JP2007212245A - Pulse radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately detect a relative distance up to a target after shortening a signal transmission time necessary for obtaining a ranging result of once high resolution in a range applied at the distance up to the target to be inherently detected when a relative speed with the target is not zero. <P>SOLUTION: A pulse radar system comprises: a complex multiplication means 17 for generating a complex signal for measuring the relative speed by generating a complex digital video signal A corresponding to a pulse train A and a complex digital video signal B corresponding to a pulse train B from a receiving signal obtained by transmitting transmission pulse trains A, B changing by prescribed frequency intervals in time division to a target direction and multiplying a complex conjugate digital video signal B reversing signs of virtual parts of the complex digital video signal A and the complex digital video signal B; a frequency spectral analysis means 18 for finding a frequency spectrum of the complex signal for measuring the relative speed; and a relative speed measurement means 19 for finding the relative speed with the target by using the frequency spectrum. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pulse radar apparatus that performs distance measurement with a correct high-range resolution by synthetic band processing even when the relative speed to a target is not zero.

  In the conventional pulse radar device, in order to perform synthetic band processing when the relative velocity between the pulse radar device and the target is not 0, a synthetic band mode and a relative velocity measurement mode are provided, and measurement is performed in the relative velocity measurement mode. There is a technique that performs a combined band process after performing a relative speed correction on a signal acquired in the combined band mode using a relative speed (see, for example, Patent Document 1). Further, Non-Patent Document 1 is a prior art document related to the synthesis band processing.

Japanese Patent No. 3709698 (page 5, FIG. 1) “High-Resolution Radar” by Donald R. Wehner, Second Edition, Artech House, Chapter 5, 197-237

However, the prior art has the following problems. FIG. 6 is a diagram showing transmission pulses in a conventional pulse radar device. In the pulse radar apparatus using the synthetic band processing, as shown in FIG. 6, the transmission frequency is set to f _{0 to} f _N−1 for each pulse with respect to _N transmission pulses St _{0 to} St _N−1 at the time of transmission. Until the frequency step interval Δf.

  During reception, each received signal reflected from the target is divided and received for each range bin by a range gate, down-converted with a local oscillation signal having the same frequency and the same initial phase as the transmission pulse, and an I component video signal, Q A component video signal is generated. Furthermore, the band can be synthesized by performing inverse Fourier transform on N I component video signals and Q component video signals in the same range bin, and a high resolution relative distance in each range bin can be obtained.

FIG. 7 is a diagram showing the state of received signal strength in a conventional pulse radar device. When the relative speed between the pulse radar device and the target is not 0, there is a problem that the relative distance R ₀ cannot be obtained accurately due to the influence of the relative speed. That is, when the relative speed is not 0, the relative distance between the pulse radar device obtained by increasing the distance resolution ΔR by the synthesis band processing and the target is the relative distance between the pulse radar device at the reference time and the target. A distance different from the distance R ₀ is indicated.

In FIG. 7, Srp indicates a reflected signal from the target when the relative speed with respect to the target is 0, and Srp ′ indicates a reflected signal from the target when the relative speed with respect to the target is not 0. . When the relative speed is 0, the relative distance R ₀ can be obtained from the reflected signal Srp. However, when the relative speed is not 0, the relative distance R ₀ cannot be obtained from the reflected signal Srp ′. .

  As a solution to this problem, in the conventional technique described in Patent Document 1, a composite band mode and a relative speed measurement mode are provided, and a relative speed measured in the relative speed measurement mode is used to obtain a signal acquired in the composite band mode. Then, after performing relative velocity correction, synthetic band processing is performed to obtain a high-resolution distance measurement result.

  Therefore, in order to obtain one high-resolution distance measurement result, both the observation time in the relative velocity measurement mode and the observation time in the composite band mode are required. Furthermore, since separate received signals are used for the processing of the relative speed measurement mode and the combined band mode, there is a problem that the accuracy of the relative speed correction deteriorates for a target having a large relative speed change.

