GB2418313A - Direction finder - Google Patents

Direction finder Download PDF

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Publication number
GB2418313A
GB2418313A GB0518236A GB0518236A GB2418313A GB 2418313 A GB2418313 A GB 2418313A GB 0518236 A GB0518236 A GB 0518236A GB 0518236 A GB0518236 A GB 0518236A GB 2418313 A GB2418313 A GB 2418313A
Authority
GB
United Kingdom
Prior art keywords
receiving
antenna
mixer
target
deviation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB0518236A
Other versions
GB0518236D0 (en
GB2418313B (en
Inventor
Frank Gottwald
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of GB0518236D0 publication Critical patent/GB0518236D0/en
Publication of GB2418313A publication Critical patent/GB2418313A/en
Application granted granted Critical
Publication of GB2418313B publication Critical patent/GB2418313B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • 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
    • G01S13/06—Systems determining position data of a target
    • G01S13/42—Simultaneous measurement of distance and other co-ordinates
    • G01S13/44—Monopulse radar, i.e. simultaneous lobing
    • 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
    • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
    • G01S3/14—Systems for determining direction or deviation from predetermined direction
    • G01S3/46—Systems for determining direction or deviation from predetermined direction using antennas spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems
    • G01S3/48—Systems for determining direction or deviation from predetermined direction using antennas spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured
    • 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
    • G01S13/93—Radar or analogous systems specially adapted for specific applications for anti-collision purposes
    • G01S13/931—Radar or analogous systems specially adapted for specific applications for anti-collision purposes of land vehicles
    • 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
    • G01S13/06—Systems determining position data of a target
    • G01S13/46—Indirect determination of position data
    • G01S2013/466—Indirect determination of position data by Trilateration, i.e. two antennas or two sensors determine separately the distance to a target, whereby with the knowledge of the baseline length, i.e. the distance between the antennas or sensors, the position data of the target is determined
    • 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
    • G01S13/06—Systems determining position data of a target
    • G01S13/46—Indirect determination of position data
    • G01S2013/468—Indirect determination of position data by Triangulation, i.e. two antennas or two sensors determine separately the bearing, direction or angle to a target, whereby with the knowledge of the baseline length, the position data of the target is determined

Abstract

A receiving array with several antenna columns is provided to determine the target angle of deviation in a pulse radar system. There is one downlink mixer (43) for each antenna column and a delay line (9) between at least one antenna column and the downlink mixer. An evaluation unit (6) determines the phase difference between the output signals of the downlink mixers corresponding to the Doppler shift of a radar target. From this the angular position of the target can be determined. The received signal may be scanned in order to determine the Doppler shift and hence the speed of the target.

