one-half divider circuit into a four-phase signal.

REFERENCES:
patent: 4985781 (1991-01-01), Hirasawa
"Nikkei Electronics", Sep. 5, 1988, No. 455, pp. 179-183, and English translation.
The Institute of Television Engineers of Japan (ITEJ) Technical Report vol. 12, No. 17, pp. 1-6, TEBS' 88-8 May, 1988.
VHS YC I chip "HA118105" by Hitachi, Technical Manual.

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