JPH11175884A - Speed measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a vehicle and to measure speed without being affected by reflected waves from vehicles running back, forth and next to the vehicle whose speed is measured. SOLUTION: A reception antenna 15 with wider beam width than that of an antenna 2 is added to the antenna 2 of a conventional radar speed measuring device 3 and reception intensity of the antenna 2 is compared with that of the reception antenna 15. When the reception intensity of the antenna is more than that of the reception antenna 15 by a prescribed value, a fact that the vehicle whose speed is measured is not affected by the vehicles running back, forth and next to it is confirmed and the speed of the vehicle is measured.

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 installed on a road to measure the speed of a vehicle traveling on the road. Here, for convenience of explanation, a radar speed measuring device will be described below as an example of the speed measuring device.

[0002]

2. Description of the Related Art A radar speed measuring device is installed on a lane and measures the speed based on the Doppler frequency of a vehicle traveling on the lane. When the vehicle speed is higher than a predetermined speed, a speed warning is displayed on an information board. Information is displayed, or a command is issued to the photographing device to photograph the vehicle. For this reason, the radar speed measurement device needs to accurately measure the speed of the vehicle traveling in the lane, and if the speed information of the vehicle is not accurate, it may provide incorrect information to the driver,
A major problem arises, such as accidentally capturing an image of a vehicle. FIG. 7 is a diagram showing an installation state of a radar speed measuring device, and FIG. 8 is a block diagram showing a configuration of a conventional radar speed measuring device. In the figure, 1a and 1b are lanes set on the road, 2 is an antenna of a radar speed measuring device provided corresponding to the lane 1a, 3 is a radar speed measuring device main body, 4a, 4b and 4c are on a lane. 5 is an information board, 6 is an imaging device, 7 is a transmitter, 8 is a pulse generator, 9a is a first pulse modulator for pulse-modulating the output of the transmitter 7, and 10 is a pulse generator 8. 9b is a delay circuit for delaying the output of the transmitter 7 for a predetermined time.
A second pulse modulator for pulse-modulating the section with the output of the delay circuit 10, 11a a first mixer for mixing the output of the antenna 2 and the output of the second pulse modulator 9b, and 12a for the first mixer 11a. A first amplitude detector for detecting the amplitude from the output, 13 is a frequency detector for detecting the Doppler frequency from the output of the first mixer 11a and detecting the speed of the vehicle 4a, and 14 is a first amplitude detector 12a. Frequency detector 13
Is a controller that outputs vehicle speed information to the information board 5 from the output of the camera and outputs a command to the photographing device 6 to photograph.

Next, the operation will be described. In FIG. 7, the antenna 2 of the radar speed measuring device measures the speed of a vehicle traveling on the lane 1a. Therefore, the antenna 2 of the radar speed measuring device is required to reliably detect a vehicle passing through the lane 1a, such as the vehicle 4a, and to accurately measure the speed. 1b may be detected erroneously for a vehicle traveling on the lane 1a or a vehicle 4c traveling before and after the vehicle 4a on the lane 1a, or the influence of the vehicles 4b and 4c when the antenna 2 is measuring the speed of the vehicle 4a. It is required not to receive the wrong speed.

In FIG. 8, a transmitter 7 oscillates a continuous wave. The first pulse modulator 9a pulse-modulates the output of the transmitter 7 according to the output of the pulse generator 8, and outputs a transmission signal. The antenna 2 radiates the transmission signal to the vehicle 4a and receives the reflected wave. The received reflected wave is the first
Is mixed with the output of the second pulse modulator 9b by the mixer 11a, and then amplitude-detected by the first amplitude detector 12a. When the output of the first amplitude detector 12a is larger than a predetermined value, Detect the vehicle. Also, the first mixer 1
The Doppler frequency is detected by the frequency detector 13 using the output of 1a. In the controller 14, the first amplitude detector 1
Using the vehicle detection output of 2a and the vehicle speed output of the frequency detector 13, speed information is output to an information board and a shooting command is output to a shooting device for a vehicle having a predetermined speed or higher.