Description

Receiving system for determining a target angle of deviation
Prior art
Pulse radar systems are used to determine distance and speed of objects in road traffic. A radar system of this kind operates, for example, at 24. 125GHz. Determining target angles of deviation of relevant objects is normally carried out by several radar sensors by means of triangulation or trilateration. A single radar sensor is not capable of estimating the direction. It measures only the distance and radial speed.
To determine the angle of deviation of relevant objects there are other methods besides the triangulation and trilateration methods, in which the antenna diagram is pivoted. Phase shifters are necessary this, executed analogously or discretely. A device of this kind is known from DE10256524. 4. However, this requires at least one phase shifter which can be switched over and/or one or more quadrature mixers (I/Q mixers).
Methods are also known which perform digital antenna pivoting. An antenna array is used, in which the antenna columns are evaluated separately. The phase information in the individual columns is drawn on to determine the angle deviation.
Advantages of the invention With the measures of claim 1, i.e. a receiving array consisting of several antenna columns is provided, a downlink mixer is provided in the receiving branch for each antenna column, a delay link is provided between at least one antenna column and an associated downlink mixer, an evaluating unit is set up to process the output signals of the downlink mixer in such a way that a phase shift can be ascertained from at least two receiving branches by scanning the receiving signal showing a phase shift and therefore the target angle of deviation for a target object can be determined, a receiving system, space-saving in terms of hardware, for determining the target angle of deviation in a pulse radar system can be achieved, which, in particular, needs no expensive quadrature mixer (I/Q mixer), but manages with one single mixer per antenna column. The antenna columns can be constructed identically.
It is only necessary to provide a delay link, e.g. implemented by an extended supply line with a longitudinal or phase difference of a quarter of the operating wavelength on the line, in one of at least two receiving branches between the antenna column and the mixer.
Expensive RF converters are not necessary.
If the electromagnetic wave reflected from an object comes directly from the front on to the receiving array, the antenna system behaves like an antenna column with an I/Q mixer. The most important targets in front of a motor vehicle, in other words in the lane of travel, are thus detected as in customary systems. There are no gaps in stationary situations.
In respect of the RF front end there is practically no difference in terms of outlay and costs between this structure and conventional SRR (short range radar) systems.
If the reflected signals are incident from the side (deviation in azimuth), phase shifts in the signals arise because of the basic interval between the antenna columns.
These angle differences diverging from 90 degrees are utilised for determining the deviation. With two receiving columns it is thus possible to measure precisely one target in respect of the angle of deviation in one range gate.
Advantageous configurations are disclosed in the subordinate claims.
Description of embodiment examples
Before going into details of the actual invention, conventional receiving systems are explained for better understanding.
Fig. 1 shows a two-column receiving system with four patches 1 per column. The patches 1 of each column lead in each case to a duct 2 of the patch carrier (RF board). The conductor paths running on the back of the RF board (equipping side) are drawn as dotted lines.
In the left receiving path a switchable 1-bit 180-degree phase shifter 3 is provided. After the summation point of the two receiving paths there follows a downlink mixer 4, to which a local oscillator frequency LO is fed. The receiving signal is fed to an evaluating unit 6 via a following low pass 5.
The phase shifter in O degrees state generates beam maximum in the main beam direction (total beam). In 180 degrees state the phase shifter generates two lateral beams and a zero point in the main beam direction (differential beam).
The lateral beams have a phase difference of 180 degrees, required for deciding ("target on right, target on left".
The 1-bit 180-degree phase shifter 3 has approximately 3 dB losses, which effects an uneven distribution of power. This can be taken into account as required by an asymmetrical power splitter before the mixer. The downlink mixer is embodied as an I/Q mixer. The angle measurement is done by amplitude and phase comparison of total and differential beam (monopulse). The interval between the columns is in the range 0.5... 0.55 lambda 0 = operating wavelength, i.e. 6.2 mm... 6.8 mm, so that secondary lobes remain low and no additional ambiguities occur in the detection area.
Owing to the total additional attenuation losses, in particular duct losses, a smaller antenna gain is to be expected than with the previous one-column arrangement. The switchover of the phase states (0 degrees/180 degrees) is preferably done in the same range gate, thereby either double scanning time (20 ms) or with identical scanning time (10 ms) only half the number of pulses (half integration gain).
The disadvantages of this arrangement are: - greater space requirement on RF layer for 180 degree phase shifter, - high interlinking of the antenna columns owing to the small interval, - low range/performance owing to additional losses and the integration loss - high computer outlay for additional task of angle estimation (update rate), - little memory for additional task of angle estimation, too great a target fluctuation during switchover (phase and amplitude errors).
The number of columns can be increased. For example, with four columns two can be switched together in each case.
In the receiving system according to Fig. 2, instead of a 180-degree phase shifter two I/Q mixers 41 and 42 with corresponding circuitry are provided.
This concept has the following characteristics: - no integration loss, as there is no switchover, - no problem in respect of target fluctuation, as there is no switchover, - additional attenuation only owing to ducts, no additional (asymmetrical) power splitters, therefore possibly higher antenna gain than with one- column arrangement (at least higher gain than in Fig. 1), - angle evaluation by digital, possibly high-resolution methods, such as, e.g. Music, Esprit, or by classic methods such as single journey evaluation or monopulse evaluation, - interval between columns in the range of 050.55 lambda 0, i.e. 6.2 mm... 6.8 mm, therefore high unambiguous range in azimuth guaranteed (±50 degrees), - large space requirement on RF layer for second I/Q mixer, - high intercoupling of the antenna columns owing to the small interval, - high computer outlay for additional task of angle estimation (update rate), - little memory for additional task of angle estimation.
Instead of a second mixer, a changeover switch 7 for the individual receiving paths can also be provided (Fig. 3).
However, this leads to switchover losses. The power of the column not active at the time possibly has to be absorbed.
Variants with 180-degree hybrids 8, e.g. Ratrace, are also possible (Fig. 4), which, however, require a great deal of space on the equipping side both for the 180-degree hybrid and for the second I/Q mixer.
In the receiving system according to the invention according to Fig. 5 one single downlink mixer 43 is necessary per antenna column, in other words no I/Q mixer.
Between at least one antenna column and one downlink mixer a delay link 9 is provided, preferably with an electrical length of a quarter of the operating wavelength. The interval between columns amounts to approximately half the operating wavelength.
If according to the invention only a single mixer is used, it is provided to gain the phase information by scanning the sinusoidal receiving signal (in the case of relative movements only). Owing to the double shift, targets moved relative to the receiving system generate a sinusoidal signal at the mixer output. This signal then has to be scanned, depending on the speed of the relevant objects, until the phase has been able to be determined. This time delay has to be adapted to the corresponding object and speed situations by intelligent algorithms or evaluation software. In stationary situations a single receiving sensor can ascertain only the distance. The smallest movements in the millimetre range are sufficient to measure the phase or the phase difference between the two (or n) receiving signals. Evaluation takes place in the evaluation unit 6.
In Fig. 6 an embodiment example according to the invention with three patch antenna columns is illustrated. It is suitable for measuring two objects. Only three single mixers, one each for each antenna column, are necessary. To reduce expense a delay link 9 is possibly provided in only one of the receiving paths. The signal processing can also be done in the common evaluation unit 61 according to amplification and A-D conversion. The evaluation unit 61 can be constructed for carrying out tracking, for producing a history of the targets and/or for adaptive triggering of range gates (taking into consideration signal delays for different distance ranges).
According to Fig. 7 the receiving system can have in general n columns for detecting n-1 targets.

