US3914557A
Expired / Lapsed
US
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Multifrequency tone detecting arrangement
Assignee: AT&T Inc
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Filing: 1973-04-11
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Granted: 1975-10-21
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Expires: 1993-04-11
Abstract
Abstract A receiver for multifrequency call signals is disclosed which discriminates against the detection of any except a predetermined plurality of tone signals occurring in specified frequency bands. The detection is accomplished by a plurality of reasonatoramplifiers tuned to the specified frequencies each of which has a threshold controllable device at its output. The signals received by a group of the resonator-amplifiers are summed and the resultant signal, amplified to a predetermined amount, is applied to establish the threshold of the threshold controllable device. In one embodiment, the sampling signal is a summation signal developed from a group of the resonator-amplifiers tuned to a band of high frequency signals and this summation signal is amplified to establish the threshold for the group of resonatoramplifiers serving a band of lower frequency signals, and viceversa. In this manner the cut-apart filter and instantaneous limiter circuits required by prior art arrangements are eliminated so that the instant receiver can be constructed without the use of numerous inductors required in a cut-apart filter.
Inventors
- 👤 John Francis O'neill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 13:06
CPC Classifications
H; H04; H04Q; H04Q1/00; H04Q1/18; H04Q1/30; H04Q1/44; H04Q1/444; H04Q1/45; H04Q1/453
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
165 words
An arrangement for discriminating against the detection of a signal in either of a first or second band of signal frequencies in the absence of a signal from the other band of signal frequencies, comprising a respective circuit for resonating in response to the occurrence of each signal in said first band of frequencies, a respective circuit for resonating in response to the occurrence of each signal in said second band of frequencies, a threshold sensitive device respective to each of said resonating circuits, and means for setting the threshold of the threshold sensitive device respective to each resonating circuit of said first band of frequencies in accordance with the signal amplitude of any of the signals of said second band of frequencies, said threshold setting means including means for sampling each resonating circuit from said first and said second band of frequencies to develop a respective summation signal whose amplitude is proportional to the sum of the outputs of each of said resonating circuits.
Claim 2
Dependent Claim
165 words
An arrangement for discriminating against the detection of a signal in either of a first or second band of signal frequencies in the absence of a signal from the other band of signal frequencies, comprising a respective circuit for resonating in response to the occurrence of each signal in said first band of frequencies, a respective circuit for resonating in response to the occurrence of each signal in said second band of frequencies, a threshold sensitive device respective to each of said resonating circuits, and means for setting the threshold of the threshold sensitive device respective to each resonating circuit of said first band of frequencies in accordance with the signal amplitude of any of the signals of said second band of frequencies, said threshold setting means including means for sampling each resonating circuit from said first and said second band of frequencies to develop a respective summation signal whose amplitude is proportional to the sum of the outputs of each of said resonating circuits.
Claim 3
Dependent Claim
35 words
An arrangement for discriminating in accordance with claim 1, wherein said setting means includes means for detecting a singal having a frequency outside the band of said first and said second band of signal frequencies.
Claim 4
Dependent Claim
31 words
An arrangement according to claim 1 wherein each said threshold setting means comprises amplifier means connecteD between said sampling means and said threshold sensitive device respective to each said resonating circuit.
Claim 5
Dependent Claim
53 words
An arrangement according to claim 1 wherein said sampling means includes resistor summing means having a respective input resistor connected between each said resonating circuit and said amplifier means and wherein said amplifier means is adjusted to have a gain lower than that which will off-set the attenuation of said resistor summing means.
Claim 6
Dependent Claim
209 words
An arrangement for discriminating against the detection of a signal in either of a first or second band of signal frequencies when the signal in the second or first band of said frequencies has an amplitude more than n times the amplitude of the signal present in the first or second of said frequency bands comprising a respective circuit for resonating in response to the occurrence of each signal in said first band of frequencies, a respective circuit for resonating in response to the occurrence of each signal in said second band of frequencies, a threshold sensitive device respective to each of said resonating circuits, and means for setting the threshold of the threshold sensitive device respective to each resonating circuit of said first band of frequencies in accordance with the signal amplitude of any of signals of said second band of frequencies, said setting means including means for summing the outputs of said resonating circuit respective to each signal in said first and said second band of frequencies, means for amplifying the output of said summing means, and means for increasing the threshold of said threshold sensitive device when more than one signal of a predetermined amplitude occurs in either said first or said second band of frequencies.
Claim 7
Dependent Claim
209 words
An arrangement for discriminating against the detection of a signal in either of a first or second band of signal frequencies when the signal in the second or first band of said frequencies has an amplitude more than n times the amplitude of the signal present in the first or second of said frequency bands comprising a respective circuit for resonating in response to the occurrence of each signal in said first band of frequencies, a respective circuit for resonating in response to the occurrence of each signal in said second band of frequencies, a threshold sensitive device respective to each of said resonating circuits, and means for setting the threshold of the threshold sensitive device respective to each resonating circuit of said first band of frequencies in accordance with the signal amplitude of any of signals of said second band of frequencies, said setting means including means for summing the outputs of said resonating circuit respective to each signal in said first and said second band of frequencies, means for amplifying the output of said summing means, and means for increasing the threshold of said threshold sensitive device when more than one signal of a predetermined amplitude occurs in either said first or said second band of frequencies.
