JPH10246770A - Radar equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve precision of a calculation distance by calculating a distance on the basis of a propagation delay time from transmission of a pulse signal to receiving in the case where an integration value in which a reflection pulse signal is obtained to be successively integrated at constant intervals exceeds a threshold value, and judging whether it is the reflection pulse signal by a judgement means in the case where it does not exceed the threshold value. SOLUTION: A control part 15 searches whether the integration value of a threshold value Vt2 or less for judging the existence and absence of a reflection body exists. At some time, it is judged whether the integration point of the threshold value Vt1 or more of a noise level exists. Because a reflection pulse signal or the fluctuation of the noise level is judged since at some time the integration point is between the threshold values Vt1 -Vt2 , pulse signal transmission is stopped once. It is judged whether the integration point of the threshold value Vt1 or more of the noise level exists. In the case where it does not exist, it is judged that a receiving pulse signal exists, and pulse signal transmission is started. A judgement part searches the four peak values of the output of the integration value, these are connected by straight lines to make intersection points the peak points, and a propagation delay time, i.e., a distance up to the reflection body is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar apparatus, and more particularly to a radar apparatus which transmits a pulse signal in a predetermined direction, receives a reflected pulse signal reflected by a reflector, and reduces a propagation delay time from transmission to reception. The present invention relates to a radar device that measures a distance to a reflector based on the radar device.

[0002]

2. Description of the Related Art As a conventional radar apparatus, for example, FIG.
The following are known. In this device, a pulse signal composed of a radio wave, a light wave, a sound wave, or the like is transmitted from a pulse signal transmitting unit 101, and when the pulse signal is reflected by a reflector in front, a reflected pulse signal receiving unit 10
3 is received. Next, the reception signal variable section 105 variably sets the amplification gain according to the control signal from the control section 113 and amplifies the reception signal. Next, in the distance calculating / integrating section 107, the amplified received signal is sequentially integrated by each capacitor for a predetermined time. Next, the A / D converter 1
At 09, each integrated value is subjected to A / D conversion to be converted into integrated value data. When the integrated value data exceeds a preset threshold value VR, the determination unit 111 determines that the received signal is a signal received at the time of reflection by the reflector. Here, the control unit 113 measures the distance to the reflector based on the propagation delay time from transmission of the pulse signal to reception of the pulse signal.

[0003] Here, referring to FIG.
7 will be described in detail. Each of the integrators 1 to n is composed of resistors R1 to Rn and capacitors C1 to Cn.
To n are input to the reception signal. Each integrator is turned on for a predetermined time. That is, conduction is performed at a certain distance interval. Next, the integrated value at the point at that distance is output from each integrator and output to the A / D converter 109.

Next, the operation of the distance calculation and integration unit 107 will be described with reference to a timing chart shown in FIG. At timing (1) shown in FIG. 9, the transmission pulse signal having the pulse width T2 is transmitted from the pulse signal transmission unit 101 at the interval T1. At timing (2), the received pulse signal is received by the reflected pulse signal receiving unit 103 with a delay time corresponding to the distance to the reflector. At timing (3), the switch SW shown in FIG. 8 is sequentially turned on using a gate signal having an interval Td corresponding to a distance of, for example, 20 m because of the reciprocation in the radar apparatus.

At timings (4), (5) and (6),
At this time, during the time when the received pulse signal exists, an output of an integrated value corresponding to the signal strength of the received signal is obtained in the integrator. Next, at timing (7), the determination unit 111 searches for four peak values of the output of the integrated value, connects them with a straight line, and sets the intersection as the peak point of the received signal. This peak point is defined as a propagation delay time from transmission of the pulse signal to reception of the pulse signal, that is, a distance to the reflector.

In a conventional radar device, a reflection signal reflected by a vehicle in front of the radar device is received, and a threshold value VR is set to a value equal to or higher than a noise distribution in order to determine an integrated value. If the threshold value VR is exceeded, it is determined that there is a vehicle serving as a reflector.

