JPH10111353A - Radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an radar appropriate as an on-vehicle radar which precisely detects variation of output strength for a signal source. SOLUTION: A directional coupler 46 is connected to a signal source 56 that generates signals with a given output strength. A mixer 42 and a circulator 32 are connected to the directional coupler 46. A transmitting/receiving aerial 12 is connected to the circulator 32 through a rotary resistance attenuator 16. The circulator 32 is communicated with the mixer 42 to transmit the receiving signal which is received by the transmitting/receiving aerial 12. After the rotary resistance attenuator 16 is electrically cut off, the strength of synthetic signal generated by the mixer 42 is detected. When the strength is larger than standard value, the output strength of signal source 56 is determined too large. When the strength is smaller than standard value, the output strength of signal resource 56 is determined too small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device, and more particularly, to a radar device suitable for a vehicle-mounted radar device.

[0002]

2. Description of the Related Art Conventionally, Japanese Patent Application Laid-Open No.
As disclosed in No. 84, a radar device is known.
The above-mentioned conventional radar device includes a transmission / reception antenna disposed behind the vehicle. A signal source for generating a transmission signal of a predetermined frequency is connected to the transmission / reception antenna.
When an object exists near the transmitting / receiving antenna, a signal emitted from the transmitting / receiving antenna is reflected by the object and received by the transmitting / receiving antenna.

When a relative speed exists between an object and a transmitting / receiving antenna, a Doppler shift corresponding to the relative speed is superimposed on a received signal received by the transmitting / receiving antenna. Further, the time required for the signal emitted from the transmitting / receiving antenna to be reflected by the object and being received by the transmitting / receiving antenna is a time corresponding to the distance between the transmitting / receiving antenna and the object. According to the above-mentioned conventional radar device, the distance to the target is measured based on the time required until the reception signal is received after the transmission signal is emitted, and the Doppler superimposed on the reception signal is measured. The relative speed of the object is detected based on the magnitude of the shift.

By the way, in the above-mentioned conventional radar device, the output intensity of the transmission signal supplied from the signal source to the transmission / reception antenna changes according to the temperature characteristics of the signal source. When the output intensity of the transmission signal emitted from the transmission / reception antenna changes due to the change in the output intensity of the transmission signal emitted from the signal source, the detection area of the object changes in both the length direction and the width direction. .

In using the detection result of an object for various controls, it is sometimes desired that the detection area is always constant. The above-mentioned conventional device has a function of monitoring the output intensity of a signal circulating from a circuit on the transmission side to a circuit on the reception side. When no signal is received from the outside by the transmitting / receiving antenna, the level of the signal wrapping around from the transmitting-side circuit to the receiving-side circuit has a value corresponding to the output strength of the transmission signal supplied to the transmitting / receiving antenna. Therefore, in a situation where an external signal is not received by the transmitting / receiving antenna, the above-described requirements are corrected by correcting the output intensity of the transmission source based on the output intensity of a signal circulating from the circuit on the transmitting side to the circuit on the receiving side.
That is, it is possible to satisfy the requirement that the detection range of the target object be constant.

[0006]

However, the transmitting / receiving antenna usually receives some external signal. Also,
In the above-mentioned conventional device, when any signal is received by the transmission / reception antenna, it cannot be avoided that the signal goes from the circuit on the transmission side to the circuit on the reception side. For this reason, with the above-described conventional apparatus, the output intensity of the transmission signal supplied from the signal source to the transmission / reception antenna cannot be accurately measured.

The present invention has been made in view of the above points, and it is a first object of the present invention to provide a radar apparatus capable of accurately measuring the output intensity of a signal emitted from a signal source.
The purpose of. Further, the present invention provides a radar apparatus capable of preventing the intensity of a transmission signal reaching a transmission / reception antenna from becoming excessive when the output intensity of a signal emitted from a signal source fluctuates. The purpose of.

It is a third object of the present invention to provide a radar apparatus which can maintain the detection sensitivity of an object at a predetermined level when the intensity of a signal emitted from a signal source fluctuates. I do.

[0009]

A first object of the present invention is to provide a radar apparatus for detecting an object existing in front of a transmission / reception antenna, which generates a signal with a predetermined output intensity. A source, a directional coupler for dividing a signal supplied from the signal source into a transmission signal and a feedback signal, and a transmission signal supplied from the directional coupler to the transmission / reception antenna, and the transmission / reception antenna A circulator for passing the signal received at the receiving signal as a received signal, a synthesized signal generating means for generating a synthesized signal by synthesizing the received signal and the feedback signal, and an object for detecting an object based on the synthesized signal Detecting means, conduction state control means for controlling a conduction state between the transmission / reception antenna and the circulator, and shutting off the transmission / reception antenna and the circulator; And the combined signal strength detecting means for detecting the output intensity of the synthesized signal in the state, are achieved by a radar apparatus comprising a.