Claims (7)

  1. Claims 1. Receiving system, in particular for determining the target angle
    of deviation in a pulse radar system, with the following features: - a receiving array consisting of several antenna columns is provided, - one downlink mixer (43) is provided in the receiving branch for each antenna column, - a delay link (9) is provided between at least one antenna column and one associated downlink mixer (43), - an evaluation unit (6, 61) is set up to process the output signals of the downlink mixer (43) in such a way that a phase shift can be ascertained from at least two receiving branches by scanning the receiving signal showing a double shift and therefore the target angle of deviation for a target object can be determined.
  2. 2. Receiving system according to claim 1, characterized in that the evaluation unit (6, 61) is set up to carry out scanning of the receiving signal, which is sinusoidal because of the double shift, as a function of the speed of a target object until the phase shift can be determined.
  3. 3. Receiving system according to claim 1 or 2, characterized in that the basic interval between the antenna columns is chosen as approximately half the operating wavelength.
  4. 4. Receiving system according to one of claims 1 to 3, characterized in that the delay link (9) has an electrical length of a quarter of the operating wavelength in at least one of the antenna columns.
  5. 5. Receiving system according to one of claims 1 to 4, characterized in that to determine the target angle of deviation of two objects a receiving array with a total of three antenna columns and one downlink mixer (43) in each case is provided for each antenna column.
  6. 6. Receiving system according to claim 5, characterized in that a delay link (9) is provided in only one of the receiving paths.
  7. 7. Any of the receiving systems substantially as hereinbefore described with reference to figures 5 to 7 of the accompanying drawings.
GB0518236A 2004-09-17 2005-09-07 Receiving system for determining a target angle of deviation Expired - Fee Related GB2418313B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE102004045108A DE102004045108A1 (en) 2004-09-17 2004-09-17 Receiving system for determining a target filing angle

Publications (3)

Publication Number Publication Date
GB0518236D0 GB0518236D0 (en) 2005-10-19
GB2418313A true GB2418313A (en) 2006-03-22
GB2418313B GB2418313B (en) 2007-03-28

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB0518236A Expired - Fee Related GB2418313B (en) 2004-09-17 2005-09-07 Receiving system for determining a target angle of deviation

Country Status (3)

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DE (1) DE102004045108A1 (en)
FR (1) FR2875605A1 (en)
GB (1) GB2418313B (en)

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1252152A (en) * 1958-11-07 1971-11-03
US4236159A (en) * 1975-02-03 1980-11-25 The United States Of America As Represented By The Secretary Of The Navy Passive direction finding system
US4443801A (en) * 1981-06-15 1984-04-17 The United States Of America As Represented By The Secretary Of The Army Direction finding and frequency identification method and apparatus
GB2167183A (en) * 1984-10-25 1986-05-21 Gec Avionics Direction finding arrangement
JPH028763A (en) * 1988-06-27 1990-01-12 Nippon Hoso Kyokai <Nhk> Automatic antenna directing device
FR2742552A2 (en) * 1986-09-23 1997-06-20 Dassault Electronique Interferometric receiver with measurement of instantaneous frequency
JPH1062506A (en) * 1996-08-20 1998-03-06 Mitsubishi Electric Corp Angle measuring equipment
JP2004347458A (en) * 2003-05-22 2004-12-09 Nakayo Telecommun Inc Radio wave direction finder

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1252152A (en) * 1958-11-07 1971-11-03
US4236159A (en) * 1975-02-03 1980-11-25 The United States Of America As Represented By The Secretary Of The Navy Passive direction finding system
US4443801A (en) * 1981-06-15 1984-04-17 The United States Of America As Represented By The Secretary Of The Army Direction finding and frequency identification method and apparatus
GB2167183A (en) * 1984-10-25 1986-05-21 Gec Avionics Direction finding arrangement
FR2742552A2 (en) * 1986-09-23 1997-06-20 Dassault Electronique Interferometric receiver with measurement of instantaneous frequency
JPH028763A (en) * 1988-06-27 1990-01-12 Nippon Hoso Kyokai <Nhk> Automatic antenna directing device
JPH1062506A (en) * 1996-08-20 1998-03-06 Mitsubishi Electric Corp Angle measuring equipment
JP2004347458A (en) * 2003-05-22 2004-12-09 Nakayo Telecommun Inc Radio wave direction finder

Also Published As

Publication number Publication date
FR2875605A1 (en) 2006-03-24
DE102004045108A1 (en) 2006-03-23
GB0518236D0 (en) 2005-10-19
GB2418313B (en) 2007-03-28

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 20120907