[0007]

By the way, in the conventional radar device, the noise level is the average value of the noise normalized as a Gaussian distribution, as shown at timing (1) shown in FIG. It was assumed that there was a certain level below the threshold.

However, as shown in a timing (2) shown in FIG. 10, the distribution of the noise level fluctuates due to the temperature, the power supply voltage, the aging of the element, and the like, so that the average value of the noise level is inevitable. fluctuate. As a result, when the noise level distribution exceeds a threshold value VR for determining the presence or absence of a reflector, there is a problem that this point is erroneously determined as a reflector to be captured.

On the other hand, the lower the threshold value VR is, the farther the reflector can be caught. On the other hand, if the threshold value VR is set high in anticipation of fluctuations in the noise level distribution, the detection distance decreases. There was such a problem. Further, in the conventional radar device, when calculating the distance as shown in a timing (6) shown in FIG. 9, four points are selected in descending order from the maximum value among the total integrated values, and the result is shown in FIG. As in timing (7), these two points are connected by a straight line, and the intersection is calculated as the distance to the reflector.

At this time, the calculation accuracy of the distance is maintained on the assumption that the noise level exists in a Gaussian distribution and that the average value of the noise level does not fluctuate at a constant level. As a result, if there is no level fluctuation at the points of the integrated voltage outputs # 4 and # 7, the peak point can be detected as shown at timings (1) and (2) in FIG.

However, when the integrated value of the received signal fluctuates due to the fluctuation of the noise level, as shown at timings (3) and (4) in FIG.
4, the point # 7 moves upward, and as a result, a change occurs in the inclination of the straight line. As a result, there is a problem that a variation component Δd corresponding to an error occurs in the calculated distance as shown in FIG. .

As described above, the conventional radar apparatus is based on the premise that the noise level exists in a Gaussian distribution and that the average value of the noise is constant and does not fluctuate.
A change in the noise level causes a decrease in the receiving sensitivity of about 6 dB, resulting in a problem that the maximum detection distance is shortened by about 20% and the accuracy of the calculated distance is deteriorated.

The present invention has been made in view of the above, and an object of the present invention is to provide a radar apparatus which can contribute to improvement in accuracy of a calculated distance.

[0014]

According to the first aspect of the present invention,
To solve the above problem, after sending the pulse signal,
If the integrated value obtained by receiving the reflected pulse signal reflected by the reflector and sequentially integrating at a certain interval exceeds a predetermined threshold value, based on the propagation delay time from transmission to reception of the pulse signal. A radar device that calculates a distance to a reflector by using a reference signal, and when the integrated value does not exceed the predetermined threshold value, the radar device includes a determination unit that determines whether the signal is the reflected pulse signal. I do.

According to a second aspect of the present invention, in order to solve the above-mentioned problem, the determining means controls to stop sending the pulse signal when the integrated value does not exceed the predetermined threshold value. The gist of the present invention is to include control means for performing the above operation and second judgment means for judging whether or not the integrated value when there is no signal exceeds the noise level threshold during the stop period of the pulse signal.

According to a third aspect of the present invention, in order to solve the above-mentioned problem, the second determining means determines that the reflected pulse signal is not detected when an integrated value at the time of no signal does not exceed a noise level threshold value. The point is that the integral value is determined as a value effective for calculating the distance to the reflector.

According to a fourth aspect of the present invention, in order to solve the above-mentioned problem, the second determining means determines whether or not the integrated value when there is no signal exceeds a noise level threshold value by using the reflected pulse signal. The gist is that the integral value is determined as an invalid value for calculating the distance to the reflector.

According to a fifth aspect of the present invention, in order to solve the above-mentioned problem, when the integrated value at the time of no signal exceeds a noise level threshold value, the second determining means determines a value based on the integrated value. To change the threshold value of the noise level.

According to a sixth aspect of the present invention, in order to solve the above-mentioned problem, the second determination means includes a first storage means for storing a plurality of noise levels from the past, and a plurality of noise levels from the past. And a second storage means for storing the average value of the noise level as a threshold value of the noise level.

According to a seventh aspect of the present invention, in order to solve the above-mentioned problem, when the integrated value at the time of no signal exceeds the noise level threshold, the first storage means sets the integrated value to the minimum. The point is to update as old data.

According to an eighth aspect of the present invention, when the average value of the noise level exceeds a threshold value of the noise level, the second storage means newly stores the average value. The main point is to update the threshold value of the noise level.

[0022]

According to the first aspect of the present invention, after transmitting a pulse signal, a reflected pulse signal reflected by a reflector is received, and an integrated value obtained by successively integrating at a predetermined interval is a predetermined value. If the reflected pulse signal does not exceed the threshold value, it is determined whether or not the reflected pulse signal is reflected by the reflector, even when the reflected pulse signal is attenuated. Is determined, the accuracy of the calculated distance can be improved.

According to the second aspect of the present invention, when the integrated value of the received reflected pulse signal does not exceed a predetermined threshold value, the transmission of the pulse signal is controlled to be stopped, During the stop period of the pulse signal, by determining whether or not the integrated value at the time of no signal exceeds the noise level threshold value, even when the reflected pulse signal is attenuated, it is reflected by the reflector. It can be determined whether or not the reflected pulse signal is a reflected pulse signal, and as a result, it is possible to contribute to the improvement of the accuracy of the calculated distance.

According to the third aspect of the present invention, when the integrated value when there is no signal does not exceed the noise level threshold value, the integrated value based on the reflected pulse signal is used to calculate the distance to the reflector. By determining as a valid value, it is possible to determine that the reflected pulse signal is a reflected pulse signal reflected by the reflector even when the reflected pulse signal is attenuated. It can contribute to improvement.

According to the present invention, when the integrated value when there is no signal exceeds the noise level threshold, the integrated value based on the reflected pulse signal is used to calculate the distance to the reflector. By making the determination as an invalid value, erroneous determination can be prevented, and as a result, it is possible to contribute to improvement in the accuracy of the calculated distance.

According to the fifth aspect of the present invention, when the integrated value at the time of no signal exceeds the noise level threshold value, the noise level threshold value is changed based on the integrated value. Thus, at the next determination, the determination can be performed using the latest noise level threshold, and as a result,
It is possible to prevent erroneous determination and further contribute to improvement in accuracy of the calculated distance.

According to the present invention, a plurality of noise levels from the past are stored, and an average value of the plurality of noise levels from the past is stored as a noise level threshold. Extreme fluctuation of the threshold value can be prevented, and as a result, a stable threshold value can be set.

According to the present invention, when the integrated value at the time of no signal exceeds the threshold value of the noise level, the integrated value is updated as the oldest data.
It is possible to sequentially update the integrated value of the noise level, and as a result, it is possible to set the threshold value of the noise level suitable for the current noise level state.

According to the present invention, when the average value of the noise level exceeds the threshold value of the noise level, the average value is updated as a new threshold value of the noise level. Thus, it is possible to set a threshold value of the noise level suitable for the current noise level state.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a diagram showing a block configuration of a radar device 1 according to a first embodiment of the present invention.
In the figure, a radar device 1 includes a pulse signal transmitting unit 3 that transmits a pulse signal composed of radio waves, light waves, sound waves, and the like, a reflected pulse signal receiving unit 5 that receives a reflected signal of the transmitted pulse signal by a reflector. A reception signal gain variable unit 7 for variably setting the amplification gain of the received signal by a control signal and amplifying the received signal in order to calculate the distance; A distance calculating / integrating unit 9 for integrating using an RC integrator made of C, an A / D converting unit 11 for converting the integrated value into a digital signal, and a quantized integrated value from the A / D converting unit 11 being predetermined. A judgment unit 13 for judging whether the integrated value is due to the reflector, and for judging whether or not this integrated value is due to the reflector, timing of A / D conversion, distance Calculated and, a control unit 15 for controlling the setting of the amplification gain of the received signal, and a pulse signal transmission control unit 17 for controlling the pulse signal sending unit 3 by the timing signal from the control unit 15. The determination unit 13
Is configured to hold the integrated value after A / D conversion as necessary.

Next, the operation of the radar apparatus 1 will be described with reference to FIGS. In FIG. 1, the control unit 15
At regular intervals T1, a timing signal is output to the pulse signal transmission control unit 17, and the pulse signal transmission control unit 17 outputs a timing signal having a pulse width T2 to the pulse signal transmission unit 3 from the rise of the timing signal. Next, the pulse signal transmitting unit 3 transmits a pulse signal composed of a radio wave, a light wave, a sound wave, or the like, for example, to the front of the vehicle.

Here, when a reflected signal from a reflector or the like in front of the vehicle is received by the reflected pulse signal receiving section 5, a received signal is output. On the other hand, since the gain of the received signal gain variable section 7 is controlled by the control section 15, the received signal is amplified by the received signal gain variable section 7. Next, the amplified reception signal is input to the distance calculation integration unit 9. Note that the specific configuration of the distance calculation and integration section 9 is the same as that shown in FIG.

In the distance calculating / integrating section 9, a conduction signal is sequentially added to the gate signal input, and the ON / OFF operation of a switch SW provided at the input of each integrator causes the received signal at a predetermined distance to become 1. And the analog signal level at that time is obtained as an integrated value.
Further, the integrated value from each integrator is sequentially selected and A / D
Output to the converter 11. The A / D converter 11 quantizes the integrated value of the analog signal level and converts it into an integrated value of digital data (hereinafter simply referred to as an integrated value).

The timings (1) and (2) shown in FIG.
The “O” marks in (2) and (3) are integration points indicating the level of the integrated value. For integration points that contain only noise,
The value is almost に 対 し て of the lower limit and the upper limit of the input level. Each integrated value of this noise alone is stored in the internal latch circuit of the determination unit 13. On the other hand, at the integration point where the received signal exists, the level of the received signal is higher than the noise, so that the level of the received signal is dominant over the noise, and the voltage level appears higher than the integrated value of only the noise according to the input level.

At this time, if the integrated value is equal to or larger than the threshold value Vt2 stored in the internal latch circuit of the judging section 13, this integrated value is judged as a reflected pulse signal from the reflector. Next, four points are selected from the difference value between the integrated value and the integrated value of only noise in ascending order of the respective integrated values, and two points of each of the integrated values are connected by a straight line, and the intersection is defined as the peak point of the received signal.

Next, the case where the noise level fluctuates will be described with reference to the timing chart shown in FIG. Even if the noise level fluctuates, the presence / absence of the reflector can be determined without any problem when a reception signal equal to or more than the threshold value Vt2 for determining the presence / absence of the reflector is received.

However, if an integrated value which is equal to or less than the threshold value Vt2 for determining the presence or absence of a reflector and is larger than the noise level is obtained, it is probably due to a change in the noise level or from the reflector. It cannot be determined whether the reflected signal is merely small. That is, as at the timing (1) shown in FIG. 2, the integrated voltage outputs # 3 and # 4 are larger than the noise level by ΔV1 and ΔV2, respectively.

Therefore, the control unit 15 outputs a stop signal to the pulse signal transmission control unit 17 to temporarily stop the transmission of the pulse signal. At this time, if the integrated voltage outputs # 3 and # 4 become the same as the state of the timing (1) and do not change, as in the timing (2) shown in FIG. 2, there is no reflected pulse signal from the reflector. And judge.
That is, it is determined that the noise level is changed. Next, the integrated value is stored as a new integrated value of noise in the internal latch of the determination unit 13 and is rewritten anew.

On the other hand, when the transmission of the pulse signal is temporarily stopped by the pulse signal transmission control unit 17, the integration points of the integrated voltage outputs # 3 and # 4 are set to black points as shown at timing (3) shown in FIG. When the noise level becomes equal to or less than the threshold value Vt1, it is determined that the reflected pulse signal from the reflector in front of the vehicle is small only because the noise level becomes equal to or less than the threshold value Vt2 for determining the presence or absence of the reflector. In this case, the noise level is not updated.

Next, the control operation of the control unit 15 of the radar device 1 will be described with reference to the flowchart shown in FIG.
First, in step S10, the control unit 15 searches for an integration point equal to or less than a threshold value Vt2 for determining the presence or absence of a reflector. If there is no integrated value equal to or smaller than the threshold value Vt2, the process proceeds to step S70, and the distance measurement is completed. On the other hand, if there is an integration point equal to or less than the threshold value Vt2, the process proceeds to step S20
Proceed to.

In step S20, the control unit 15 determines whether there is an integration point equal to or higher than the noise level threshold value Vt1. If there is no integration point equal to or greater than the noise level threshold value Vt1, the process proceeds to step S70, and the distance measurement ends because there is no received signal. On the other hand, if there is an integration point equal to or greater than the noise level threshold, the process proceeds to step S30.
In step S30, since the integration point is between the threshold values Vt1 and Vt2, the control unit 15 sends a stop signal to output a stop signal to determine whether the signal is a reflected pulse signal from the reflector or a change in noise level. The output of the pulse signal from the pulse signal transmitter 3 to the controller 17 is temporarily stopped.

Next, in step S40, it is determined whether there is an integration point equal to or higher than the noise level threshold value Vt1.
If there is no integration point equal to or greater than the threshold value Vt1, it is determined that there is no noise fluctuation and that a received pulse signal from the reflector exists, and the process proceeds to step S70. On the other hand, when there is an integration point equal to or larger than the threshold value Vt1, the process proceeds to step S50. In step S50, it is determined that there is noise fluctuation, and this integration point is stored in the internal latch circuit of the determination unit 13 as a new noise level threshold.

Next, in step S60, the control unit 15
Starts a pulse signal from the pulse signal transmitting unit 3 by periodically outputting a timing signal. Step S7
At 0, the distance to the reflector is calculated as follows. First, in the process of step S10, when there is no integrated value equal to or less than the threshold value Vt2, or in the process of step S20, there is no integrated point equal to or more than the noise level threshold value Vt1, or in the process of step S40, If there is no integration point equal to or greater than the threshold value Vt1, the determination unit 13 searches for four peak values of the integrated value output, connects them with a straight line, and sets the intersection as the peak point of the received signal. This peak point is defined as a propagation delay time from transmission of the pulse signal to reception of the pulse signal, that is, a distance to the reflector.

Thus, after transmitting the pulse signal,
When the reflected pulse signal reflected by the reflector is received and the integrated value obtained by successively integrating at a constant interval does not exceed the predetermined threshold value Vt2, it is determined whether or not the reflected pulse signal is a reflected pulse signal. Even when the reflected pulse signal is attenuated, it is determined whether or not the reflected pulse signal is a reflected pulse signal reflected by the reflector, so that it is possible to contribute to improvement in accuracy of the calculated distance.

When the integrated value of the received reflected pulse signal does not exceed the predetermined threshold value Vt2, control is performed so as to stop the transmission of the pulse signal. The integrated value at the time is the noise level threshold Vt1
By determining whether or not the reflected pulse signal exceeds the calculated distance, it is possible to determine whether or not the reflected pulse signal is a reflected pulse signal reflected by the reflector even when the reflected pulse signal is attenuated. Can be improved.

When the integrated value when there is no signal does not exceed the noise level threshold value Vt1, the integrated value based on the reflected pulse signal is determined as a value effective for calculating the distance to the reflector. Even when the reflected pulse signal is attenuated, it can be determined that the reflected pulse signal is a reflected pulse signal reflected by the reflector, and as a result, the accuracy of the calculated distance can be improved.

When the integrated value at the time of no signal exceeds the noise level threshold value Vt1, the integrated value based on the reflected pulse signal is determined as an invalid value for the calculation of the distance to the reflector. Judgment can be prevented, and as a result,
This can contribute to improvement in the accuracy of the calculated distance.

When the integrated value at the time of no signal exceeds the noise level threshold value Vt1, the threshold value of the noise level is changed based on the integrated value, so that the latest determination will be performed at the next determination. The determination can be performed using the threshold value of the noise level. As a result, erroneous determination can be prevented, and further, the accuracy of the calculated distance can be improved.

In the first embodiment, the case where the noise level threshold value Vt1 is set to a value larger than the actually observed noise level has been described, but the present invention is applied only in such a case. Without being limited to the above, when the threshold value Vt1 of the noise level is set to a value smaller than the actually observed noise level, it is similarly determined whether or not the signal is a reflected pulse signal reflected by the reflector. As a result, the accuracy of the calculated distance can be improved.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
FIG. 3 is a diagram showing a block configuration of a radar device 21 according to the embodiment. The feature is that, in addition to the block configuration of the radar apparatus 1 shown in FIG. 1, the distance calculation integrated value storage unit 23 storing the integrated value output from the A / D conversion unit 11 and the distance calculation integrated value storage unit 23 The noise fluctuation determining unit 25 determines the fluctuation of the noise level from the stored integrated value.

Next, the operation of the radar device 21 will be described with reference to the timing chart shown in FIG. The basic operation of the radar device 21 according to the second embodiment is the same as the operation described in the first embodiment. In addition to this basic operation, the integrated value of only the past noise is stored in the distance calculation integrated value accumulating section 23, and the noise level fluctuation is determined by the noise fluctuation determining section 25 from the stored integrated value.

The distance calculation integrated value accumulating section 23 stores, for example, integrated values of only 100 noises retroactively, and calculates an average value from the integrated values of the 100 noises to calculate the noise level. The threshold value is Vt1. here,
If the integrated value is equal to or less than the threshold value Vt2 for determining the presence or absence of a reflector and is greater than the noise level threshold value Vt1,
It cannot be determined whether the change is due to the noise level or whether the reflected pulse signal from the reflector is merely small. That is, FIG.
As shown in timing (1) shown in FIG.
# 4 is larger than the noise level by ΔAV1 and ΔAV2, respectively. Since it is equal to or less than the threshold value Vt2 for determining the presence or absence of a reflector, it is determined that there is no reflector, but is larger than the noise level threshold value Vt1.

Therefore, the control unit 15 outputs a stop signal to the pulse signal transmission control unit 17 to temporarily stop the transmission of the pulse signal from the pulse signal transmission unit 3. If the integrated value at that time is equal to or less than the threshold value Vt1 of the noise level, it is determined that the integrated value is equal to or less than the threshold value Vt2 for determining the presence / absence of the reflector and that there is a pulse signal reflected by the reflector. In this case, the distance calculation integrated value accumulating unit 2
3 does not store the integrated value of only noise.

Also, as shown at timing (1) shown in FIG. 5, if the integrated values are the same as ΔV1 and ΔV2 even when the transmission pulse signal is stopped, it is assumed that the noise level fluctuates and the integration is performed. The value is stored in the distance calculation integrated value accumulating section 23, and is replaced with the oldest data of the integration point. As described above, when it is determined that the noise level has fluctuated, the noise level is always updated one by one from the oldest one.

Further, as shown at the timing (2) shown in FIG. 5, the average values ΔAV1 and ΔAV2 of the noise data stored in the distance calculation integrated value storage unit 23 are equal to the noise threshold value Vt1.
If this is the case, the average value is set to the new noise level threshold V, as indicated by the black point shown at timing (3).
Let it be t1.

Next, the control operation of the control unit 15 of the radar device 21 will be described with reference to the flowchart shown in FIG. First, in step S110, the noise fluctuation determination unit 2
Step 5 determines whether there is an integration point equal to or greater than the noise level variation range. That is, it is determined whether or not there is a point where the integration point is equal to or higher than the noise threshold value Vt1. If the integrated value is equal to or greater than the noise threshold value Vt1, the process proceeds to step S120. on the other hand,
If the integrated value is equal to or less than the noise threshold value Vt1, step S
Go to 190.

