US3760269A
Expired / Lapsed
US
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Multi-frequency tone detector
Assignee: AG Communication Systems Corp
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Filing: 1972-07-31
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Granted: 1973-09-18
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Expires: 1992-07-31
Abstract
Abstract A multi-frequency tone detector wherein tone detection is accomplished by timing the interval or period of the input tone signal to determine its frequency. Preferably counting, or timing, is accomplished over more than one period, eight in a preferred embodiment, to reduce the effect of noise. A programmable counter is used, with the count thereof being programmed to establish recognition bandwidth limits. The programmable counter is reset each time it counts to a programmed lower or upper bandwidth limit, thus permitting a smaller counter and less memory and logic than otherwise would be required, to be used.
Inventors
- 👤 R Beeman
- 👤 L Tarr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:07
CPC Classifications
G; G04; G04F; G04F10/00; G04F10/04; H; H04; H04Q; H04Q1/00; H04Q1/18; H04Q1/30; H04Q1/44; H04Q1/444; H04Q1/45; H04Q1/457
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
206 words
A multi-frequency tone detector comprising: a. a programmable counter; b. a source of clock pulses for providing clock pulses to said programmable counter at an established rate; c. decoder output means coupled to and serving to program said programmable counter to establish recognition bandwidth limits for a plurality of tone signals in accordance with its output state; d. means for setting the output state of said decoder output means to an initial state immediately upon the occurrence of an input wave form; e. means operated by said programmable counter for advancing the output state of said decoder output means each time clock pulses corresponding to a programmed lower or upper bandwidth limit of a tone signal are counted, whereby said programmable counter each time it reaches a count corresponding to the lower or upper bandwith limit of a tone signal advances the output state of said decoder output means and is reset by the latter in accordance with its output state; and f. means for reading the output state of said decoder output means at the end of the period of said input wave form, the output state of said decoder output means providing a distinct indication of the frequency of a valid input tone signal.
Claim 2
Dependent Claim
206 words
A multi-frequency tone detector comprising: a. a programmable counter; b. a source of clock pulses for providing clock pulses to said programmable counter at an established rate; c. decoder output means coupled to and serving to program said programmable counter to establish recognition bandwidth limits for a plurality of tone signals in accordance with its output state; d. means for setting the output state of said decoder output means to an initial state immediately upon the occurrence of an input wave form; e. means operated by said programmable counter for advancing the output state of said decoder output means each time clock pulses corresponding to a programmed lower or upper bandwidth limit of a tone signal are counted, whereby said programmable counter each time it reaches a count corresponding to the lower or upper bandwith limit of a tone signal advances the output state of said decoder output means and is reset by the latter in accordance with its output state; and f. means for reading the output state of said decoder output means at the end of the period of said input wave form, the output state of said decoder output means providing a distinct indication of the frequency of a valid input tone signal.
Claim 3
Dependent Claim
47 words
The multi-frequency detector of claim 1, further including means for multiplying the period of said input wave form, whereby the measured period of said input wave form is the sum of a plurality of periods, said programmable counter being programmed to count clock pulses in corresponding fashion.
Claim 4
Dependent Claim
13 words
The multi-frequency detector of claim 2, wherein the measured period is eight periods.
Claim 5
Dependent Claim
35 words
The multi-frequency detector of claim 2, wherein said means operated by said programmable counter for advancing the output state of said decoder output means comprises a state counter in the form of a binary counter.
Claim 6
Dependent Claim
56 words
The multi-frequency detector of claim 4, wherein said decoder output means comprises a BCD to decimal decoder including output means which when read provide a distinct indication of the frequency of a valid input tone signal, said BCD to decimal decoder decoding the output of said binary state counter to provide a plurality of output states.
Claim 7
Dependent Claim
35 words
The multi-frequency detector of claim 2, further including encoder means coupled between said decoder output means and said programmable counter for programming the latter in accordance with the output state of said decoder output means.
Claim 8
Dependent Claim
63 words
The multi-frequency detector of claim 1, wherein said source of clock pulses Is operable under the control of said decoder output means to provide clock pulses to said programmable counter at a first rate when said decoder output means is in said initial state, and at a second rate when said decoder output means is in a state other than said initial state.
Claim 9
Dependent Claim
25 words
The multi-frequency detector of claim 1, wherein said decoder output means when in a predetermined state inhibits said programmable counter to prevent it from counting.
Claim 10
Dependent Claim
31 words
The multi-frequency of claim 2, further including means for resetting the output circuitry of said decoder output means if the period of said input wave form ends before a pre-established time.
Claim 11
Dependent Claim
22 words
The multi-frequency detector of claim 4, further including means for resetting said state counter each time an input wave form is received.
References Cited (Backward Citations)
US3537001A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-17 | 1977-03-19 | 1977-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-17 | 1981-03-19 | 1981-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-17 | 1985-03-19 | 1985-09-18 | $7700.00 | Window Closed / Lapsed |