JP5197125B2 - Pulse radar equipment - Google Patents

Description

  The present invention relates to a pulse radar device that measures a high-resolution resolution of a reflected wave from a target by synthetic band processing and suppresses clutter.

For example, Non-Patent Document 1 discloses a conventional pulse radar device that performs high-distance resolution measurement using synthetic band processing and suppresses clutter. In this apparatus, at the time of transmission, transmission is performed at the same frequency for two consecutive transmission pulses, and at different frequencies that change stepwise for each of the two consecutive transmission pulses.
At the time of reception, after suppressing clutter by MTI (Moving Target Indicator) processing on the received signal for the transmission pulse of the same continuous frequency, perform band synthesis using signals after MTI processing of all different frequencies, Ranging with high range resolution.
Japanese Patent Application Laid-Open No. 2004-228561 has a description of applying MTI processing to combined band processing, but specific transmission pulses are transmitted or specific processing is performed on received signals. No explanation is given.
Furthermore, Non-Patent Document 2 is a prior art document related to the synthesis band processing, and Non-Patent Document 3 is a prior art document related to MTI processing.

JP 11-2111815 A Zhang, Q .; Yeo, T.S .; Du, G., `` ISAR imaging in strong ground clutter by using a new stepped-frequency signal mode '', IGRASS'02 2002.Page (s): 2753-2755 vol.5 “High-Resolution Radar” by Donald R. Wehner, Second Edition, Artech House, Chapter 5, 197-237 Supervised by Takashi Yoshida, "Revised Radar Technology", IEICE, P.67-84.

  However, the prior art has the following problems. First, in order to clarify the problems of the prior art, the principle of MTI processing will be described. In general, MTI processing is used to suppress a clutter and detect a moving target such as an aircraft in an environment where clutter from the ground or the like exists.

  When the pulse radar device is stationary, as shown in FIG. 16, a relative speed is generated between the target such as an aircraft that is a moving object and the pulse radar device, and reflection from the target such as an aircraft that is a moving object. A Doppler frequency corresponding to the relative speed is generated in the received signal. On the other hand, the relative speed is 0 m / sec between the clutter such as the ground which is a stationary object and the pulse radar apparatus, and the reflected reception signal from the clutter such as the ground which is a stationary object is not affected by the Doppler frequency. (The Doppler frequency is 0 Hz.)

  The MTI processing uses this Doppler frequency and, as shown in FIG. 17, performs subtraction between reflected reception signals for transmission pulses of the same frequency separated by a certain time interval (in the case of FIG. 17, one pulse repetition period). The reflected reception signal from the reflector having a relative speed of 0 m / sec, that is, the reflected reception signal from the clutter is suppressed.

In the conventional pulse radar device described in Non-Patent Document 1, clutter suppression processing is performed by MTI processing on received signals for consecutive transmission pulses having the same frequency. Therefore, the time interval between two pulses for performing MTI processing is a pulse repetition period T _pri , and the suppression characteristic by MTI processing for the signal after the combined band processing for the relative velocity v between the radar device and the reflector in that case is It is represented by

Here, N is the number of transmission pulses, f ₀ is the transmission minimum frequency, Δf is the frequency step width, and c is the speed of light.

FIG. 18 shows the case where the number of transmission pulses N = 512, the minimum transmission frequency f ₀ = 10 GHz, the frequency step width Δf = 1 MHz, the pulse repetition period T _pri = 50 μsec, and the relative speed v is changed from −20 to 20 m / sec. The suppression characteristics of MTI processing are shown.

As can be seen from FIG. 18, it can be seen that the MTI processing of the conventional pulse radar apparatus can suppress the received signal from the reflector whose relative speed is 0 m / sec. However, for example, a target with a relative speed of 15 m / sec is suppressed by about 16 dB, and there is a problem that the detection performance of a low-speed moving target deteriorates.

  The present invention has been made to solve the above-described problems, and provides a pulse radar device capable of suppressing clutter, performing high-distance resolution ranging by synthetic band processing, and excellent in low-speed moving target detection performance. The purpose is to obtain.