FIG. 9 is an explanatory diagram of the directivity pattern of the antenna 2, wherein a is a main lobe and b is a side lobe. FIG. 7 schematically shows the relationship between the main lobe a and the side lobe b. The main lobe a having a high gain irradiates the vehicle 4a traveling on the lane 1a with a transmission signal and receives its reflected wave. However, the antenna 2 has a plurality of side lobes b around the main lobe a as shown in FIG. 9 and emits a weak radio wave in a direction other than the main lobe. These radio waves are radiated to the vehicle 4b traveling in the lane 1b and the vehicle 4c traveling before and after the vehicle 4a, and receive the reflected waves. In this case, the output of the antenna 2 is such that the reflected waves from the vehicles 4b and 4c are added to the reflected waves from the vehicle 4a, so that the intensity and the Doppler frequency are different from those in the case of the reflected waves only from the vehicle 4a. Becomes If the reflected waves from the vehicle have the same intensity, the output of the antenna 2 is less affected because the reflected wave of the vehicle 4a is larger than the vehicles 4b and 4c by the difference in antenna gain, but the effect is small. The reflected wave greatly changes more than the antenna gain difference depending on the shape and size of the vehicle. In some cases, the output of the antenna 4 causes the outputs of the vehicles 4b and 4c to be larger than the output of the vehicle 4a. There is. As described above, the conventional radar velocity measuring device simultaneously receives not only the reflected wave from the vehicle 4a received from the main lobe of the antenna 2 but also the reflected waves of the vehicles 4b and 4c received from the side lobes. When the reflected wave of 4c is strong, it may be stronger than the reflected wave of the vehicle 4a.
Because the strength of the received signal or the Doppler frequency changes, the wrong vehicle is detected, the wrong speed is detected, the speed displayed on the information board is wrong, or the vehicle is not shown in the image of the image capturing device Or

[0006]

In the configuration shown in FIG.
It is unknown whether the signal is received in the main lobe or the side lobe of the antenna. For this reason, if the reflected wave received from a source other than the main lobe is equal to or higher than a predetermined level by the amplitude detector and the frequency detector is a Doppler frequency within a predetermined range, the vehicle may be erroneously overspeeded even if there is no corresponding vehicle. And the speed of the vehicle is measured incorrectly.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and is intended to prevent a vehicle from being erroneously detected or an erroneous speed from being measured due to the influence of a reflected wave received from a side lobe. The purpose is to.

[0008]

A velocity measuring apparatus according to a first aspect of the present invention further includes a second sensor having a wider beam width than that of the conventional first sensor. Can be compared with the received signal of the first sensor, and it can be determined from the comparison result whether or not the vehicle is the vehicle.

Further, according to the second invention, when the speed detected by the first invention is equal to or higher than a predetermined value, the vehicle in excess of the speed can be left as a photograph by photographing the vehicle.

In the radar velocity measuring apparatus according to the third invention, a receiving antenna having a wider main lobe beam width is added as compared with the conventional antenna, and the receiving strength of this receiving antenna is compared with that of the conventional antenna. By doing so, when the reception strength of the conventional antenna is higher than a predetermined value, it is possible to determine that the reflected wave from the main lobe has been measured without being affected by the side lobe.

According to the fourth invention, the received signal of the conventional antenna and the received signal of the receiving antenna having a wide beam width are respectively AD-converted, and the AD-converted signal is Fourier-transformed, so that the received signal is converted. Frequency analysis is performed, and for each of the same frequency components subjected to the frequency analysis, the intensity of the conventional antenna and the reception antenna having a wide beam width are compared, and when the reception intensity of the conventional antenna is higher than a predetermined value, the sidelobe is used. , And it can be determined that the reflected wave from the main lobe has been measured.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 shows a block diagram of the first embodiment. 2a, 5, 6, 7, 8, 9a,
9b, 10, 11a, 12a and 13 are the same as the conventional device. 15 is a receiving antenna, 11b is a second mixer that mixes the output of the receiving antenna 15 and the output of the second pulse modulator 9b, and 12b is a second amplitude detector that detects the amplitude of the output of the second mixer 11b. , 16 are comparators for comparing the outputs of the first amplitude detector 12a and the second amplitude detector 12b, and 17 is for outputting speed information to the information plate 5 from the output of the comparator 16 and the output of the frequency detector 13. And a decision unit that outputs a photographing command to the photographing device 6.

