US3648178A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multiplex fm transmitter
Assignee: U S Holding Co Inc
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Filing: 1969-09-04
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Granted: 1972-03-07
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Expires: 1989-09-04
Abstract
Abstract A first variable attenuator is coupled between the FDM baseband source and the FM modulator. The output signal of the first attenuator is RMS detected to provide a control signal for this attenuator to adjust the amplitude of the baseband signal applied to the FM modulator and, hence, the frequency deviation thereof. An increase in frequency deviation enables a reduction in the EIRP (effective isotropic radiated power) for the same S/N, or an increase in S/N for the same EIRP. A second variable attenuator controlled by the same control signal operates in an inverse fashion, as compared to the first variable attenuator, on the carrier amplitude to maintain a constant S/N ratio.
Inventors
- 👤 David E Hershberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:31
CPC Classifications
H; H04; H04B; H04B14/00; H04B14/002; H04B14/006
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
143 words
A frequency modulation transmitter comprising: a source of frequency division multiplex baseband signal; a frequency modulator to frequency modulate a carrier signal; first means coupled between said source and said modulator responsive to the amplitude of said baseband signal at the output of said first means to adjust the amplitude of said baseband signal prior to coupling to said modulator to thereby enable control of the baseband level; second means coupled to said modulator to transmit the output signal of said modulator; and third means coupled between said modulator and said second means responsive to the amplitude of said baseband signal at the output of said first means to adjust the amplitude of said carrier signal at the output of said modulator opposite to the adjustment of the amplitude of said baseband signal by said first means to maintain the signal-to-noise ratio constant.
Claim 2
Dependent Claim
143 words
A frequency modulation transmitter comprising: a source of frequency division multiplex baseband signal; a frequency modulator to frequency modulate a carrier signal; first means coupled between said source and said modulator responsive to the amplitude of said baseband signal at the output of said first means to adjust the amplitude of said baseband signal prior to coupling to said modulator to thereby enable control of the baseband level; second means coupled to said modulator to transmit the output signal of said modulator; and third means coupled between said modulator and said second means responsive to the amplitude of said baseband signal at the output of said first means to adjust the amplitude of said carrier signal at the output of said modulator opposite to the adjustment of the amplitude of said baseband signal by said first means to maintain the signal-to-noise ratio constant.
Claim 3
Dependent Claim
24 words
A transmitter according to claim 1, wherein said third means includes a variable amplitude control means coupled between said modulator and said second means.
Claim 4
Dependent Claim
14 words
A transmitter according to claim 2, wherein said control means includes a variable attenuator.
Claim 5
Dependent Claim
99 words
A transmitter according to claim 1, wherein said first means includes a first variable amplitude control means coupled between said source and said modulator, and a root-mean-square detector coupled to the output of said first control means to produce a control signal to control said first control means for adjustment of the amplitude of said baseband signal; and said third means includes a second variable amplitude control means coupled between said modulator and said second means and to said detector responsive to said control signal to provide said adjustment of said carrier signal at the output of said modulator.
Claim 6
Dependent Claim
40 words
A transmitter according to claim 4, wherein said first control means includes a first variable attenuator having a given attenuation characteristic; and said second control means includes a second variable attenuator having an attenuation characteristic opposite said given attenuation characteristic.
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) | 1975-03-07 | 1975-09-06 | 1976-03-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-03-07 | 1979-09-06 | 1980-03-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-03-07 | 1983-09-06 | 1984-03-07 | $7700.00 | Window Closed / Lapsed |