The pulse radar device according to the present invention is
A transmission pulse train whose transmission frequency changes at a predetermined frequency without overlap in each pulse repetition period generates a transmission signal that is repeated and transmits it in the target direction, and transmits it from the target and background reflected signals obtained at each pulse repetition period A pulse radar device that generates a received video signal using the same reference intermediate frequency signal as the signal,
In order to generate a transmission signal, a pulse repetition period and a pulse repetition period / frequency control for setting transmission signals of N frequencies whose transmission frequencies change at a predetermined frequency without overlapping each pulse repetition period as a set of transmission pulse trains And
A clutter suppressor that suppresses clutter, which is a reflected signal from the background by MTI processing, using a received video signal for a transmission pulse of the same frequency from a transmission pulse train of a transmission pulse of a transmission signal that is continuously and repeatedly transmitted ;
A combined bander for performing combined band processing using signals after MTI processing for transmission pulses of all frequencies by the clutter suppressor;
It has a detector that calculates the amplitude value of the output from the combined bander and outputs the target high-resolution ranging result by the combined band processing,
The pulse repetition period / frequency controller controls the pulse repetition period, the transmission frequency, so that the amount of suppression of the previous MTI process in the clutter suppressor for a target in a predetermined relative speed range is equal to or less than a predetermined value. Sets the change in frequency for each transmission pulse in the previous period.

According to the pulse radar device of the present invention, a transmission pulse train whose transmission frequency changes at a predetermined frequency without overlapping each pulse repetition cycle transmits a repeated transmission signal in a target direction,
Using the same frequency as the transmission pulse from the target and background reflected signal obtained at each pulse repetition period, the generated received video signal is used to generate a clutter that is a reflected signal from a reflector other than the target by MTI processing. Suppression is performed by a clutter suppressor, and a combined band processing is performed by using a signal after the MTI processing for the transmission pulses of all frequencies by the clutter suppressor by a combining bander, and an output from the combining bander is performed by a detector. In addition to being able to suppress clutter and using high-resolution resolution by combining band processing, low-speed movement is possible. It is possible to reduce degradation of target detection performance.

  A preferred embodiment of a pulse radar device according to the present invention will be described below with reference to the drawings. The pulse radar apparatus according to the present invention can suppress clutter and can perform distance measurement with a high distance resolution by synthetic band processing, and can reduce degradation of low-speed moving target detection performance.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a pulse radar device according to Embodiment 1 of the present invention. The function of each component will be described with reference to FIG.

The pulse repetition period / frequency controller 1 sets one pulse repetition period and repeatedly sets N frequencies whose transmission frequencies change at a predetermined frequency without overlapping each pulse repetition period. FIG. 2 shows a specific frequency setting example. In this example, N frequencies whose frequencies change stepwise for each pulse are set repeatedly with a transmission minimum frequency f ₀ and a frequency step interval Δf.

At that time, the suppression characteristic by the MTI processing for the signal after the combined band processing is calculated in advance using the following equation, and the transmission is performed so that the suppression degree in the range of the relative velocity v between the assumed radar apparatus and the reflector is small. The number of pulses N, the minimum transmission frequency f ₀ , the frequency step width Δf, and the pulse repetition period T _pri are set.

In FIG. 3, for example, when it is desired to set the degree of suppression of the signal after the combined band processing by the MTI processing to the reflected reception signal from the reflector whose relative speed with the radar device is in the range of 10 to 20 m / sec to −5 dB or more. The suppression characteristic calculated | required using (2) is shown. In this case, the number N of transmission pulses, the minimum transmission frequency f ₀ , the frequency step width Δf, and the pulse repetition period T _pri are N = 512, f ₀ = 10 GHz, the frequency step width Δf = 1 MHz, and T _pri = 50 μsec, respectively. .

The timing generator 2 uses the pulse repetition period information from the pulse repetition period / frequency controller 1 to generate timing signals at intervals of the pulse repetition period T _pri . This timing signal is used as a frequency switching signal in the frequency synthesizer 3, used as a pulse modulation signal in the pulse modulator 7, and used as a transmission / reception switching signal in the transmission / reception switch 9.

The frequency synthesizer 3 generates a frequency for each pulse repetition period T _pri according to the transmission frequency information input from the pulse repetition period / frequency controller 1 by a timing signal (corresponding to a frequency switching signal) from the timing generator 2. And output to the distributor 4a.

  The distributor 4a divides the input signal from the frequency synthesizer 3 into two, outputs one to the frequency converter 6a as a local oscillation signal for generating a transmission signal, and the other as a local oscillation signal for generating an intermediate frequency signal. Output to the frequency converter 6b.