On the other hand, the maximum measurement distance R _max that can be measured without ambiguity in the combined band processing is expressed by the following equation (1) using the frequency step interval Δf.

However, c represents the speed of light. On the other hand, the distance range R _bin of one range _bin is expressed by the following equation (2) using the transmission pulse width T _p .

Therefore, in order to achieve high range resolution without ambiguity within the range range R _{bin of} one range bin by combining band processing, the maximum distance R _max that can be measured without ambiguity is set to be equal to or greater than the range range R _bin of one range _bin . There is a need to. Therefore, it is necessary to set the frequency step width Δf and the transmission pulse width T _p so as to satisfy the relationship of the following equation (3).

Therefore, the frequency step size Δf may be a maximum, a value of the reciprocal of the transmission pulse width T _p. In order to maximize the target reflected signal-to-noise power, it is desirable that the 3 dB Down bandwidth of the matched filter at the final stage of the receiver is 1.2 times the reciprocal of the transmission pulse width. Therefore, when the frequency step width Δf as the reciprocal of the transmission pulse width T _p, band B _rx of the last stage of the receiver is expressed by the following equation (4).

FIG. 8 is a diagram showing matched filter characteristics at the final stage of the receiver in a conventional pulse radar device, and shows characteristics with a center frequency of zero. FIG. 9 is a diagram showing the timing of received pulses from _two different distances (R ₁ , R ₂ ) in a conventional pulse radar device.

FIG. 9A shows a case where the reception pulse corresponding to the transmission pulse is received within the same pulse repetition period T _{pri as} the transmission pulse when the distance to the target is R ₁ . FIG. 9B shows a case where the reception pulse corresponding to the transmission pulse is received within the next pulse repetition period T _pri of the transmission pulse when the distance to the target is R ₂ . .

  Further, FIG. 10 is a diagram showing matched filter characteristics corresponding to FIG. 9 in the conventional pulse radar apparatus. FIG. 10A shows a matched filter characteristic corresponding to the received pulse pattern of FIG. FIG. 10B shows matched filter characteristics corresponding to the received pulse pattern of FIG. 9B.

When the transmission frequency is changed at every constant frequency step interval Δf from f ₀ to f _N−1 for each pulse, as shown in FIG. 9A, the relative distance from the target is expressed by the following equation (5). When the distance R ₁ is shorter than the distance R _pri corresponding to the pulse repetition period shown, the frequency of the received pulse and the frequency of the local oscillation signal always match.

For example, the received pulse of frequency f _0, will be down-converted by a local oscillation signal of a frequency f _0, the center frequency is zero of the generated video signal, the bandwidth B _v of 3dBDown is represented by the following formula (6) Value.

  Therefore, the spectrum of the received pulse and the matched filter shape are as shown in FIG. 10A on the frequency axis, and the received pulse passes through the matched filter so that the received pulse can be extracted accurately.

However, as shown in FIG. 9B, for example, when the relative distance to the target is R ₂ longer than R ₁ by a distance R _pri corresponding to the pulse repetition period, the frequency is at the local oscillation signal of frequency f _1. The received pulse of f ₀ will be returned. Therefore, the received pulse having the frequency f ₀ is down-converted by the local oscillation signal having the frequency f ₁ , and a frequency component of −Δf is generated in the generated video signal.

  This means that, as shown in FIG. 10B, on the frequency axis, a spectrum of a received pulse whose frequency is shifted by −Δf is input to the matched filter. Therefore, in the received pulse spectrum shown in FIG. 10 (b), the components indicated by the diagonal lines pass through the matched filter.

Therefore, if the initial phase of each transmitted pulse is changed at regular intervals, when the synthetic band processing, the received signal strength is somewhat degraded, for the relative distance of R ₂ target, though, the relative distance R _The distance measurement is performed so that the distance R ₁ is shorter than the distance R ₁ by a distance R _pri corresponding to the pulse repetition period.

