JP2002116252A - Radar signal processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a radar signal processing device for stably processing only a target under a condition, where another aircraft is transmitting electric waves. SOLUTION: The frequency difference between effective frequency bins after detecting the target is stored, and by making the frequency bin where a difference value for each frequency bin becomes a constant multiple of the frequency stored at frequency database equipment invalid, misdetections by an interference wave spectrum are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse type radar signal processing apparatus mounted on an aircraft and performing search and tracking for another aircraft.

[0002]

2. Description of the Related Art A pulse-type radar signal processing apparatus mounted on an aircraft for searching and tracking another aircraft as a target emits a pulse-modulated transmission wave, and the other aircraft also emits a pulse-like signal. In this case, the received signal received by the own aircraft reflects not only the reflected wave from the other aircraft due to the transmitted wave of the own aircraft, but also the influence of the pulsed radiation wave of the other aircraft. The interference wave spectrum due to the cross modulation causes erroneous detection in the signal processing area, and there is a problem that it is difficult to detect and track another aircraft.

FIG. 7 is a diagram showing a conventional radar signal processing device mounted on an aircraft. An antenna 1 radiates a pulsed transmission wave in a space in a specific direction and receives a reflected wave.
2 is a transmitter that generates the transmission wave, 3 is a transmission / reception switch that supplies a transmission signal from the transmitter 2 to the antenna 1 and supplies a reception signal to the receiver, 4 is a receiver that amplifies and detects the reception signal, An A / D (Analog / Digita) 5 converts a signal output from the receiver 4 into a digital video signal.
1) a converter, 6 is a frequency analyzer for performing a fast Fourier transform on the digital video signal output from the A / D converter 5 to calculate a frequency spectrum, and 7 is a specific analyzer from the output value of the frequency analyzer 6. An amplitude detector 8 detects the amplitude of the frequency, and 8 is a CFAR (Constant False A).
a target detector that performs target detection processing such as alarm rate (constant false alarm probability) and detects an effective frequency bin; and 9 extracts target information from the effective frequency bin output from the target detector 8 and performs detection / tracking processing. It is a target data processor.

A conventional radar signal processing apparatus is configured as described above. For example, under the situation shown in FIG.
The own machine 10 generates a transmission wave 12 at the pulse repetition frequency PRF1 at the transmitter 2 and radiates it from the antenna 1 toward the aircraft 11. The reflected wave 13 from the aircraft 11 is transmitted to the antenna 1
, And amplify and detect with the receiver 4. The output of the receiver 4 is converted into a digital video signal by an A / D converter 5, a frequency analysis is performed by a frequency analyzer 6, and an amplitude spectrum characteristic for each frequency bin obtained by an amplitude detector 7 is obtained. obtain.

FIG. 8A is a view showing a situation in which the aircraft 11 does not emit radio waves, and FIG. 8B is a view showing a situation in which the aircraft 11 also emits pulsed transmission waves. 14 is a transmission wave of the aircraft 11, and 15 is a reception wave of the antenna 1 of the own aircraft 10.

FIG. 9 shows an example of the operation of the amplitude detector 7. FIG. 9A shows an amplitude spectrum characteristic output from the amplitude detector 7 under the situation of FIG.
(B) shows an example of the amplitude spectrum characteristic output from the amplitude detector 7 under the situation of FIG. 8 (b).
In FIG. 9A, reference numeral 16 denotes a target amplitude spectrum corresponding to the reflected wave 13 of the aircraft 11.

The target detector 8 can detect only frequency bins corresponding to the target, and the target data processor 9 can perform detection and tracking processing based on information on only the target. On the other hand, in FIG. 9B, an interference wave spectrum 17 due to the cross modulation of the pulsed transmission wave 12 of the own device 10 and the transmission wave 14 of the aircraft 11 is generated.