  The reference intermediate frequency signal generator 5 generates a reference intermediate frequency signal. The frequency converter 6a generates a transmission carrier signal having a frequency that is the sum of the frequency of the local oscillation signal from the distributor 4a and the frequency of the reference intermediate frequency signal generated by the reference intermediate frequency signal generator 5.

The pulse modulator 7 _applies a predetermined pulse to the transmission carrier signal generated by the frequency converter 6a for each pulse repetition period T _pri by a timing signal from the timing generator 2 (corresponding to a pulse modulation signal). Pulse modulation with width T _p is performed. The power amplifier 8 takes in the output signal of the pulse modulator 7 and performs power amplification.

The transmission / reception switch 9 outputs an input signal from the power amplifier 8 at a predetermined time interval for each pulse repetition period T _pri by a timing signal (corresponding to a transmission / reception switching signal) from the timing generator 2. The antenna 10 radiates the input signal from the transmission / reception switch 9 to space as a transmission signal.

The transmission signal radiated to the space is reflected on the target 11 and the background, is received as a reflected signal by the antenna 10, and is output to the transmission / reception switch 9. The transmission / reception switch 9 uses the timing signal from the timing generator 2 (corresponding to the transmission / reception switching signal) to input the input signal from the antenna 10 to the frequency converter 6b at a predetermined time interval for each pulse repetition period T _pri. Output.

  The frequency converter 6b is also supplied with a local oscillation signal from the distributor 4a for generating an intermediate frequency signal. Then, the frequency converter 6 b generates an intermediate frequency signal that is the difference between the frequency of the received signal and the frequency of the local oscillation signal, and outputs the intermediate frequency signal to the intermediate frequency amplifier 12.

  The intermediate frequency amplifier 12 amplifies the power of the intermediate frequency signal and outputs the result to the distributor 4b. The distributor 4b divides the intermediate frequency signal amplified by the intermediate frequency amplifier 12 into two and outputs them to the phase detectors 14a and 14b.

  On the other hand, the 90-degree hybrid unit 13 separates the reference intermediate frequency signal generated by the reference intermediate frequency signal generator 5 into two signals having a phase difference of 90 degrees, and outputs them to the phase detectors 14a and 14b. . The phase detectors 14a and 14b have a frequency which is a difference between the frequency of the intermediate frequency signal and the frequency of the reference intermediate frequency signal from the input signal from the distributor 4b and the input signal from the 90-degree hybrid unit 13, and each of the phase detectors 14a and 14b is 90 °. I component and Q component video signals (hereinafter referred to as I and Q video signals) having a phase difference of degrees are generated.

The generated I, Q video signals, A / D converter 15a of the sampling frequency 1 / _{T p} (corresponding to the inverse of the transmit pulse width _{T p),} is input to 15b, the same spacing as the transmitted pulse width _{T p} It is converted into digital I and Q video signals for each range bin and stored in the video signal storage memory 16. The video signal storage memory 16 stores a complex digital video signal having digital I video signals of all range bin numbers having a time interval of 2N times the pulse repetition period T _pri as real parts and digital Q video signals as imaginary parts.

As shown in FIG. 4, the clutter suppressor 17 has N sets of the same range bin number obtained from the received signals for the transmission pulses of the same frequency separated from the video signal storage memory 16 by a time interval of N times T _pri. These complex digital video signals are taken out, MTI processing is performed on each set of complex digital video signals, N MTI-processed complex digital video signals are generated, and output to the synthesis bander 18.

Synthetic band 18 is by inverse Fourier transform the MTI processing after complex digital video signal input from the clutter suppressor 17 performs synthesis of bandwidth, it generates a complex signal having a pulse width T _p following distance resolution ΔR Then, the result is output to the envelope detector 19. The envelope detector 19 obtains the amplitude values of all the complex signals input from the synthesis bander 18 and outputs them to the display unit 20 as a high-resolution relative distance measurement result by the synthesis band process. The display 20 displays the input signal from the envelope detector 19.

  As described above, according to the first embodiment, in the pulse radar apparatus that can suppress clutter and can measure a distance with high range resolution by the synthesis band processing, it is possible to reduce deterioration of the low-speed moving target detection performance. Can be planned.

Embodiment 2. FIG.
FIG. 5 shows the number N of transmission pulses, the minimum transmission frequency f ₀ , the frequency step width Δf, and two types of pulse repetition periods T _pri1 and T _pri in the pulse repetition period / frequency controller 1 according to the second embodiment of the present invention. _{This is} an example of setting _pri2 . The configuration diagram of the pulse radar device is the same as FIG.

