JPH10246777A - Radar equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contrive loss reduction of a receiving signal and improvement of target tracking performance by providing a means for predicting influence of an eclipse, and selecting proper PRF(pulse repetition frequency) on the basis of the prediction result. SOLUTION: When a receiving signal from a target is output from a receiver 4 during an i-th sampling time, it is distributed to a multiplier 9 of Σ channel and another multiplier 10 of Δchannel by a distributor 7. In addition, a Σgate signal is output to the multiplier 9 by a receiving gate generator 6 and a modulation signal from the Σ gate signal and a phase modulation generator 8 is output to an adder 10, respectively. The distributed receiving signal and the Σ gate signal are multiplied by each other in the multiplier 9, output Σi is obtained and output Δi is obtained by the multiplier 10. Spectral analysis is performed by a spectral analysis means 5, and an error signal δis output by an error calculation means 11 from SΣi and SΔi removing an unnecessary signal from output Σi and Δi. A PRF switch means 12a compares the error signal δ with a PRF switch reference value V, and a switch command is output.

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 searching for and tracking a target.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional radar device.
In FIG. 5, 1 is a transmitter for generating a transmission wave and supplying a reference signal to each component, 2 is a duplexer for preventing the transmission wave from going directly to the input of the receiver 4, and 3 is a transmission / reception switch. An antenna for irradiating a target with a wave and receiving a reflected wave from the target, and a receiving unit for detecting and amplifying the reflected wave received by the antenna while the receiving gate signal is being output from the receiving gate generator and outputting a received signal. 5 is a spectrum analyzing means for separating a target from a received signal to obtain a relative speed with respect to the target and tracking the target, and 6 generates a reception gate signal for cutting off the input of the receiver while irradiating the transmission wave. It is a reception gate generator.

The conventional radar apparatus is configured as described above, irradiates a transmission wave output from the transmitter 1 to a target from an antenna 3, receives a reflected wave from the target by the antenna 3, and receives the reflected light. The wave is detected and amplified by the receiver 4,
The received signal which is the output of the receiver 4 is converted into a spectrum analysis means 5
The target is tracked by separating the target signal and calculating the target speed.

[0004]

Since the conventional radar apparatus is configured as described above, as shown in FIG. 6, all or a part of the reflected wave from the target is received during irradiation of the transmission wave. Since the input of the receiver 4 is sometimes cut off by the reception gate signal, Eclipse (Eclipsing) occurs in which the reflected wave is lost only in the hatched portion in FIG. As a result, the S / N deteriorates, and it becomes difficult to separate the target signal by the spectrum analysis means 5, so that there is a problem that stable tracking cannot be performed.

[0005]

According to a first aspect of the present invention, there is provided a radar apparatus for generating a signal for distributing a received signal to a Σch multiplier and a Δch multiplier, and a signal for changing the phase at the center of the reception gate.変 調 c that multiplies the reception gate signal by the signal divided by the phase modulation generator
h multiplier, a Δch multiplier that multiplies the similarly divided signal by the reception gate signal, and performs phase modulation by an output signal of the phase modulation generator, a Δch multiplier, Δc
h calculating means for calculating an error from each output of the multiplier of h and outputting an error signal; and a PRF (Pulse R
This is provided with a PRF switching means for making a determination to switch an epi frequency (PET) and outputting a PRF switching command.

A radar apparatus according to a second aspect of the present invention is the radar apparatus according to the first aspect of the present invention, wherein PRF switching means having different operations is provided.

[0007] A radar apparatus according to a third aspect of the present invention is the radar apparatus according to the first aspect of the present invention and the radar apparatus according to the second aspect of the present invention, wherein PRF switching means having different operations is provided.

A radar apparatus according to a fourth aspect of the present invention is different from the radar apparatus according to the first aspect in that the distance to error data indicating the relationship between the distance to the target and the error signal for each PRF, Distance prediction means for predicting the distance to the target from the error data and the error signal, and distance tracking means for predicting the distance to the current target from the distance between the distance-to-error data and the target and the previously predicted target distance When,
PRF selecting means for selecting an optimum PRF from the predicted distance and the distance-to-error data.

[0009]

Embodiment 1 FIG. 1 is a block diagram showing Embodiment 1 of the present invention.
6 are the same as those in FIG. 5, 7 is a divider for distributing the received signal to each of the Σch multiplier and Δch multiplier, and 8 generates a signal that changes the phase at the center of the reception gate. A phase modulation generator 9 is a Σch multiplier for multiplying the reception signal distributed by the distributor 7 by a reception gate signal, and 10 is a phase modulation unit that multiplies the reception gate signal by an output signal of the phase modulation generator. And 11 is an error calculating means for calculating an error from the result of spectral analysis of the outputs of the Σch multiplier 9 and the Δch multiplier 10 by the spectrum analyzing means 5 and outputting an error signal δ. 12a is the error signal δ and the PRF switching reference value V
5 is a PRF switching means for outputting a PRF switching command, which is newly added to FIG.