In the present invention, a signal emitted from a signal source is supplied to a transmitting / receiving antenna via a directional coupler and a circulator, and is also supplied to a composite signal generating means via a directional coupler. A signal received by the transmitting / receiving antenna is supplied to the combined signal generating means. Therefore, the output strength of the synthesized signal is affected by the output strength of the signal supplied from the directional coupler and the output strength of the signal received by the transmitting / receiving antenna.

When the conduction between the transmitting / receiving antenna and the combined signal generating means is interrupted by the conduction state control means, the signal received by the transmitting / receiving antenna cannot reach the combined signal generating means. In this case, the signal that reaches the combined signal generation means is only a signal whose source is a signal source. Therefore, in the present invention, the output intensity of the signal detected by the combined signal intensity detection means has a value that accurately reflects the output intensity of the signal source.

A second object of the present invention is to provide the radar apparatus according to the first aspect, wherein the transmission signal emitted from the circulator is attenuated at a predetermined attenuation rate and supplied to the transmission / reception antenna. This is achieved by a radar apparatus comprising: a transmission signal attenuator; and an attenuation factor controller that controls the predetermined attenuation factor based on a detection result of the combined signal intensity detector.

In the present invention, when it is detected that the output intensity of the signal source is excessive based on the detection value of the combined signal strength detection means, the attenuation rate control means and the transmission signal attenuation means pass through the circulator. The transmission signal is attenuated to an appropriate intensity and supplied to the transmission / reception antenna. For this reason,
The output strength of the transmission signal output from the transmitting and receiving antenna is
Even when the output intensity of the signal source is excessive, it is controlled to an appropriate intensity.

According to a second aspect of the present invention, in the radar apparatus according to the second aspect, the conduction state control means and the transmission signal attenuating means include the transmission / reception antenna and the circulator. And a rotary resistance attenuator configured to pass a signal at an attenuation rate according to the rotation angle of the resistance plate, and the combined signal strength detection unit determines the rotation angle of the resistance plate, The rotation type resistance attenuator includes a cutoff rotation angle realizing unit that controls an angle at which the rotary resistance attenuator is in a cutoff state, and the attenuation rate control unit sets the rotation angle of the resistance plate to a detection result of the combined signal strength detection unit. The present invention is also achieved by a radar apparatus including a rotation angle control unit that controls the output intensity of a transmission signal reaching the transmission / reception antenna to a desired intensity based on the transmission signal.

In the present invention, the signal received by the transmission / reception antenna reaches the combined signal generation means through the rotary resistance attenuator. Accordingly, when the resistance plate of the rotary resistance attenuator is set to the predetermined cutoff rotation angle by the cutoff rotation angle realizing means, the transmitting / receiving antenna and the combined signal generating means are cut off. At this time, the combined signal has a value that accurately reflects the output intensity of the signal source.

In the present invention, the transmission signal emitted from the directional coupler reaches the transmission / reception antenna through the rotary resistance attenuator. The attenuation rate of the rotary resistance attenuator is controlled by the rotation angle control means so that the output intensity of the transmission signal reaching the transmission / reception antenna becomes a desired intensity. Therefore, even if the output intensity of the transmission signal emitted from the signal source is excessive, the output intensity of the transmission signal reaching the transmission / reception antenna does not become excessive.

Further, a third object of the present invention is to provide a radar apparatus according to the second aspect, wherein the relative output of the combined signal is based on the detection result of the combined signal strength detecting means. This is achieved by a radar apparatus including relative intensity correction means for correcting intensity.

In the present invention, when the output intensity of the transmission source is too low, the absolute intensity of the combined signal is lower than when the output intensity is normal. In such a case, the relative intensity correction means increases the amplification factor when the synthesized signal is subjected to signal processing, or lowers the threshold value used for comparison with the synthesized signal, for example. Is performed to increase the relative output intensity of Therefore, in the present invention, appropriate detection sensitivity is maintained even when the output intensity of the transmission source is too low.

[0019]

FIG. 1 is a block diagram showing a radar apparatus 10 according to an embodiment of the present invention. The radar device 10 shown in FIG. 1 is used while mounted on a vehicle.
The radar device 10 includes a transmission / reception antenna 12 whose irradiation range is in front of the vehicle. A rotary resistance attenuator 16 is connected to the transmission / reception antenna 12 via a waveguide 14.

The waveguide 14 is a member for transmitting electromagnetic waves, and has a pipe of a predetermined shape inside. The shape of the waveguide of the waveguide 14 is designed according to the frequency of the electromagnetic wave to be transmitted. FIG. 2 shows a rotary resistance attenuator 16.
FIG. As shown in FIG. 2, the rotary resistance attenuator 1
6 are three pipes 18, 2 connected axially to one another.
0,22. Resistance plates 24, 26, and 28 are provided inside the conduits 18, 20, and 22, respectively. Pipes 18 and 22 provided at both ends of the three pipes are:
It is assembled so that rotation does not occur around the axis, and the direction of the electric field E of the electromagnetic wave supplied to the rotary resistance attenuator 16 is perpendicular to the resistance plates 24 and 28. I have. On the other hand, the pipeline 20 disposed at the center of the three pipelines is assembled so that rotation around its axis is permitted. The rotary resistance attenuator 16 has a built-in rotation angle control mechanism (not shown) for controlling the rotation angle θ of the pipeline 20 to an angle corresponding to a command signal supplied from the outside.

