JP3518299B2 - 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 installed on a road and measuring the speed of a vehicle traveling on the road. For convenience of explanation, a radar velocity measuring device will be described below as an example of the velocity measuring device.

[0002]

2. Description of the Related Art A radar speed measuring device is installed on a lane and measures the speed from the Doppler frequency of a vehicle traveling on that lane. When the speed of the vehicle is higher than a predetermined speed, a speed warning is displayed on an information board. Information is displayed and a command is issued to the photographing device to photograph the vehicle. Therefore, in the radar speed measurement device, it is necessary to accurately measure the speed of the vehicle traveling in the lane, and if the speed information of the vehicle is not accurate, provide incorrect information to the driver,
A big problem such as accidentally taking an image of a vehicle occurs. FIG. 5 is a diagram showing an installation situation of the radar velocity measuring device, and FIG. 6 is a block diagram showing a configuration of a conventional radar velocity measuring device. In the figure, 1a and 1b are lanes set on a 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 lanes. A vehicle that travels through the vehicle, 5 is an information board, 6 is a photographing 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 Of the output of the transmitter 7 by a delay circuit for delaying the output of the transmitter for a predetermined time.
A second pulse modulator for pulse-modulating the output section of the delay circuit 10, 11a is a first mixer for mixing the output of the antenna 2 and the output of the second pulse modulator 9b, and 12a is for the first mixer 11a. A first amplitude detector that detects the amplitude from the output, 13 is a frequency detector that detects the Doppler frequency from the output of the first mixer 11a, and detects the speed of the vehicle 4a, and 14 is a first amplitude detector 12a. Frequency detector 13
Is a controller that outputs the speed information of the vehicle to the information board 5 or outputs a command to the imaging device 6 to take an image.

Next, the operation will be described. In FIG. 5 , the antenna 2 of the radar speed measuring device measures the speed of the vehicle traveling in the lane 1a. Therefore, the antenna 2 of the radar speed measuring device is required to reliably detect a vehicle that passes through the lane 1a like the vehicle 4a and measure the speed accurately, and conversely, to another lane like the vehicle 4b. 1b or a vehicle 4c traveling in front of or behind the vehicle 4a even on the lane 1a may be erroneously detected, or the influence of the vehicles 4b and 4c may be detected when the antenna 2 measures the speed of the vehicle 4a. It is required not to receive and measure the wrong speed.

In FIG . 6 , the 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 this transmission signal to the vehicle 4a and receives its reflected wave. The received reflected wave is the first
Is mixed with the output of the second pulse modulator 9b in 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
By using the vehicle detection output of 2a and the vehicle speed output of the frequency detector 13, speed information is output to the information board and a shooting command is output to the imaging device for a vehicle having a predetermined speed or higher.

FIG . 7 is an explanatory view of the directivity pattern of the antenna 2, where a is a main lobe and b is a side lobe. FIG. 5 schematically shows the relationship between the main lobe a and the side lobe b. The main lobe a with a high gain irradiates the vehicle 4a traveling in the lane 1a with the transmission signal and receives the reflected wave. However, the antenna 2 has a plurality of side lobes b around the main lobe a as shown in FIG. 7 , and radiates weak radio waves in directions other than the main lobe. These radio waves are radiated to the vehicle 4b traveling in the lane 1b and the vehicle 4c traveling in front of and behind 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 wave from the vehicle 4a, so that the intensity and the Doppler frequency are different from those of the reflected wave from the vehicle 4a only. Becomes If the reflected wave from the vehicle has the same intensity, the output of the antenna 2 is less affected because the reflected wave of the vehicle 4a is larger than the reflected waves of the vehicles 4b and 4c by the difference in antenna gain. The reflected wave greatly changes more than the antenna gain difference depending on the shape and size of the vehicle, and in some cases, the output of the antenna 2 is larger than the output of the vehicle 4b or the vehicle 4c. There is. As described above, the conventional radar velocity measuring device simultaneously receives the reflected waves of the vehicles 4b and 4c received from the side lobes, in addition to the reflected waves from the vehicle 4a received from the main lobe of the antenna 2, so that the vehicle 4b, If 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 and the Doppler frequency change, the wrong vehicle is detected, the wrong speed is detected, the speed displayed on the information board is wrong, or the vehicle is not displayed in the image of the image capturing device. Or

[0006]

In the configuration shown in FIG . 6 ,
It is unknown whether the signal is received in the main lobe or the side lobe of the antenna. Therefore, if the reflected wave received from other than the main lobe exceeds the predetermined level at the amplitude detector and the Doppler frequency is within the predetermined range by the frequency detector, it is erroneously overspeeded even though there is no corresponding vehicle. There was a problem such as that the vehicle was detected or the speed of the vehicle was measured by mistake.

