US3875347A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multifrequency signal receiver
Assignee: AG Communication Systems Corp
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Filing: 1973-10-01
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Granted: 1975-04-01
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Expires: 1993-10-01
Abstract
Abstract A receiver for detection of multifrequency tones as used for signaling purposes in telecommunication systems. Active bandpass filters are employed with digital logic networks to make the circuitry independent of the inherent slow rise and ringing characteristics of the filters.
Inventors
- 👤 Jamil K Alaily
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:51
CPC Classifications
H; H04; H04Q; H04Q1/00; H04Q1/18; H04Q1/30; H04Q1/44; H04Q1/444; H04Q1/45; H04Q1/453
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
235 words
A receiver for detection of multifrequency tone signals comprising: a plurality of comparator circuits; a plurality of tone responsive circuits, each connected between a common source of multifrequency tone signals and a different one of said comparator circuits and each operated in response to receipt of a different single frequency tone signal, to couple said received signal to said connected comparator circuit; rectifier means connected between said source of multifrequency tone signals and each of said comparator circuits, operated in response to said multifrequency tone signals to couple a direct current potential corresponding in amplitude to the amplitude of said multifrequency tone signals to each of said comparator circuits; whereby said comparator circuit in response to a single frequency tone signal and DC potential from said rectifier means, generates an output signal of fixed delay; output means connected to the output of each of said comparator circuits, comprising: a first trigger circuit connected to said source of multifrequency tone signals, said trigger circuit operated in response to a multifrequency tone signal to generate a trigger pulse of predetermined duration; a first plurality of gate circuits each connected to a different one of said comparator circuits and each connected to said first trigger circuit, each of said gate circuits operated in response to coincidence of an output signal from said connected comparator circuit and said first trigger pulse to generate an output signal of fixed duration.
Claim 2
Dependent Claim
235 words
A receiver for detection of multifrequency tone signals comprising: a plurality of comparator circuits; a plurality of tone responsive circuits, each connected between a common source of multifrequency tone signals and a different one of said comparator circuits and each operated in response to receipt of a different single frequency tone signal, to couple said received signal to said connected comparator circuit; rectifier means connected between said source of multifrequency tone signals and each of said comparator circuits, operated in response to said multifrequency tone signals to couple a direct current potential corresponding in amplitude to the amplitude of said multifrequency tone signals to each of said comparator circuits; whereby said comparator circuit in response to a single frequency tone signal and DC potential from said rectifier means, generates an output signal of fixed delay; output means connected to the output of each of said comparator circuits, comprising: a first trigger circuit connected to said source of multifrequency tone signals, said trigger circuit operated in response to a multifrequency tone signal to generate a trigger pulse of predetermined duration; a first plurality of gate circuits each connected to a different one of said comparator circuits and each connected to said first trigger circuit, each of said gate circuits operated in response to coincidence of an output signal from said connected comparator circuit and said first trigger pulse to generate an output signal of fixed duration.
Claim 3
Dependent Claim
102 words
A receiver as claimed in claim 1 wherein said output means further include a second trigger circuit connected to said source of multifrequEncy tone signals operated in response to a multifrequency tone signal to generate a second trigger pulse of duration equivalent to said multifrequency tone signal; a second plurality of gate circuits each connected to a different one of said first gate circuits and each connected to said second trigger circuit, each of said gate circuits operated in response to coincidence of an output signal from said connected first gate circuit and said second trigger pulse to generate an output signal.
Claim 4
Dependent Claim
35 words
A receiver as claimed in claim 1 wherein each of said comparator circuits further include potential adjustment means connected to said rectifier means, operated to adjust the amount of fixed delay of said output signals.
Claim 5
Dependent Claim
29 words
A receiver as claimed in claim 1 wherein said rectifier means include a full wave rectifier and integrator means connected between said full wave rectifier and said comparator circuits.
Claim 6
Dependent Claim
31 words
A receiver as claimed in claim 1 wherein each of said gate circuits are connected to a different one of said comparator circuits through an inverter and a retriggerable monostable multivibrator.
Claim 7
Dependent Claim
32 words
A receiver as claimed in claim 1 wherein each of said second plurality of gate circuits are connected to a different one of said plurality of first gate circuits by an inverter.
Claim 8
Dependent Claim
48 words
A receiver as claimed in claim 2 wherein there are further icluded inhibit means connected between each of said comparator circuits and said second trigger means operated in response to an output signal from anyone of said comparator circuits to inhibit the operation of said second trigger means.
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) | 1978-03-31 | 1978-09-30 | 1979-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-31 | 1982-09-30 | 1983-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-31 | 1986-09-30 | 1987-04-01 | $7700.00 | Window Closed / Lapsed |