In the radar device configured as described above, when a reception signal from a target is output from the receiver 4 during the i-th sampling time, the divider 7 uses the multiplier 9 for Σch and the multiplier for Δch. It is distributed to 10. The receiving gate generator 6 outputs a multiplier 9 whose Σ gate signal is Δch.
Then, the Δ gate signal and the phase modulation signal from the phase modulation generator are output to the multiplier 10 of Δch, respectively. FIG. 7 shows the relationship between the transmission wave, the Σ gate signal, the Δ gate signal, the phase modulation signal, and the reflected wave and the error signal δ. Σch multiplier 9
Then, the divided reception signal is multiplied by the Σgate signal, and as a result, the output Σi of the multiplier 9 of Σch is obtained. Similarly, a multiplier 1 for Δch is obtained from the received signal, the Δ gate signal, and the phase modulation signal.
An output Δi of 0 is obtained. By performing spectrum analysis in the spectrum analysis means 5, SΣi and SΔi from which unnecessary signals have been removed from Σi and Δi are obtained. An error calculation is executed by the error calculation means 11 from SΣi and SΔi to output an error signal δ. The error calculation is as shown in Equation 1.

[0011]

(Equation 1)

The error signal δ calculated by the error calculation of Equation 1 indicates the position of the received signal. As shown in FIG. 7, when the reflected wave is at the position with respect to the transmitted wave, the error signal δ is − When the position is 1, the error signal δ is 0.
The error signal δ is 1 at the position shown in FIG. FIG.
Is a flowchart showing the operation of the PRF switching means 12a. The PRF switching means 12a determines whether or not to switch the PRF by comparing the error signal δ with the PRF switching reference value V, and issues a PRF switching command based on the result. Output. The PRF switching reference value V is a positive integer of 1 or less, and the smaller the value is set, the less the effect of the eclipse is, but the more frequently the PRF is changed. In FIG. 8, steps 31 and 32 determine the presence or absence of the influence of eclipse from the error signal δ and the PRF switching reference value V. Output.

Second Embodiment FIG. 2 is a block diagram showing a second embodiment of the present invention. FIG. 2 is the same as 1 to 11 in FIG. 1 PRF switching means 1
Reference numeral 2a denotes a newly added PRF switching means 12b having a different operation. FIG. 9 shows the operation of the PRF switching means 12b.
Steps 41 and 42 for performing F switching determination are newly added. The PRF switching means 12b outputs the error signal δ and PR
It is determined whether or not to switch the PRF based on the F switching reference value V and the relative speed v, and a PRF switching command is output based on the result. In FIG. 9, if it is determined in step 31 or 32 that there is an eclipse effect, the increase or decrease of the eclipse effect in the future is predicted in steps 41 and 42 from the target relative speed. 33 outputs a PRF switching command.

Third Embodiment FIG. 3 is a block diagram showing a third embodiment of the present invention. The configuration of FIG. 1 is the same as that of 1 to 11 and is the same as that shown in FIG. 1 PRF switching means 1
The PRF switching means 12c, which operates differently from the PRF switching means 12a of FIG. 2a and FIG. 2, is newly added. FIG. 10 shows the operation of the PRF switching means 12c.
8, the error signal δ, the PRF switching reference value V, the relative speed v, the received signal SΣi at the i-th sampling time, and the N-th received signal SΣ (i-N) from the i-th sampling time. A step of determining whether to switch the PRF is added. Here, N is any positive integer. If eclipse has occurred in steps 31, 32, 41, and 42, but the effect is expected to decrease in the future, eclipse degree calculation is executed in step 51. The eclipse degree calculation is as shown in Expression 2 and predicts the eclipse degree.

[0015]

(Equation 2)

If it is determined in step 52 that the eclipse degree X, which is the result of the eclipse degree calculation of the above equation 2, is greater than 0, a PRF switching command is output in step 33.

Fourth Embodiment FIG. 4 is a block diagram showing a fourth embodiment of the present invention. In FIG. 1, distance-to-error data 13 indicating the relationship between a target distance and an error signal δ, In the case where the distance is unknown, a PRF with the least influence of Eclipse is selected, and distance predicting means 14 for predicting the distance to the target is added. The distance predicting means 14 sends the P
If the distance to the target is unknown when the RF switching command is output, the PRFs are switched in order, and an error calculation is performed for each PRF to select a PRF with the minimum error signal δ. Further, a target distance prediction operation is performed based on the error signal δ and the distance-to-error data 13 obtained in each PRF to predict the distance to the target. In the target distance prediction operation, the predicted value of the target distance is narrowed down to a range corresponding to the error signal δ by referring to the distance vs. error data 13 based on the error signal δ obtained in a certain PRF, and then the PRF is changed. In the same manner, the predicted value of the target distance is further narrowed down. By repeating the above, the distance to the target is predicted. For example, distance vs. error data 13
Is as shown in FIG. 11 and the distance to the target is R1, when the PRF is PRF1, the error signal δ is 0, PR
Assume that the error signal δ at F2 is −0.5 and the error signal δ at PRF3 is 0.3. Error signal δ is 0 in PRF1
From the distance vs. error data 13, a distance range in which the error signal δ is 0 ± k is searched in the PRF1 by using the PRF1, so that the distance R to the target is A1, A2,
It is limited to the range of A3 and A4. Here, k is a threshold coefficient. Similarly, in PRF2, the error signal δ is -0.
5, the target distance ranges are A1, A2, A3, A
4 where the error signal δ is -0.5 ± k in PRF2
4 and B5, and similarly, since the error signal δ is 0.3 in PRF3, the distance R1 to the target is predicted to be within the range of C5.