  Next, the operation of the pulse radar apparatus according to the second embodiment will be described with a focus on a new pulse repetition period / frequency controller 1 and a clutter suppressor 17 different from those of the first embodiment.

The pulse repetition period / frequency controller 1 sets two types of pulse repetition periods T _pri1 and T _pri2, and N frequencies whose transmission frequencies change at a predetermined frequency without overlapping each pulse repetition period T _pri1 ; The same N frequencies are used for each pulse repetition period T _pri2, and N frequencies whose frequencies change in the same order without overlap are successively set.

FIG. 5 shows a specific frequency setting example. In this example, the first minimum transmission at a pulse repetition period T _PRI1 frequency f _0, sets the N frequency to frequency changes stepwise every pulse frequency step interval Delta] f, then a pulse repetition period T _PRI2 N frequencies whose frequencies change stepwise for each pulse are set with a transmission minimum frequency f ₀ and a frequency step interval Δf.

At that time, the suppression characteristic by the MTI processing for the signal after the combined band processing is calculated in advance using the following equation, and the transmission is performed so that the suppression degree in the range of the relative velocity v between the assumed radar apparatus and the reflector is small. The number of pulses N, the transmission minimum frequency f ₀ , the frequency step width Δf, and the pulse repetition period T _pri1 and T _pri2 are set.

For example, in the case of FIG. 6, when it is desired that the degree of suppression of the signal after the combined band processing by the MTI processing with respect to the reflected reception signal from the reflector having a relative speed of 2 to 20 m / sec with the radar apparatus is −5 dB or more. This is the suppression characteristic obtained using (3). In this case, the number of transmission pulses N, transmission minimum frequency f ₀ , frequency step width Δf, pulse repetition period T _pri , T _pri2 are N = 512, f ₀ = 10 GHz, frequency step width Δf = 1 MHz, T _pri1 = 50 μsec and T _pri2 = 60 μsec.

  Thereafter, the process from the timing generator 2 to the video signal storage memory 16 is the same as that of the first embodiment.

As shown in FIG. 7, the clutter suppressor 17 receives ((N−n) T _pri1 + nT _pri2 ) [n = 0, 1,..., N−1] times from the video signal storage memory 16. N sets of complex digital video signals having the same range bin number obtained from received signals for transmission pulses of the same frequency separated by time intervals are extracted, and MTI processing is performed on each set of complex digital video signals to obtain N MTIs. After processing, a complex digital video signal is generated and output to the synthesis bander 18.

  The components after the synthesis bander 18 are the same as those in the first embodiment.

As described above, according to the second embodiment, the same number of transmission pulses N and minimum transmission frequency can be obtained in a pulse radar apparatus that can suppress clutter and can perform distance measurement with high range resolution by synthetic band processing. When f ₀ and frequency step width Δf are used, the pulse repetition period T _{pri is set} to two different from T _pri1 and T _pri2 , _thereby reducing the degradation of the low-speed moving target detection performance compared to the first embodiment. Can be planned.

Embodiment 3 FIG.
FIG. 8 shows an example of setting the number N of transmission pulses, the minimum transmission frequency f ₀ , the frequency step width Δf, and the pulse repetition period T _pri in the pulse repetition period / frequency controller 1 according to the third embodiment of the present invention. The configuration diagram of the pulse radar device is the same as FIG.

  Next, the operation of the pulse radar apparatus according to the third embodiment will be described with a focus on a new pulse repetition period / frequency controller 1 and a clutter suppressor 17 different from those of the first embodiment.

  The pulse repetition period / frequency controller 1 sets one pulse repetition period and uses the same N frequencies as N frequencies whose transmission frequencies change at a predetermined frequency without overlapping each pulse repetition period, N frequencies whose frequencies change without overlap in different orders are set in succession.

FIG. 8 shows a specific frequency setting example. In this example, the frequency step interval −Δf is calculated from the N frequencies whose frequency changes stepwise for each pulse at the transmission minimum frequency f ₀ and the frequency step interval Δf, and the transmission maximum frequency f ₀ + (N−1) Δf. Thus, N frequencies whose frequencies change stepwise for each pulse are set repeatedly.