This indicates that there is a risk of erroneous ranging if there is a target at a relative distance where there is no target. In addition, when the received signal intensity from a reflector far from the distance R _pri corresponding to the pulse repetition period, such as reflection from the ground, is very large, the target closer to the distance R _pri corresponding to the pulse repetition period is There is a problem that detection is impossible due to being buried in the received signal from the reflector farther away than the distance R _pri corresponding to the pulse repetition period.

  The present invention has been made in order to solve the above-described problems, and in order to obtain a single high-resolution distance measurement result even when the relative speed between the pulse radar device and the target is not zero. The purpose is to obtain a pulse radar device capable of detecting a relative distance to a target with high accuracy after shortening a necessary signal transmission time interval within a range applicable to a distance to a target to be originally detected. .

  The pulse radar device according to the present invention has a transmission pulse train A whose transmission frequency changes by a predetermined frequency interval every pulse repetition period, and a pulse train B whose transmission frequency changes by a predetermined frequency interval with the same number of pulses as the pulse train A. A pulse radar device that generates a I component video signal and a Q component video signal by receiving a reflected signal obtained at each pulse repetition period and transmitting in a target direction by division, and obtained from a received signal with respect to a transmission signal of a pulse train A Complex digital video signal A having the same I / O video signal of the same range bin number as the real part and the Q component video signal as the imaginary part, and the I component video signal of the same range bin number obtained from the received signal with respect to the transmission signal of the pulse train B To generate a complex digital video signal B having a real part and a Q component video signal as an imaginary part. A complex multiplier for multiplying the digital signal A and the complex conjugate digital video signal B obtained by inverting the sign of the imaginary part of the complex digital video signal B to generate a complex signal for relative speed measurement; and a frequency of the complex signal for relative speed measurement A frequency spectrum analyzing means for obtaining a spectrum and a relative speed measuring means for obtaining a relative speed with respect to the target using the frequency spectrum are provided.

  According to the present invention, by using a transmission signal composed of a plurality of pulse trains satisfying a predetermined condition, the relative speed can be detected based on the same received signal, and the relative speed between the pulse radar device and the target can be detected. Even if is not 0, the signal transmission time interval required to obtain a single high-resolution distance measurement result is shortened within a range applicable to the distance to the target to be detected, and then the target is highly accurate. Thus, a pulse radar device that can detect the relative distance up to can be obtained.

Hereinafter, a preferred embodiment of a pulse radar device of the present invention will be described with reference to the drawings.
The pulse radar device of the present invention performs relative velocity correction by performing relative velocity measurement with the target using the same received signal and high-resolution relative distance measurement with the target by synthetic band processing after the relative velocity correction. Improving accuracy and shortening the received signal observation time necessary to obtain a high-resolution relative distance from the target by one synthesis band processing, and further to a distance farther than the distance corresponding to the pulse repetition period It is possible to suppress the reflection signal from a certain object.

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 timing generator 1 generates a timing signal at intervals of a pulse repetition period T _pri . This timing signal is used as a frequency switching signal in the frequency synthesizer 2, 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.

On the other hand, the frequency setting device 3 sets the order of the frequencies of the same two N pulse trains A and B so as to satisfy the following conditions, and outputs the order of the frequencies to the frequency synthesizer 2.
(Condition 1) The pulse intervals A and B are assumed to have the same frequency interval.
(Condition 2) The same frequency difference between the pulse trains A and B is assumed to be the same.

  FIG. 2 is a diagram showing an example of pulse trains A and B in the first embodiment of the present invention, and is set based on the above-described conditions 1 and 2. FIG. In FIG. 2, N is 16, the frequency interval of pulse train A and the frequency interval of pulse train B are 2Δf, which is twice the frequency step interval Δf, and the frequency difference of the same number between A and B is Δf. Is shown.

The frequency synthesizer 2 alternately changes the frequency every pulse repetition period T _pri in accordance with the order of the pulse trains A and B input from the frequency setting device 3 by the timing signal (corresponding to the frequency switching signal) from the timing generator 1. And output to the distributor 4a. More specifically, first _{f 0,} f 2 of the pulse train A, _..., and output _{f 30,} followed by _f 1 pulse train _B, f 3, and outputs _..., and _{f 31,} like this The output consisting of 32 will be repeated.

