US3909549A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multifrequency signalling device and particularly signalling receiver thereof
Assignee: Individual
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Filing: 1973-06-26
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Granted: 1975-09-30
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Expires: 1993-06-26
Abstract
Abstract A signalling receiver has a number of selective filters, each selective corresponding to one of the voice frequencies of the signalling plan. Each filter is associated with a detector and a signal envelope detector circuit, and, in turn, these detectors are followed by a shaping circuit for giving the detector a slow rising leading edge wave front and a fast falling trailing edge. The significance of the slow rising wave front is that it tends to limit the signal to the fundamental frequency, as contrasted with a square wave form which tends to have an infinite number of harmonics. The signal received in the signalling receiver is applied either simultaneously with or slightly before the envelope detector circuit. The selective filters have controlled selectivity. The outlet signal from the shaping circuit is applied to the selectivity control means of the filters.
Inventors
- 👤 Andre Tarridec
- 👤 Jean Leon Marie Joubert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 09:51
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/1295; H03H11/1217; H04; H04Q; H04Q1/00; H04Q1/18; H04Q1/30; H04Q1/44; H04Q1/444; H04Q1/46
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
157 words
A multifrequency signalling receiver comprising a plurality of selective filter means, each selective filter having controlled selectivity tuned to a corresponding one of the signalling frequencies received by the multifrequency receiver, signal envelope detector means coupled with each filter and including a signal envelope detector circuit followed by a shaping circuit for giving a slowly changing leading edge to the output signal from said signal envelope detector means, means for substantially simultaneously applying the input signal received by said signalling receiver to the selective filters and to the said signal envelope detector means, means for applying the output signal of said shaping circuit to control the selectivity of the said filters so that a maximum selectivity is attained in each of the filters only when the output signal of the shaping circuit has reached a predetermined amplitude, and decision circuit means for giving an output signal when the output of said receiver coincides with a recognized code.
Claim 2
Dependent Claim
157 words
A multifrequency signalling receiver comprising a plurality of selective filter means, each selective filter having controlled selectivity tuned to a corresponding one of the signalling frequencies received by the multifrequency receiver, signal envelope detector means coupled with each filter and including a signal envelope detector circuit followed by a shaping circuit for giving a slowly changing leading edge to the output signal from said signal envelope detector means, means for substantially simultaneously applying the input signal received by said signalling receiver to the selective filters and to the said signal envelope detector means, means for applying the output signal of said shaping circuit to control the selectivity of the said filters so that a maximum selectivity is attained in each of the filters only when the output signal of the shaping circuit has reached a predetermined amplitude, and decision circuit means for giving an output signal when the output of said receiver coincides with a recognized code.
Claim 3
Dependent Claim
29 words
A signalling receiver according to claim 1 wherein said shaping circuit includes means for giving the output signal of said signal contour detector means a steeply changing trailing edge.
Claim 4
Dependent Claim
119 words
A signalling receiver according to claim 1, wherein said selective filters are active band filters including a plurality of resistances with two feedback circuits, one of the resistances of the feed back circuits being variable and comprising in parallel a fixed resistance having a value which tunes the filter to its maximum selectivity and the drain-source circuit of a field effect transistor, the gate of which is connected to the output of said shaping circuit, and means responsive to an absence of a wave shaping circuit output signal for providing practically no resistance in said drain-source circuit and responsive to an appearance of said wave shaping circuit output signal for providing a very large resistance at the drain-source circuit.
Claim 5
Dependent Claim
63 words
A signalling receiver according to claim 1, wherein said selective filters comprise at least two band filters in series, the first of said filters having at least a fixed selectivity centered on a predetermined frequency and the latter of said filters having at least one controlled selectivity which when it operates with its total selectivity is likewise centered on the said predetermined frequency.
Claim 6
Dependent Claim
187 words
A multifrequency signal receiver comprising: automatic gain controlled amplifier means, rejector filters coupled between the input of said receiver and said amplifier means to eliminate undesirable frequencies, a plurality of selective filters each having a controlled selectivity tuned to one of the signal frequencies, a signal envelope detector circuit means followed by a shaping circuit means for giving to the outlet signal of the said signal envelope detector a slowly changing leading edge, means for applying the output signal of the said rejector filters in parallel to the said automatic gain control amplifier means and to the signal envelope detector circuit means, said shaping circuit giving a slowly changing leading edge to said signal envelope, means for applying the output signal of said shaping circuit to said gain control amplifier means to control said amplifier so that it is operating at its fixed gain once the said output signal of said shaping circuit has reached its maximum amplitude in absolute value, the gain of said amplifier being minimum in the absence of signal and means responsive to the output of said receiver for indicating apparently valid signals.
