JP3058223B2 - Speed measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed measuring device of a radio wave type for measuring the speed of a target object (for example, a vehicle traveling on a road) using a radio wave beam. The device of the present invention is effective in accurately measuring the speed of a target object without being sensed by a target object whose speed is to be measured and without being affected by interference or interference from other devices. Can be used.

[0002]

2. Description of the Related Art In a conventionally known speed measuring device for a vehicle, for example, CW, FM-C
W, pulses, and the like are modulated by various modulation methods into a transmission signal, and this signal (radio wave) is projected toward the traveling vehicle, and the reception signal reflected from the traveling vehicle and returned (ie, Doppler frequency deviation) This signal is mixed with the transmission signal to detect a Doppler frequency component, and the speed of the traveling vehicle is measured based on the amount of deviation of the frequency.

[0003]

As described above, the conventional speed measuring device uses a system (radio wave system) in which a radio wave is projected toward the direction of a traveling vehicle that is facing and a reflected wave is received. Therefore, as has been seen in recent years, a detection element having good detection sensitivity has been developed and manufactured, so that it is possible to receive a measurement projection radio wave beyond a measurement range of a vehicle speed. Therefore, there is a problem of so-called “reverse detection” in which the fact that the speed measurement is being performed is detected by the traveling vehicle that is facing the vehicle.

Further, when measuring the running speed of a vehicle by arranging it at a plurality of locations, the radio wave type speed measuring device is affected by the interference of the emitted radio waves between the devices. It requires some ingenuity. That is, it is necessary to set transmission frequencies sufficiently separated between the devices, and therefore, it is necessary to prepare a plurality of transmission frequencies.
For this reason, there is a problem that it is difficult to operate a plurality of devices simultaneously at the same place to measure the speed of the traveling vehicle.

The present invention has been made in view of the problems in the prior art, and provides a speed measuring device capable of accurately measuring the speed of a target object without being sensed by an approaching target object. It is intended to be.
Another object of the present invention is to accurately measure the speed of a target object without being affected by interference between a plurality of speed measuring devices of the present invention when the plurality of speed measuring devices are arranged.

[0006]

To solve the above problems [Means for Solving the Problems] According to the present invention, there is provided an apparatus for measuring the velocity of the target object to come close to each other, means for generating a carrier signal for transmission, reference numeral A code generator for generating an encoded two-phase random signal for modulation in response to an output of the clock generator set to a frequency corresponding to the speed measurement range by the setting signal means and a code setting signal; Means for directly performing spreading modulation on the transmission carrier signal using the encoded two-phase random signal, and projecting the modulated transmission carrier signal as a beam toward the target object via a circulator, An antenna for receiving a reflected wave from a target object; a mixer for mixing a signal corresponding to the received reflected wave with the transmission carrier signal to generate an intermediate frequency signal; A correlator for performing a correlation demodulation between a frequency signal and a signal having the same sign as the sign of the two-phase random signal for modulation; and a relative velocity difference between the target object and the present apparatus among the correlated demodulated signals. Means for passing only the corresponding Doppler frequency component, means for pulse-forming the Doppler frequency component, measuring the period thereof, and detecting the Doppler frequency corresponding to the speed of the target object; and Means for calculating the speed of the target object using information means of the projection beam angle calculated in accordance with the measurement situation, and outputting speed information of the target object. You.

In the above-mentioned speed measuring apparatus, a signal provided between the code generator and the correlator and having the same code as the code of the two-phase random signal for modulation is shifted by two or more bits and delayed. A delay circuit having a delay circuit for controlling the switching of the delay circuit in response to a bit switching signal, and a delay setting device for generating the bit switching signal based on bit setting signal generating means ; The two-phase random signal may be shifted by two or more bits according to a bit switching signal from the delay setting device, thereby variably setting the effective measurement range of the apparatus according to the measurement situation .

[0008] The apparatus further comprises a variable attenuator provided on a path from the transmission carrier signal being modulated to being input to the mixer via the antenna, wherein the variable attenuator is provided with a delay setting unit for setting the attenuation of the variable attenuator to the delay setting unit. May be controlled on the basis of a control signal from the controller, thereby controlling the transmission output of the present apparatus to a value necessary for a distance to an effective measurement range according to the bit setting signal.