At that time, the suppression characteristic by the MTI processing for the signal after the combined band processing is calculated in advance using the following equation, and the transmission is performed so that the suppression degree in the range of the relative velocity v between the assumed radar apparatus and the reflector is small. The number of pulses N, the minimum transmission frequency f ₀ , the frequency step width Δf, and the pulse repetition period T _pri are set.

For example, in the case of FIG. 9, when it is desired that the degree of suppression of the signal after the combined band processing by the MTI processing with respect to the reflected reception signal from the reflector having a relative speed of 1 to 20 m / sec with the radar apparatus is −5 dB or more. This is the suppression characteristic obtained using (4). In this case, the number N of transmission pulses, the minimum transmission frequency f ₀ , the frequency step width Δf, and the pulse repetition period T _pri are N = 512, f ₀ = 10 GHz, the frequency step width Δf = 1 MHz, and T _pri = 50 μsec, respectively. .

  Thereafter, the process from the timing generator 2 to the video signal storage memory 16 is the same as that of the first embodiment.

As shown in FIG. 10, the clutter suppressor 17 sends a time interval of T _pri of (2N−2n−1) [n = 0, 1,..., N−1] times from the video signal storage memory 16. N sets of complex digital video signals having the same range bin number obtained from received signals for transmission pulses of the same frequency apart from each other are extracted, MTI processing is performed on each set of complex digital video signals, and after N MTI processing A complex digital video signal is generated and output to the synthesis bander 18.

  The components after the synthesis bander 18 are the same as those in the first embodiment.

As described above, according to the third embodiment, the same number of transmission pulses N, minimum transmission frequency, in a pulse radar apparatus that can suppress clutter and can perform distance measurement with high range resolution by synthetic band processing. When f ₀ , frequency step width Δf, and pulse repetition period T _pri are used, it is possible to reduce deterioration of the low-speed moving target detection performance more than in the first embodiment.

Embodiment 4 FIG.
FIG. 11 shows the number N of transmission pulses, the minimum transmission frequency f ₀ , the frequency step width Δf, and two types of pulse repetition periods T _pri1 and T _pri in the pulse repetition period / frequency controller 1 according to the fourth embodiment of the present invention. _{This is} an example of setting _pri2 . The configuration diagram of the pulse radar device is the same as FIG.

  Next, the operation of the pulse radar apparatus according to the fourth embodiment will be described with a focus on a new pulse repetition period / frequency controller 1 and clutter suppressor 17 different from those of the first embodiment.

The pulse repetition period / frequency controller 1 sets two types of pulse repetition periods T _pri1 and T _pri2, and N frequencies whose transmission frequencies change at a predetermined frequency without overlapping each pulse repetition period T _pri1 ; The same N frequencies are used for each pulse repetition period T _pri2, and N frequencies whose frequencies change without overlap are sequentially set in different orders.

FIG. 11 shows a specific frequency setting example. In this example, the first minimum transmission at a pulse repetition period T _PRI1 frequency f _0, sets the N frequency to frequency changes stepwise every pulse frequency step interval Delta] f, then a pulse repetition period T _PRI2 From the transmission maximum frequency f ₀ + (N−1) Δf, N frequencies whose frequencies change stepwise for each pulse are set at a frequency step interval −Δf.

At that time, the suppression characteristic by the MTI processing for the signal after the combined band processing is calculated in advance using the following equation, and the transmission is performed so that the suppression degree in the range of the relative velocity v between the assumed radar apparatus and the reflector is small. The number of pulses N, the transmission minimum frequency f ₀ , the frequency step width Δf, and the pulse repetition period T _pri1 and T _pri2 are set.

For example, in FIG. 12, when the degree of suppression of the signal after the combined band processing by the MTI processing with respect to the reflected reception signal from the reflector having a relative speed of 1 to 20 m / sec with the radar device is to be −5 dB or more, This is the suppression characteristic obtained using (5). In this case, the number of transmission pulses N, transmission minimum frequency f ₀ , frequency step width Δf, and pulse repetition period T _pri are N = 512, f ₀ = 10 GHz, frequency step width Δf = 1 MHz, T _pri1 = 50 μsec, T _pri2 = 60 μsec.

  Thereafter, the process from the timing generator 2 to the video signal storage memory 16 is the same as that of the first embodiment.

As shown in FIG. 13, the clutter suppressor 17 receives ((N−n) T _pri1 + (N−n−1) T _pri2 ) [n = 0, 1,... , N-1] times, N sets of complex digital video signals having the same range bin number obtained from the received signals for transmission pulses of the same frequency separated by time intervals are extracted, and MTI processing is performed on each set of complex digital video signals. , N complex MTI-processed complex digital video signals are generated and output to the synthesis bander 18.

