GB2035006A - Method and apparatus for measuring the speed of a moving object - Google Patents

Method and apparatus for measuring the speed of a moving object Download PDF

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Publication number
GB2035006A
GB2035006A GB7933981A GB7933981A GB2035006A GB 2035006 A GB2035006 A GB 2035006A GB 7933981 A GB7933981 A GB 7933981A GB 7933981 A GB7933981 A GB 7933981A GB 2035006 A GB2035006 A GB 2035006A
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Prior art keywords
speed
autocorrelation
beams
velocity
antenna
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Granted
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GB7933981A
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GB2035006B (en
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Patelhold Patenverwertungs and Elektro-Holding AG
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Patelhold Patenverwertungs and Elektro-Holding AG
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Publication of GB2035006A publication Critical patent/GB2035006A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/91—Radar or analogous systems specially adapted for specific applications for traffic control
    • G01S13/92—Radar or analogous systems specially adapted for specific applications for traffic control for velocity measurement
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/50—Systems of measurement based on relative movement of target
    • G01S13/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
    • G01S13/60—Velocity or trajectory determination systems; Sense-of-movement determination systems wherein the transmitter and receiver are mounted on the moving object, e.g. for determining ground speed, drift angle, ground track

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

The speed of moving objects is measured using the Doppler Radar principle. A mixer M receives the reflected radiation from the beams St1, St2 delivered by the antenna (A) and generates a Doppler signal (ds) having a velocity dependent frequency. An evaluation circuit DA produces from the Doppler signal (ds), a signal (vgr) which is applied to an autocorrelation circuit K to determine the timing of the autocorrelation window. The maximum time tau max of the autocorrelation function of the Doppler signal ds when divided into the separation (distance L) of the microwave beams (St1, St2) yields a more accurate velocity measurement. <IMAGE>