The conduit 18 of the rotary resistive attenuator 16 communicates with the waveguide 14 communicating with the transmitting / receiving antenna 12. On the other hand, the conduit 22 of the rotary resistance attenuator 16 communicates with the first port 34 of the circulator 32 via the waveguide 30. The circulator 32 includes a first port 34, a second port 36, and a third port 38. The circulator 32 allows the electromagnetic wave input to the third port 38 to pass only through the first port 34, allows the electromagnetic wave input to the first port 34 to pass only to the second port 36, and inputs the electromagnetic wave to the second port 36. 3rd port 3
8 is a device designed to pass only.

A mixer 42 is connected to the second port 36 of the circulator 32 via a waveguide 40.
On the other hand, a first port 48 of a directional coupler 46 is connected to a third port 38 of the circulator 32 via a waveguide 44. The directional coupler 46 includes a first port 48,
A second port 50 and a third port 52 are provided. The directional coupler 46 converts the electromagnetic wave input to the third port 52 into a first port 48 and a second port 50 at a predetermined ratio.
And a device to pass through.

The third port 52 of the directional coupler 46 has
A signal source 56 is connected via a waveguide 54. On the other hand, the second port 50 of the directional coupler 46 has the waveguide 5
The mixer 42 is connected via the reference numeral 8. Signal source 56
Transmits an electromagnetic wave signal of a predetermined frequency to the directional coupler 46 at a predetermined output intensity. Also, the mixer 42
Synthesizes the electromagnetic waves guided from the waveguide 40 and the waveguide 58 to generate a composite wave in which the frequencies of both are superimposed.

The composite wave generated by the mixer 42 is
The signal is supplied to the amplifier 62 via the waveguide 60. Amplifier 6
2 generates an electric signal (hereinafter, this signal is referred to as a composite signal) that has the same cycle as the composite wave and has an output intensity corresponding to the output intensity of the composite wave. The signal processing circuit 64 is connected to the amplifier 62. The composite signal generated by the amplifier 62 is processed by the signal processing circuit 64.

A composite wave generated by the mixer 42, and
The synthesized signal generated based on the synthesized wave includes the frequency of the electromagnetic wave supplied from the directional coupler 46 via the waveguide 58 and the frequency of the electromagnetic wave supplied from the circulator 32 via the waveguide 40. After the information about the deviation and their electromagnetic waves are emitted from the signal source 56,
And information on the output intensity when these electromagnetic waves are combined, and the like. The signal processing circuit 64 has a function of detecting the frequency deviation, the transmission time difference, and the output intensity of the composite wave by processing the composite signal.

The signal processing circuit 64 has a function of supplying a command signal to a rotation angle control mechanism (a mechanism for changing the rotation angle θ of the pipeline 20) provided in the rotary resistance attenuator 16. doing. Therefore, the pipeline 20 of the rotary resistance attenuator 16 realizes the rotation angle θ according to the command signal supplied from the signal processing circuit 64.

The radar device 10 shown in FIG. 1 starts operating when an ignition switch of the vehicle is turned on. Specifically, when the ignition switch is turned on, the signal source 56 starts transmitting an electromagnetic wave signal of a predetermined frequency at a predetermined output. The electromagnetic wave signal emitted from the signal source 56 reaches the directional coupler 46 through the waveguide 54. The electromagnetic wave signal that has reached the directional coupler 46 is distributed to the waveguide 44 and the waveguide 58 at a predetermined distribution ratio.

The electromagnetic wave signal distributed to the waveguide 44 reaches the rotary resistance attenuator 16 through the circulator 32 and the waveguide 30. On the other hand, the electromagnetic wave signal distributed to the waveguide 58 reaches the mixer 42. The electromagnetic wave signal that has reached the rotary resistance attenuator 16 passes through the rotary resistance attenuator 16 and then reaches the transmission / reception antenna 12 through the waveguide 14. The transmission / reception antenna 12 transmits the electromagnetic wave signal supplied in this manner as a transmission signal to the front thereof.

When passing through the waveguide 14, the output intensity of the electromagnetic wave signal is attenuated at an attenuation rate corresponding to the rotation angle θ of the conduit 20. Hereinafter, the principle that the output intensity of the electromagnetic wave signal is attenuated when passing through the rotary resistance attenuator 16 will be described with reference to FIG. FIG. 2A shows the circulator 32.
Shows the electric field strength E which the electromagnetic wave signal supplied from has at the time when it reaches the conduit 28 of the rotary resistance attenuator 16.
The horizontal axis shown in FIGS. 2A to 2F is the line 18,
The angle is parallel to the resistance plates 24 and 28 provided in 22.