Pulse sequence A shown in FIG. 2 on the basis of the conditions 1 and 2, by setting the frequency of B, the reflected signals from where the relative distance of the distance R _pri for a longer R ₂ corresponding to the pulse repetition period than R ₁ (That is, the reflected signal from a target other than the target to be detected originally) returns to the local oscillation signal of frequency f ₂ as a reception pulse of frequency f ₀ . Therefore, the received pulse having the frequency f ₀ is down-converted with the local oscillation signal having the frequency f ₂ , and a frequency component of −2Δf is generated in the generated video signal. Further, a larger frequency component of 29Δf is generated at the boundary between the pulse train A and the pulse train B.

FIG. 3 is an explanatory diagram of a matched filter corresponding to the pulse train of FIG. 2 in Embodiment 1 of the present invention. The fact that a frequency component of −2Δf is generated in the video signal generated by down-converting the received signal from R ₂ is that the frequency is shifted by −2Δf to the matched filter on the frequency axis as shown in FIG. The spectrum of the received pulse is input.

Therefore, when the frequency of the spectrum of the reception pulse is shifted by −2Δf in this way, the reception pulse does not pass through the matched filter. As a result, the reflected signal from the target whose relative distance is longer than the distance R _pri corresponding to the pulse repetition period does not pass through the matched filter and does not affect the subsequent synthesis band processing, thereby preventing erroneous detection. it can.

  The distributor 4a divides the input signal from the frequency synthesizer 2 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 uses a timing signal (corresponding to a pulse modulation signal) from the timing generator 1 with respect to the transmission carrier signal generated by the frequency converter 6a, for each pulse repetition period T _pri. 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 from the timing generator 1 (corresponding to a transmission / reception switching signal). The antenna 10 radiates the input signal from the transmission / reception switch 9 to space as a transmission signal.

The transmission signal is reflected on the target 11 and the background, is received by the antenna 10 as a reflected signal, and is output to the transmission / reception switch 9. The transmission / reception switch 9 uses the timing signal from the timing generator 1 (corresponding to the transmission / reception switching signal) to send 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.

  The complex multiplier 17 receives from the video signal storage memory 16 a complex digital video signal A having the same range bin number obtained from received signals for N transmission pulses having different frequencies included in the pulse train A generated by the frequency synthesizer 2. Take out.

  Further, the complex multiplier 17 is a complex digital video having the same range bin number obtained from the received signal for N transmission pulses having different frequencies included in the pulse train B generated by the frequency synthesizer 2 from the video signal storage memory 16. Take out signal B.

  The complex multiplier 17 multiplies the complex conjugate digital video signal B obtained by inverting the sign of the imaginary part of each of the N complex digital video signals A and B with the same number, thereby obtaining N A plurality of complex digital signals (X (0) to X (N-1)) for relative speed measurement are generated. FIG. 4 is an explanatory diagram of a complex digital signal for relative speed measurement generated by the complex multiplier 17 according to Embodiment 1 of the present invention. Further, the complex multiplier 17 outputs the generated N complex digital signals for measuring relative speed to the frequency spectrum analyzer 18.

V _A (n) (n = 0, 1,..., N−1) corresponding to the complex digital video signal A when the relative velocity between the pulse radar device and the target is v, and the complex digital video signal B The corresponding V _B (n) (n = 0, 1,..., N−1) is expressed by the following equations (7) and (8), respectively.

Here, I represents the amplitude of the complex digital video signal. Here, both the complex digital video signal A and the complex digital video signal B have the same value for all n. Therefore, for V _A (n) corresponding to the complex digital video signal A and V _B ^* (n) corresponding to the complex conjugate digital video signal B obtained by inverting the sign of the imaginary part of the complex digital video signal B, When the processing shown in FIG. 4 is performed, a complex speed digital signal X (n) (n = 0, 1,..., N−1) as an output signal is represented by the following equation (9). The

However, “*” in V _B ^* (n) represents a complex conjugate.

