Stereo demodulator with high frequency de-emphasis compensation
AssigneeTrio Kabushiki Kaisha
InventorAtsushi Ogawa
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Abstract
The tendency for a sample-and-hold stereo multiplex demodulator having sampling pulses with low duty ratios to deemphasize the high frequency characteristics of the demodulated right and left signals is compensated for by connecting a pair of amplifiers to the right and left outputs and emphasizing the high-frequency characteristics thereof only during stereo reception.
Claims2
In a stereodemodulator for demodulating a composite stereo signal including a sample-and-hold stereo multiplex demodulator having (a) an oscillator, the output of which is phase synchronous with and double in frequency that of a pilot signal in said composite stereo signal and (b) circuitry for deriving from the oscillator output signal, a pair of oppositely phased, low duty ratio sample pulses for sampling said composite stereo signal to obtain left and right signals therefrom, the improvement comprising
- pilot signal detecting means for detecting the presence of said pilot signal in said composite stereo signal;
- and
- a pair of frequency sensitive amplifiers respectively responsive to said left and right signals, said amplifiers including control means for varying the respective high-frequency characteristics thereof, said control means being responsive to said pilot signal detecting means to emphasize the high-frequency characteristics of said pair of amplifiers to thereby compensate for de-emphasis of the high frequency range of the right and left signals caused by said sample-and-hold stereo multiplex demodulator.
Dependencies are inferred from the claim text.