JPH1123697A - Radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately control a gain regardless of the level of signal strength from a plurality of targets by providing an integration circuit for integrating a reception signal for a specific time and controlling the reception signal according to the integration output of a reception integration means with an overlapping exceeding a transmission pulse width. SOLUTION: A pulse signal transmission means 1 of, for example, electronic waves and light transmits a pulse signal is transmitted at a constant interval by a control means 3. The control means 3 controls an integration means 5, a reception integration means 11, an integration value judging means 2, and a judging means 7. The integration means 5 integrates a reflection pulse signal that is amplified by a gain-controlling means 4. An VD converter 6 converts the output of the integration means 5 and the judging mean 7 calculates distance from the integration signal. A reflection pulse signal that is received by the reflection pulse signal reception means 2 is inputted to the reception integration means 11, the integration means 11 calculates distance to a target, switches integration output according to the distance, and appropriately controls gain whatever signal may be input regardless of a near-distance or long-distance signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device for measuring a distance to a target by using electromagnetic waves, light, or sound waves, and more particularly to an appropriate gain irrespective of the magnitude of signal strength from a plurality of targets. The present invention relates to a radar device that can execute control.

[0002]

2. Description of the Related Art As a conventional radar apparatus, for example, FIG.
The following are known. 1 means for transmitting a pulse signal of radio waves, light, sound waves, etc., 2 means for receiving a reflected pulse signal of the transmitted pulse signal at a target,
3 means for controlling the pulse signal sending means 1, integrating means 5, 8 and judging means 7, 4 means for controlling the gain of the received signal, 5 integrating the received reflected pulse signal for a predetermined time. It is a means for performing
Means having an electric circuit configuration shown by 0, and 6 is an A / D converter for converting the output of the integrating means 5 into a digital signal.
Reference numeral 7 denotes a determination unit, which also has a function of calculating a distance from the integrated signal.

FIG. 10 is an electric circuit diagram showing a specific configuration of the integrating means 5 shown in FIG. 9. A reflected pulse signal (received signal input) receives an integrator composed of a resistor Rn and a capacitor Cn via a switch SWn. Connected to be input to In.

The switches SW1, SW2,..., SWn are turned on sequentially by the control means 3 of FIG. For example, if integration is performed every 10 m, 10 m
, The switches SWn are turned on sequentially. Then, the received signal is input to the integrator In connected to the switch SWn, and integration is performed. That is, the switch SW1 is 0 m, the switch SW2 is 10 m,
Are output to integration outputs # 1 and # 2, respectively.

FIG. 11 shows an example of a timing chart of each signal. (1) is a transmission pulse having a width of at least the sampling period Δt. (2) is the reflected reception pulse signal, which is received with a delay time Td proportional to the distance to the reflector.
(3) is an integration gate pulse signal, which is a timing signal for turning on / off the switch SWn in FIG.
(4) shows the integrated output from each integrator In of FIG. (5) shows a procedure for calculating the distance to the target, in which two peak values of the integrated output are searched, two points before and after the peak value are connected by a straight line, and the intersection is defined as the peak value of the received signal. , And a time T from when the pulse signal is transmitted.

FIG. 12 is an electric circuit diagram showing the integrating means 8 of FIG. 9. The reflected pulse signal is connected to an integrator I consisting of a resistor R and a capacitor C via a switch SW. The switch SW in the integrating means 8 is
The conduction is carried out for a predetermined time by the control means 3 of FIG.

FIG. 13 shows the operation timing. While the gate signal .DELTA.t of the switch SW is ON, FIG.
The second switch SW is turned on to integrate the received signal. That is, when the switch SW is turned on, it is charged,
When not conducting, the voltage is maintained. Here, the gate time Δt
Is conducted for a long time, for example, for a long time in terms of distance, an integrated output is obtained regardless of the distance of the received signal, as shown in (2) and (3) of FIG. In the gain control means 4 shown in FIG. 9, the gain of the received signal is controlled using this output.

[0008]

By the way, in the conventional radar apparatus as shown in FIG. 9, for example, as shown in FIG. When both of the signals of the target 10 at a long distance are received, no particular problem occurs because the reception intensity of the signal at a long distance is generally lower.

However, in a vehicle radar,
The signal strength of the target on the far side is larger than the signal strength of the target on the near side, such as when the distant target is a reflector installed on the road side of the road or a vehicle with a large reflectivity, etc. There are cases. For this reason, as shown in FIG. 16, there is a problem that the signal after the gate pulse Δt becomes large, which hinders the gain control of the received signal.

Further, since the voltage of the integrated output is the area ratio between the time interval Δt of the gate signal and the area of the received signal, the longer the time interval Δt of the gate signal is, the smaller the integrated output of the received signal becomes. However, there is a problem that gain control becomes difficult.

