US3902122A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for speeding-up the attack time of a tone-coded radio receiver
Assignee: Ericsson Inc
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Filing: 1974-07-10
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Granted: 1975-08-26
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Expires: 1994-07-10
Abstract
Abstract In a shared-channel communication system a tone-coded radio receiver is unsquelched only when it receives a tone of the proper frequency for that receiver. Usually, the tone is a single audio frequency below the normally used transmitted voice frequency. A frequency selective filter is needed so that a given receiver is unsquelched only in response to a tone of the proper frequency. Such a filter introduces a time delay which may prevent transmitted information from being heard or utilized for a short time at the beginning of the transmission. Thus, important information such as identification or status may be completely lost. The radio receiver is therefore provided with a timing circuit which causes the receiver to become unsquelched for a selected time interval starting at the beginning of a transmission, and extending long enough to permit the receiver to produce the initial information until the frequency selective filter unsquelches the receiver. The receiver may also include means to prevent the initial information from being heard by a user.
Inventors
- 👤 Ronald C Sisson
- 👤 Frederick E Spangler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 14:32
CPC Classifications
H; H04; H04W; H04W88/00; H04W88/02; H04W88/022; H04W88/025; H04W88/027; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/34; H03G3/344; H03J; H03J7/00; H03J7/18
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
237 words
In a tone-coded radio receiver adapted to produce only those transmissions having a tone of selected frequency, said receiver having: a radio frequency circuit; a demodulator coupled to said radio frequency circuit; a control circuit having a signal path input coupled to said demodulator, a signal path output, and a control input; a tone filter having an input coupled to said demodulator and an output coupled to said control circuit control input for permitting signals to pass through said control circuit signal path in response to a demodulated tone of selected frequency; and a carrier detector coupled to said demodulator for detecting the presence of a received carrier; an improved circuit for speeding-up the response time of said radio receiver comprising: a. a timing circuit having an input for detected carrier signals and an output or producing a signal of predetermined time duration in response to a detected carrier signal applied to said timing circuit input; b. means connected to said timing circuit input and adapted to be connected to said carrier detector for supplying detected carrier signals to said timing circuit; c. and means connected to said timing circuit output and adapted to be connected to said control circuit control input for permitting said control circuit signal path to pass signals in response to each of said signals of said predetermined time duration, thereby permitting said receiver to produce signals without delay by said tone filter.
Claim 2
Dependent Claim
237 words
In a tone-coded radio receiver adapted to produce only those transmissions having a tone of selected frequency, said receiver having: a radio frequency circuit; a demodulator coupled to said radio frequency circuit; a control circuit having a signal path input coupled to said demodulator, a signal path output, and a control input; a tone filter having an input coupled to said demodulator and an output coupled to said control circuit control input for permitting signals to pass through said control circuit signal path in response to a demodulated tone of selected frequency; and a carrier detector coupled to said demodulator for detecting the presence of a received carrier; an improved circuit for speeding-up the response time of said radio receiver comprising: a. a timing circuit having an input for detected carrier signals and an output or producing a signal of predetermined time duration in response to a detected carrier signal applied to said timing circuit input; b. means connected to said timing circuit input and adapted to be connected to said carrier detector for supplying detected carrier signals to said timing circuit; c. and means connected to said timing circuit output and adapted to be connected to said control circuit control input for permitting said control circuit signal path to pass signals in response to each of said signals of said predetermined time duration, thereby permitting said receiver to produce signals without delay by said tone filter.
Claim 3
Dependent Claim
263 words
In a tone-coded radio receiver adapted to produce only those tranmissions having a tone of seleccted audio frequency, said receiver having: a radio frequency circuit; a demodulator coupled to said radio frequency circuit; a control circuit having a signal path input coupled to said demodulator, a signal path output, and a control input; a carrier detector having an input coupled to said demodulator and an output; a tone filter having an input coupled to said demodulator and an output; and means coupling said control input of said control circuit to said carrier detector output and to said tone filter output for permitting signals to pass through said control circuit signal path in response to both a detected carrier signal and a demodulated tone of selected frequency; an improved circuit for speeding-up the attack time of said radio receiver comPrising: a. a timing circuit having an input for detected carrier signals and an output for producing a signal of selected time duration in response to a detected carrier signal applied to said timing circuit input; b. means connected to said timing circuit input and adapted to be connected to said carrier detector output for supplying detected carrier signals to said timing circuit; c. and means connected to said timing circuit output and adapted to be connected to said control input of said control circuit for permitting signals to pass through said control circuit signal path in response to both a detected carrier signal and a signal of selected time duration, thereby permitting said receiver to produce signals without delay caused by said tone filter.
Claim 4
Dependent Claim
263 words
In a tone-coded radio receiver adapted to produce only those tranmissions having a tone of seleccted audio frequency, said receiver having: a radio frequency circuit; a demodulator coupled to said radio frequency circuit; a control circuit having a signal path input coupled to said demodulator, a signal path output, and a control input; a carrier detector having an input coupled to said demodulator and an output; a tone filter having an input coupled to said demodulator and an output; and means coupling said control input of said control circuit to said carrier detector output and to said tone filter output for permitting signals to pass through said control circuit signal path in response to both a detected carrier signal and a demodulated tone of selected frequency; an improved circuit for speeding-up the attack time of said radio receiver comPrising: a. a timing circuit having an input for detected carrier signals and an output for producing a signal of selected time duration in response to a detected carrier signal applied to said timing circuit input; b. means connected to said timing circuit input and adapted to be connected to said carrier detector output for supplying detected carrier signals to said timing circuit; c. and means connected to said timing circuit output and adapted to be connected to said control input of said control circuit for permitting signals to pass through said control circuit signal path in response to both a detected carrier signal and a signal of selected time duration, thereby permitting said receiver to produce signals without delay caused by said tone filter.
Claim 5
Dependent Claim
43 words
The improved circuit of claim 2, and further comprising means coupled to said timing circuit output and adapted to be connected to the audio circuit of said radio receiver for blocking audible signals during the presence of said signal of selected time duration.
References Cited (Backward Citations)
US3564419A
Cited
US3657655A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-25 | 1979-02-24 | 1979-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-25 | 1983-02-24 | 1983-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-25 | 1987-02-24 | 1987-08-26 | $7700.00 | Window Closed / Lapsed |