Claim 8
Dependent Claim
102 words
An arrangement for discriminating against the detection of any but a predetermined number of discrete frequencies in a frequency band comprising a respective circuit tuned to resonate at each said discrete frequency, a threshold control device for each said tuned circuit, means for summing the outputs produced by each said tuned circuit, and means for delivering an amplified component of said summed signal to the threshold device in each said tuned circuit to cut off said threshold device in each said tuned circuit delivering an output of a frequency other than the frequency at which said circuit is discretely tuned to resonate.
Claim 9
Dependent Claim
102 words
An arrangement for discriminating against the detection of any but a predetermined number of discrete frequencies in a frequency band comprising a respective circuit tuned to resonate at each said discrete frequency, a threshold control device for each said tuned circuit, means for summing the outputs produced by each said tuned circuit, and means for delivering an amplified component of said summed signal to the threshold device in each said tuned circuit to cut off said threshold device in each said tuned circuit delivering an output of a frequency other than the frequency at which said circuit is discretely tuned to resonate.
Claim 10
Dependent Claim
150 words
An arrangement for detecting the simultaneous presence of a pair of signals in each of two bands of nonharmonically related signaling frequencies in the band of voice frequencies wherein each signaling frequency is detectable by a respective resonating circuit and in which a logic arrangement is connected to the output of each resonating circuit to decode the signaling path characterized in that the arrangement includes circuitry for discriminating against the detection of any signal when a signal from only one of the band of signaling frequencies is present comprising an operational amplifier connected between the output of each resonating circuit and the decoding logic circuit and a circuit for adjusting the threshold of the operational amplifier in accordance with the sum of the amplitudes of all signals present in one of the two bands of frequencies and the amplitude of any voice frequency present outside the two bands of frequencies.
Claim 11
Dependent Claim
150 words
An arrangement for detecting the simultaneous presence of a pair of signals in each of two bands of nonharmonically related signaling frequencies in the band of voice frequencies wherein each signaling frequency is detectable by a respective resonating circuit and in which a logic arrangement is connected to the output of each resonating circuit to decode the signaling path characterized in that the arrangement includes circuitry for discriminating against the detection of any signal when a signal from only one of the band of signaling frequencies is present comprising an operational amplifier connected between the output of each resonating circuit and the decoding logic circuit and a circuit for adjusting the threshold of the operational amplifier in accordance with the sum of the amplitudes of all signals present in one of the two bands of frequencies and the amplitude of any voice frequency present outside the two bands of frequencies.
Claim 12
Dependent Claim
136 words
An arrangement for detecting one of a plurality of permissible discrete tone signals, and for discriminating against the detection of any other tone in a predetermined band of frequencies comprising a respective circuit for resonating in response to the occurrence of each said discrete signal frequency, a circuit for sampling the output of each said resonating circuits to develop a control signal which is the sum of the amplitudes of the signal presented by each said resonating circuit, utilization circuit means, a respective threshold sensitive device connected between each said resonating circuit and said uTilization device, and means for delivering said control signal from said sampling circuit to each said threshold sensitive device for establishing the minimum signal which must be present at any said resonating circuit output to be coupled to said utilization circuit means.
Claim 13
Dependent Claim
136 words
An arrangement for detecting one of a plurality of permissible discrete tone signals, and for discriminating against the detection of any other tone in a predetermined band of frequencies comprising a respective circuit for resonating in response to the occurrence of each said discrete signal frequency, a circuit for sampling the output of each said resonating circuits to develop a control signal which is the sum of the amplitudes of the signal presented by each said resonating circuit, utilization circuit means, a respective threshold sensitive device connected between each said resonating circuit and said uTilization device, and means for delivering said control signal from said sampling circuit to each said threshold sensitive device for establishing the minimum signal which must be present at any said resonating circuit output to be coupled to said utilization circuit means.
Claim 14
Dependent Claim
43 words
An arrangement for detecting a tone signal according to claim 8 wherein said threshold sensitive device comprises a transistor having its base signal supplied by a respective one of said resonating circuits and its emitter signal supplied by said sampling circuit control signal.
Claim 15
Dependent Claim
61 words
An arrangement for detecting a tone signal according to claim 9 wherein said sampling circuit includes an impedance summing circuit means having a respective element connected to each said resonating circuit at one end of each said element and to a common point at the other end and amplifier means connected between said common point and each said threshold sensitive device.
Claim 16
Dependent Claim
36 words
An arrangement for detecting a tone signal according to claim 10 wherein said amplifier means is adjusted to have a gain lower than that which will compensate for the attenuation introduced by said impedance circuit means.
Claim 17
Dependent Claim
134 words
An arrangement for detecting a tone signal according to claim 11 further comprising a respective circuit for resonating in response to the occurrence of each discrete signal frequency in a second frequency band, a second sampling circuit connected to the output of each resonating circuit for said second frequency band, said second circuit including second amplifier means having an input and an output, said second amplifier means output developing a second control signal, a respective threshold sensitive device connected between each said resonating circuit for said second frequency band and said utilization device, means for delivering a first fraction of the output of said second amplifying means to each said threshold sensitive device for said second frequency band and another fraction of said output to the amplifying means of said first-mentioned band of frequencies.
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) | 1978-10-20 | 1979-04-21 | 1979-10-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-20 | 1983-04-21 | 1983-10-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-20 | 1987-04-21 | 1987-10-21 | $7700.00 | Window Closed / Lapsed |