JP3855829B2 - Radar device, radar signal processing device, program - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radar apparatus that detects a target by transmitting and receiving pulsed radar waves, and a radar signal processing apparatus and program used therefor.
[0002]
[Prior art]
Conventionally, a pulse-type radar device (hereinafter referred to as “pulse radar”) is known as one of radar devices that detect a target by transmitting and receiving radar waves. In this pulse radar, for example, as described in “Basics and Applications of Millimeter Wave Technology” (Realize, (1998) p232 to p233), a pulsed radar wave (transmission pulse) is transmitted and a radar wave is also transmitted. From the result of measuring the time difference between the two pulses, that is, the round trip time t of the radar wave (reflected wave), from the target reflected from the target, the distance to the target using the following equation (1) Seeking R
[0003]
R = C · (t−t0) / 2 (1)
However, C is the speed of light, C = 3 × 10 ⁸ m / s, and t0 is a signal delay in the circuit.
[0004]
[Problems to be solved by the invention]
By the way, in the pulse radar, a microwave of 24 GHz band called an ISM band is considered as one of the selection branches of the use frequency band. Since this ISM band is used in various devices, there is a problem that when using the pulse radar as an in-vehicle radar or the like outdoors, it is easy to cause interference with these devices when the surrounding radio wave condition cannot be controlled. there were.
[0005]
In particular, in-vehicle radar, it is assumed that a vehicle equipped with the same type of in-vehicle radar is present in the vicinity, and therefore, it is considered that interference is more likely to occur.
And, in the conventional pulse radar, when receiving a radio wave that exceeds its detection sensitivity, it does not have a function to distinguish whether it is a reflected wave from the target or an interference wave from other equipment, There has been a problem of erroneous detection such as outputting a target distance that does not actually exist based on the interference wave.
[0006]
In order to solve the above problems, an object of the present invention is to reduce erroneous detection due to interference waves in a radar apparatus that detects a target by transmitting and receiving pulsed radar waves.
[0010]
[Means for Solving the Problems]
The radar apparatus according to claim 1 , wherein the time measuring means causes the transmitting / receiving means to transmit a pulsed radar wave and measures the time until the transmitting / receiving means receives the radar wave. The interference determination means is receiving an interference wave when the measured time exceeds the detection period necessary for receiving a reflected wave from a target existing within a preset maximum detection distance. It is determined that
[0011]
The maximum detection distance is an upper limit distance at which a reflected wave from a target reflecting a radar wave can be received with a detectable signal intensity. That is, if the received radar wave is a reflected wave from the target, it is not detected beyond the detection period, and it can be immediately determined that it is an interference wave.
[0012]
The radar apparatus according to claim 1 is configured such that, when the interference determination unit determines that the interference wave is being received, for example, the notification unit notifies the fact as described in claim 3. Accordingly, it is possible to prevent the user from making an erroneous determination based on the detection result of the erroneously detected non-existing target. Further, as described in claim 4 , the output prohibiting means includes the radar. If the device is configured to prohibit the output of the target detection results, various processes and controls that use the target detection results may output incorrect processing results depending on the target detection results that do not exist, It is possible to prevent execution.
[0013]
In the case of the radar device according to claim 1, if the interference determination means does not receive the radar wave during the monitoring period set after the detection period has elapsed, the transmission permission means causes the transmission / reception means to transmit the radar wave. If it is permitted and a radar wave is received during the monitoring period, the monitoring period extending means may be configured to reset the monitoring period.
[0014]
In other words, during the monitoring period when the reflected wave should not be received, the surrounding radio wave condition is monitored, and if the radar wave is received, that is, if the interference wave exists, the monitoring period is restarted. By setting, the transmission of the radar wave is postponed, and the radar wave is transmitted after the radar wave is not received during the monitoring period, that is, after confirming that there is no interference wave. .
[0015]
Therefore, according to the present invention, the target can be detected when there is no interference wave and the surrounding radio wave condition is good.