When the frequency spectrum analysis is performed on the complex digital signal X (n) (n = 0, 1,..., N−1) for relative speed measurement represented by the above equation (9), the first term exp (−j2πf ₀ (2v / c) NT _pri ), second term exp (−j2πΔf (−2R ₀ / c)), and third term exp (−j2πNΔf (2v / c) T _pri ) are variables, respectively. Since n is an unrelated term, these only affect the initial phase.

On the other hand, the fourth term exp (−j2π (2N−1) Δf (2v / c) nT _pri ) represents a Doppler frequency for a signal having a transmission carrier frequency of (2N−1) Δf. When inverse Fourier transform is used as the frequency spectrum analysis method, a signal obtained by inverse Fourier transform at N points with respect to the complex digital signal X (n) for relative speed measurement represented by the above formula (9), that is, relative speed measurement. The frequency spectrum P _X (k ′) of the complex digital signal for use is expressed by the following equation (10).

  As described above, the frequency spectrum analyzer 18 obtains the frequency spectrum of the complex digital signal for relative speed measurement from the complex multiplier 17 by using the inverse Fourier transform, and outputs the result to the relative speed meter 19.

From the above equation (10), it can be seen that the amplitude value (intensity) obtained as the absolute value of P _X (k ′) becomes the peak value when the following equation (11) holds.

If the value of k ′ at which the amplitude value of P _X (k ′) takes the maximum value is k _p , the relative velocity v between the pulse radar device and the target is obtained using the following equation (12) by obtaining k _p. Can be requested.

  As described above, the relative velocity measuring device 19 obtains the relative velocity with respect to the target by detecting the peak signal of the amplitude value of the frequency spectrum of the complex digital signal for measuring the relative velocity from the frequency spectrum analyzer 18, and the result Is output to the relative speed corrector 20.

The relative speed corrector 20 uses the relative speed with the target obtained by the relative speed measuring device 19 as v _cal , and relative speed correction amounts Z _A (n) and Z _R (represented by the following equations (13) and (14)). n).

Further, the relative speed corrector 20 takes out the same complex digital video signal A and complex digital video signal B as those used in the complex multiplier 17 for measuring the relative speed with respect to the target from the video signal storage memory 16, and The relative speeds indicated by the equations (15) and (16) are corrected, and complex digital video signals V _cA (n) and V _cB (n) after the relative speed correction are obtained.

Then, the relative speed corrector 20 outputs the obtained complex digital video signals V _cA (n) and V _cB (n) after the relative speed correction to the rearranger 21. The rearranger 21 arranges the corresponding transmission frequencies in ascending order or descending order with respect to the signal obtained by combining both the complex digital video signals V _cA (n) and V _cB (n) after the relative speed correction. The rearranged and rearranged complex digital video signals are generated and output to the synthesis bander 22.

  That is, the rearranger 21 takes the pulse train A and the pulse train B alternately and rearranges them so that the frequency numbers are in the order of f0, f1,. Then, the rearranged complex digital video signal is generated.

Synthetic band 22 is by inverse Fourier transform of the complex digital video signal rearranged input from rearranging unit 21 performs synthesis of band, a complex signal having a pulse width T _p following distance resolution ΔR The result is output to the envelope detector 23. The envelope detector 23 obtains the amplitude values of all the complex signals input from the synthesis bander 22 and outputs the amplitude values to the display unit 24 as a result of high distance resolution relative distance measurement by the synthesis band process. The display 24 displays the input signal from the envelope detector 23.

  As described above, according to the first embodiment, when the relative speed between the pulse radar device and the target is not 0, by using the transmission signal composed of a plurality of pulse trains that satisfy the predetermined condition, It is possible to easily obtain the relative speed by calculating the complex signal for measuring the relative speed from the corresponding reception result.