As shown in FIG. 2A, the circulator 3
The electromagnetic wave signal supplied from 2 reaches the rotary resistance attenuator 16 in a transmission mode in which the direction of the electric field strength E is perpendicular to the resistance plate 28 of the conduit 22. Resistance plate 28
Reflects the component of the electromagnetic wave arriving at the conduit 22 in which the direction of the electric field strength E is parallel to the resistance plate 28 or disappears as a resistance heat.

FIG. 2B shows the electric field intensity E of the electromagnetic wave signal after passing through the conduit 22. As in the present embodiment, when the resistance plate of the conduit 28 is orthogonal to the direction of the electric field strength E of the electromagnetic wave signal reaching the conduit 28, the electric field strength of the electromagnetic wave signal is attenuated when passing through the conduit 28. Not done. For this reason, the electric field strength E of the electromagnetic wave signal is as shown in FIG.
As shown in (b), the value is the same before and after passing through the pipeline 28.

The electromagnetic wave signal passing through the pipe 22 is
Reach 0. As shown in FIG.
Are rotated by an angle θ from the horizontal direction. FIG. 2 (c)
Indicates the electric field strength E of the electromagnetic wave signal when the electromagnetic wave signal reaches the pipe 20. As shown in FIG. 2C, the electric field intensity E
Can be considered separately as a component E sin θ parallel to the resistance plate 26 and a component E cos θ perpendicular to the resistance plate 26.

FIG. 2D shows the electric field strength of the electromagnetic wave signal when passing through the pipe 20. The direction of the electric field strength E of the electromagnetic wave signal arriving at the conduit 20 is
Is reflected when passing through the conduit 20, or is consumed as resistive heat. For this reason, the electric field strength of the electromagnetic wave signal
sθ.

FIG. 2E shows the electric field strength Ecosθ of the electromagnetic wave signal when the electromagnetic wave signal reaches the pipe 18. The resistance plate 24 of the pipe 18 is similar to the resistance plate 28 of the pipe 22,
It is kept horizontal. As shown in FIG. 2E, the electric field E cos θ of the electromagnetic wave signal has a component E parallel to the resistance plate 24.
cos θ · sin θ and a component E cos ² θ perpendicular to the resistance plate 26
And can be considered separately.

FIG. 2F shows the electric field strength Ecos ² θ of the electromagnetic wave signal at the time when the electromagnetic wave signal has passed through the pipe 18. The component E cos θ · sin θ in which the direction of the electric field intensity is parallel to the resistance plate 24 in the electromagnetic wave signal that has reached the conduit 18 is reflected when passing through the conduit 18 or consumed as resistance heat. For this reason, the electric field strength of the electromagnetic wave signal becomes Ecos ² θ at the time when the electromagnetic wave signal passes through the pipeline 18.

As described above, the rotary resistance attenuator 16 can attenuate the electric field strength of the electromagnetic wave signal supplied from the circulator 32 by a factor of cos ² θ and supply the signal to the transmitting / receiving antenna 12. In particular, according to the rotary resistance attenuator 16, the circulator 32 and the transmission / reception antenna 12 can be cut off by giving a rotation angle of θ = 90 ° to the pipeline 20.

The output strength of the transmission signal transmitted from the transmitting / receiving antenna 12 is proportional to the square of the electric field strength of the electromagnetic wave signal supplied to the transmitting / receiving antenna 12. Therefore, the electric field strength of the electromagnetic wave signal is reduced to cos ² by the rotary resistance attenuator 16.
Once attenuated theta doubled, the output intensity of the transmission signal transmitted from the transmitting and receiving antenna 12 will be attenuated to cos ⁴ theta times.

The electromagnetic wave signal supplied to the transmitting / receiving antenna 12 is transmitted as a transmission signal as described above. When an object exists in front of the transmitting / receiving antenna 12,
The transmission signal transmitted from the transmission / reception antenna 12 is reflected by the object and received as a reflection signal by the transmission / reception signal. When the distance L exists between the transmission / reception antenna 12 and the object, the reflected signal is transmitted to the transmission / reception antenna 12 at the time when the time required for the transmission signal to propagate the distance 2L elapses after the transmission signal is transmitted. Received. When a relative speed RV exists between the transmitting / receiving antenna 12 and the object, a Doppler shift corresponding to the relative speed RV is superimposed on the frequency of the reflected signal.

The received signal received by the transmitting / receiving antenna 12 reaches the circulator 32 through the waveguide 14, the rotary resistance attenuator 16, and the waveguide 30. The received signal that has reached the circulator 32 is supplied to the mixer 42 through the waveguide 40. When a received signal is transmitted from circulator 32 to mixer 42, mixer 42
Synthesizes the electromagnetic wave signal supplied from the directional coupler 46 and the received signal to generate a synthesized wave. The electromagnetic wave signal supplied from the directional coupler 46 to the mixer 42 can be regarded as a signal having the same phase in time and the same frequency as the transmission signal transmitted from the transmission / reception antenna 12. . Therefore, the synthesized wave generated by the mixer 42 includes information on a time phase difference between the transmission signal and the reception signal,
That is, information on the distance L to the object, and
Information about the frequency deviation between the transmission signal and the reception signal, that is, information about the relative speed RV of the object is included.