FIG. 11 is a diagram showing an example of a processing result in the target detector 8 with the amplitude spectrum characteristic of FIG. 9B as an input. There is a problem that the frequency bin of the interference wave spectrum 17 in FIG. 9B is detected, and the interference wave spectrum caused by the cross modulation is detected as a target other than the true target.

In FIG. 10, the output of the effective frequency bin detected as the target is represented as "1".
Reference numeral 19 denotes an erroneous detection area based on the interference wave spectrum.

[0010]

In the conventional radar signal processing apparatus as described above, the influence of the pulsed radiated wave of another aircraft is affected by the interference wave spectrum when another aircraft is transmitting radio waves. As a result, the interference spectrum appears in the amplitude spectrum characteristic of the amplitude detector 7, and this interference wave spectrum is erroneously detected by the target detector 8, and the erroneously detected information is processed by the target data processor 9.

The present invention has been made in order to solve such a problem. Even in a situation where another aircraft 11 is transmitting radio waves, information on only the target is stably transmitted to the target data processor 9. It is an object of the present invention to obtain a radar signal processing device capable of processing by using the radar signal processing.

[0012]

According to a first aspect of the present invention, there is provided a radar signal processing apparatus comprising: a frequency database unit for storing a frequency value in advance; a frequency bin storage unit for storing a frequency of an effective frequency bin of a target detector; A frequency difference storage unit that obtains a frequency difference between adjacent effective frequency bins for each effective frequency bin and stores a difference value for each effective frequency bin, and a difference value for each frequency bin that is a constant multiple of the frequency stored in the frequency database unit. By providing a frequency bin selector that invalidates the frequency bins that are to be used, erroneous detection due to the interference wave spectrum is suppressed.

[0013] A radar signal processing apparatus according to a second aspect of the present invention comprises:
A frequency database device for storing the frequency value, and a frequency bin shift circuit for shifting the output value of the target detector by a frequency bin corresponding to the frequency stored in the frequency database device. A second frequency bin selector that performs a difference operation with the output value of the bin shift circuit and enables only the frequency bin having a positive value,
Suppress erroneous detection due to the interference wave spectrum.

A radar signal processing apparatus according to a third aspect of the present invention comprises:
A frequency bin storage circuit that stores the frequency value of the effective frequency bin that is the output of the target detector, and a frequency that determines the frequency difference between adjacent effective frequency bins for each effective frequency bin and stores the difference value for each effective frequency bin A difference storage device, a histogram measurement device for measuring the frequency of the difference value in the frequency difference storage device, and a third frequency bin selector for invalidating an effective frequency bin giving a difference value that maximizes the measurement frequency of the histogram measurement device , Erroneous detection due to the interference wave spectrum is suppressed.

[0015] A radar signal processing apparatus according to a fourth aspect of the present invention comprises:
A frequency bin storage circuit that stores the frequency value of the effective frequency bin that is the output of the target detector, and a frequency that determines the frequency difference between adjacent effective frequency bins for each effective frequency bin and stores the difference value for each effective frequency bin A difference storage device, a histogram measurement device for measuring the frequency of the difference value of the frequency difference storage device, an effective frequency bin receiving a certain threshold value, the measurement frequency and the threshold value of the histogram measurement device, and providing a frequency value greater than the threshold value And a frequency bin selector that nullifies the error, thereby suppressing erroneous detection due to the interference wave spectrum.

According to a fifth aspect of the present invention, there is provided a radar signal processing apparatus comprising:
A frequency database device for storing frequency values in advance,
A frequency bin storage circuit for storing a frequency value of an effective frequency bin output from the target detector; a frequency difference between adjacent effective frequency bins for each effective frequency bin; and a difference value stored for each effective frequency bin A frequency difference storage unit, a remainder operation unit that divides an output value of the difference frequency storage unit by the frequency stored in the frequency database unit and calculates a remainder,
The second is to measure the histogram of the output value of the remainder arithmetic unit.
And a fifth frequency bin selector for invalidating an effective frequency bin that gives a remainder in which the measurement frequency of the second histogram measuring device is maximized. Oppress.

