US3573642A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Band-limited fm detector
Assignee: Motorola Solutions Inc
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Filing: 1969-03-10
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Granted: 1971-04-06
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Expires: 1989-03-10
Abstract
Abstract The output IF signal of an FM receiver is coupled to an AND gate and also used to actuate a timer. The timer output is coupled to a second input of the AND gate and the initial output of the timer enables the AND gate for a fixed predetermined time period. The initial portion of the IF signal disables the AND gate while the terminal portion of each cycle of the IF signal enables the AND gate. The AND gate puts out a signal consisting of a series of pulses which are filtered or integrated to develop an output signal, which is a linear function of the frequency over the band of the FM detector.
Inventors
- 👤 Thomas M Yackish
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 09:50
CPC Classifications
H; H03; H03D; H03D3/00; H03D3/02; H03D3/04
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
212 words
A band-limited detector for a frequency-modulated wave which alternates between first and second voltage levels, wiTh the frequency of alternation varying from a center frequency in a range between a lowest frequency and a highest frequency, such detector including in combination, timer means adapted to develop an enabling signal for a fixed predetermined time interval after actuation thereof, which time interval is within the range from one-half the period of the lowest frequency of the modulated wave to the period of the highest frequency of the modulated wave, means coupled to said timer means for receiving the frequencymodulated wave and for actuating said timer means in response to each transition of the frequency-modulated wave from the first voltage level to the second voltage level, an AND gate coupled to said timer means and receiving said enabling signal therefrom, means applying the frequency-modulated wave to said AND gate, said AND gate being responsive to said enabling signal and to the frequency-modulated wave to develop an output signal only during the coincidence of said enabling signal and of the first voltage level of the frequency-modulated wave, and means coupled to said AND gate and responsive to said output signal to develop a signal which is a function of the modulation of the frequency-modulated wave.
Claim 2
Dependent Claim
212 words
A band-limited detector for a frequency-modulated wave which alternates between first and second voltage levels, wiTh the frequency of alternation varying from a center frequency in a range between a lowest frequency and a highest frequency, such detector including in combination, timer means adapted to develop an enabling signal for a fixed predetermined time interval after actuation thereof, which time interval is within the range from one-half the period of the lowest frequency of the modulated wave to the period of the highest frequency of the modulated wave, means coupled to said timer means for receiving the frequencymodulated wave and for actuating said timer means in response to each transition of the frequency-modulated wave from the first voltage level to the second voltage level, an AND gate coupled to said timer means and receiving said enabling signal therefrom, means applying the frequency-modulated wave to said AND gate, said AND gate being responsive to said enabling signal and to the frequency-modulated wave to develop an output signal only during the coincidence of said enabling signal and of the first voltage level of the frequency-modulated wave, and means coupled to said AND gate and responsive to said output signal to develop a signal which is a function of the modulation of the frequency-modulated wave.
Claim 3
Dependent Claim
26 words
The band-limited detector of claim 1 wherein, said fixed predetermined time interval is made equal to the period of the highest frequency of said frequency-modulated wave.
Claim 4
Dependent Claim
40 words
The band-limited detector of claim 1 wherein, the frequency-modulated wave has a fixed duty cycle and said fixed predetermined time interval is made equal to the period of the lowest frequency of said frequency-modulated wave multiplied by said duty cycle.
Claim 5
Dependent Claim
44 words
The band-limited detector of claim 1 wherein, the frequency-modulated wave has a fixed 50 percent duty cycle and a fixed center frequency, and said fixed predetermined time interval is made equal to three-fourths of the period of said center frequency of the frequency-modulated wave.
Claim 6
Dependent Claim
32 words
The band-limited detector of claim 1 wherein, said means coupled to said AND gate is a filter for developing a signal equal to the average direct current voltage of said output signal.
Claim 7
Dependent Claim
223 words
A band-limited detector for a frequency-modulated wave having a fixed center frequency and which varies in frequency between a lowest frequency and a highest frequency, including in combination, limiter means adapted to receive the frequency-modulated wave and responsive thereto to amplify and limit the same whereby the limited frequency-modulated wave undergoes a transition from a first voltage level to a second voltage and from said second voltage level to said first voltage level during one period thereof, timer means coupled to said limiter means and responsive to said limited frequency-modulated wave to develop an enabling signal for a fixed predetermined time interval after said transition from said first voltage level to said second voltage level, which time interval is within the range from one-half the period of the lowest frequency of the modulated wave to the period of the highest frequency of the modulated wave, an AND gate coupled to said timer means and to said limiter means and responsive to said enabling signal and to said limited frequency-modulated wave to develop an output signal only during the coincidence of said enabling signal and of the first voltage level of said limited frequency-modulated wave, and filter means coupled to said AND gate and responsive to said output signal to develop a signal which is a function of the modulation of the frequency-modulated wave.
Claim 8
Dependent Claim
223 words
A band-limited detector for a frequency-modulated wave having a fixed center frequency and which varies in frequency between a lowest frequency and a highest frequency, including in combination, limiter means adapted to receive the frequency-modulated wave and responsive thereto to amplify and limit the same whereby the limited frequency-modulated wave undergoes a transition from a first voltage level to a second voltage and from said second voltage level to said first voltage level during one period thereof, timer means coupled to said limiter means and responsive to said limited frequency-modulated wave to develop an enabling signal for a fixed predetermined time interval after said transition from said first voltage level to said second voltage level, which time interval is within the range from one-half the period of the lowest frequency of the modulated wave to the period of the highest frequency of the modulated wave, an AND gate coupled to said timer means and to said limiter means and responsive to said enabling signal and to said limited frequency-modulated wave to develop an output signal only during the coincidence of said enabling signal and of the first voltage level of said limited frequency-modulated wave, and filter means coupled to said AND gate and responsive to said output signal to develop a signal which is a function of the modulation of the frequency-modulated wave.
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) | 1974-04-05 | 1974-10-05 | 1975-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-05 | 1978-10-05 | 1979-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-05 | 1982-10-05 | 1983-04-06 | $7700.00 | Window Closed / Lapsed |