However, for example, in the case of interference between radar devices configured in the same manner, even if a monitoring period is provided, if the same operation is performed at the same time, they interfere with each other after the monitoring period, and this is repeated. The device may not be available for a long time.
[0016]
Further, in the radar apparatus according to the first aspect, if the transmission permission means does not receive a radar wave during the monitoring period reset by the monitoring period extension means , the transmission permission means further sets a waiting period set to a random length. It is configured to permit the transmission of radar waves after elapse .
In this case, since a waiting period of a random length is inserted before the transmission of the radar wave, the interfering radar devices transmit the radar wave at the same timing after the monitoring period elapses and interfere with each other again. Can be surely prevented.
[0017]
By the way, the interference wave does not necessarily appear only in the monitoring period, and may appear in the detection period. Therefore, as described in claim 2 , the reception intensity detection means measures the reception intensity of the radar wave received by the transmission / reception means, and the distance calculation means uses the time measured by the time measurement means as a radar wave to the target. As the round trip time, the distance to the target is obtained, and the information discarding means measures the received intensity measured by the received intensity measuring means for the radar wave received during the detection period. If it is larger than the theoretical maximum received intensity at the obtained distance, the information obtained based on the radar wave may be discarded.
The theoretical maximum received intensity is the reflection characteristics of the largest reflectors (walls, etc.) that are assumed to be around the vehicle, the transmission power of radar waves, propagation loss in the atmosphere, and the distance to the target. This is the received intensity obtained based on signal intensity fluctuations due to multiple reflections. That is, if the received radar wave is a reflected wave from the target, the received intensity cannot be greater than the Hosoda received intensity, and this can be immediately determined as an interference wave.
[0018]
In other words, even if an interference wave is mixed in the radar wave received during the detection period, it is determined whether or not it is an interference wave individually, and if it is an interference wave, the information obtained based on this is removed. Therefore, only information obtained based on the reflected wave can be output.
[0019]
The interference determination means in the radar device according to claim 1 is configured as a radar signal processing device as a radar signal processing device independent of other means constituting the radar device as described in claim 5. May be.
[0020]
And each means which comprises the signal processing apparatus for radar of Claim 5 may comprise as a program for functioning a computer as those means like Claim 6 .
In this case, the program is recorded on a computer-readable recording medium such as FD, MO, DVD, CD-ROM, hard disk, memory card, etc., and the stored program is loaded into a computer system as necessary. It can be used by starting. In addition, a program may be recorded as a computer-readable recording medium using a ROM or backup ROM, and the ROM or backup RAM may be incorporated into a computer system. Further, the program is not limited to the one recorded on the recording medium, and may be used by being loaded and activated via a network.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Reference examples and embodiments of the present invention will be described below with reference to the drawings .
[Reference example]
FIG. 1 is a block diagram illustrating a configuration of a radar apparatus according to a reference example .
[0022]
As shown in FIG. 1, the radar apparatus 2 includes a pulse generator 4 that generates a pulse signal (hereinafter referred to as “transmission pulse signal”) Ps according to a timing signal C, and a pulse of the transmission pulse signal Ps according to the transmission pulse signal Ps. A high frequency signal in the microwave band is generated for a width period (about 30 ns in this reference example ), this is transmitted as a radar wave, and when the radar wave is received, the received intensity is measured and intensity data A is output. And a pulse radar transmission / reception unit 6 that demodulates the received radar wave and outputs a pulse signal (hereinafter referred to as “reception pulse signal”) Pr.
[0023]
Further, the radar apparatus 2 uses the time difference from when the transmission pulse signal Ps is input to the pulse radar transmission / reception unit 6 to when the reception pulse signal Pr is output from the pulse radar transmission / reception unit 6 as the round trip of the radar wave to the target TG. Time difference measurement unit 8 that measures time and outputs time data DT as the measurement result, supply of timing signal C to pulse generator 4, time data DT from time difference measurement unit 8, and pulse radar transmission / reception unit 6 And a control unit 10 that executes processing such as detecting the distance to the target TG and the presence or absence of interference based on the intensity data A.