The composite wave generated by the mixer 42 is converted into an electric signal, that is, a composite signal by the amplifier 62. The signal processing circuit 64 calculates a distance L between the transmitting / receiving antenna 12 and the target and a relative speed R of the target based on the synthesized signal.
V and the output intensity of the composite wave, ie, the mixer 42
The output intensity of the composite wave generated in is detected.

Incidentally, the output intensity of the electromagnetic wave signal transmitted from the signal source 56 fluctuates due to the temperature characteristics of the signal source 56 and the like. If the output intensity of the electromagnetic wave signal emitted from the signal source 56 becomes excessive and the output intensity of the transmission signal emitted from the transmission / reception antenna 12 becomes excessive due to the influence, the detection range of the target object becomes smaller than normal. Expanded in the length and width directions. On the other hand, if the output intensity of the electromagnetic wave signal emitted from the signal source 56 becomes too small and the output intensity of the transmission signal emitted from the transmitting / receiving antenna 12 becomes too small due to the influence, the output intensity of the reflected signal becomes small, The objects existing in the area planned as the range,
A situation occurs in which the object is not properly recognized.

As described above, the detection range of the object is expanded,
Alternatively, if a situation occurs in which an object existing in an area expected as a detection range is not properly recognized, for example, inconvenience may occur when the detection result is applied to vehicle control. The radar apparatus 10 according to the present embodiment includes a signal source 5
6 is characterized in that the above inconvenience can be avoided even when the output characteristics fluctuate.

FIGS. 3 and 4 show a flowchart of an example of a control routine executed by the signal processing circuit 64 to realize the characteristic functions of this embodiment. The routine shown in FIG. 3 is executed in a situation where the output characteristics of the signal source 56 are guaranteed to be the reference characteristics, such as when the vehicle is shipped. When the routine shown in FIG. 3 is started, first, the process of step 100 is executed.

In step 100, the output characteristics of the signal source 56 are
Necessary for the characteristics to become the reference characteristics (hereinafter P_i0conditions
) Is determined. Book station
Specifically, at the time of shipment of the vehicle, P_i0conditions
Is determined to hold. P _i0Judge if condition is not satisfied
If it has been done,
Routines are terminated. On the other hand, P_i0Condition is satisfied
Is determined, the process of step 102 is executed next.
Is done.

In step 102, the rotary resistance attenuator 1
The process of setting the rotation angle θ of the pipeline 20 to 90 ° is executed. The rotation angle θ of the conduit 20 of the rotary resistance attenuator 16 is 90
When the angle is set to °, the waveguide 30 and the waveguide 14 are cut off. In this case, all the electromagnetic wave signals supplied from the circulator 32 to the rotary resistance attenuator 16 are reflected or extinguished by the rotary resistance attenuator 16 and do not reach the transmission / reception antenna 12. In addition, all signals received by the transmission / reception antenna 12 due to the influence of external noise or the like are reflected or extinguished by the rotary resistance attenuator 16 and do not reach the circulator 32.

The electromagnetic wave signal supplied from the circulator 32 to the rotary resistance attenuator 16 and reflected by the rotary resistance attenuator 16 then reaches the mixer 42 through the circulator 32 and the waveguide 40. At this time, the mixer 42 is supplied with an electromagnetic wave signal generated by the signal source 56 from both the directional coupler 46 and the circulator 32. Therefore, the output intensity of the signal source 56 is accurately reflected on the output intensity of the composite wave generated under such a situation. As described above, in the system according to the present embodiment, by performing the processing in step 102, it is possible to generate a composite signal that accurately reflects the output intensity of the signal source 56. When the processing of step 102 is completed,
Next, the process of step 104 is performed.

In step 104, the output intensity of the synthesized signal generated as described above is stored as _Pi0 . When the processing of step 104 is completed, the routine shown in FIG. 3 is completed. According to the above processing, P _i0 is the signal source 5
6 can be grasped as a characteristic value representing the reference output intensity.

The routine shown in FIG. 4 is executed when the vehicle is started.
The process is executed each time a situation set in advance as a case where a change in the output characteristics of the signal source 56 is to be corrected is established. When the routine shown in FIG. 4 is started, first, the process of step 110 is executed. In step 110, it is determined whether the correction condition is satisfied. In step 110, it is determined that the correction condition is satisfied immediately after the ignition switch of the vehicle is switched from the off state to the on state. In this step 110, if it is determined that the correction is not established, the current routine is terminated without any further processing. On the other hand, if it is determined that the correction condition is satisfied, the process of step 112 is performed next.