  Further, the same reception result as that used to calculate the relative speed is corrected by relative speed, and synthetic band processing is performed based on the reception result after correcting the relative speed, thereby ranging to the target. The result can be determined. Thereby, even when the relative speed between the pulse radar device and the target is not 0, the distance measurement result is not mistaken due to the influence of the relative speed, and the high-resolution relative distance measurement result can be obtained.

Furthermore, by setting the frequency difference between adjacent transmission signals to be twice or more the frequency step interval, it is possible to remove the reflected signal from the target farther than the distance R _pri corresponding to the pulse repetition period. As a result, it is possible to prevent false detection or non-detection of the original target to be detected that is closer than the distance R _pri corresponding to the pulse repetition period.

Furthermore, the deterioration of the relative distance measurement result due to the influence of the relative speed can be prevented, and the reflected signal from the target farther than the distance R _pri corresponding to the pulse repetition period can be removed, so that the pulse radar device and the target Even if the relative speed between the two is not 0, the signal transmission time interval necessary to obtain one high-resolution distance measurement result is shortened within a range applicable to the distance to the target to be detected originally. It is possible to obtain a pulse radar device that can detect the relative distance to the target with high accuracy.

Embodiment 2. FIG.
FIG. 5 is a configuration diagram of the pulse radar apparatus according to Embodiment 2 of the present invention. The pulse radar device according to the second embodiment in FIG. 5 is further provided with an adder (adding means) 25 at the subsequent stage of the envelope detector 23 as compared with the pulse radar device according to the first embodiment in FIG. The difference is that there is no rearranger 21.

Next, the operation of the pulse radar device according to the second embodiment will be described focusing on the configuration different from that of the first embodiment. In FIG. 5, the operation up to the relative speed corrector 20 is the same as the operation of the first embodiment. The complex digital video signals V _cA (n) and V _cB (n) after the relative speed correction obtained by the relative speed corrector 20 are output to the synthesis _bander 22.

The synthesis bander 22 performs band synthesis by performing inverse Fourier transform on each of the complex digital video signals V _cA (n) and V _cB (n) after the relative speed correction input from the relative speed corrector 20. , it generates a complex signal having a pulse width T _p following distance resolution [Delta] R, and outputs the result to the envelope detector 23. The envelope detector 23 obtains the amplitude value of the complex signal, which is the result of each synthesized band input from the synthesized bander 22, and outputs it to the adder 25.

  The adder 25 adds the amplitude values of the respective combined band results from the envelope detector 23 between the same range bins, and outputs the result to the display 24 as a high distance resolution relative distance measurement result by the combined band processing. . The display 24 displays the input signal from the envelope detector 23.

  As described above, according to the second embodiment, the same effect as in the first embodiment can also be obtained by performing addition processing between the same range bins after each combined band processing corresponding to a plurality of pulse trains. Can do.

  In the above-described embodiment, the case where two sets of pulse trains A and B are used has been described. However, the present invention is not limited to this. For example, if four sets of pulse trains A to D are used, the frequency difference between adjacent ones in the same pulse train is four times Δf, and the frequency difference in the same order of pulse trains A and B, B and C, and C and D is Δf. Good. In this case, although the amount of calculation processing increases, the frequency difference between adjacent neighbors is 4Δf, so that it is possible to enhance the unnecessary signal removal effect by the matched filter.