[0024]
Here, the control unit 10 includes a known microcomputer including a CPU, ROM, RAM, I / O, timer, and the like, and the timing signal C, time data DT, and intensity data described above are transmitted to the inside of the radar apparatus 2. In addition to inputting / outputting A, distance information used for displaying the distance to the target TG to the outside of the radar device 2 and interference information used for displaying the presence / absence of interference are output. .
[0025]
The ROM constituting the control unit 10 stores an interference determination table in which the distance to the target TG and the maximum reception intensity at the distance are associated with each other, as well as various processing programs executed by the control unit 10. Has been.
As shown in FIG. 2, the interference determination table is set such that the maximum reception intensity decreases as the distance increases. In addition, since the actual reception intensity becomes larger as the target has a larger size and better reflectivity (for example, the vehicle is larger for humans and vehicles), it is assumed that the maximum reception intensity exists around the vehicle, for example. Reflection characteristics of the largest reflectors (walls, etc.), characteristics of the pulse radar transceiver 6 (radar wave transmission power, conversion efficiency of antennas that transmit and receive radar waves), propagation loss in the atmosphere, distance to the target It is obtained on the basis of signal intensity fluctuations caused by a plurality of reflected waves.
[0026]
Next, processing executed by the control unit 10 will be described.
In the control unit 10, a transmission process for generating the timing signal C and a reception process for detecting the distance to the target and the presence or absence of interference based on the time data DT and the intensity data A are executed in parallel.
[0027]
Among these, the transmission processing is periodically started by a timer interrupt, and at least every fixed time interval (100 μs in this reference example ) longer than the time required for the radar wave to reciprocate the maximum detection distance of the radar device 2. In addition, the timing signal C is generated.
[0028]
On the other hand, the reception process will be described with reference to the flowchart shown in FIG. However, whenever the time data DT and the intensity data A are output from the time difference measurement unit 8 and the pulse radar transmission / reception unit 6, they are combined at any time and written in a predetermined area of the RAM of the microcomputer constituting the control unit 10. And Data obtained by combining the time data DT and the intensity data A is also referred to as target data below. In addition, when a plurality of radar waves are received with respect to one transmission of the radar wave, target data is individually generated for each of them.
[0029]
As shown in FIG. 3, when this process is activated, it is first determined whether or not there is unprocessed target data (S110). If there is no unprocessed target data, the process waits by repeatedly executing the same step. On the other hand, if there is unprocessed target data, the distance to the target TG is calculated based on the time data DT therein (S120).
[0030]
Then, based on the calculated distance and the interference determination table stored in the ROM, the maximum reception intensity at the distance is obtained (S130), and whether or not the input intensity data A is larger than the maximum reception intensity. Judgment is made (S140).
If the intensity data A is less than or equal to the maximum received intensity, the target data is based on the reflected wave from the target, and distance information representing the distance obtained in S120 is output to an external display device or the like. (S150), the process returns to S110.
[0031]
On the other hand, if the intensity data A is greater than the maximum received intensity, the target data is determined to be based on the interference wave, and interference information is output to an external display device or the like to notify that the interference wave has been received (S160). Further, the process at the time of interference is executed (S170), and the process returns to S110.
[0032]
Here, the process at the time of interference may be, for example, simply discarding the distance calculated in S120 together with the target data used for the calculation, or prohibiting the generation of the timing signal C by the transmission process for a certain period. May be .
[0033]
As described above, in the radar apparatus 2 of the present reference example , by comparing the intensity data A with the maximum received intensity, whether the target data obtained by receiving the radar wave is due to a reflected wave from the target or interference It is determined whether it is due to a wave, distance information is output if it is due to a reflected wave from the target, and interference information is output if it is due to an interference wave.
[0034]
Therefore, according to the radar apparatus 2 of this reference example , an interference wave having a reception intensity that cannot be a reflected wave from the target (for example, a direct wave from another radar apparatus) is erroneously detected as a reflected wave from the target. Can be reliably prevented.
Further, in this reference example , since it is determined whether or not each target data is based on the interference wave individually, the reflected wave and the interference wave from the target are transmitted for one transmission of the radar wave. Can be received in a mixed manner, the two can be separated and only the distance of the target that actually exists can be obtained.
[Implementation form]
To the next for the implementation embodiment will be described.
[0035]
In the present embodiment, the contents of the transmission process and the reception process executed by the control unit 10 are only partially different from those of the reference example , and thus these processes will be mainly described.
First, the contents of the transmission process executed by the control unit 10 in the present embodiment will be described with reference to the flowchart shown in FIG.
[0036]
As shown in FIG. 4, when this processing is started, first, a timing signal C is generated, thereby causing the pulse generator 4 to generate a transmission pulse signal, and further causing the pulse radar transmission / reception unit 6 to transmit a radar wave (S210). ). The elapsed time after the generation of the timing signal C exceeds a detection period (300 ns in the present embodiment) set longer than at least the time required for the radar wave to reciprocate the maximum detection distance of the radar device 2. (S220), and if it does not exceed the detection period, it waits by repeatedly executing the same step. Time data DT and intensity data A output from the time difference measuring unit 8 and the pulse radar transmitting / receiving unit 6 during this detection period are sequentially stored in the RAM as target data.
[0037]
On the other hand, if the elapsed time after generation of the timing signal C exceeds the detection period, an interference flag described later is reset (S230), and this time, the elapsed time after the end of the detection period is preset. It is determined whether or not the monitoring period (5 μs in this embodiment) has been exceeded (S240). If the monitoring period has not been exceeded, the writing of target data to the RAM is monitored. The target data is discarded and an interference wave monitoring process for setting an interference flag indicating that the interference wave has been received is executed (S250), and the process returns to S240.
[0038]
In S240, if the elapsed time from the end of the detection period exceeds the monitoring period, it is determined whether the interference flag is set (S260). If the interference flag is set, The monitoring period is reset and the interference flag is reset (S270). Further, the interference display setting for notifying that the interference wave is being received is performed using the display device or the like (S280), and the process returns to S240.
[0039]
In S260, if the interference flag is not set, whether or not the interference display is set, that is, the target data is written (reception of radar wave) during the monitoring period, and the monitoring period is reset. It is determined whether it has been done (S290). If the interference display setting is not set, the process directly returns to S210. On the other hand, if the interference display setting is set, the interference display setting is canceled (S300), and after waiting for a random time (S310), the process returns to S210. Return.
[0040]
In other words, if no radar wave (interference wave) is received during the monitoring period by this processing, the timing signal C has a fixed period of (detection period) + (monitoring period) as shown in FIG. appear. On the other hand, when a radar wave is received during the monitoring period, as shown in FIG. 5B, the generation period of the timing signal C is extended by resetting the monitoring period, and during the reset monitoring period. If no radar wave is received, the timing signal C is generated after a random period has elapsed after the end of the monitoring period.
[0041]
Next, the reception process is the same as the reception process described in the reference example , except that S160 is omitted, and in S170, only the distance obtained in the corresponding S120 and the deletion of the target data used for the calculation are deleted. Except for the point that it is configured to perform, the configuration is exactly the same. In the present embodiment, the reception process processes only the target data written in the RAM during the detection period.
In the present embodiment, the pulse generator 4, the pulse radar transceiver unit 6, the time difference measuring unit 8 is the time measuring means, S120 distance calculating means, S160 is reporting means, S240～S270 is interference determination means, S260, S290 , S310 corresponds to transmission permission means, S270 corresponds to monitoring period extension means, S280 corresponds to notification means, S170 corresponds to information discarding means, and the control unit 10 corresponds to a signal processing device for radar.
[0042]
As described above, in the present embodiment, when target data is detected outside the detection period necessary for the radar wave to reciprocate the maximum detection distance of the radar device 2, that is, when an interference wave is received. Then, the transmission of the radar wave is postponed, and the transmission of the radar wave is resumed after waiting for the interference wave not to be received.
