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US4041494A
Expired / Lapsed
US
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Distance measuring method and apparatus
Assignee: United States Department of Transportation
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Filing: 1975-11-10
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Granted: 1977-08-09
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Expires: 1995-11-10
Abstract
Abstract The direction and/or distance between a fixed point and a vehicle or between two vehicles located on a common vehicle way are measured by an intermediate frequency interferometric technique wherein signals are transmitted from a single antenna to a receiver system comprising three equally spaced linearly arranged antennas. The technique encompasses determination of the path length differences between the transmitting antenna and each of the receiving antennas. The path length differences are thereafter employed to compute the distance to and/or direction between the transmitting antenna and the linearly aligned receiving antennas.
Inventors
- 👤 Harold I. Ewen
- 👤 George G. Haroules
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:08
CPC Classifications
G; G01; G01S; G01S11/00; G01S11/02; G01S11/04; G01S3/00; G01S3/02; G01S3/14; G01S3/46
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
168 words
A method for the measurement of distance comprising the steps of: generating a carrier frequency signal; generating a modulation signal; employing the modulation and carrier signals to generate a first sideband signal at a frequency related to said carrier frequency; simultaneously transmitting the carrier and first sideband signals; receiving the transmitted carrier and sideband signals at three points linearly spatially displaced along a common baseline; extracting the intermediate frequency from the carrier and sideband signals received at each point to thereby provide three intermediate frequency signals each having a different phase relationship commensurate with the respective distances between the point of transmission and points of reception; comparing the phase at said intermediate frequency of two pair of the three signals provided by extracting the intermediate frequency to obtain information corresponding to the differences in phase between the compared intermediate frequency signals of each pair; and summing the phase differences at the intermediate frequency to provide a measure of the distance from the baseline to the point of transmission.
Claim 2
Independent Claim
168 words
A method for the measurement of distance comprising the steps of: generating a carrier frequency signal; generating a modulation signal; employing the modulation and carrier signals to generate a first sideband signal at a frequency related to said carrier frequency; simultaneously transmitting the carrier and first sideband signals; receiving the transmitted carrier and sideband signals at three points linearly spatially displaced along a common baseline; extracting the intermediate frequency from the carrier and sideband signals received at each point to thereby provide three intermediate frequency signals each having a different phase relationship commensurate with the respective distances between the point of transmission and points of reception; comparing the phase at said intermediate frequency of two pair of the three signals provided by extracting the intermediate frequency to obtain information corresponding to the differences in phase between the compared intermediate frequency signals of each pair; and summing the phase differences at the intermediate frequency to provide a measure of the distance from the baseline to the point of transmission.
Claim 3
Dependent Claim
40 words
The method of claim 1 further comprising: subtracting the phase differences at the intermediate frequency to provide a measure of the angle between the direction normal to the midpoint of the baseline and the direction to the point of transmission.
Claim 4
Dependent Claim
27 words
The method of claim 2 wherein the step of extracting each intermediate frequency includes: heterodyning the received carrier and sideband signals to derive the intermediate frequency signal.
Claim 5
Dependent Claim
35 words
The method of claim 1 wherein the step of receiving the transmitted signals includes: positioning three receiving antennas along a common baseline with a separation distance equivalent to the wave length of the modulation signal.
Claim 6
Dependent Claim
70 words
The method of claim 4 wherein the step of comparing phase comprises: comparing the phase of the signal derived from extraction of the intermediate frequency from the carrier and sideband signals as received at the central of the three antennas with each of the signals derived from extraction of the intermediate frequency from the carrier and sideband signals as received at each antenna located at each end of the baseline.
Claim 7
Dependent Claim
27 words
The method of claim 5 wherein the step of extracting the intermediate frequency includes: heterodyning the received carrier and sideband signals to derive the intermediate frequency signal.
Claim 8
Dependent Claim
36 words
The method of claim 6 comprising: subtracting the phase difference information to provide a measure of the angle between the direction normal to the midpoint of the baseline and the direction to the point of transmission.
Claim 9
Dependent Claim
155 words
A passive distance measuring system comprising: means for generating and simultaneously transmitting a carrier frequency signal and a first sideband signal displaced in frequency from said carrier by an intermediate frequency; means for receiving the transmitted carrier and sideband signals, said receiving means including: three receiving antennas linearly spatially displaced along a common baseline; and heterodyning means connected to each receiving antenna for providing output signals commensurate with said intermediate frequency, each of said intermediate frequency output signals having the same frequency and each of said signals having a phase relationship dependent upon the distance between the respective receiving antenna and the transmitting antenna; and means connected to said receiving means and said heterodyning means for comparing the phase of pairs of said intermediate frequency output signals, said comparing means providing an output signal commensurate with the difference between the phase differences of said compared signals as an indication of the direction to the transmitter.
Claim 10
Dependent Claim
155 words
A passive distance measuring system comprising: means for generating and simultaneously transmitting a carrier frequency signal and a first sideband signal displaced in frequency from said carrier by an intermediate frequency; means for receiving the transmitted carrier and sideband signals, said receiving means including: three receiving antennas linearly spatially displaced along a common baseline; and heterodyning means connected to each receiving antenna for providing output signals commensurate with said intermediate frequency, each of said intermediate frequency output signals having the same frequency and each of said signals having a phase relationship dependent upon the distance between the respective receiving antenna and the transmitting antenna; and means connected to said receiving means and said heterodyning means for comparing the phase of pairs of said intermediate frequency output signals, said comparing means providing an output signal commensurate with the difference between the phase differences of said compared signals as an indication of the direction to the transmitter.
Claim 11
Dependent Claim
38 words
The apparatus of claim 8 further comprising: additional comparing means providing an output signal commensurate with the sum of the phase differences of said compared signals as an indication of the distance between the baseline and the transmitter.
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) | 1980-08-08 | 1981-02-07 | 1981-08-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-08 | 1985-02-07 | 1985-08-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-08 | 1989-02-07 | 1989-08-09 | $7700.00 | Window Closed / Lapsed |