Description

SPECIFICATION Method and apparatus for measuring the speed of a moving object The invention relates to a method and apparatus for measuring the speed of a moving object.
Systems of Doppler radar, in particular systems using an antenna which irradiates along a relatively long section of roadway, are known from (inter alia) DE-OS 2237 139 and ZEV-Glas. Ann. (1977), No.
3 (March), pp. 79-82. Two measurement units, which radiate in different directions, can be used for compensating for the variable angle between radiation direction and speed vector (see CH-PS 522 315).
Furthermore, correlation devices are in use for effecting velocity measurement with optical means.
The correlation time is determined between two sensors. In this respect attention is directed to, for example DE-OS 2312 588.
However, the above proposals entail drawbacks.
The Doppler radar devices require elaborate technical recources, as two complete radar systems are needed. The existing correlation devices, though less sensitive to the tilting effect, have the drawback that they operate by optical techniques. For applications in track radar, and also for many industrial applications, dirtying is one of the main problems of the optical devices. Correlation devices are also elaborate and expensive when they are operated digitally, as large data memories are required and many multiplications have to be carried out. This drawback is particularly pronounced when the order of magnitude of the correlation time is not known.
With a view to mitigating at least some of the foregoing disadvantages, there is provided in accordance with a first aspect of the invention; a method of measuring the speed of a moving subject, which comprises transmitting by means of a microwave antenna (A), extending in the direction of movement at least two microwave beams intersecting the path of the object, evaluating the Doppler frequency to obtain a coarse measurement of the speed, and autocorrelating the Doppler frequency signal within an autocorrelation window determined by the coarse speed measurement to obtain a more accurate measurement of the time taken by the object to traverse the distance between the two beams, the latter time being indicated by the maximum value of the autocorrelation function.
According to a second aspect of the invention, there is provided apparatus for measuring the velocity of an object, comprising a microwave oscillator, a mixer and an antenna operative to radiate at least two beams intersecting the path of the object, an evaluation circuit connected to receive a velocity dependent Doppler frequency signal and operative to produce a control signal, and an autocorrelation circuit connected to autocorrelate the Doppler frequency signal within a time window determined by the control signal produced by the evaluation circuit.
With the aid of the invention there may be obtained a velocity measurement approximately independent of the angle between the radar beams and the velocity of travel. Furthermore, the Doppler apparatus and the correlator employ the same mic rowave components or part.
The invention will now be further described, by way of example, with reference to an embodiment illustrated in the accompanying drawing.
A microwave slot antenna A, extends in the direction of travel of the object of which the velocity is to be measured and does not radiate along its whole length but, as illustrated, through (for example) the openings 01 and 02 in the vicinity of the two ends.
St1 and St2 are the two beams. The apparatus includes a termination As, a mixer M, and a microwave oscillator Mo. RU designates a static rough background, against which the movement takes place. It is alternatively possible for a number of radiating part-sections to be arranged at regular intervals; under certain circumstances this will improve the correlation. It will also be advantageous to use a slot antenna with at least two mutally offset, homologous groups of slots.
The mixer M receives the reflected radiation delivered by the antenna and generates a primary Doppler signal ds having a velocity representative frequency. The evaluation circuit DA evaluates the primary Doppler signal do and produces at its output a control signal Vgr, which corresponds to the coarse value of the speed. This signal is fed to a control input of an autocorrelation circuit K which receives at its input the primary Doppler signal ds. The control circuit serves to determine the autocorrelation window.At the output of the autocorrelation circuit K appears the more accurate value of the speed, which is obtained from the equation V = L/TmaX, where L is the mean distance between the two beams St1 and St2, and Tmax designates the time point of the autocorrelation maximum.
As the approximate value of the speed is known from the Doppler frequency signal da, the autocorrelation window can be considerably narrower than that employed in optical velocity measuring apparatus thus simplifying the operation of the autocorrelator.
1. A method of measuring the speed of a moving object, which comprises transmitting by means of a microwave antenna (A) extending in the direction of movement at least two microwave beams intersecting the path of the object, evaluating the Doppler frequency to obtain a coarse measurement of the speed, and autocorrelating the Doppler frequency signal within an autocorrelation window determined by the coarse speed measurement to obtain a more accurate measurement of the time taken by the object to traverse the distance between the two beams, the latter time being indicated by the maximum value of the autocorrelation function.
2. The method as claimed in claim 1, wherein a slot antenna with two radiating openings in the vicinity of the two antenna ends is employed, the speed being evaluated from the formula V = LlTmax where L is the mean distance between the two beams (St1, St2), andrmax is the time of the autocor
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Method and apparatus for measuring the speed of a moving object The invention relates to a method and apparatus for measuring the speed of a moving object. Systems of Doppler radar, in particular systems using an antenna which irradiates along a relatively long section of roadway, are known from (inter alia) DE-OS 2237 139 and ZEV-Glas. Ann. (1977), No. 3 (March), pp. 79-82. Two measurement units, which radiate in different directions, can be used for compensating for the variable angle between radiation direction and speed vector (see CH-PS 522 315). Furthermore, correlation devices are in use for effecting velocity measurement with optical means. The correlation time is determined between two sensors. In this respect attention is directed to, for example DE-OS 2312 588. However, the above proposals entail drawbacks. The Doppler radar devices require elaborate technical recources, as two complete radar systems are needed. The existing correlation devices, though less sensitive to the tilting effect, have the drawback that they operate by optical techniques. For applications in track radar, and also for many industrial applications, dirtying is one of the main problems of the optical devices. Correlation devices are also elaborate and expensive when they are operated digitally, as large data memories are required and many multiplications have to be carried out. This drawback is particularly pronounced when the order of magnitude of the correlation time is not known. With a view to mitigating at least some of the foregoing disadvantages, there is provided in accordance with a first aspect of the invention; a method of measuring the speed of a moving subject, which comprises transmitting by means of a microwave antenna (A), extending in the direction of movement at least two microwave beams intersecting the path of the object, evaluating the Doppler frequency to obtain a coarse measurement of the speed, and autocorrelating the Doppler frequency signal within an autocorrelation window determined by the coarse speed measurement to obtain a more accurate measurement of the time taken by the object to traverse the distance between the two beams, the latter time being indicated by the maximum value of the autocorrelation function. According to a second aspect of the invention, there is provided apparatus for measuring the velocity of an object, comprising a microwave oscillator, a mixer and an antenna operative to radiate at least two beams intersecting the path of the object, an evaluation circuit connected to receive a velocity dependent Doppler frequency signal and operative to produce a control signal, and an autocorrelation circuit connected to autocorrelate the Doppler frequency signal within a time window determined by the control signal produced by the evaluation circuit. With the aid of the invention there may be obtained a velocity measurement approximately independent of the angle between the radar beams and the velocity of travel. Furthermore, the Doppler apparatus and the correlator employ the same mic rowave components or part. The invention will now be further described, by way of example, with reference to an embodiment illustrated in the accompanying drawing. A microwave slot antenna A, extends in the direction of travel of the object of which the velocity is to be measured and does not radiate along its whole length but, as illustrated, through (for example) the openings 01 and 02 in the vicinity of the two ends. St1 and St2 are the two beams. The apparatus includes a termination As, a mixer M, and a microwave oscillator Mo. RU designates a static rough background, against which the movement takes place. It is alternatively possible for a number of radiating part-sections to be arranged at regular intervals; under certain circumstances this will improve the correlation. It will also be advantageous to use a slot antenna with at least two mutally offset, homologous groups of slots. The mixer M receives the reflected radiation delivered by the antenna and generates a primary Doppler signal ds having a velocity representative frequency. The evaluation circuit DA evaluates the primary Doppler signal do and produces at its output a control signal Vgr, which corresponds to the coarse value of the speed. This signal is fed to a control input of an autocorrelation circuit K which receives at its input the primary Doppler signal ds. The control circuit serves to determine the autocorrelation window.At the output of the autocorrelation circuit K appears the more accurate value of the speed, which is obtained from the equation V = L/TmaX, where L is the mean distance between the two beams St1 and St2, and Tmax designates the time point of the autocorrelation maximum. As the approximate value of the speed is known from the Doppler frequency signal da, the autocorrelation window can be considerably narrower than that employed in optical velocity measuring apparatus thus simplifying the operation of the autocorrelator. CLAIMS
1. A method of measuring the speed of a moving object, which comprises transmitting by means of a microwave antenna (A) extending in the direction of movement at least two microwave beams intersecting the path of the object, evaluating the Doppler frequency to obtain a coarse measurement of the speed, and autocorrelating the Doppler frequency signal within an autocorrelation window determined by the coarse speed measurement to obtain a more accurate measurement of the time taken by the object to traverse the distance between the two beams, the latter time being indicated by the maximum value of the autocorrelation function.
2. The method as claimed in claim 1, wherein a slot antenna with two radiating openings in the vicinity of the two antenna ends is employed, the speed being evaluated from the formula V = LlTmax where L is the mean distance between the two beams (St1, St2), andrmax is the time of the autocor relation maximum.
3. A method according to claim 1, in which a slot antenna with a number of openings arranged at regular intervals is employed.
4. A method according to claim 1, in which a slot antenna with at least two mutally offset, homologous groups of slots is employed.
5. Apparatus for measuring the velocity of an object, comprising a microwave oscillator, a mixer and an antenna operative to radiate at least two beams intersecting the path of the object, an evaluation circuit connected to receive a velocity dependent Doppler frequency signal and operative to produce a control signal, and an autocorrelation circuit connected to autocorrelate the Doppler frequency signal within a time window determined by the control signal produced by the evaluation circuit.
6. Apparatus for measuring the speed of a moving object constructed, arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawing.
GB7933981A 1978-10-03 1979-10-01 Method and apparatus for measuring the speed of a moving object Expired GB2035006B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH1024378A CH633637A5 (en) 1978-10-03 1978-10-03 METHOD OF MEASURING THE SPEED OF A MOVING OBJECT.