According to a sixth aspect of the present invention, there is provided a radar signal processing apparatus comprising:
The database stores frequency values determined from the pulse repetition frequency transmitted by the partner device and the pulse repetition frequency transmitted by the device itself.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a view showing a first embodiment of the present invention, in which 1 to 9 are exactly the same as the conventional apparatus. Reference numeral 20 denotes a frequency database unit that stores a predetermined frequency value, 21 denotes a frequency bin storage unit that stores the frequency value of an effective frequency bin detected by the target detector 8, and 22 denotes an adjacent frequency bin. A difference frequency storage unit for obtaining a frequency difference from an effective frequency bin and storing a difference value for each effective frequency bin, 23 is an effective frequency bin for which the difference value for each frequency bin is a constant multiple of the frequency stored in the frequency database unit 10 Is a first frequency bin sorter that nullifies.

In the radar signal processing apparatus configured as described above, the effective frequency bins obtained in the target detector 8 are the same as in the conventional case.

In FIG. 8B, the transmission wave 1
9 is PRF1, and the pulse repetition frequency of the transmission wave 14 of the aircraft 11 is PRF2.
Since the interference wave spectrum 17 in (b) is caused by cross modulation, the frequency difference Δf between adjacent effective frequency bins has a relationship of “Equation 1”.

[0021]

(Equation 1)

Here, m and n are arbitrary integers.

In the frequency database unit 20, for example,
The frequency difference Δfmin which becomes the minimum value among the frequency differences Δf determined by the combination of the constants m and n is stored.

FIG. 2 shows the output values of the target detector 8 and the state between the interference wave spectra. As shown in FIG. 2, the frequency between the interference wave spectra is an integral multiple of the frequency difference Δfmin. Here, k is an arbitrary integer.

The frequency bin memory 21 stores, for example, the frequency of each effective frequency bin output from the target detector 8 as f
(I). Here, i is 1 to n, and n is the total number of effective frequency bins. “Equation 2” is an equation showing an operation example of the difference frequency storage unit 22.

[0026]

(Equation 2)

Here, fd (i) is the difference frequency in the effective frequency bin i. The difference frequency fd (i) in the erroneous detection region based on the interference wave spectrum in FIG. 2 is an integral multiple of the frequency Δfmin. By providing a first frequency bin selector 23 for invalidating an effective frequency bin i in which the difference frequency fd (i) is an integral multiple of Δfmin stored in the frequency database unit 20, erroneous detection due to an interference wave spectrum is suppressed. be able to.

Embodiment 2 FIG. 3 is a view showing a second embodiment of the present invention. In the drawing, reference numerals 1 to 9 are exactly the same as those of the conventional apparatus. 20 is a frequency database unit that stores a predetermined frequency value, 24 is a frequency bin corresponding to the frequency value stored in the frequency database unit 20,
A frequency bin shift circuit that shifts the output value of the target detector 8; and a second operation that performs a difference operation between the output value of the target detector 8 and the output value of the frequency bin shift circuit 24 to enable only the positive frequency bins. Frequency bin selector.

In the radar signal processing apparatus configured as described above, the effective frequency bins obtained in the target detector 8 are the same as in the conventional case. The frequency database unit 20 stores, for example, a frequency value given by “Equation 1”. The frequency difference between the frequency bins of the interference wave spectrum obtained by the target detector 8 has, for example, a relationship as shown in FIG.
By subtracting the output result of the frequency bin shift circuit 24 for shifting the effective frequency bin of the target detector 8 by the frequency difference Δfmin × k from the output value of the target detector 8, the effective frequency bins caused by the interference wave spectrum are canceled. Therefore, erroneous detection can be suppressed.

Embodiment 3 FIG. 3 is a view showing a third embodiment of the present invention, in which 1 to 9 are exactly the same as the conventional apparatus. 21 and 22 perform the same operation as that of the first embodiment. 26 is a first histogram measuring device for measuring the frequency of the difference value in the difference frequency storage device 22, 27
Is a third frequency bin selector that invalidates an effective frequency bin that gives a difference value at which the measurement frequency of the first histogram measuring device 26 becomes maximum.