In step 112, the rotary resistance attenuator 1
The process of setting the rotation angle θ of the pipeline 20 to 90 ° is executed. The rotation angle θ of the conduit 20 of the rotary resistance attenuator 16 is 90
When the angle is set to °, the waveguide 30 and the waveguide 14 are cut off as described above, and a composite signal that accurately reflects the output intensity of the signal source 56 is generated. When the process of step 112 is completed, the process of step 114 is performed next.

At step 114, the output intensity of the synthesized signal generated as described above is stored as P _i1 . According to the above processing, P _i1 can be grasped as a characteristic value representing the output intensity of the signal source 56 when the correction condition is satisfied. When the process of step 114 is completed, the process of step 116 is executed.

In step 116, the ratio of the characteristic value _Pi1 when the correction condition is satisfied to the characteristic value _Pi0 of the reference output intensity, e = P
_It is determined whether _i1 / _Pi0 is greater than "1".
If e> 1, it is determined that the output intensity of the electromagnetic wave signal emitted from the signal source 56 is higher than the reference output intensity, that is, the output intensity of the signal source 56 is excessive. Can be. In this case, step 118
Is performed.

In step 118, the above-mentioned step 116
The rotation angle θ to be given to the pipeline 20 of the rotary resistance attenuator 16 is calculated by substituting e obtained in the following equation into the following equation. θ = cos ⁻¹ (e ^−1/4 ) (1) As described above, according to the rotary resistance attenuator 16, the electric field strength of the electromagnetic wave signal supplied from the circulator 30 to the transmission / reception antenna 12 is represented by cos ^2. attenuating the theta times, i.e., the output of the transmission signal transmitted from the transmitting and receiving antenna 12 may be attenuated to a cos ⁴ theta times.

If the output intensity of the electromagnetic wave signal supplied from the circulator 32 to the rotary resistance attenuator 16 is “P” when the signal source 56 shows the reference output characteristic, when step 118 is executed, The output intensity of the electromagnetic wave signal supplied from the circulator 32 to the rotary resistance attenuator 16 can be expressed as “P * e”. In this case, when the rotation angle θ represented by the above equation (1) is given to the pipeline 20 of the rotary resistance attenuator 16, the transmission / reception antenna 12
The output intensity P ^* of the electromagnetic wave signal supplied to the power supply becomes "P" as in the following equation.

P ^* = P * e * cos ⁴ θ = P * e * (1 / e) = P (2) As described above, according to the processing in step 118, the output characteristics of the signal source 56 Is increased, the output intensity of the electromagnetic wave signal reaching the transmitting / receiving antenna 12 can be maintained at an appropriate level. When the processing in step 118 is completed, the current routine is completed.

If it is determined in step 114 that e> 1 does not hold, it can be determined that the output intensity of the signal source 56 is appropriate or insufficient. In this case, the process of step 120 is executed next. Step 120
In this case, the rotation angle θ of the conduit 20 of the rotary resistance attenuator 16 is controlled to “0”. When the rotation angle θ is set to “0”, the electromagnetic wave signal supplied from the circulator 32 toward the rotary resistance attenuator 16 reaches the transmission / reception antenna 12 without being attenuated. In this case, the transmitting / receiving antenna 12
The output intensity of the transmission signal transmitted from the “P”
Can be used to represent “P * e”. When the process of step 120 is completed, the process of step 122 is executed next.

In step 122, a correction for amplifying the output intensity of the composite signal is executed inside the signal processing circuit 64. Specifically, a process of amplifying the combined signal with an amplification factor A for canceling that the output intensity of the transmission signal is attenuated by e times is executed. When the process of step 122 ends, the current routine ends. In addition, amplification rate A
Is “e ⁻² ” when the received signal 12 used for the analysis of the object is attenuated by e times by the rotary resistance attenuator 16.
Is set to “e ⁻¹ ” when the received signal 12 used for analyzing the target object is not attenuated by the rotary resistance attenuator 16.

According to the above processing, when the output characteristic of the signal source 56 fluctuates on the decreasing side, the relative strength of the synthesized signal can be increased when the signal processing is performed. For this reason, even when the output characteristics of the signal source 56 fluctuate on the decreasing side, the target object can be detected with appropriate sensitivity.

As described above, according to the radar apparatus 10 of the present embodiment, the correction for eliminating the influence of the output characteristic of the signal source 56 when the output characteristic fluctuates to the increasing side and when the output characteristic fluctuates to the decreasing side. Can be applied. For this reason,
According to the radar device 10, it is possible to always detect an object with appropriate sensitivity within a fixed detection area regardless of fluctuations in the output characteristics of the signal source 56.

In the above embodiment, the function of separating the transmitting / receiving antenna 12 from the circulator 32 is realized by using the rotary resistance attenuator 16, but the present invention is not limited to this. For example, the above function may be realized by providing a shutter-shaped shielding mechanism between the transmission / reception antenna 12 and the circulator 32.

Further, in the above-described embodiment, the correction when the output intensity of the signal source 56 is excessive is performed by using the rotary resistance attenuator 16, but the present invention is not limited to this. Instead, even when the output of the signal source 56 fluctuates to the increasing side, the effect may be canceled by signal processing.