In the above-mentioned speed measuring apparatus, the apparatus further comprises a clock oscillator for supplying a clock set to a frequency corresponding to the speed measuring range to the code generator, wherein the frequency of the oscillation clock of the clock oscillator is set to an external value. The speed measurement range may be variably set by changing the clock frequency setting signal from the CPU. Furthermore, the codes of the two-phase random signals generated from the code generators of the respective devices of the above-described speed measuring device are set to different codes from each other, and are simultaneously arranged at a plurality of different positions.
Speeds of multiple target objects that face each other
May be measured .

[0010]

According to the above arrangement, the output of the code generator, that is, the code of the two-phase random signal is variably set based on the code setting signal, and the signal modulated using the set code is projected as a radio beam. Then, a reflected wave from the target object is received and detected, and correlation demodulation is performed with a modulation code, a Doppler frequency component is detected, and velocity information of the target object is output using information of a projection beam angle. Therefore, the transmission power density per unit frequency band is suppressed to a small value, the possibility of interfering with other devices is low, and confidentiality can be provided. Therefore, it is possible to accurately measure the speed of the target object without being detected back by the target object that is facing.

A delay circuit provided between the code generator and the correlator for shifting a signal having the same sign as that of the modulation two-phase random signal by two or more bits and delaying the signal; In the case where the apparatus further comprises a delay unit having means for controlling the switching in response to a bit switching signal, and a delay setting unit that generates the bit switching signal based on an external bit setting signal, By variably setting the bit delay of the modulation code based on the bit setting signal, the effective measurement range of the present apparatus can be changed and set. This makes it possible to arrange the present device at a position invisible from the target object (for example, displaced backward from the side of the road) and measure the speed of the target object.

Further, when the above-mentioned speed measuring devices are arranged and used at a plurality of locations, the codes of the two-phase random signals generated from the code generators of the respective devices are variably set to different codes. Each device can be made less susceptible to the effects of interference from the emitted radio waves. For details of other structural features and operations of the present invention,
A description will be given using embodiments described below with reference to the accompanying drawings.

[0013]

FIG. 1 shows the configuration of a speed measuring apparatus according to one embodiment of the present invention. In the figure, 11 is an oscillator for generating a carrier signal fo for transmission, 12 is a directional coupler for extracting the output fo of the oscillator, 13 is a clock oscillator responding to a clock frequency setting signal CKS from the outside, The clock oscillator variably sets the output clock frequency to a frequency corresponding to the speed measurement range (that is, the effective distance of the projection beam) by changing the voltage value using, for example, a voltage controlled oscillator. Reference numeral 14 denotes a code generator which responds to a code setting signal CDS from the outside and an output clock of the clock oscillator 13. The code generator is constituted by a shift register or the like. Generate an encoded two-phase random signal (ie, modulation code) MS.

Reference numeral 15 denotes an output of the code generator 14 (modulation code M
S) and a modulator responsive to the transmitted carrier signal fo supplied via the directional coupler 12, said modulator comprising, for example, a diode-balanced modulator, wherein the transmitted carrier signal fo is modulated by said modulation code. Is directly spread-spectrum modulated. 16 projects the beam toward the traveling vehicle 30 facing the vehicle, and also displays the traveling vehicle 30 on the beam.
An antenna 17 receives a reflected wave from the antenna, a circulator 17 guides the output of the modulator 15 to the antenna 16, and receives a reflected wave signal received by the antenna. A mixer for mixing a part of the output (signal fo) to generate an intermediate frequency signal, and 19 is a video amplifier for amplifying the output of the mixer.

Reference numeral 20 denotes a correlation between the output of the video amplifier 19 (intermediate frequency signal) and the output of the code generator 14 (ie, a two-phase random signal having the same sign as the signal MS obtained by modulating the transmission carrier signal fo). A correlator 21 for demodulation outputs a Doppler-shifted reflected wave component from the traveling vehicle 30 of the output signal component of the correlator 20, that is, a Doppler frequency component (fd) corresponding to a relative speed difference between the traveling vehicle 30 and the present apparatus 10. ) Are shown, and a Doppler filter and amplifier are shown that amplify its signal components. Reference numeral 22 denotes a frequency detector which forms a pulse of the signal having the Doppler frequency component, measures the pulse period, and detects a Doppler frequency fd corresponding to the speed of the traveling vehicle 30 based on the pulse.