  The components after the synthesis bander 18 are the same as those in the first embodiment.

As described above, according to the fourth embodiment, the same number of transmission pulses N, minimum transmission frequency, in a pulse radar apparatus that can suppress clutter and can perform distance measurement with high range resolution by synthetic band processing. When f ₀ and frequency step width Δf are used, the pulse repetition period T _{pri is set} to two different from T _pri1 and T _pri2 , _thereby reducing the degradation of the low-speed moving target detection performance compared to the first embodiment. Can be planned.

Embodiment 5 FIG.
FIG. 14 is a configuration diagram of the pulse radar apparatus according to the fifth embodiment of the present invention. The pulse radar device according to the fifth embodiment in FIG. 14 is compared with the pulse radar device according to the first to fourth embodiments in FIG. 1 between the envelope detector 19 and the display 20. The difference is that a relative speed distance measuring device 21 is further provided.

  Next, the operation of the pulse radar device according to the fifth embodiment will be described with a focus on the relative velocity / distance measuring instrument 21 having a configuration different from that of the first embodiment. In the configuration of FIG. 14, the operation up to the envelope detector 19 is the same as the operation of the first embodiment.

  The envelope detector 19 obtains the amplitude values of all the complex signals input from the synthesis bander 18 and outputs the high-resolution relative distance measurement result by the synthesis band process to the relative velocity distance measurement unit 21.

  In the processing described in the first to fourth embodiments, MTI processing is performed using received signals at different times, and pulse trains having different frequency changes for each transmission pulse are used. Since the pulse repetition period is used, depending on the relationship between the pulse repetition period, the transmission frequency, the frequency change for each transmission pulse, and the relative speed of the target, even if the target number is one, there are two peaks in the high-resolution relative distance measurement result. Is born. FIG. 15 shows an example when two peaks occur in the high-resolution relative distance measurement result.

The relative velocity distance measuring device 21 uses the information of the two peak distances R ₁ and R ₂ and the pulse repetition period, the transmission frequency, and the frequency change for each transmission pulse in the high-resolution relative distance measurement result. The velocity v and the relative distance R _cal are obtained. The obtained relative velocity v _cal and relative distance R _cal are output to the display 20.

For example, in the case of the pulse repetition period, the transmission frequency, and the frequency change for each transmission pulse shown in the second embodiment, the relative velocity v _cal and the relative distance R _cal can be obtained by the following equations, respectively.

Or

Further, in the case of the pulse repetition period, the transmission frequency, and the frequency change for each transmission pulse shown in the third embodiment, the relative velocity v _cal and the relative distance R _cal can be obtained by the following equations, respectively.

Or

Furthermore, in the case of the pulse repetition period, the transmission frequency, and the frequency change for each transmission pulse shown in the fourth embodiment, the relative velocity v _cal and the relative distance R _cal can be obtained by the following equations, respectively.

Or

It is also possible to obtain the relative distance R _cal from the distances R ₁ and R _{2 of the} two peaks in the high resolution relative distance measurement result by the following equation.

