Patent US4301455A successfully refreshed from Google Patents.
US4301455A
Expired / Lapsed
US
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Groundspeed measurement system
Assignee: Government of the United States of America
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Filing: 1979-10-17
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Granted: 1981-11-17
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Expires: 1999-10-17
Abstract
Abstract A measurement system for determining the groundspeed of an aircraft during final approach and landing, by measuring at the aircraft the Doppler shift of a radio signal, and/or its modulation components, transmitted by a fixed ground station. The carrier signal is allowed to drift; it is provided with a modulated tone on the carrier having a frequency signature that identifies the direction and magnitude of this carrier frequency drift. In a second embodiment the Doppler cycles are not counted directly, but rather fixed increments of a cycle wavelength are measured; the time period of each segment is inverted to obtain a value proportional to the Doppler frequency.
Inventors
- 👤 Forrest G. Yetter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:47
CPC Classifications
G; G01; G01S; G01S11/00; G01S11/02; G01S11/10; G01S1/00; G01S1/02; G01S1/08; G01S1/14; G01S1/16
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
120 words
A method of measuring the motion of a receiving station relative to a transmitting station, comprising: generating electromagnetic energy in the radio frequency spectrum at the transmitting station; radiating said energy; detecting said energy at the receiving station; heterodyning said detected energy at said receiving station to generate a first reference frequency; synthesizing a second reference frequency at said receiving station which has a value equal to said first reference frequency when there is no relative motion between said transmitting station and said receiving station; mixing said first reference frequency with said second reference frequency to isolate a Doppler frequency; and processing said Doppler frequency to generate a signal having a value that is functionally related to said relative motion.
Claim 2
Independent Claim
120 words
A method of measuring the motion of a receiving station relative to a transmitting station, comprising: generating electromagnetic energy in the radio frequency spectrum at the transmitting station; radiating said energy; detecting said energy at the receiving station; heterodyning said detected energy at said receiving station to generate a first reference frequency; synthesizing a second reference frequency at said receiving station which has a value equal to said first reference frequency when there is no relative motion between said transmitting station and said receiving station; mixing said first reference frequency with said second reference frequency to isolate a Doppler frequency; and processing said Doppler frequency to generate a signal having a value that is functionally related to said relative motion.
Claim 3
Independent Claim
147 words
A method for measuring the motion of a receiving station relative to a transmitting station, comprising: generating electromagnetic energy in the radio frequency spectrum at the transmitting station; sampling a part of said energy; generating a first reference frequency; mixing said sampled energy and said first reference frequency to generate a difference frequency; modulating the energy output of said transmitting station with said difference frequency; detecting said modulated energy output at said receiving station; generating a second reference frequency at said receiving station; synthesizing at said receiving station additional frequencies from said second reference frequency; heterodyning said detected energy with said synthesized additional frequencies to produce a third reference frequency; demodulating said detected energy; mixing said demodulated energy with said reference frequency to produce a Doppler frequency; and processing said Doppler frequency to produce a signal having a value that is functionally related to said relative motion.
Claim 4
Independent Claim
147 words
A method for measuring the motion of a receiving station relative to a transmitting station, comprising: generating electromagnetic energy in the radio frequency spectrum at the transmitting station; sampling a part of said energy; generating a first reference frequency; mixing said sampled energy and said first reference frequency to generate a difference frequency; modulating the energy output of said transmitting station with said difference frequency; detecting said modulated energy output at said receiving station; generating a second reference frequency at said receiving station; synthesizing at said receiving station additional frequencies from said second reference frequency; heterodyning said detected energy with said synthesized additional frequencies to produce a third reference frequency; demodulating said detected energy; mixing said demodulated energy with said reference frequency to produce a Doppler frequency; and processing said Doppler frequency to produce a signal having a value that is functionally related to said relative motion.