In the radar signal processing device configured as described above, the effective frequency bins obtained in the target detector 8 are the same as in the conventional case. The difference frequency storage unit 22 calculates the difference frequency fd (i) in the i-th effective frequency bin, for example, as given by “Equation 2”. The first histogram measuring device 26 measures the histogram of the difference frequency fd (i) given by “Equation 2”.

As shown in FIG. 2, many effective frequency bins due to the interference wave spectrum are generated in the target detector 8, and
In addition, since there is a relation of "Equation 1" between the interference wave spectra,
The value of the difference frequency fd (i) at which the frequency of the first histogram measuring device 26 becomes maximum becomes the i-th effective frequency bin corresponding to the interference wave spectrum. Third frequency bin selector 27
By invalidating the i-th interference wave spectrum, erroneous detection due to the interference wave spectrum can be suppressed.

Embodiment 4 FIG. 5 is a view showing a fourth embodiment of the present invention, in which 1 to 9 are exactly the same as the conventional apparatus. 21 to 22 and 26 are Embodiment 3
Are the same as those shown in FIG. Reference numeral 28 denotes a fourth frequency bin selector which receives the measurement result of the first histogram measuring device 26 and the threshold value, and invalidates a frequency bin which gives a frequency larger than the threshold value. Reference numeral 29 denotes a threshold value.

In the radar signal processing apparatus configured as described above, the effective frequency bins obtained in the target detector 8 are the same as in the conventional case. The difference frequency storage unit 12 calculates the difference frequency fd (i) in the i-th effective frequency bin, for example, as given by “Equation 2”. The first histogram measuring device 26 measures the histogram of the difference frequency fd (i) given by “Equation 2”.

Since the frequency difference between the interference wave spectra has a characteristic such as "Equation 1", the first histogram measuring device 26 sets the difference frequency fd (i) at the i-th effective frequency bin in the interference wave spectrum. i) appears at a certain frequency or higher. Effective for the fourth frequency bin selector 28
By giving a threshold value 29 as an invalidity determination criterion and invalidating an effective frequency bin giving a difference frequency fd (i) that is equal to or higher than a certain frequency, erroneous detection due to an interference wave spectrum can be suppressed.

Embodiment 5 FIG. 6 is a view showing a fifth embodiment of the present invention, in which 1 to 9 are exactly the same as the conventional apparatus. 20 to 22 are exactly the same as the radar signal processing device of the first embodiment. Reference numeral 30 denotes a remainder computing unit that divides the output value of the difference frequency storage unit 22 by the frequency stored in the frequency database unit 20 to calculate a remainder, and 31 denotes a second histogram that measures the histogram of the output value of the remainder computing unit 30 A measuring device and a fifth frequency bin selector 32 deactivate an effective frequency bin that gives a remainder that maximizes the measurement frequency of the second histogram measuring device 31.

In the radar signal processing apparatus configured as described above, the effective frequency bins obtained in the target detector 8 are the same as in the conventional case. The operation of the difference frequency storage unit 12 is given as, for example, “Equation 2”, and calculates the difference frequency fd (i) in the i-th effective frequency bin. As shown in FIG. 2, the difference frequency fd (i) between the interference wave spectra
Has a certain characteristic, the remainder obtained by dividing the difference frequency fd (i) value in the interference wave spectrum by the frequency value stored in the frequency database unit 20 concentrates on a certain value.

The output value of the remainder computing unit 30 is measured by the second histogram measuring unit 21, and interference is generated by the fifth frequency bin selecting unit 22 that invalidates the effective frequency bin giving the remainder that maximizes the frequency. It is possible to suppress erroneous detection due to the wave spectrum.