The present invention has been made in view of such problems of the prior art, and has as its object to provide a radar apparatus capable of executing appropriate gain control regardless of the magnitude of signal strength from a plurality of targets. Aim.

[0012]

In order to achieve the above object, a radar apparatus according to the present invention transmits an electromagnetic wave, light, or sound wave, and receives a reflected wave of the transmitted electromagnetic wave, light, or sound wave by a reflector. In a radar device that integrates the reception signal for a predetermined time by an integration circuit including an analog switch and a resistance capacitor, the radar device includes a plurality of integration circuits that integrate the reception signal for a predetermined time, and Each of the predetermined times has a receiving integration means having an overlap of at least the transmission pulse width,
The gain control of the reception signal is performed by the integration output of the reception integration means.

In the radar apparatus according to the present invention, when performing gain control of a received signal, the integration time of a plurality of integration circuits for integrating the received signal has an overlap that is equal to or larger than the transmission pulse width. In this case, the integrated output of the received signal existing in each of the two integrated circuits is the same, and as a result, appropriate gain control can be performed using either of the integrated outputs.

In the radar apparatus according to the present invention, although not particularly limited, an integrated output integrated by the receiving integration means is monitored, and an integrated value of a signal having a short detection distance is preferentially used for gain control of the received signal. Is preferred. When trying to execute gain control using a received signal of a certain target, if a target exists at a shorter distance than that, the gain is preferentially used for gain control. Even if it is stronger, a received signal of a target existing in a short distance will be adopted, and appropriate gain control can be performed.

[0015]

According to the radar apparatus of the present invention, appropriate gain control can be performed regardless of the magnitude of signal strength from a plurality of targets.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, which will be described with reference to FIGS.

First, the structure will be described. 1 is radio wave, light,
This is a means for transmitting a pulse signal such as a sound wave.
As shown in (1), the control means 3 sends out pulse signals at regular intervals.

Reference numeral 2 denotes a means for receiving a reflected pulse signal of the transmitted pulse signal at the target, and receives the delayed pulse signal with a delay time Td proportional to the distance to the reflector as shown in FIG. Is done.

3 is a means for controlling the pulse signal transmitting means 1, the integrating means 5, the receiving and integrating means 11, the integrated value judging means 12 and the judging means 7, and 4 is a gain control means for receiving the reflected light. Amplify the pulse signal.

Reference numeral 5 denotes a unit for integrating the reflected pulse signal amplified by the gain control unit 4, and is specifically composed of an analog switch and a resistance capacitor as shown in FIG.

That is, the reflected pulse signal is transmitted to the switch S
It is connected via Wn to an integrator In consisting of a resistor Rn and a capacitor Cn. Here, the switch SWn is sequentially turned on by the control means 3 at intervals of a certain distance. For example, assuming that the integration is performed every 10 m, the switches SW1, SW2,... SWn are turned on in order of time corresponding to 10 m. And
The received signal is input to the integrator In connected to the switch SWn, and integration is performed. That is, the switch S
The switch W2 outputs integrated outputs corresponding to 0 m and the switch SW2 outputs integrated outputs corresponding to 10 m as integrated outputs # 1 and # 2, respectively.

Reference numeral 6 denotes an A / D converter for converting the output of the integrating means 5 into a digital signal. Reference numeral 7 denotes a judging means, which also has a function of calculating a distance from the integrated signal.

FIG. 11 also shows an example of a timing chart of each signal in the present embodiment, and FIG.
Is a transmission pulse having a width of at least the sampling period Δt as described above. FIG. 2B shows the received pulse signal reflected as described above, which is received with a delay time Td proportional to the distance to the reflector.

FIG. 3C shows an integration gate pulse signal, which is a timing signal for turning on and off the switch SWn in FIG. Each integrated output is converted into a digital signal by the A / D converter 6.

FIG. 4D shows the integrated output from each integrator In of FIG. Also, FIG.
This shows the procedure for calculating the distance to the target. It finds two peak values of the integrated output, connects the two points before and after it with a straight line, sets the intersection as the peak value of the received signal, The time T after the transmission is obtained. These processes are executed by the determination means 7.

As shown in FIG. 2, the receiving and integrating means 11 according to the present embodiment has a plurality of integrating means In including a switch SWn, a resistor Rn and a capacitor Cn.

The reflected pulse signal received by the reflected pulse signal receiving means 2 is input to the receiving integration means 11,
This signal is connected to each integrator In. The switches SW1, SW2,..., SWn are sequentially turned on at a predetermined time Δt, as shown in FIG.

Here, if the reflected pulse signal is within the conduction time of the switch SW1 (gate # 1) in the case where the target is at a short distance, as shown in FIGS. 3 (1) and (2). , The reflected pulse signal is the integral output # 1 shown in FIG.
Obtained from Then, gain control of the received pulse signal is performed by the gain control means 4 from the integrated output # 1.