Reference numeral 23 denotes a traveling vehicle 30 using the output (Doppler frequency fd) of the frequency detector 22 and information (θ) of the projection beam angle supplied from another circuit in the apparatus or from the outside.
Is a speed calculator that calculates the speed of the speed and outputs it as speed information V. The speed calculator 23 calculates the following equation: fd =
The traveling speed V of the traveling vehicle 30 is calculated based on 2V / λ · cos θ. Here, λ indicates the wavelength of the transmission carrier signal fo.

As shown in FIG. 2, the projection beam angle θ depends on the beam projection direction from the apparatus 10 and the traveling vehicle 30.
Is defined by the angle between In this case, it is assumed that the traveling vehicle 30 travels in parallel along the road, the device 10 is installed on one side of the road, and the speed V of the traveling vehicle 30 is measured based on the side of the road. Although the projection beam has a width, it is shown by one straight line for simplification in the illustrated example.

The projection beam angle θ is set by adjusting the arrangement of the apparatus 10 so that the projection beam direction of the antenna 16 is directed to a predetermined angle, or by measuring the projection beam angle and externally setting the angle. You may make it input angle information ((theta)). Alternatively, angle information may be automatically input using an angle measuring device or the like. The speed measuring device 10 of the present embodiment configured as described above is arranged on at least one of both sides of the road (see FIGS. 6 and 7) at the time of actual measurement, and calculates the speed V of the traveling vehicle that is facing the road. And has the function of outputting the data.

That is, in the above configuration, the modulator 15
Performs direct spread modulation on the transmission carrier signal fo supplied from the oscillator 11 via the directional coupler 12 by the coded two-phase random signal (modulation code) MS from the code generator 14, and performs the modulation. Signal is circulator 1
The reflected wave signal is projected from the antenna 16 to the traveling vehicle 30 via the antenna 16 via the antenna 7, and the reflected wave signal is received by the antenna 16 and input to the mixer 18 via the circulator 17. The mixer 18 mixes a part of the output (transmitted carrier signal fo) of the directional coupler 12 with a received signal from the circulator 17 as a local signal and outputs the signal as an intermediate frequency signal. This intermediate frequency signal is amplified by the video amplifier 19 and then input to the correlator 20. In the correlator 20,
Correlation demodulation is performed between the output of the video amplifier 19 and the coded two-phase random signal MS for modulation from the code generator 14, and the demodulated signal is a Doppler filter and an amplifier 2.
After passing only a predetermined frequency component (fd) through 1 and further amplified, the frequency detector 22 detects the frequency. The output (Doppler frequency fd) of the detector 22 is input to the speed calculator 23, and the speed of the traveling vehicle 30 is calculated using the information (θ) of the projection beam angle as described above, and is output as speed information V. . This speed information V is
The data is supplied to a display, a printer, or the like (not shown) to be displayed or recorded and displayed.

The principle of operation relating to correlation and demodulation of a two-phase random signal is described, for example, in the document "SPREAD S
PECTRUM SYSTEMS, by RCDIXON ", and the present embodiment utilizes this principle. Specifically, an M-sequence code, a GOLD code, or the like is used as a two-phase random signal. This two-phase random signal generates a high correlation output for a signal that is in phase with its own code, and generates an extremely low correlation output for another code or a code whose phase is shifted by one or more bits. It has the property of obtaining a high signal gain (for example, see the above-mentioned document "SPREAD SPECT
RUM SYSTEMS ").

Therefore, by utilizing this principle and variably setting the output of the code generator 14, that is, the coded two-phase random signal (modulation code MS) based on the code setting signal CDS, the traveling running opposite to each other is performed. The speed of the traveling vehicle 30 can be accurately measured without being sensed (reversely detected) by the vehicle 30 side. Further, the speed measurement range can be set by variably setting the frequency of the oscillation clock of the clock oscillator 13 based on the clock frequency setting signal CKS.