Further, in the above embodiment, the signal source 5
6, when the output intensity is too small, the effect is canceled by amplifying and correcting the combined signal inside the signal processing circuit 64. However, the present invention is not limited to this. Alternatively, the relative output intensity of the composite signal may be improved by a method of lowering the threshold used for comparison with the composite signal.

In the above embodiment, the electromagnetic wave signal transmitted from the directional coupler 46 to the circulator 32 side is the same as the “transmission signal” of the first embodiment, and the electromagnetic wave signal transmitted from the directional coupler 46 to the mixer 42 side. The transmitted electromagnetic wave signal corresponds to the “feedback signal” in claim 1.

In the above embodiment, the mixer 4
2. The amplifier 2 and the amplifier 62 correspond to the "combined signal generating means" according to claim 1, and the signal processing circuit 64 corresponds to the "object detecting means", "combined signal strength detecting means", and the claim. In “Attenuation rate control means” described in 2 above,
The rotary resistance attenuator 16 corresponds to the “conduction state control means” of the first aspect and the “transmission signal attenuation means” of the second aspect, respectively.

Further, in the above embodiment, the signal processing circuit 64 executes the processing of the steps 102 and 112, whereby the "interrupt rotation angle realizing means" according to the third aspect becomes the steps 116 and 118. The "rotation angle control means" according to claim 3 is executed by executing the processing in step 3, and the "relative intensity correction means" according to claim 4 is executed by executing the processing in steps 116 and 122. Has been realized.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 5 shows a radar device 7 according to this embodiment.
FIG. The radar device 70 is realized as a planar circuit by using a microstrip line. The radar device 10 shown in FIG. An attenuator array 76 is connected to the transmission / reception antenna 72 via a microstrip line 74. The microstrip line 74 is a transmission line for transmitting an intermediate frequency IF signal. The attenuator array 76 includes a plurality of attenuators 78 that achieve different attenuation rates.
_{-1 to} 78-n.

A switch circuit 80 is connected to the attenuator 78 via a microstrip line 79. The switch circuit 80 includes the microstrip line 8.
1 and communicates with the first port 84 of the circulator 82. The circulator 82 has the first to third ports 8 similarly to the circulator 32 shown in FIG.
4, 86, 88 are devices designed to pass IF signals supplied only to predetermined ports.

A mixer 90 is connected to a second port 86 of the circulator 82 via a microstrip line 89. On the other hand, a directional coupler 92 is connected to a third port 88 of the circulator 82 via a microstrip line 91. Also, the directional coupler 9
2, a signal source 95 and a mixer 9 via microstrip lines 93 and 94 in addition to the circulator 82.
0 is connected.

The signal source 95 is a device for transmitting an IF signal having a predetermined frequency with a predetermined output intensity. The directional coupler 92 distributes the IF signal emitted from the signal source 95 to the circulator 82 and the mixer 90 at a predetermined ratio, similarly to the directional coupler 46 shown in FIG. The mixer 90 combines the IF signal supplied from the directional coupler 94 and the IF signal supplied from the circulator 82 to generate a composite wave, similarly to the mixer 42 shown in FIG.

The composite wave generated by the mixer 90 is
The signal is supplied to an amplifier 97 via a microstrip line 96. The amplifier 97 is a circuit that amplifies the composite wave at a predetermined magnification. The composite signal generated by the amplifier 97 is supplied to a signal processing circuit 98. Signal processing circuit 98
Detects a target present in front of the transmitting / receiving antenna 72 based on the combined signal supplied as described above, and switches the switch circuit 80 based on the output strength of the combined signal.
And the attenuator array 76.

According to the system of the present embodiment, the transmission / reception antenna 72 and the circulator 82 can be separated by turning off the switch circuit 80. Therefore, if the switch circuit 80 is turned off, the signal source 95
Characteristic values (corresponding to P _i0 and P _i1 in the first embodiment) accurately reflecting the output intensity of the first embodiment. Therefore, the system according to the present embodiment can detect the fluctuation range of the output intensity of the signal source 95 by the same method as that of the first embodiment.

Further, according to the system of the present embodiment, by activating any one of the plurality of attenuators 78 _{-1 to} 78 -n provided in the attenuator array 76, the circulator 82 transmits the attenuator. The IF signal supplied to the array 76 is appropriately attenuated and supplied to the transmission / reception antenna 72, and the relative output strength of the composite signal supplied to the signal processing circuit 98 is appropriately increased or decreased therein. Can be done.

Therefore, according to the system of the present embodiment, the same function as that of the radar apparatus 10 of the above-described first embodiment, that is, when the output intensity of the signal source 95 fluctuates, is not affected by the fluctuation. It is possible to realize a function of maintaining the detection area of the target object in a fixed area.

In the above embodiment, the IF signal transmitted from the directional coupler 92 to the circulator 82 is added to the “transmission signal” of the first embodiment by the directional coupler 9.
The IF signal transmitted from the second to the mixer 90 corresponds to the “feedback signal” of the first aspect.