Next, the operation will be described. FIG. 3 is an explanatory diagram of a receiving antenna pattern. In the drawing, a and b are the same as the antenna patterns of FIG. c is an antenna pattern of the receiving antenna 15. Since the antenna 2 and the receiving antenna 15 having a wider beam width than the antenna 2 have a high gain in the antenna 2 within the range of the main lobe of the antenna 2, the reflected wave from the direction of the main beam has the intensity of the received signal of the antenna 2. Is stronger than the strength of the received signal of the receiving antenna 15, but the reflected wave from outside the main lobe of the antenna 2 has a higher gain in the receiving antenna 15, so that the strength of the received signal of the receiving antenna 15 is higher. Is stronger than the reception intensity of the antenna 2. Therefore,
By comparing the received signal strengths of the antenna 2 and the receiving antenna 15, it is possible to identify whether the received signal is reflected from the range of the main lobe of the antenna 2 or from outside the range of the main lobe of the antenna 2. Can be. In FIG. 3, the antenna 2 and the receiving antenna 15
Is mixed with the output of the second pulse modulator 9b in the first mixer 11a and the second mixer 11b, respectively.
The reception intensity is detected by the first amplitude detector 12a and the second amplitude detector 12b. The output of the first amplitude detector 12a and the output of the second amplitude detector 12b are compared by a comparator 16, and if the difference between these outputs is equal to or more than a predetermined value, the reflection from the range of the main lobe is detected. It is determined that the wave is not affected by the reflection from outside the range of the main lobe, and the vehicle is detected. The determiner 17 uses the vehicle detection output of the comparator 16 and the vehicle speed output of the frequency detector 13 to output speed information to an information board and output a shooting command to a shooting device for a vehicle having a speed higher than a predetermined speed. I do.

Embodiment 2 FIG. FIG. 2 shows a block diagram of the second embodiment. 2, 3, 5, 6, 7, 8, 9a, 9b,
10, 11a, 11b, and 15 are the same as those in the third embodiment. Reference numeral 18 denotes an AD converter for AD-converting the outputs of the first mixer 11a and the second mixer 11b, and 19 an AD converter 18
A Fourier transformer 20 for performing a discrete Fourier transform on the output of the antenna 2 is provided. Is a detector that detects

Next, the operation will be described. 4A and 4B are explanatory diagrams of the output of the Fourier transformer 19. FIG. 4A shows the Doppler frequency component of the signal received by the antenna 2, and FIG. 4B shows the Doppler frequency component of the signal received by the receiving antenna 15. As described above, the received signals of the antenna 2 and the receiving antenna 15 are subjected to Fourier transform and divided into Doppler frequency components, so that the reception intensity of each Doppler frequency component can be compared. Therefore, when the traveling speeds of the vehicle 4a and the vehicles 4b and 4c are different, the Doppler frequency components are different, so that
These can be separated for strength comparison. For example, considering the case where the speed of the vehicle is faster in the order of the vehicles 4a, 4b, and 4c, the output of the antenna 2 is the same as the Doppler frequency component corresponding to the traveling speed of the vehicle 4a.
5 is greater than the output of the antenna 5 by a predetermined value or more, it can be determined that the vehicle is in the main lobe. Therefore, the vehicle is determined to be a vehicle other than the main lobe. As described above, in the case of vehicles having different running speeds, the vehicle in the main lobe can be identified as a vehicle other than the main lobe for each Doppler frequency component. It is possible to measure the traveling speed of the vehicle inside.

In the first and second embodiments, a radar speed measuring device has been described as an example of a speed measuring device. However, it goes without saying that the present invention can be applied to a laser speed measuring device.

[0017]

Since the present invention is configured as described above, it has the following effects.

According to the first invention, the velocity measuring device adds the second sensor having a wider beam width than the first sensor, and compares the reception signals of the first sensor and the second sensor. Accordingly, it is determined whether or not the received signal is a signal from within the beam width of the first sensor, and only the signal within the beam width of the first sensor outputs a speed measurement result, and the beam width of the first sensor is determined. It is possible not to output the speed measurement result for the outside signal.

Further, according to the second invention, the speed measurement result of only the signal within the beam width of the first sensor is displayed on the display panel, and the signal outside the beam width of the first sensor is erroneously displayed. Never do.

According to the third aspect, the radar speed measuring apparatus adds a receiving antenna having a higher gain than the antenna outside the main lobe of the antenna, and compares the output of the receiving antenna with the output of the conventional antenna. As a result, it is possible to identify a received signal from outside the main lobe of the antenna, so that the vehicle is not affected by a vehicle traveling before and after the speed measurement vehicle or a vehicle traveling in the adjacent lane. Upon confirmation, the vehicle can be detected and its speed can be measured, so that it is possible to eliminate erroneous detection of the vehicle and measurement of the wrong speed.