It is a block diagram of the pulse radar apparatus in Embodiment 1 of this invention. It is the figure which showed an example of the pulse trains A and B in Embodiment 1 of this invention. It is explanatory drawing of the matched filter corresponding to the pulse train of FIG. 2 in Embodiment 1 of this invention. It is explanatory drawing of the complex digital signal for relative speed measurement produced | generated by the complex multiplier in Embodiment 1 of this invention. It is a block diagram of the pulse radar apparatus in Embodiment 2 of this invention. It is the figure which showed the transmission pulse in the conventional pulse radar apparatus. It is the figure which showed the state of the received signal strength in the conventional pulse radar apparatus. It is a figure which shows the matched filter characteristic of the receiver last stage in the conventional pulse radar apparatus. It is the figure which showed the timing of the reception pulse from two kinds of distances in the conventional pulse radar apparatus. It is a figure which shows the matched filter characteristic corresponding to FIG. 9 in the conventional pulse radar apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Timing generator, 2 Frequency synthesizer, 3 Frequency setter, 4a, 4b Divider, 5 Reference intermediate frequency signal generator, 6a, 6b Frequency converter, 7 Pulse modulator, 8 Power amplifier, 9 Transmission / reception switcher, 10 Antenna, 11 target, 12 intermediate frequency amplifier, 13 90 degree hybrid, 14a, 14b phase detector, 15a, 15b A / D converter, 16 video signal storage memory, 17 complex multiplier (complex multiplier), 18 Frequency spectrum analyzer (frequency spectrum analyzing means), 19 Relative speed measuring device (relative speed measuring means), 20 Relative speed corrector (relative speed correcting means), 21 Reordering device (reordering means), 22 Synthetic band device ( Synthesis band means), 23 envelope detector, 24 display, 25 adder (addition means).

Claims (4)

A transmission pulse train A whose transmission frequency changes by a predetermined frequency interval for each pulse repetition period, and a pulse train B whose transmission frequency changes by a predetermined frequency interval with the same number of pulses as the pulse train A are transmitted in a time division manner in a target direction. A pulse radar device that receives a reflection signal obtained at each pulse repetition period and generates an I component video signal and a Q component video signal,
The complex digital video signal A having the same I / O video signal of the same range bin number obtained from the received signal with respect to the transmission signal of the pulse train A and the imaginary part of the Q component video signal, and the received signal with respect to the transmission signal of the pulse train B To generate a complex digital video signal B having the same range bin number of the same range bin number as a real part and a Q component video signal as an imaginary part, and the imaginary part of the complex digital video signal A and the complex digital video signal B Complex multiplication means for multiplying the complex conjugate digital video signal B having the sign of
A frequency spectrum analyzing means for obtaining a frequency spectrum of the complex signal for relative velocity measurement;
A pulse radar apparatus comprising: a relative speed measuring unit that obtains a relative speed with respect to the target using the frequency spectrum. The pulse radar device according to claim 1, wherein
A pulse radar apparatus, further comprising frequency setting means for making a difference in transmission frequency between pulses in the same order between the pulse train A and the pulse train B constant. In the pulse radar device according to claim 1 or 2,
For the complex digital video signal A and the complex digital video signal B used to generate the complex signal for measuring the relative speed by the complex multiplication means, the relative speed calculated by the relative speed measurement means was used. A relative speed correction unit that performs correction and generates a complex digital video signal A after the relative speed correction and a complex digital video signal B after the relative speed correction;
With respect to a signal obtained by combining both the complex digital video signal A after the relative speed correction and the complex digital video signal B after the relative speed correction generated by the relative speed correction means, the corresponding transmission frequencies are in ascending or descending order. Rearrangement means for generating a complex digital video signal rearranged so that
A pulse radar apparatus, further comprising: a synthesis band unit that performs band synthesis using the complex digital video signal generated by the rearrangement unit and obtains a relative distance from the target with a predetermined resolution. . In the pulse radar device according to claim 1 or 2,
For the complex digital video signal A and the complex digital video signal B used to generate the complex signal for measuring the relative speed by the complex multiplication means, the relative speed calculated by the relative speed measurement means was used. A relative speed correction unit that performs correction and generates a complex digital video signal A after the relative speed correction and a complex digital video signal B after the relative speed correction;
Band synthesis is performed using each of the complex digital video signal A after the relative speed correction and the complex digital video signal B after the relative speed correction generated by the relative speed correction means, and signals after the respective synthesis bands And a signal after the synthesis band using the complex digital video signal A and a signal after the synthesis band using the complex digital video signal B are added together with the target with a predetermined resolution. An addition means for calculating a relative distance.

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