In the above embodiment, the mixer 9
0 and the amplifier 97 correspond to the "combined signal generating means" according to claim 1, and the signal processing circuit 98 corresponds to the "object detecting means", "combined signal strength detecting means", and the claim. 2. The "conduction state control means" according to claim 2, wherein the switch circuit 80 is added to the "attenuation rate control means" according to claim 2.
The attenuator array 76 corresponds to the “transmission signal attenuating means” of the second aspect.

Further, in the above-described embodiment, when the output intensity of the signal source 95 is too low, the signal processing circuit 98 increases the relative output intensity of the composite signal inside the signal source 95, thereby achieving the above-described operation. Item 4 “relative intensity correction means” is realized.

[0076]

As described above, according to the first aspect of the present invention, it is possible to generate a composite signal reflecting only the output intensity of the signal source by cutting off the transmission / reception antenna and the composite signal generation means. . Therefore, according to the present invention, the intensity of the signal emitted from the signal source can be accurately measured.

According to the second aspect of the present invention, when the output intensity of the signal source is excessive, the transmission signal can be appropriately attenuated and transmitted to the transmission / reception antenna. Therefore, according to the present invention, it is possible to prevent the intensity of the transmission signal reaching the transmission / reception antenna from becoming excessive when the intensity of the signal emitted from the signal source changes.

According to the third aspect of the present invention, by controlling the rotation angle of the resistance plate of the rotary resistance attenuator, the function of cutting off the transmission / reception antenna and the combined signal generation means, and the directional coupling The function of appropriately attenuating the transmission signal emitted from the transmitter before reaching the transmitting / receiving antenna can be realized with a simple structure and simple control. Therefore, according to the present invention, the invention described in claim 2 can be realized with a simple configuration.

According to the fourth aspect of the present invention, when the absolute intensity of the combined signal is reduced due to the output intensity of the signal source being too small, the relative strength of the combined signal is reduced. Enhancing corrections can be made. Therefore, according to the present invention, even when the intensity of the signal emitted from the signal source fluctuates, the detection sensitivity of the object can be maintained at a predetermined level.

[Brief description of the drawings]

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

FIG. 2 is a view for explaining the structure and operation of the rotary resistance attenuator shown in FIG. 1;

FIG. 3 is a flowchart illustrating an example of a control routine executed by the signal processing circuit illustrated in FIG. 1;

FIG. 4 is a flowchart illustrating an example of another control routine executed by the signal processing circuit illustrated in FIG. 1;

FIG. 5 is a block diagram of a radar apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 10, 70 Radar device 12, 72 Transmission / reception antenna 16 Rotary resistance attenuator 18, 20, 22 Pipeline 24, 26, 28 Resistance plate 32, 82 Circulator 42, 90 Mixer 46, 92 Directional coupler 56, 95 Signal source 62,97 amplifier 64,98 signal processing circuit

Claims (4)

[Claims] 1. A radar device for detecting an object existing in front of a transmission / reception antenna, a signal source for generating a signal with a predetermined output intensity, and a signal supplied from the signal source being converted into a transmission signal and a feedback signal. A directional coupler that distributes, a circulator that supplies a transmission signal supplied from the directional coupler to the transmission / reception antenna, and passes a signal received by the transmission / reception antenna as a reception signal; Combined signal generating means for combining the feedback signal and the combined signal to generate a combined signal; object detecting means for detecting an object based on the combined signal; and a conductive state for controlling a conductive state between the transmitting / receiving antenna and the circulator. Control means; and a combined signal strength detecting an output strength of the combined signal in a state where the transmitting / receiving antenna and the circulator are cut off. Radar apparatus characterized by comprising: means out, the. 2. The radar apparatus according to claim 1, wherein the transmission signal emitted from the circulator is attenuated at a predetermined attenuation rate and supplied to the transmission / reception antenna, and the combined signal strength detection unit detects the transmission signal. And a damping rate control means for controlling the predetermined damping rate based on a result. 3. The radar device according to claim 2, wherein the conduction state control unit and the transmission signal attenuating unit include:
The transmission / reception antenna is provided between the circulator and the circulator, and comprises a rotary resistance attenuator that allows a signal to pass at an attenuation rate according to a rotation angle of a resistance plate. The rotation angle of the resistance plate
The rotary resistance attenuator further includes a cutoff rotation angle realizing unit that controls an angle at which the rotary resistance attenuator is in a cutoff state, and the attenuation rate control unit sets a rotation angle of the resistance plate to a detection result of the combined signal strength detection unit. A radar apparatus comprising: a rotation angle control unit for controlling an output intensity of a transmission signal reaching the transmission / reception antenna to a desired intensity based on the transmission intensity. 4. The radar device according to claim 2, further comprising: a relative intensity correction unit that corrects a relative output intensity of the composite signal based on a detection result of the composite signal intensity detection unit. apparatus.