[0039]

According to the first and sixth aspects of the invention, the frequency difference between the effective frequency bins after the target is detected is stored, and the difference value for each frequency bin becomes a constant multiple of the frequency stored in the frequency database. By invalidating the frequency bins, erroneous detection based on the interference wave spectrum can be suppressed, and target information of only the partner device can be stably obtained.

According to the second and sixth aspects, the effective frequency bin after the target detection is shifted by the frequency stored in the frequency database unit, and the output value after the shift and the output value after the target detection are differentiated. As a result, effective frequency bins caused by the interference wave spectrum are canceled out, erroneous detection by the interference wave spectrum can be suppressed, and target information of only the partner device can be stably obtained.

According to the third aspect, the histogram measurement of the frequency difference between the effective frequency bins after the target detection is performed, and the effective frequency bin having the maximum frequency is invalidated.
It is possible to suppress erroneous detection due to the interference wave spectrum, and to stably obtain target information of only the partner device.

According to the fourth aspect, the histogram of the frequency difference between the effective frequency bins after the target is detected is measured, and the effective frequency bins having frequencies exceeding the threshold value are invalidated, so that the interference wave spectrum is reduced. It is possible to suppress the erroneous detection due to and to stably obtain the target information of only the other device.

According to the fifth and sixth aspects of the invention, the frequency difference between the effective frequency bins after the target is detected is divided by the frequency stored in the frequency database to obtain a remainder. By performing a histogram measurement of the remainder and invalidating the effective frequency bin giving the remainder whose frequency is maximized, it suppresses erroneous detection caused by the interference wave spectrum and stabilizes the target information only of the partner device. Obtainable.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of a first embodiment of a radar signal processing device according to the present invention;

FIG. 2 is a diagram illustrating the operation of the first embodiment of the present invention.

FIG. 3 is a configuration diagram showing a configuration of a second embodiment of the radar signal processing device according to the present invention;

FIG. 4 is a configuration diagram showing a configuration of a third embodiment of the radar signal processing device according to the present invention;

FIG. 5 is a configuration diagram illustrating a configuration of a fourth embodiment of the radar signal processing device according to the present invention;

FIG. 6 is a configuration diagram showing a configuration of a fifth embodiment of the radar signal processing device according to the present invention;

FIG. 7 is a diagram illustrating a configuration of a conventional radar signal processing device.

FIG. 8 is a diagram illustrating an example of an operation mode of a conventional radar signal processing device.

FIG. 9 is a diagram showing an example of the operation of a conventional amplitude detector.

FIG. 10 is a diagram showing an example of the operation of a conventional target detector.

[Explanation of symbols]

Reference Signs List 8 target detector, 9 target data processor, 20 frequency database unit, 21 frequency bin storage, 22 difference frequency storage, 23 first frequency bin selector, 24 frequency bin shift circuit, 25 second frequency bin selector ,
26 first histogram measuring device, 27 third frequency bin selecting device, 28 fourth frequency bin selecting device, 29 threshold value, 30 remainder operation device, 31 second histogram measuring device, 32 fifth frequency bin selecting device .

Claims (6)