Claim 5
Independent Claim
116 words
A method of measuring the motion of receiving station relative to transmitting station, comprising: generating electromagnetic energy in the radio frequency spectrum at the transmitting station; generating a modulation signal and applying said signal to said energy; radiating said electromagnetic energy with said modulation signal impressed thereon; detecting at the receiving station said energy radiated by said transmitting station; demodulating said detected energy; generating a reference frequency at a value having a known relation to the frequency of said modulation signal impressed on said energy radiated by said transmitting station; and mixing said demodulated signal with said reference signal to generate a Doppler signal having a parameter value that is functionally related to said relative motion.
Claim 6
Independent Claim
116 words
A method of measuring the motion of receiving station relative to transmitting station, comprising: generating electromagnetic energy in the radio frequency spectrum at the transmitting station; generating a modulation signal and applying said signal to said energy; radiating said electromagnetic energy with said modulation signal impressed thereon; detecting at the receiving station said energy radiated by said transmitting station; demodulating said detected energy; generating a reference frequency at a value having a known relation to the frequency of said modulation signal impressed on said energy radiated by said transmitting station; and mixing said demodulated signal with said reference signal to generate a Doppler signal having a parameter value that is functionally related to said relative motion.
Claim 7
Dependent Claim
53 words
A method of measuring the motion of a receiving station relative to a transmitting station as recited in claim 3 including multiplying the frequency of said demodulated energy and mixing said multiplied frequency with a synthesized frequency that is a synchronized multiple of said transmitter modulation signal frequency to generate said Doppler signal.
Claim 8
Dependent Claim
50 words
A method of measuring the motion of a receiving station as recited in claim 3, including multiplying the frequency of said demodulated energy and mixing said multiplied frequency with a synthesized frequency that is offset from a synchronized multiple of said transmitter modulation signal frequency to generate said Doppler signal.
Claim 9
Dependent Claim
61 words
A method of measuring the motion of a receiving station relative to a transmitting station as recited in claim 3, including measuring an increment of the wavelength of said Doppler signal by accumulating a first quantity of pulses that is proportional to said increment and generating a second quantity of pulses that is proportional to the frequency of said Doppler signal.
Claim 10
Independent Claim
88 words
A method of measuring the distance of a receiving station from a reference location comprising detecting a directional beam of electromagnetic energy radiated from a first ground station; generating pulses having a repetition frequency proportiponal to the range rate of said receiving station relative to a second ground station; counting said pulses for a finite period of time, initiating said counting action in response to the detection of said directional beam; and converting the quantity of pulses counted in said finite period of time to units of distance.
Claim 11
Independent Claim
88 words
A method of measuring the distance of a receiving station from a reference location comprising detecting a directional beam of electromagnetic energy radiated from a first ground station; generating pulses having a repetition frequency proportiponal to the range rate of said receiving station relative to a second ground station; counting said pulses for a finite period of time, initiating said counting action in response to the detection of said directional beam; and converting the quantity of pulses counted in said finite period of time to units of distance.
Claim 12
Dependent Claim
36 words
A method of measuring the distance of a receiving station from a reference location as in claim 7 wherein said pulse count is converted to distance units from said receiving station to said first ground station.
Claim 13
Dependent Claim
36 words
A method of measuring the distance of a receiving station from a reference location as in claim 7 wherein said pulse count is converted to distance units from said receiving station to said second ground station.
Claim 14
Dependent Claim
48 words
A method of measuring the distance of a receiving station from a reference location as in claim 7 wherein said pulse count is converted to distance units from said receiving station to a designated point along a straight line that passes through said first and second ground stations.
Claim 15
Dependent Claim
33 words
A method of measuring the distance of a receiving station from a reference location as in claim 7 wherein said first ground station is a marker beacon component of an instrument landing system.
Claim 16
Dependent Claim
32 words
A method of measuring the distance of a receiving station from a reference location as in claim 7 wherein said second ground station is the localizer component of an instrument landing system.
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) | 1984-11-16 | 1985-05-18 | 1985-11-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-11-16 | 1989-05-18 | 1989-11-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-11-16 | 1993-05-18 | 1993-11-17 | $7700.00 | Window Closed / Lapsed |