Claim 7
Dependent Claim
187 words
A multifrequency signal receiver comprising: automatic gain controlled amplifier means, rejector filters coupled between the input of said receiver and said amplifier means to eliminate undesirable frequencies, a plurality of selective filters each having a controlled selectivity tuned to one of the signal frequencies, a signal envelope detector circuit means followed by a shaping circuit means for giving to the outlet signal of the said signal envelope detector a slowly changing leading edge, means for applying the output signal of the said rejector filters in parallel to the said automatic gain control amplifier means and to the signal envelope detector circuit means, said shaping circuit giving a slowly changing leading edge to said signal envelope, means for applying the output signal of said shaping circuit to said gain control amplifier means to control said amplifier so that it is operating at its fixed gain once the said output signal of said shaping circuit has reached its maximum amplitude in absolute value, the gain of said amplifier being minimum in the absence of signal and means responsive to the output of said receiver for indicating apparently valid signals.
Claim 8
Dependent Claim
79 words
A signalling receiver according to clAim 5, wherein said automatic gain control amplifier means includes a variable resistance mounted in a parallel circuit for applying part of a signal from said rejector filters to the input of the automatic gain control amplifier, means for controlling the value of said resistance by a conventional automatic gain control circuit responsive to the level of the output signal of the said amplifier and by the output signal of the said shaping circuit.
Claim 9
Dependent Claim
54 words
A multifrequency signalling receiver according to claim 6 and a field effect transistor having a source, drain and gate, said variable resistance element being the source-drain circuit of said field effect transistor, and means for applying to the gate the sum of said automatic gain control circuit signal and said shaping circuit output signal.
Claim 10
Dependent Claim
29 words
A signalling receiver according to claim 5 and means jointly responsive to said signal envelope detector circuit means and said shaping circuit for controlling the automatic gain control amplifier.
Claim 11
Dependent Claim
87 words
A signalling receiver according to claim 5 wherein said input of said receiver comprises a differential operational amplifier including means for connecting the inputs of the differential amplifier to a two wire communication line, and including a signal transmitter means responsive to the output of the means for indicating valid signals wherein its output circuit comprises two operational amplifiers functioning as current amplifiers and the outputs of which are connected respectively to the two wires, the signals applied to the two current amplifiers being in phase opposition.
Claim 12
Dependent Claim
154 words
A multifrequency signalling receiver comprising at least one selective filter means having controlled selectivity tuned to a corresponding one of the signalling frequencies received by the multifrequency receiver, signal envelope detector means coupled with said filter and including a signal envelope detector circuit followed by a shaping circuit for giving a slowly changing leading edge to the output signal from said signal envelope detector means, means for substantially simultaneously applying the input signal received by said signalling receiver to the selective filter means and to the said signal envelope detector means, means for applying the output signal of said shaping circuit to control the selectivity of the said filter means so that a maximum selectivity is attained in the filter only when the output signal of the shaping circuit has reached a predetermined amplitude, and decision circuit means for giving an output signal when the output of said receiver coincides with a recognized code.
Claim 13
Dependent Claim
154 words
A multifrequency signalling receiver comprising at least one selective filter means having controlled selectivity tuned to a corresponding one of the signalling frequencies received by the multifrequency receiver, signal envelope detector means coupled with said filter and including a signal envelope detector circuit followed by a shaping circuit for giving a slowly changing leading edge to the output signal from said signal envelope detector means, means for substantially simultaneously applying the input signal received by said signalling receiver to the selective filter means and to the said signal envelope detector means, means for applying the output signal of said shaping circuit to control the selectivity of the said filter means so that a maximum selectivity is attained in the filter only when the output signal of the shaping circuit has reached a predetermined amplitude, and decision circuit means for giving an output signal when the output of said receiver coincides with a recognized code.
References Cited (Backward Citations)
US3780230A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |