US3728475A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Beat signal suppression system for a system for transmitting a frequency modulated wave or a device for recording and reproducing a frequency modulated wave
Assignee: Victor Company of Japan Ltd
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Filing: 1970-07-06
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Granted: 1973-04-17
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Expires: 1990-07-06
Abstract
Abstract A system for transmitting or recording and reproducing a frequency modulated wave suppresses beats produced by a carrier wave and a signal component of high energy level distribution, which is disposed in a range of higher frequencies of a wave signal. A frequency component, which is liable to be reproduced as a beat signal, is subjected to pre-emphasis. A demodulated signal obtained by demodulating the frequency modulated signal is subject to deemphasis with a characteristic opposite to the preemphasis characteristics applied to the wave signal. Thus the frequency-phase characteristics of the signals is uniform throughout the system, whereby the influence exerted by moire beat interference on the demodulated signal can be minimized.
Inventors
- 👤 Y Inoue
- 👤 A Morita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 00:09
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/79; H04N9/80; H04N9/82; H04N5/00; H04N5/76; H04N5/91; H04N5/92; H04N5/923
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
173 words
A beat signal suppression system for a magnetic recording and reproducing apparatus which records and reproduces a wave signal having a high level energy distribution in its higher frequency range, said system comprising pre-emphasis circuit means for preemphasizing an undivided band of frequencies within the wave signal, modulator means for frequency-modulating a carrier frequency responsive to the output signal of said pre-emphasis circuit means, said pre-emphasized range of frequencies including a range of beat frequency signals between the carrier frequency and the frequencies of the high level energy range, said frequency range of the beat signal being lower than the higher frequency range of the wave signal, means for recording the frequency-modulated output signal of the modulator means on a magnetic medium, means for reproducing the recorded frequencymodulated signal from the magnetic medium, demodulator means for demodulating the reproduced frequency-modulated signal, and deemphasis circuit means for de-emphasizing the output signal of said demodulator means, said de-emphasis circuit means having frequency characteristics which are opposite to the frequency characteristics of said pre-emphasis circuit means.
Claim 2
Dependent Claim
173 words
A beat signal suppression system for a magnetic recording and reproducing apparatus which records and reproduces a wave signal having a high level energy distribution in its higher frequency range, said system comprising pre-emphasis circuit means for preemphasizing an undivided band of frequencies within the wave signal, modulator means for frequency-modulating a carrier frequency responsive to the output signal of said pre-emphasis circuit means, said pre-emphasized range of frequencies including a range of beat frequency signals between the carrier frequency and the frequencies of the high level energy range, said frequency range of the beat signal being lower than the higher frequency range of the wave signal, means for recording the frequency-modulated output signal of the modulator means on a magnetic medium, means for reproducing the recorded frequencymodulated signal from the magnetic medium, demodulator means for demodulating the reproduced frequency-modulated signal, and deemphasis circuit means for de-emphasizing the output signal of said demodulator means, said de-emphasis circuit means having frequency characteristics which are opposite to the frequency characteristics of said pre-emphasis circuit means.
Claim 3
Dependent Claim
43 words
A beat signal suppression system as defined in claim 1 in which said wave signal is an NTSC color video signal recorded and reproduced by a magnetic recording and reproducing device by a low carrier wave residual side band wave frequency modulated system.
Claim 4
Dependent Claim
35 words
The beat signal suppression system as defined in claim 1 wherein said pre-emphasis circuit means has frequency characteristics in which a range of intermediate frequencies is emphasized with respect to a range of high frequencies.
Claim 5
Dependent Claim
53 words
The beat signal suppression system as defined in claim 1 wherein said wave signal is an NTSC color video signal, said pre-emphasis circuit means having frequency characteristics in which a range of intermediate frequencies is emphasized with respect to a range of frequencies near the subcarrier wave of said NTSC color video signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-16 | 1976-10-16 | 1977-04-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-16 | 1980-10-16 | 1981-04-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-16 | 1984-10-16 | 1985-04-17 | $7700.00 | Window Closed / Lapsed |