If there is an integrated value equal to or larger than the noise threshold value Vt1, in step S120, the integration point is set to the threshold value Vt1 to Vt1.
Since it is between Vt2, the reflected pulse signal from the reflector
The control unit 15 determines whether the noise level has fluctuated.
Outputs a stop signal to the pulse signal transmission control unit 17 to temporarily stop the transmission of the pulse signal from the pulse signal transmission unit 3.

In step S130, it is determined whether there is an integration point equal to or higher than the noise level threshold value Vt1. If there is no integration point equal to or greater than the threshold value Vt1, it is determined that there is no change in the noise level and that there is a reflected pulse signal from the reflector, and the process proceeds to step S190. on the other hand,
If there is an integration point equal to or greater than the threshold value Vt1, the process proceeds to step S140. If the noise level is equal to or more than the noise threshold value Vt1, it is determined in step S140 that the noise level fluctuates and the integrated value is stored in the distance calculation integrated value accumulating unit 23
To be stored.

Here, in step S150, it is determined whether or not 100 integrated points of the noise level have been stored in the distance calculation integrated value accumulating section 23. If only 100 noise level integration points are stored, the process proceeds to step S160. On the other hand, if 100 have not been stored yet, the process proceeds to step S190.

In step S160, as shown at timing (2) shown in FIG. 5, the noise variation determination unit 25 determines that the average values ΔAV1 and ΔAV2 of the past noise data stored in the distance calculation integrated value storage unit 23 are noise. It is determined whether or not the threshold value Vt1 has been reached. If the average value of the past noise data is equal to or larger than the noise threshold value Vt1, the process proceeds to step S170. On the other hand, the average value is the noise threshold V
If it is not greater than t1, the process proceeds to step S190.

Next, when the average value of the noise data exceeds the noise threshold value Vt1, in step S170, this average value is changed to a threshold value of a new noise level as indicated by a black point at timing (3). The value Vt1 is set in the determination unit 13. Next, in step S180, the control unit 15 periodically outputs the timing signal to start transmitting the pulse signal from the pulse signal transmitting unit 3, and returns to the normal distance measuring operation.

Next, in step S190, the distance to the reflector is calculated as follows. First, step S
If the integrated value is equal to or smaller than the noise threshold value Vt1 in the process of step 110, or the threshold value Vt1 is determined in the process of step S130.
If there are no such integration points, or if the integration of the noise level has not yet been stored in the distance calculation integration value storage unit 23 in the process of step S150, or if the distance calculation integration value storage unit 23 If the average values ΔAV1 and ΔAV2 of the past noise data accumulated in the above are not equal to or larger than the noise threshold value Vt1, the determination unit 13 searches for four peak values of the integrated value output, and connects them with a straight line. The intersection is defined as the peak point of the received signal. This peak point is defined as a propagation delay time from transmission of the pulse signal to reception of the pulse signal, that is, a distance to the reflector.

As described above, by storing a plurality of noise levels from the past and storing the average value of the plurality of noise levels from the past as the noise level threshold value Vt1, extreme fluctuation of the threshold value can be prevented. Can be prevented, so that
A stable threshold value Vt1 can be set. Also,
When the integrated value at the time of no signal exceeds the threshold value Vt1 of the noise level, the integrated value of the noise level can be sequentially updated by updating the integrated value as the oldest data. As a result, A noise level threshold value Vt1 suitable for the current noise level state can be set.

When the average value of the noise level exceeds the threshold value Vt1 of the noise level, the average value is updated as a new threshold value Vt1 of the noise level, thereby conforming to the current noise level state. The threshold value Vt1 of the noise level can be set.

As a result, in the radar device of the present invention, when the noise level distribution fluctuates due to temperature, power supply voltage, changes over time of the elements, etc., the reflected pulse signal is attenuated. Even in such a case, since it is possible to determine whether or not the signal is a reflected pulse signal reflected by the reflector, the receiving sensitivity can be improved by about 6 dB as compared with the conventional radar apparatus, and as a result, The accuracy of the calculated distance can be improved.