  The pulse radar device of the present invention can be used for, for example, a device for tracking a target aircraft or an air traffic control radar.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the pulse radar apparatus in Embodiment 1 of this invention. It is explanatory drawing of the example of a pulse signal setting by a pulse repetition period and frequency controller. 6 is a suppression characteristic diagram obtained by a calculation formula in order to make the signal suppression degree after the combined band processing by the MTI processing of the reflected reception signal in Embodiment 1 be −5 dB or more. FIG. 6 is an explanatory diagram of an MTI processing operation by the clutter suppressor according to Embodiment 1. FIG. It is explanatory drawing of the example of a pulse signal setting by the pulse repetition period and frequency controller in Embodiment 2 of this invention. FIG. 10 is a suppression characteristic diagram obtained by a calculation formula in order to make the signal suppression degree after the combined band processing by the MTI processing of the reflected reception signal in the second embodiment be −5 dB or more. FIG. 10 is an explanatory diagram of an MTI processing operation by a clutter suppressor according to the second embodiment. It is explanatory drawing of the example of a pulse signal setting by the pulse repetition period and frequency controller in Embodiment 3 of this invention. FIG. 10 is a suppression characteristic diagram obtained by a calculation formula in order to make a signal suppression degree after combined band processing by MTI processing of a reflected reception signal in Embodiment 3 to be −5 dB or more. FIG. 10 is an explanatory diagram of an MTI processing operation by a clutter suppressor according to the third embodiment. It is explanatory drawing of the example of a pulse signal setting by the pulse repetition period and frequency controller in Embodiment 4 of this invention. FIG. 10 is a suppression characteristic diagram obtained by a calculation formula in order to make a signal suppression degree after combined band processing by MTI processing of a reflected reception signal in Embodiment 4 to be −5 dB or more. FIG. 10 is an explanatory diagram of an MTI processing operation by a clutter suppressor according to a fourth embodiment. It is a block diagram of the pulse radar apparatus of Embodiment 5 of this invention. It is a characteristic view when two peaks occur in the high-resolution relative distance measurement result. It is a wave form diagram which shows the relationship between a transmission pulse and a reflected received signal when a pulse radar apparatus and a target have relative speed. It is a functional block diagram of the MTI processing part in the conventional pulse radar apparatus. It is a suppression characteristic figure by MTI processing of the conventional pulse radar device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1; Pulse repetition period and frequency controller, 2; Timing generator, 3; Frequency synthesizer, 4a, 4b; Distributor, 5; Reference intermediate frequency signal generator, 6a, 6b; Frequency converter, 7; 8; power amplifier, 9; duplexer, 10; antenna, 11; target, 12; intermediate frequency amplifier, 13; 90-degree hybrid, 14a, 14b; phase detector, 15a, 15b; A / D converter 16; Memory for storing video signal, 17; Clutter suppressor, 18; Synthetic bander, 19; Envelope detector, 20; Display, 21;

Claims (6)

A transmission pulse train whose transmission frequency changes at a predetermined frequency without overlap in each pulse repetition period generates a transmission signal that is repeated and transmits it in the target direction, and transmits it from the target and background reflected signals obtained at each pulse repetition period A pulse radar device that generates a received video signal using the same reference intermediate frequency signal as the signal,
In order to generate a transmission signal, a pulse repetition period and a pulse repetition period / frequency control for setting transmission signals of N frequencies whose transmission frequencies change at a predetermined frequency without overlapping each pulse repetition period as a set of transmission pulse trains And
A clutter suppressor that suppresses clutter, which is a reflected signal from the background by MTI processing, using a received video signal for a transmission pulse of the same frequency from a transmission pulse train of a transmission pulse of a transmission signal that is continuously and repeatedly transmitted ;
A combined bander for performing combined band processing using signals after MTI processing for transmission pulses of all frequencies by the clutter suppressor;
Equipped with a detector that calculates the amplitude value of the output from the synthesis bander and outputs the target high-resolution ranging result by the synthesis band process,
The pulse repetition period / frequency controller controls the pulse repetition period, the transmission frequency, so that the amount of suppression of the previous MTI process in the clutter suppressor for a target in a predetermined relative speed range is equal to or less than a predetermined value. A pulse radar apparatus characterized by setting a change in frequency for each transmission pulse in the previous period . The pulse repetition period / frequency controller sets all transmission pulse trains that are continuously repeated and transmitted so as to have the same transmission frequency, a change in frequency for each transmission pulse, and the same pulse repetition period. The pulse radar device according to claim 1, wherein: The pulse repetition period / frequency controller is configured to set a transmission pulse train that is continuously repeated and transmitted so as to have the same transmission frequency and a change in frequency for each transmission pulse, but to have different pulse repetition periods. The pulse radar device according to claim 1, wherein: The pulse repetition period / frequency controller sets the transmission pulse trains that are continuously repeated and transmitted so as to have the same transmission frequency and the same pulse repetition period, but different frequency changes for each transmission pulse. The pulse radar device according to claim 1, wherein: The pulse repetition period / frequency controller sets transmission pulse trains that are continuously repeated and transmitted so as to have the same transmission frequency but different pulse repetition period and frequency change for each transmission pulse. The pulse radar device according to claim 1, wherein A relative speed distance meter is added to obtain the target relative speed and relative distance using the high resolution distance measurement result after the synthesis band processing and the information on the pulse repetition period, the transmission frequency, and the frequency change for each previous transmission pulse. The pulse radar device according to any one of claims 1 to 5 , wherein the pulse radar device is characterized in that:

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