The present invention has been made in order to solve the above problem, and prevents the vehicle from being erroneously detected or the erroneous speed being measured due to the influence of the reflected wave received from the side lobe. The purpose is to

[0008]

The velocity measuring device according to the first aspect of the present invention includes a second sensor having a beam width wider than that of the conventional first sensor.
The intensity of each received signal is compared and the received signal of the first sensor is compared.
If the signal strength is greater than or equal to the received signal strength of the second sensor,
It is judged that the vehicle concerned, and the strength of the received signal of the first sensor is
If the strength of the signal received by the 2 sensor is less than
Identification means for determining whether the vehicle is the vehicle
The strength of the received signal of the first sensor is used by the output of another means.
Speed information output that outputs the detected vehicle speed
And means.

According to the second aspect of the invention, when the speed detected by the first aspect of the invention is equal to or higher than a predetermined value, by photographing the vehicle, the overspeed vehicle can be left as a photograph.

The radar velocity measuring apparatus according to the third aspect of the present invention further includes a receiving antenna having a beam width of the main lobe wider than that of the conventional antenna, and compares the receiving intensity of this receiving antenna with that of the conventional antenna. By doing so, when the reception intensity of the conventional antenna is larger than the predetermined value, it can be determined that the reflected wave from the main lobe is measured without any influence from the side lobe.

According to the fourth aspect of the invention, the received signal of the conventional antenna and the received signal of the receiving antenna with a wide beam width are respectively AD-converted, and the AD-converted signal is Fourier-transformed to obtain the received signal. Frequency analysis is performed, and the strengths of the conventional antenna and the receiving antenna with a wide beam width are compared for each of the same frequency components subjected to this frequency analysis. When the receiving strength of the conventional antenna is greater than a predetermined value, the side lobe is calculated. It is possible to determine that the reflected wave from the main lobe has been measured without being affected by.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION 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. Reference numeral 15 is a receiving antenna, 11b is a second mixer for mixing the output of the receiving antenna 15 and the output of the second pulse modulator 9b, and 12b is a second amplitude detector for detecting the amplitude of the output of the second mixer 11b. , 16 is a comparator for comparing the output of the first amplitude detector 12a and the output of the second amplitude detector 12b, and 17 is for outputting the speed information from the output of the comparator 16 and the output of the frequency detector 13 to the information plate 5. Alternatively, it is a judging device that outputs a photographing command to the photographing device 6.

Next, the operation will be described. FIG. 3 is an explanatory diagram of the receiving antenna pattern. In the figure, a and b are the same as the antenna pattern of FIG. c is the 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 of the antenna 2 in the range of the main lobe of the antenna 2, the reflected wave from the direction of the main beam has the strength of the received signal of the antenna 2. Is stronger than the received signal strength of the receiving antenna 15, but the reflected wave from the outside of the main lobe of the antenna 2 has a higher gain in the receiving antenna 15, so 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 intensities of the reception signals of the antenna 2 and the reception antenna 15, it is possible to identify whether the reception signal is reflected from the range of the main lobe of the antenna 2 or is reflected from the range of the main lobe of the antenna 2. You can In FIG. 3, the antenna 2 and the receiving antenna 15
The output of is mixed with the output of the second pulse modulator 9b by 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 the comparator 16, and if the difference between these outputs is greater than or equal to a predetermined value, reflection from within the range of the main lobe. It is a wave and is reflected from outside the range of the main lobe. 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 the information board and output a shooting command to the image capturing device for vehicles having a predetermined speed or higher. To do.

Embodiment 2. 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 is an AD converter for AD converting the outputs of the first mixer 11a and the second mixer 11b, and 19 is an AD converter 18
A Fourier transformer for performing a discrete Fourier transform on the output of the vehicle, and 20 indicates the speed of the vehicle in the main lobe by comparing the intensity of each Doppler frequency component of the received signal from the output of the Fourier transformer 19 with the outputs of the antenna 2 and the receiving antenna 15. Is a detector for detecting.

Next, the operation will be described. 4A and 4B are explanatory diagrams of the output of the Fourier transformer 19. FIG. 4A is a Doppler frequency component of the reception signal of the antenna 2, and FIG. 4B is a Doppler frequency component of the reception signal of the reception antenna 15. In this way, the reception signals of the antenna 2 and the reception antenna 15 are Fourier-transformed 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,
These can be separated for strength comparison. For example, considering a case where the speed of the vehicle is higher in the order of the vehicles 4a, 4b, 4c, the Doppler frequency component corresponding to the traveling speed of the vehicle 4a is output from the antenna 2 to the receiving antenna 1
Since it is larger than the output of 5 by a predetermined value or more, it can be determined that the vehicle is in the main lobe. Is also large, it is determined to be a vehicle other than the main lobe. As described above, in the case of vehicles with different traveling speeds, it is possible to identify whether the vehicle in the main lobe is a vehicle other than the main lobe for each Doppler frequency component, and even if the vehicle is traveling in a place other than the main lobe, The traveling speed of the vehicle inside can be measured.

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

[0017]

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

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

According to the second invention, the velocity measurement result of only the signal within the beam width of the first sensor is displayed on the display plate, and the signal outside the beam width of the first sensor is erroneously displayed. There is nothing to do.

According to the third aspect of the invention, the radar velocity measuring apparatus adds a receiving antenna having a higher gain than the antenna outside the range of the main lobe of the antenna, and compares the output of this receiving antenna with that of the conventional antenna. By doing so, it is possible to identify the received signal from outside the range of the antenna main lobe, so that it is not affected by the vehicle traveling in front of and behind the speed measurement vehicle or the vehicle traveling in the adjacent lane. By checking, the vehicle can be detected, its speed can be measured, and it is possible to prevent erroneous detection of the vehicle and erroneous speed measurement.

According to the fourth aspect of the invention, the outputs of the conventional antenna and the receiving antenna are subjected to the discrete Fourier transform to separate the Doppler frequency components and the intensity of the received signals can be compared. Even if there is an influence of a vehicle traveling in front of or behind the vehicle or a vehicle traveling in the adjacent lane, if the traveling speed is different, the vehicle can be detected and the traveling speed can be measured without being influenced by these vehicles. .

[Brief description of drawings]

FIG. 1 is a block diagram of a radar velocity measuring device showing a first embodiment of the present invention.

FIG. 2 is a block diagram of a radar velocity measuring device showing 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 velocity measuring device.

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

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

[Explanation of symbols]

1 lane, 2 antennas, 3 radar speed measuring device main body, 4 vehicle, 5 information board, 6 imaging 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 decision device, 18 AD converter, 19 Fourier transformer, 20 detector.

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Claims (4)

(57) [Claims] 1. A beam width of a first sensor that radiates a transmitted wave to a traveling vehicle and receives a reflected wave from the traveling vehicle, and a beam width that is wider than a beam width of a first sensor that receives the reflected wave from the traveling vehicle. a second sensor having a beam width, the intensity of the first sensor and the second sensor of each of the received signal is compared, the
The strength of the signal received by the first sensor is the strength of the signal received by the second sensor.
If the signal strength is equal to or higher than the signal strength, it is determined that the vehicle is
The strength of the signal received by the second sensor is the signal received by the second sensor.
Identifying means for identifying whether the vehicle is judged not to be the vehicle in the case No. less than the strength of, the vehicle detected with the intensity of the received signal of the first sensor by the output of said identification means And a speed information output means for outputting the speed of the speed measuring device. Wherein when the speed of the detected the vehicle is equal to or higher than a predetermined speed, the speed measuring apparatus according to claim 1, wherein is provided an imaging means for capturing the vehicle. 3. A transmitter, a pulse generator that generates pulses at a predetermined frequency and a predetermined repetition period, and a first pulse modulator that modulates the output of the transmitter with the output of the pulse generator. , A first antenna that irradiates the traveling vehicle with the output of the first pulse modulator and receives a reflected wave from the traveling vehicle; and a beam width that is wider than that of the first antenna and that reflects 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 that mixes the output of the second pulse modulator and the output of the antenna; a second mixer that mixes the output of the second pulse modulator and the output of the receiving antenna; and the first mixer. Amplitude detector for detecting the amplitude of the output of the 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 the outputs of the first amplitude detector and the second amplitude detector,
A speed measuring device comprising a judging device for judging whether or not to output speed information to an information board from the output of the comparator and the output of the frequency detector, and for outputting a shooting command to a shooting device. 4. A transmitter, a pulse generator that generates pulses at a predetermined frequency and a predetermined repetition period, and a first pulse modulator that modulates the output of the transmitter with the output of the pulse generator. An antenna that irradiates the traveling vehicle with the output of the first pulse modulator and receives a reflected wave from the traveling vehicle; and a receiving antenna that has a beam width wider than that of 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 by using the output of the delay circuit, and the second pulse. A first mixer that mixes the output of the modulator and the output of the antenna; a second mixer that mixes the output of the second pulse modulator and the output of the receiving antenna; and the output of the first mixer. Of the second mixer An AD converter that performs AD conversion on the outputs separately, a Fourier transformer that performs discrete Fourier transform on the output of this AD converter, an output of the first mixer that is discrete Fourier transformed by this Fourier transformer, and a second
It is equipped with 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 also outputs a shooting command to the shooting device. Speed measuring device.