[Claims] 1. An antenna that radiates a pulsed transmission wave in a space in a specific direction and receives a reflected wave, a receiver that amplifies and detects a signal received by the antenna, and an output signal of the receiver. A frequency analyzer for calculating a frequency spectrum; an amplitude detector for detecting an amplitude of a specific frequency from an output value of the frequency analyzer; and a target detection process for detecting an effective frequency bin from an output signal of the amplitude detector. A target detector, a frequency database unit for storing a predetermined frequency value, a frequency bin storage unit for storing a frequency value for each effective frequency bin output from the target detector, and a frequency bin storage unit A difference frequency storage unit for calculating a frequency difference between adjacent effective frequency bins for each effective frequency bin and storing a frequency difference value for each effective frequency bin; A frequency bin selector for invalidating an effective frequency bin whose wave number difference value is a constant multiple of the frequency stored in the frequency database unit. 2. An antenna that radiates a pulsed transmission wave in a space in a specific direction and receives a reflected wave, a receiver that amplifies and detects a signal received by the antenna, and an output signal of the receiver. A frequency analyzer for calculating a frequency spectrum, an amplitude detector for detecting an amplitude of a specific frequency from an output value of the frequency analyzer, a target for performing target detection processing from an output signal of the amplitude detector and detecting an effective frequency bin A detector, a frequency database device that stores a predetermined frequency value, and a frequency bin shift circuit that shifts an output value of the target detector by a frequency bin corresponding to the frequency value stored in the frequency database device. A frequency bin selector for performing a difference operation between the output value of the target detector and the output value of the frequency bin shift circuit to validate a positive value frequency bin. A radar signal processing device. 3. An antenna that radiates a pulsed transmission wave in a space in a specific direction and receives a reflected wave, a receiver that amplifies and detects a signal received by the antenna, and an output signal of the receiver. A frequency analyzer for calculating a frequency spectrum; an amplitude detector for detecting an amplitude of a specific frequency from an output value of the frequency analyzer; and a target detection process for detecting an effective frequency bin from an output signal of the amplitude detector. A frequency difference between a target detector, a frequency bin memory that stores a frequency value for each effective frequency bin output from the target detector, and an adjacent effective frequency bin stored for each effective frequency bin stored in the frequency bin memory And a difference frequency storage for storing a frequency difference value for each effective frequency bin; a histogram measuring device for measuring the frequency of the difference value of the difference frequency storage; A frequency bin selector for invalidating an effective frequency bin that gives a difference value at which the measurement frequency of the gram measuring device is maximized. 4. An antenna that radiates a pulsed transmission wave into a space in a specific direction and receives a reflected wave, a receiver that amplifies and detects a signal received by the antenna, and an output signal of the receiver. A frequency analyzer for calculating a frequency spectrum; an amplitude detector for detecting an amplitude of a specific frequency from an output value of the frequency analyzer; and a target detection process for detecting an effective frequency bin from an output signal of the amplitude detector. A frequency difference between a target detector, a frequency bin memory that stores a frequency value for each effective frequency bin output from the target detector, and an adjacent effective frequency bin stored for each effective frequency bin stored in the frequency bin memory And a difference frequency storage device that stores a frequency difference value for each effective frequency bin, a histogram measurement device that measures the frequency of the difference value of the difference frequency storage device, A radar signal processing apparatus, comprising: a frequency bin selector that receives a threshold value, a measurement frequency of the first histogram measuring device, and a threshold value, and invalidates an effective frequency bin that provides a frequency greater than the threshold value. 5. An antenna that radiates a pulsed transmission wave into a space in a specific direction and receives a reflected wave, a receiver that amplifies and detects a signal received by the antenna, and an output signal of the receiver. A frequency analyzer for calculating a frequency spectrum; an amplitude detector for detecting an amplitude of a specific frequency from an output value of the frequency analyzer; and a target detection process for detecting an effective frequency bin from an output signal of the amplitude detector. A target detector, a frequency database unit for storing a predetermined frequency value, a frequency bin storage unit for storing a frequency value for each effective frequency bin output from the target detector, and a frequency bin storage unit A difference frequency storage unit for determining a frequency difference between adjacent effective frequency bins for each effective frequency bin and storing a frequency difference value for each effective frequency bin; Is divided by the frequency stored in the frequency database unit, the remainder computing unit for calculating the remainder, a histogram measuring unit for performing a histogram measurement of the output value of the remainder computing unit, and the measurement frequency of the histogram measuring device is A frequency bin selector for invalidating an effective frequency bin giving a maximum remainder. 6. A radar signal processing device mounted on an aircraft, wherein the frequency database device stores a frequency value determined from a pulse repetition frequency transmitted by a counterpart device and a pulse repetition frequency transmitted by its own device. 6. The radar signal processing device according to claim 1, wherein: