US3860925A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Velocity-altimeter frequency-modulation continuous-wave doppler system
Assignee: Singer Co
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Filing: 1974-01-09
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Granted: 1975-01-14
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Expires: 1994-01-09
Abstract
Abstract A restricted range velocity-altimeter frequency-modulation continuous-wave Doppler system is provided which utilizes relatively simple, inexpensive and straightforward circuitry in its altimeter module. The altimeter module is effective in producing altitude outputs as a function of signal amplitudes, rather than signal phase angles as is usual in the prior art. Moreover, costly calibration circuits are obviated in the altimeter module by using a post intermediate frequency leakage signal in the determination of zero altitude readings.
Inventors
- 👤 Jr Ernest F Darboven
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 23:33
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/50; G01S13/58; G01S13/60; G01S13/06; G01S13/08; G01S13/32; G01S13/34; G01S13/88; G01S13/882
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
166 words
In a frequency-modulated continuous-wave aircraft Doppler radar navigational system, which includes a transmitter for transmitting a frequency-modulated continuous-wave signal, and a receiver for receiving the corresponding Doppler-shifted frequency-modulated continuous-wave echo signal including a leakage component (J1); the combination of: a post intermediate frequency circuit coupled to the receiving including sine-cosine demodulating means for eliminating the leakage component (J1) and further including first and second filter means coupled to said demodulating means for rejecting the resulting zero speed leakage term; a sine signal channel coupled to said first filter means and including a first rectifier for establishing a direct current analog of the demodulated sine signal from the demodulating means; a cosine signal channel coupled to said second filter means and including a second rectifier for establishing a direct current analog of the demodulated cosine signal from the demodulator; and output circuitry coupled to the first and second rectifiers for producing a gate signal having a duration which is a measure of the altitude of the aircraft.
Claim 2
Dependent Claim
166 words
In a frequency-modulated continuous-wave aircraft Doppler radar navigational system, which includes a transmitter for transmitting a frequency-modulated continuous-wave signal, and a receiver for receiving the corresponding Doppler-shifted frequency-modulated continuous-wave echo signal including a leakage component (J1); the combination of: a post intermediate frequency circuit coupled to the receiving including sine-cosine demodulating means for eliminating the leakage component (J1) and further including first and second filter means coupled to said demodulating means for rejecting the resulting zero speed leakage term; a sine signal channel coupled to said first filter means and including a first rectifier for establishing a direct current analog of the demodulated sine signal from the demodulating means; a cosine signal channel coupled to said second filter means and including a second rectifier for establishing a direct current analog of the demodulated cosine signal from the demodulator; and output circuitry coupled to the first and second rectifiers for producing a gate signal having a duration which is a measure of the altitude of the aircraft.
Claim 3
Dependent Claim
60 words
The combination defined in claim 1, and which includes a first mixer in said sine signal channel interposed between said first rectifier and said first filter means, and a second mixer in said cosine signal channel interposed between said second rectifier and said second filter means, said mixers serving to translate the center of the Doppler spectrum to direct current.
Claim 4
Dependent Claim
33 words
The combination defined in claim 1, and which includes low-pass filter means in said sine signal channel and in said cosine signal channel to filter out a major portion of the passband noise.
Claim 5
Dependent Claim
33 words
The combination defined in claim 1, and which includes first and second smoother amplifier means in the sine and cosine signal channels respectively coupled To the outputs of the first and second rectifiers.
Claim 6
Dependent Claim
50 words
The combination defined in claim 1, and which includes a sine calibrate channel connected to the output of the sine-cosine demodulating means for receiving the demodulated sine signal therefrom, and a cosine calibrate channel connected to the output of the sine-cosine demodulating means for receiving the demodulated cosine signal therefrom.
Claim 7
Dependent Claim
54 words
The combination defined in claim 5, and which includes first, second, third and fourth mixer means respectively coupling the sine and cosine signal channels and the sine and cosine calibrate channels to said output circuitry; and means for introducing signals to said last-named mixer means to establish a signal phase and a calibrate phase.
Claim 8
Dependent Claim
35 words
The combination defined in claim 6, in which said output circuitry includes a first summing network connected to the first and second mixture, and a second summing network connected to the third and fourth mixers.
Claim 9
Dependent Claim
25 words
The combination defined in claim 7, in which said output circuitry includes a buffer and comparator network coupled to the first and second summing networks.
Claim 10
Dependent Claim
28 words
The combination defined in claim 8, and which includes first and second filter networks respectively coupling the first and second summing networks to said buffer and comparator network.
References Cited (Backward Citations)
US3150365A
Cited
US3334344A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-01-13 | 1978-07-15 | 1979-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-13 | 1982-07-15 | 1983-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-13 | 1986-07-15 | 1987-01-14 | $7700.00 | Window Closed / Lapsed |