[0018]

According to the first aspect of the present invention, the means for predicting the influence of eclipse is provided, and the optimum PRF is selected based on the result of the prediction, so that the loss of the received signal due to eclipse can be reduced. Thus, a radar device with improved target tracking performance can be obtained.

According to the second aspect, means for predicting the influence of eclipse different from that of the first aspect is provided, and the optimum PRF is selected based on the prediction result. A radar device with reduced signal loss and improved target tracking performance can be obtained.

Further, according to the third invention, means for predicting the influence of eclipse different from the first invention and the second invention is provided, and an optimum PRF is selected based on the prediction result. Therefore, it is possible to reduce the loss of the received signal due to the eclipse, and obtain a radar device with improved target tracking performance.

Further, according to the fourth invention, the first invention,
A means for predicting the influence of eclipse different from that of the second and third inventions is provided, and the optimum P
Since the configuration is such that RF is selected, it is possible to obtain a radar device in which the loss of the received signal due to Eclipse is reduced and the target tracking performance is improved.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a second embodiment of the radar device according to the present invention;

FIG. 3 is a diagram showing a third embodiment of the radar device according to the present invention;

FIG. 4 is a diagram showing a fourth embodiment of the radar apparatus according to the present invention;

FIG. 5 is a diagram showing a conventional radar device.

FIG. 6 is a waveform diagram for explaining the operation of the conventional radar device.

FIG. 7 is a waveform diagram for explaining the operation of the radar device according to the present invention.

FIG. 8 is a flowchart showing an operation of the radar apparatus according to the first embodiment of the present invention.

FIG. 9 is a flowchart showing an operation of the radar apparatus according to the second embodiment of the present invention.

FIG. 10 is a radar apparatus according to a third embodiment of the present invention;
6 is a flowchart showing the operation of the first embodiment.

FIG. 11 is a fourth embodiment of a radar apparatus according to the present invention.
6 is a flowchart showing the operation of the first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmitter 2 Transmission / reception switch 3 Antenna 4 Receiver 5 Spectrum analysis means 6 Reception gate generator 7 Distributor 8 Phase modulation generator 9 Multiplier of Σch 10 Multiplier of Δch 11 Error calculation means 12a PRF switching means 12b PRF switching Means 12c PRF switching means 13 Distance vs. error data 14 Distance prediction means

Claims (4)

[Claims] 1. A transmitter for outputting a transmission wave for irradiating a target and a reference signal to each component, a transmission / reception switch for switching between transmission and reception, an antenna for transmitting and receiving,
A receiver connected to the antenna, a divider for distributing a reception signal obtained by the receiver to a Σch multiplier and a Δch multiplier, and a reception generating a reception gate synchronized with the reference signal A gate generator, a phase modulation generator for generating a signal that changes the phase at the center of the reception gate, and a Σch multiplier for multiplying the reception gate signal by the signal distributed by the distributor. Δch multiplier that multiplies the received signal by the received gate signal and performs phase modulation by the output signal of the phase modulation generator;
解析 ch and Δch, each output of which is input to the multiplier, spectrum analysis means for performing spectrum analysis, error calculation means for calculating an error with respect to the result of the spectrum analysis means, and outputting an error signal; Pul
A radar apparatus comprising: PRF switching means for determining a switching (se Repetition Frequency) and outputting a PRF switching command. 2. The radar apparatus according to claim 1, wherein the determination of PRF switching is performed based on a relative speed between the error signal and a target. 3. An eclipse degree estimating means for estimating an eclipse degree, which is an eclipse degree, based on a received signal from a target and an average of past received signals, and determines PRF switching based on a relative speed between the error signal and the target. 2. The radar apparatus according to claim 1, wherein the determination is performed based on an eclipse degree. 4. For each PRF, distance-to-error data indicating the relationship between the distance to the target and the error signal, and when the distance to the target is unknown, select the optimal PRF, and select the distance-to-error data and the error signal. 2. A target distance predicting means for predicting a distance from a target to a target.
The described radar device.