Next, FIGS. 3 (3) and 3 (4) show the case where the target is at a farther distance.
2, the gain control is performed.

Here, switching between the integrated voltage outputs # 1 and # 2 becomes a problem. Therefore, in the present embodiment, at least the overlap of at least the pulse width of the output pulse is provided in the time of the gate signal of the integration means In in FIG. This will be described with reference to FIG. 4. If the received pulse signal is present between the gate pulse signals # 1 and # 2 as shown in FIG. 4, and if there is no overlap of the gate pulse signals, The values of the integration outputs # 1 and # 2 change depending on the existing position of the waveform. For this reason, when either of them is selected, the values do not match, so that gain control becomes difficult.

On the other hand, if the gate pulse signals overlap as in the present embodiment, and if they overlap by a pulse width or more as shown in the figure, the integration time Δt is the same and the pulse Since the magnitudes are the same, the same output value is obtained for both integrated outputs # 1 and # 2. Therefore, either value may be selected for the gain control.

To explain this further with reference to FIG. 5, the output of the integrated output # 1 decreases as the received pulse goes farther, but when the received pulse takes the integration time of the integrator # 2. , An output is gradually obtained as the integrated voltage output # 2. Then, in portions where the integration times overlap, both outputs have the same value.

As the pulse further departs from the integration time of the integrator # 2, the output decreases as the distance further increases. However, since the received pulse takes the integration time of the integrator # 3, the integrated output An output is gradually obtained at # 3, and thus the next integrator functions similarly.

Next, a procedure for selecting an integral output will be described. As shown in FIG. 6, since the overlap of the gate signals is set to Δt in advance, the distance L
1, L2 is known. Then, as shown in the flowchart of FIG. 7, the distance to the target is calculated (step 1), and when the distance is equal to or less than L1, the integrated output # 1 is used (step 2 → 4 → 6), and L1 is calculated. During L2, the integral output # 2 is used (steps 2 → 4 → 5), and above L2, the integral output # 3 is used (steps 2 → 3).

Further, at this time, when the integration output # 3 is used, gain control when a target enters a short distance becomes a problem. For this reason, as shown in the flowchart of FIG. 8, the integral value judging means 12 of FIG. 1 always monitors all the integrated outputs of the receiving and integrating means 11 of FIG.
1) It is determined whether there is an output at a short distance from the integrated output at a long distance (step 12), and the switching is notified to the determination means.

That is, when an output is obtained as the integral output # 1, it is determined that there is a target at a short distance, and the integral output used for gain control is switched to # 1 by interrupt processing (steps 13 → 14). . Thus, no matter what signal is input from a short distance to a long distance, appropriate gain control can be executed.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

[Brief description of the drawings]

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

FIG. 2 is an electric circuit diagram showing a reception integration means 11 according to the present invention.

FIG. 3 is a timing chart of each signal according to the embodiment of the present invention.

FIG. 4 is a timing chart of each signal according to the embodiment of the present invention.

FIG. 5 is a graph for explaining an integral output in the embodiment of the present invention.

FIG. 6 is a timing chart of each signal according to the embodiment of the present invention.

FIG. 7 is a flowchart showing the operation of the embodiment of the present invention.

FIG. 8 is a flowchart showing the operation of the embodiment of the present invention.

FIG. 9 is a block diagram showing a conventional radar device.

FIG. 10 is an electric circuit diagram showing an integrating means 5 of a conventional radar device.

FIG. 11 is a timing chart of each signal of a conventional radar device.

FIG. 12 is an electric circuit diagram showing an integrating means 8 of a conventional radar device.

FIG. 13 is a timing chart of each signal of a conventional radar device.

FIG. 14 is a timing chart of signals of a conventional radar device.

FIG. 15 is a diagram for explaining a problem of a conventional radar device.

FIG. 16 is a timing chart for explaining a problem of a conventional radar device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pulse signal sending means 2 ... Reflected pulse signal receiving means 3 ... Control means 4 ... Gain control means 5 ... Integrating means 6 ... A / D converter 7 ... Determining means 8 ... Integrating means 9 ... Radar means 10 ... Target 11 ... Reception integration means 12 ... Integration value judgment means

Claims (2)

[Claims] An electromagnetic wave, light, or sound wave is transmitted, a reflected wave of the transmitted electromagnetic wave, light, or sound wave is received by a reflector, and a predetermined time is determined by an integration circuit including an analog switch and a resistance capacitor. A radar device for integrating the received signal, comprising a plurality of integrating circuits for integrating the received signal for a predetermined time, and receiving integration means each of the predetermined times having an overlap of at least the transmission pulse width. And a gain control of the reception signal is performed by an integration output of the reception integration means. 2. A radar according to claim 1, wherein an integrated output integrated by said receiving integration means is monitored, and an integrated value of a signal having a short detection distance is preferentially used for gain control of the received signal. apparatus.