When the apparatus 10 is arranged at a plurality of locations as shown in FIGS. 6 and 7, for example, the coded two-phase random signal MS of the code generator 14 of each apparatus is converted into a different code. By variably setting, each device can be made less susceptible to interference by emitted radio waves. Thereby, as shown in FIGS. 6 and 7, if the present device 10 is appropriately arranged at a plurality of locations according to the situation of the measurement place,
It is possible to accurately measure the speeds of the vehicles 30a and 30b traveling in parallel.

FIG. 3 shows the configuration of another embodiment of the present invention. The speed measuring apparatus 10a of this embodiment includes a delay setting unit 24, a variable attenuator 25, and a delay unit 26 in addition to the configuration of FIG. The delay setter 24 generates a bit switching signal BC (described later) and a control signal AC (described later) based on an external bit setting signal BS. Variable attenuator 2
5 is connected between the directional coupler 12 and the modulator 15;
The transmission carrier signal f supplied via the directional coupler 12
o is attenuated to a signal level corresponding to the control signal AC, and sent to the modulator 15. By the variable setting of the amount of attenuation, control is performed so that the transmission output of the present apparatus becomes a value necessary for the distance to the effective measurement range according to the bit setting signal BS.

The delay unit 26 includes the code generator 14 and the correlator 2
0, and a delay circuit D for shifting the modulation code MS of the two-phase random signal from the code generator 14 by two bits and delaying it as shown in FIG.
And a switch SW for controlling connection switching of the delay circuit to the correlator 20 by the bit switching signal BC. The delay circuit D can be configured using, for example, a hybrid module of an IC and a delay line. Bit switching signal BC from delay setting device 24
By delaying the modulation code MS of the two-phase random signal by two bits through the switch SW, the effective measurement range of the present apparatus can be changed.

That is, as shown in the operation waveform diagram of FIG.
When the bit is shifted, a distance range (ie, an effective measurement range) corresponding to the reciprocating time of the radio wave by one bit before and after the distance corresponding to the reciprocating time of the radio wave can be set. Although the variable attenuator 25 is provided between the directional coupler 12 and the modulator 15 in the embodiment of FIG. 3, the variable attenuator 25 is installed at the position where the transmission carrier signal fo from the directional coupler 12 is located. Any location may be used as long as the path is modulated and input to the mixer 18 via the circulator 17 and the antenna 16. For example, it may be provided between the modulator 15 and the antenna 16 or between the antenna 16 and the input terminal of the mixer 18.

According to the embodiment of FIG. 3, the following effects can be obtained in addition to the effects obtained in the embodiment of FIG. That is,
By variably setting the bit delay of the modulation code MS based on the bit setting signal BS, for example, as shown in FIG. The speed of the traveling vehicle can be measured without the traveling vehicle 30 finding the device 10a.

In each of the embodiments described above, the same antenna 16 is used for both transmission and reception. However, an antenna for transmission and an antenna for reception may be provided separately.

[0028]

As described above, according to the present invention, a transmission radio wave by modulation using an encoded two-phase random signal is beam-projected, and a reflected wave from a target object which is facing is received and detected. By performing correlation demodulation with the modulation code and detecting the Doppler frequency component and outputting the speed information of the target object using the information of the projection beam angle, the transmission power density can be suppressed to a small value. It is possible to reduce the possibility of interfering with other devices and to provide confidentiality. As a result, the speed of the target object can be accurately measured without being detected back by the target object.

Further, when the speed measuring device of the present invention is used by arranging it at a plurality of locations, the code of the two-phase random signal generated from the code generator of each device is variably set to different codes. This makes it possible to reduce the influence of interference by the emitted radio waves between the devices. Further, when a means for delaying a signal having the same code as that of the two-phase random signal for modulation by 2 bits or more and sending the delayed signal to the correlator is provided, the bit delay of the modulation code is variably set. The effective measurement range of the device can be changed. This makes it possible to dispose the device, for example, shifted rearward from the side of the road.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a speed measuring device as one embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a projection beam from a speed measurement device and a traveling vehicle that faces the projection beam.

FIG. 3 is a block diagram showing a configuration of a speed measuring device as another embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration example of a delay unit in FIG. 3;

FIG. 5 is a signal waveform diagram for explaining an operation of the delay unit of FIG. 4;

FIG. 6 is a diagram illustrating an example of an arrangement form of a speed measurement device.

