Fm stereo demodulator
AssigneeSanyo Electric Co., Ltd.
InventorsKazuhisa Ishiguro, Mikio Yamagishi
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Abstract
Levels of a stereo sum signal and a stereo difference signal are detected by first and second level detectors (7, 9), respectively. Outputs of the first and second level detectors (7, 9) are compared with each other by a comparator (10). A voltage controlled amplifier (4) is responsive to an output of the comparator (10) for changing a level of the stereo difference signal, when a broadcasting signal including only either one of a left stereo signal and a right stereo signal is received, such that the levels of the stereo sums signal and the stereo difference signal are equal to each other.
Claims19
An FM stereo demodulator for demodulating a left stereo signal and a right stereo signal from a stereo composite signal as frequency-modulation-detected including a stereo sum signal and a stereo difference signal, comprising:
- stereo difference signal demodulating means for demodulating the stereo difference signal in said stereo composite signal,
- matrix means for generating the left stereo signal and the right stereo signal from the stereo sum signal in said stereo composite signal and said stereo difference signal from said stereo difference signal demodulating means,
- first level detecting means for detecting a level of the stereo sum signal in said stereo composite signal,
- second level detecting means for detecting a level of said stereo difference signal from said stereo difference signal demodulating means,
- first comparing means for comparing an output of said first level detecting means with an output of said second level detecting means, and
- first level adjusting means responsive to an output of said first comparing means for changing the level of at least one of said stereo sum signal and said stereo difference signal to be applied to said matrix means, when only either one of said left stereo signal and said right stereo signal is included in said stereo composite signal, such that the output of said first level detecting means is equal to the output of said second level detecting means.
An FM stereo demodulator for demodulating a left stereo signal and a right stereo signal from a stereo composite signal as frequency modulation detected including a stereo sum signal and a stereo difference signal, comprising:
- stereo difference signal demodulating means for demodulating the stereo difference signal in said stereo composite signal,
- matrix means having output terminals for said left stereo signal and said right stereo signal, respectively, for generating the left stereo signal and the right stereo signal from the stereo sum signal in said stereo composite signal and said stereo difference signal from said stereo difference signal demodulating means,
- level adjusting means for changing a level of at least one of said stereo sum signal and said stereo difference signal to be applied to said matrix means,
- separation adjusting means for applying a control signal to said level adjusting means at a time of adjustment of stereo separation, such that when a stereo composite signal includes only either one of said left and right stereo signals, a signal level of zero appears at one of said output terminals from which the other of said left and right stereo signals is to be outputted,
- storing means for storing said control signal generated from said separation adjusting means, and
- control signal supplying means for applying said control signal stored in said storing means to said level adjusting means at a time of reception of stereophonic broadcasting.
An FM stereo demodulator for demodulating a left stereo signal and a right stereo signal from a stereo composite signal a frequency modulation detected including a stereo sum signal and a stereo difference signal, comprising:
- stereo difference signal demodulating means for demodulating the stereo difference signal in said stereo composite signal,
- matrix means having output terminals for said left stereo signal and said right stereo signal, respectively, and for generating the left stereo signal and the right stereo signal from the stereo sum signal in said stereo composite signal and said stereo difference signal from said stereo difference signal demodulating means,
- level adjusting means for changing a level of at least one of said stereo sum signal and said stereo difference signal to be applied to said matrix means,
- separation adjusting means for applying a control signal to said level adjusting means at a time of adjustment of stereo separation, such that when the stereo composite signal includes only either one of said left and right stereo signals, a signal level of zero appears at one of said output terminals from which the other of said left and right stereo signals is to be outputted,
- storing means for storing said control signal which is generated from said separation adjusting means,
- control signal supplying means for applying said control signal stored in said storing means to said level adjusting means at the time of reception of stereophonic broadcasting, and
- switching means for inhibiting said control signal which is generated from said separation adjusting means from being applied to said storing means anytime except at the time of adjustment of stereo separation.
Dependencies are inferred from the claim text.