[0043]
Therefore, according to the present embodiment, the target can be detected when the surrounding radio wave condition is good, and the detection reliability can be improved.
Further, in this embodiment, when the monitoring period is reset by reception of the interference wave, when restarting the transmission of the radar wave, a random period having a random length is further inserted after the monitoring period has elapsed, and the transmission of the radar wave is performed. The timing is shifted.
[0044]
Therefore, for example, when interference occurs between similar radar devices, it is possible to prevent the devices from interfering with each other again after the monitoring period elapses, and the devices cannot be used for a long period of time.
Furthermore, in the present embodiment, for the target data detected within the detection period, the target data obtained by receiving the radar wave by comparing the intensity data A with the maximum received intensity is reflected by the reflected wave from the target. to determine due to or interference, if it is due to the interference wave is to remove it, since only is adapted to output distance information about the target data based on the reflected wave, in the case of reference example Similar effects can be obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a radar apparatus according to a reference example .
FIG. 2 is a graph showing the relationship between distance, reception intensity, and maximum reception intensity.
FIG. 3 is a flowchart showing the contents of reception processing in a reference example .
4 is a flowchart showing the contents of transmission processing in the implementation form.
FIG. 5 is an explanatory diagram showing an operation state realized by transmission processing;
FIG. 6 is an explanatory diagram showing a problem of a conventional device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 2 ... Radar apparatus 4 ... Pulse generator 6 ... Pulse radar transmission / reception part 8 ... Time difference measurement part 10 ... Control part

Claims (6)

Transmitting and receiving means for transmitting and receiving radar waves;
A time measuring means for causing the transmitting / receiving means to transmit a pulsed radar wave and measuring the time until the transmitting / receiving means receives the radar wave;
When the time measured by the time measuring means exceeds the detection period necessary for receiving the reflected wave from the target existing within the preset maximum detection distance, the interference wave is being received. If there is no reception of radar waves during the monitoring period set after the detection period has elapsed, transmission permission means for permitting transmission of radar waves by the transmission / reception means; and radar wave transmission during the monitoring period If there is reception, interference determination means comprising monitoring period extension means for resetting the monitoring period ;
Equipped with a,
The transmission permission means permits the transmission of the radar wave after the standby period set to a random length has elapsed unless a radar wave is received during the monitoring period reset by the monitoring period extending means. Radar apparatus characterized by the above. The radar apparatus according to claim 1 , wherein
A receiving intensity measuring means for measuring the receiving intensity of the radar wave received by the transmitting / receiving means;
Distance calculation means for determining the distance to the target, using the time measured by the time measurement means as the round trip time of the radar wave to the target;
When the received intensity measured by the received intensity measuring means for the radar wave received during the detection period is greater than the theoretical maximum received intensity at the distance obtained by the distance calculating means for the radar wave, the Information discarding means for discarding information obtained based on the radar wave;
A radar apparatus comprising: The radar apparatus according to claim 1 or 2 ,
A radar apparatus comprising: an informing means for informing that when the interference judging means judges that an interference wave is being received. The radar apparatus according to any one of claims 1 to 3 ,
A radar apparatus comprising: an output prohibiting unit that prohibits output of a target detection result when the interference determining unit determines that an interference wave is being received. In a radar signal processing device that detects a target that reflects a radar wave based on the time from when a pulsed radar wave is transmitted until the radar wave is received,
When the time exceeds a detection period necessary for receiving a reflected wave from a target existing within a preset maximum detection distance, it is determined that an interference wave is being received and the detection If there is no reception of radar waves during the monitoring period set after the elapse of the period, transmission permission means for permitting transmission of radar waves by the transmission / reception means; and if there is reception of radar waves during the monitoring period, the monitoring period Interference determination means comprising monitoring period extension means for resetting ,
Equipped with a,
The transmission permission means permits the transmission of the radar wave after the elapse of a standby period set to a random length if no radar wave is received during the monitoring period reset by the monitoring period extension means. A signal processing apparatus for radar. A program for causing a computer to function as each means constituting the radar signal processing apparatus according to claim 5 .

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