In the first and second embodiments, the integrated value from the distance calculating / integrating section 9 is used for the A / D converter 1
After quantizing at 1, it is determined whether or not the quantized integral value is a reflected pulse signal. However,
The present invention is not limited only to such a case. For example, after the reception signal amplified by the reception signal gain variable section is sequentially sampled by the A / D converter, the reception signals are sequentially added within a certain interval. After generating the integrated value, it may be determined whether or not this integrated value is a reflected pulse signal,
In this case, it is needless to say that the above-described effects can be obtained.

[Brief description of the drawings]

FIG. 1 is a radar apparatus 1 according to a first embodiment of the present invention.
3 is a diagram showing a block configuration of FIG.

FIG. 2 is a timing chart for explaining the operation of the radar device 1.

FIG. 3 is a flowchart for explaining a control operation by a control unit 15 of the radar device 1.

FIG. 4 is a radar apparatus 2 according to a second embodiment of the present invention.
FIG. 2 is a diagram showing a block configuration of No. 1;

FIG. 5 is a timing chart for explaining the operation of the radar device 21.

FIG. 6 is a flowchart for explaining a control operation by a control unit 15 of the radar device 21.

FIG. 7 is a diagram showing a block configuration of a conventional radar device.

FIG. 8 is a diagram showing an internal configuration of a distance calculation integration unit 107.

FIG. 9 is a timing chart for explaining the operation of a conventional radar device.

FIG. 10 is a diagram illustrating a state of an integrated value when a noise level distribution changes.

FIG. 11 is a diagram illustrating a method for calculating a distance to a reflector using a conventional radar device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 radar device 3 pulse signal transmission unit 5 reflected pulse signal reception unit 7 reception signal gain variable unit 9 distance calculation integration unit 11 A / D conversion unit 13 determination unit 15 control unit 17 pulse signal transmission control unit

Claims (8)

[Claims] 1. After a pulse signal is transmitted, a reflected pulse signal reflected by a reflector is received, and when an integrated value obtained by successively integrating at a predetermined interval exceeds a predetermined threshold value, a pulse is output. A radar device that calculates a distance to a reflector based on a propagation delay time from transmission of a signal to reception, wherein the integrated value does not exceed the predetermined threshold,
A radar apparatus comprising: a determination unit configured to determine whether the signal is the reflected pulse signal. 2. The method according to claim 1, wherein the determining unit determines that the integrated value does not exceed the predetermined threshold value.
Control means for controlling the transmission of the pulse signal to be stopped; and second determination means for determining whether or not the integrated value at the time of no signal exceeds a noise level threshold during the stop period of the pulse signal. The radar device according to claim 1, comprising: 3. The method according to claim 2, wherein when the integrated value at the time of no signal does not exceed the threshold value of the noise level, the integrated value based on the reflected pulse signal is used for calculating the distance to the reflector. The radar apparatus according to claim 2, wherein the determination is made as a valid value. 4. The method according to claim 1, wherein, when the integrated value at the time of no signal exceeds a noise level threshold, the second determining means invalidates the integrated value based on the reflected pulse signal for calculating the distance to the reflector. 3. The radar device according to claim 2, wherein the determination is made as an appropriate value. 5. The method according to claim 1, wherein when the integrated value at the time of no signal exceeds the noise level threshold, the second determining means changes the noise level threshold based on the integrated value. The radar device according to claim 2, wherein 6. The second judging means, a first storage means for storing a plurality of past noise levels, and an average value of a plurality of past noise levels as a noise level threshold value. 3. The radar device according to claim 2, further comprising a second storage unit. 7. The method according to claim 6, wherein the first storage means updates the integrated value as the oldest data when the integrated value at the time of no signal exceeds a noise level threshold value. The described radar device. 8. The method according to claim 1, wherein when the average value of the noise level exceeds a threshold value of the noise level, the second storage unit updates the average value as a new threshold value of the noise level. The radar device according to claim 6, wherein