Publications (2)

Publication Number Publication Date
GB2035006A true GB2035006A (en) 1980-06-11
GB2035006B GB2035006B (en) 1982-12-08

Family

ID=4361030

Family Applications (1)

Application Number Title Priority Date Filing Date
GB7933981A Expired GB2035006B (en) 1978-10-03 1979-10-01 Method and apparatus for measuring the speed of a moving object

Country Status (8)

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AT (1) AT377099B (en)
CH (1) CH633637A5 (en)
DE (1) DE2845127A1 (en)
FR (1) FR2438273B1 (en)
GB (1) GB2035006B (en)
IT (1) IT1123390B (en)
NL (1) NL7907308A (en)
SE (1) SE7908085L (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997037242A1 (en) * 1996-04-01 1997-10-09 Gatsometer B.V. Method and apparatus for determining the speed and location of a vehicle
CN101943753A (en) * 2010-07-29 2011-01-12 西安空间无线电技术研究所 Method for measuring microwave radar beam central transverse velocity

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3810357A1 (en) * 1988-03-26 1989-10-05 Licentia Gmbh METHOD FOR LOCAL TRAFFIC DATA ACQUISITION AND EVALUATION AND DEVICE FOR CARRYING OUT THE METHOD

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2237139C2 (en) * 1972-07-28 1982-04-29 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Doppler radar for vehicle speed measurement - has underbody hollow conductor antenna with longitudinal slot aperture
US3838424A (en) * 1973-02-20 1974-09-24 Singer Co Microwave interference pattern sensor
DE2714365C2 (en) * 1977-03-31 1984-07-05 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Doppler radar device with determination of the direction of movement

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997037242A1 (en) * 1996-04-01 1997-10-09 Gatsometer B.V. Method and apparatus for determining the speed and location of a vehicle
US6266627B1 (en) 1996-04-01 2001-07-24 Tom Gatsonides Method and apparatus for determining the speed and location of a vehicle
CN101943753A (en) * 2010-07-29 2011-01-12 西安空间无线电技术研究所 Method for measuring microwave radar beam central transverse velocity

Also Published As

Publication number Publication date
CH633637A5 (en) 1982-12-15
AT377099B (en) 1985-02-11
DE2845127A1 (en) 1980-04-17
FR2438273A1 (en) 1980-04-30
ATA573179A (en) 1984-06-15
GB2035006B (en) 1982-12-08
FR2438273B1 (en) 1985-08-23
IT1123390B (en) 1986-04-30
IT7926150A0 (en) 1979-10-01
SE7908085L (en) 1980-04-04
NL7907308A (en) 1980-04-09

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