US3582565A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tone channels for multifrequency receivers
Assignee: Automatic Electric Laboratories Inc
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Filing: 1969-01-13
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Granted: 1971-06-01
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Expires: 1989-01-13
Abstract
Abstract A tone channel of the type used in multifrequency receivers has in cascade an input band-pass filter that has a frequency curve similar to that of overcoupled filters, a limiter-amplifier, and an output band-pass filter that has narrow band-pass characteristics. The center frequency of both filters is the frequency of a desired incoming tone. After a signal ceases, ringing of the input filter caused by signal is at the peak response points of the input filter at either side of the center frequency, and it is therefore not effective to prolong ringing in the output filter.
Inventors
- 👤 Robert H Beeman
- 👤 Robert V Burns
- 👤 Robert T Cleary
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:04
CPC Classifications
H; H04; H04Q; H04Q1/00; H04Q1/18; H04Q1/30; H04Q1/44; H04Q1/444; H04Q1/45; H04Q1/453
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
254 words
A multifrequency receiver comprising: a plurality of tone channels, the input of each of said tone channels being connected to a common input of said receiver, each of said tone channels being tuned to receive a signal at a respective frequency while rejecting another signal simultaneously applied to said common input to be received by another one of said tone channels that is tuned to a frequency only slightly separated therefrom, said input circuit of each of said tone channels including an input band-pass filter with a narrow band response curve having steep skirts to reject a signal from said other one of said tone channels but with peak characteristics resembling the characteristics of an overcoupled tuning circuit that has a noticeable peak frequency response on each side of its center frequency, its center frequency being the frequency of said signal to be received by the respective tone channel, each of said tone channels having a limiter stage, an output band-pass filter and a threshold detector connected successively in cascade, the input of each of said limiter stages being connected to a respective one of said input bandpass filters, each of said output band-pass filters having a single peak response at said frequency of said signal to be received by the respective tone channel and having a frequency response curve still more narrow than that of said respective input band-pass filter to reject ringing signals which occur at each one of said peak frequencies of said input band-pass filter of said respective tone channel.
Claim 2
Dependent Claim
254 words
A multifrequency receiver comprising: a plurality of tone channels, the input of each of said tone channels being connected to a common input of said receiver, each of said tone channels being tuned to receive a signal at a respective frequency while rejecting another signal simultaneously applied to said common input to be received by another one of said tone channels that is tuned to a frequency only slightly separated therefrom, said input circuit of each of said tone channels including an input band-pass filter with a narrow band response curve having steep skirts to reject a signal from said other one of said tone channels but with peak characteristics resembling the characteristics of an overcoupled tuning circuit that has a noticeable peak frequency response on each side of its center frequency, its center frequency being the frequency of said signal to be received by the respective tone channel, each of said tone channels having a limiter stage, an output band-pass filter and a threshold detector connected successively in cascade, the input of each of said limiter stages being connected to a respective one of said input bandpass filters, each of said output band-pass filters having a single peak response at said frequency of said signal to be received by the respective tone channel and having a frequency response curve still more narrow than that of said respective input band-pass filter to reject ringing signals which occur at each one of said peak frequencies of said input band-pass filter of said respective tone channel.
Claim 3
Dependent Claim
133 words
A multifrequency receiver as claimed in claim 1 in which each of said input band-pass filters comprise a pair of adjustable resonant circuits, each of said resonant circuits having a center-tapped inductor, the center taps of said inductors being connected together, one end terminal of one of said inductors being connected to one terminal of said common input circuit, a trap circuit, one end terminal of the other of said inductors being connected through said trap circuit to the other terminal of said common input circuit, said trap circuit being tuned to frequencies adjacent to the center frequency of said resonant circuits to effectively sharpen the skirts of their frequency response curve, and the other end terminal of one of said resonant circuits being connected to said limiter of the respective tone channel.
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) | 1974-05-31 | 1974-11-30 | 1975-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-31 | 1978-11-30 | 1979-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-31 | 1982-11-30 | 1983-06-01 | $7700.00 | Window Closed / Lapsed |