FIG. 7 is a diagram showing another example of the arrangement of the speed measuring device.

FIG. 8 is a diagram showing still another example of an arrangement form of the speed measuring device.

[Explanation of symbols]

 10, 10a speed measuring device 11 oscillator 13 clock oscillator 14 code generator 15 modulator 16 antenna 17 circulator 18 mixer 20 correlator 21 Doppler filter and amplifier 22 frequency detector 23 Speed calculator 24 ... Delay setting device 25 ... Variable attenuator 26 ... Delay device 30, 30a, 30b ... Opposing traveling vehicle AC ... (Attenuation amount) control signal BC ... Bit switching signal BS ... Bit setting signal CDS ... Code setting signal CKS: Clock frequency setting signal D: 2-bit delay circuit fo: Transmission carrier signal fd: Doppler frequency MS: Encoded two-phase random signal (modulation code) SW: Switch V: Speed of traveling vehicle (speed information) ) Θ ... Projection beam angle

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-56-168575 (JP, A) JP-A-1-285000 (JP, A) JP-A-62-25276 (JP, A) JP-A-4- 62398 (JP, A) JP-A-61-275675 (JP, A) JP-A-61-205882 (JP, A) JP-A-61-96482 (JP, A) JP-A-2-77684 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01S ^7/ 00-17/88

Claims (5)

(57) [Claims] An apparatus for measuring the velocity of a target object (30) approaching, comprising: means (11) for generating a carrier signal (fo) for transmission.
And an output of the clock transmitter set to a frequency corresponding to the speed measurement range by the sign setting signal means and a sign setting signal (C
DS) for generating a modulated coded two-phase random signal (MS) in response to the transmitted carrier signal using the generated coded two-phase random signal. Means for performing direct spreading modulation (15)
Circulator (17)
An antenna (16) for projecting a beam toward the target object via the antenna and receiving a reflected wave from the target object; and mixing a signal corresponding to the received reflected wave with the transmission carrier signal. A mixer (18) for generating an intermediate frequency signal by using the same, and a correlator for performing correlation demodulation between the generated intermediate frequency signal and a signal (MS) having the same sign as the sign of the two-phase random signal for modulation. (20) means for passing only a Doppler frequency component corresponding to a relative velocity difference between the target object and the apparatus out of the correlated demodulated signal; and Means (22) for measuring the Doppler frequency (fd) corresponding to the speed of the target object; and a projection beam angle (θ calculated according to the detected Doppler frequency and the measurement situation. ) Is used to calculate the speed (V) of the target object and output the speed information of the target object.
A speed measuring device comprising: 2. The speed measuring device (10) according to claim 1, wherein:
And a delay circuit (D) provided between the code generator and the correlator for shifting a signal having the same sign as that of the two-phase random signal for modulation by two or more bits to delay the signal. Is switched by a bit switching signal (B
A delay unit (26) having means (SW) for controlling in response to C), and a delay setter (24) for generating the bit switching signal based on bit setting signal (BS) generating means. A speed measuring device for shifting the two-phase random signal by two bits or more by a bit switching signal from the delay setting device, thereby variably setting an effective measurement range of the device according to a measurement situation . 3. The speed measuring device according to claim 2,
a) further comprising: a variable attenuator (25) provided in a path from a point where the transmission carrier signal is modulated to be inputted to the mixer via the antenna, wherein the variable attenuator is configured to reduce the amount of attenuation by the delay. The control is performed based on a control signal (AC) from a setting device, whereby the transmission output of the present device is controlled to be a value required for a distance to an effective measurement range according to the bit setting signal. Speed measuring device. 4. The speed measuring device (10, 10a) according to claim 1, wherein a clock set to a frequency corresponding to the speed measuring range is supplied to the code generator. Clock oscillator (13)
And a speed measurement range variably set by changing a frequency of an oscillation clock of the clock oscillator by an external clock frequency setting signal (CKS). 5. The code of a two-phase random signal generated from a code generator of each device of the speed measuring device (10, 10a) according to any one of claims 1 to 4, different from each other. At the same time,
And set the beam angle variously and come to face each other
A velocity measuring device for measuring the velocity of a plurality of target objects .