Sampling clock reproducing apparatus
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsShin Fukuda, Masayoshi Hirashima
Life of this patent
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Abstract
Improved sampling clock reproducing apparatus for receiving digital signal which is superimposed in the television signal during a vertical blanking interval. The sampling clock signal is made by selectively gating a pilot signal from the superimposed signal, obtaining a square thereof, then passing it through a resonance circuit with a resonance frequency twice a repetition frequency of the pilot signal. Thus, the sampling clock signal of the frequency twice the repetition frequency of the pilot signal is obtainable without digital processing attaining high durability against noises.
Claims3
A sampling clock reproducing apparatus comprising:
- an input terminal for receiving a signal of information sent by being superimposed on a television signal,
- a filter connected to said input terminal and having a passing frequency equal to a frequency of a pilot signal which is included in said signal of information and has a reference phase,
- an analog multiplier for producing a square of said pilot signal, and
- a resonance circuit having a resonance frequency of twice that of said pilot signal and connected to receive an output produced by said analog multiplier to make a resonance therewith, thereby to produce a sampling clock signal.
Dependencies are inferred from the claim text.