According to the fourth aspect of the present invention, the output of the conventional antenna and the output of the receiving antenna are subjected to discrete Fourier transform, so that the intensity of the received signal can be compared for each Doppler frequency component. Even if there is an effect of a vehicle traveling before or after the vehicle or a vehicle traveling in an adjacent lane, if the traveling speed is different, the vehicle can be detected and the traveling speed can be measured without being affected by these vehicles. .

[Brief description of the drawings]

FIG. 1 is a block diagram of a radar speed measuring device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a radar speed measuring device according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of an antenna pattern of a receiving antenna.

FIG. 4 is an explanatory diagram of an output of a Fourier transformer.

FIG. 5 is an installation diagram of a radar speed measuring device.

FIG. 6 is a block diagram of a conventional radar speed measuring device.

FIG. 7 is an explanatory diagram of an antenna pattern.

[Explanation of symbols]

1 lane, 2 antenna, 3 radar speed measuring device main body, 4 vehicle, 5 information board, 6 photographing device, 7 transmitter, 8 pulse generator, 9 pulse modulator, 10 delay circuit, 11 mixer, 12 amplitude detector, 13 frequency detector, 14 controller, 15 receiving antenna, 16 comparator, 17 determiner, 18 AD converter, 19 Fourier transformer, 20 detector.

Claims (4)

[Claims] A first sensor for irradiating the traveling vehicle with a transmission wave and receiving a reflected wave from the traveling vehicle; and a beam width wider than a beam width of the first sensor for receiving the reflected wave from the traveling vehicle. A second sensor having a beam width, comparing the reception signals of the first sensor and the second sensor, identifying means for identifying whether or not the vehicle is the vehicle based on the comparison result, and an output of the identifying means; Speed information output means for outputting the speed of the vehicle detected using the reception signal of the first sensor. 2. The speed measuring device according to claim 1, further comprising: photographing means for photographing the vehicle when the detected speed of the vehicle is equal to or higher than a predetermined speed. 3. A transmitter, a pulse generator for generating a pulse at a predetermined frequency and a predetermined repetition period, and a first pulse modulator for modulating an output of the transmitter with an output of the pulse generator. A first antenna for irradiating the output of the first pulse modulator to the traveling vehicle and receiving a reflected wave from the traveling vehicle, and a beam width wider than that of the first antenna to reflect the reflected wave from the vehicle. A second receiving antenna for receiving, a delay circuit for delaying the output of the pulse generator by a predetermined time, and a second pulse for pulse-modulating a part of the output of the transmitter using the output of the delay circuit A modulator;
A first mixer for mixing the output of the second pulse modulator and the output of the antenna, a second mixer for mixing the output of the second pulse modulator and the output of the receiving antenna, and the first mixer; A first amplitude detector for detecting the amplitude of the output of the first mixer, a second amplitude detector for detecting the amplitude of the output of the second mixer, and a Doppler frequency from the output of the first mixer A frequency detector, a comparator for comparing outputs of the first amplitude detector and the second amplitude detector,
A speed measurement device comprising: a determination device that determines whether or not to output speed information to an information plate from an output of the comparator and an output of the frequency detector, and outputs a shooting command to a shooting device. 4. A transmitter, a pulse generator for generating a pulse at a predetermined frequency and a predetermined repetition period, and a first pulse modulator for modulating an output of the transmitter with an output of the pulse generator. An antenna that irradiates the output of the first pulse modulator to a traveling vehicle and receives a reflected wave from the traveling vehicle, a receiving antenna that has a wider beam width than the antenna and receives a reflected wave from the vehicle, A delay circuit for delaying the output of the pulse generator by a predetermined time; a second pulse modulator for pulse-modulating a part of the output of the transmitter using the output of the delay circuit; A first mixer for mixing the output of the modulator and the output of the antenna, a second mixer for mixing the output of the second pulse modulator and the output of the reception antenna, and an output of the first mixer. Of the second mixer An AD converter for separately performing A / D conversion on the output, a Fourier converter for performing a discrete Fourier transform on the output of the A / D converter, an output of the first mixer discretely Fourier-transformed by the Fourier converter, and a second
A detector that detects the vehicle from the output of the mixer and measures the Doppler frequency of the vehicle, determines whether to output speed information to the information board, and outputs a photographing command to the photographing device. Speed measuring device.