JPH10268040A - Pulse compression transmission/reception device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a time required for obtaining a pulse compression result by receiving double reflection pulses in a complementary train and repeating the transmission of the double transmission pulses for each pulse repetition cycle PRI. SOLUTION: Three phase-modulated pulses by Code A, Code B, and Barker trains in a complementary train have been transmitted until now, thus requiring 3PRI time. On the other hand, in a pulse compression transmission/reception device, only the phase-modulated transmission pulses by the Code A and the Code B in the complementary train are used and also two pulses are transmitted within 1 PRI, thus obtaining one pulse compression result with 1 PRI. When there is no phase modulation in a reception signal due to Doppler frequency, a range side lobe is set to 0. When there is a phase modulation, the deterioration in the peak range side lobe level is reduced. In addition, a configuration is simple, thus reducing a time required for obtaining one pulse compression result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse compression transmission / reception apparatus and a pulse compression transmission / reception method, wherein a range side lobe when a received signal has no phase modulation by a Doppler frequency is zero, and the phase modulation by a Doppler frequency is performed on the received signal. In some cases, the degradation of the peak range side lobe level is small, the structure is simple, and the time required to obtain one pulse compression result is shortened.

[0002]

2. Description of the Related Art In a pulse compression transmission / reception apparatus using an intra-pulse phase modulation method, at the time of transmission, as shown in FIG. 15, one pulse having a pulse width T is divided into M sub-pulses having a width Ts, and a code is generated for each sub-pulse. A special code sequence with length M (s
1, s2, s3, s4,..., SM), and transmits a pulse by using the received signal and the same code sequence as that used for phase modulation of the transmitted pulse. The signal is demodulated by performing a correlation process with a reference signal that has been subjected to intra-pulse phase modulation.

Here, if the received pulse signal does not have phase modulation by the Doppler frequency, the amplitude characteristic of the demodulated signal when performing pulse compression by the intra-pulse phase modulation method is as follows:
It is represented by the autocorrelation function of the code sequence used for modulation. Therefore, as a modulation code sequence used for intra-pulse phase modulation,
The distance resolution can be improved by using a signal whose value of the autocorrelation function is all zero except for the time lag tz = 0 at which the value of the autocorrelation function is completely correlated (hereinafter, the correlation value when the time lag tz = 0 is called the main lobe). Ts, that is, 1 / M of the pulse width T.

However, a binary code sequence of 0, 1 (when used for phase modulation, 0 corresponds to exp (j0) and 1 corresponds to exp (jp)) as a modulation code sequence used for phase modulation within a pulse. Is used alone, there is no sequence in which all correlation values other than the time lag tz = 0 are 0, and a correlation value called a range side lobe other than the time lag tz = 0 occurs as shown in FIG. . When the range side lobe is large, there arises a problem that, for example, a target main lobe having a small reception intensity is buried in a target range side lobe having a large reception intensity.

[0005] In a pulse compression transmitting / receiving apparatus using a binary code sequence, one of the methods for setting the range side lobe to 0 is, as shown in FIG. 17, a correlation value other than the time lag tz = 0, that is, the absolute value of the range side lobe. There is a method in which pulse compression is performed using two types of binary code sequences having the same value and opposite codes and the same code length, and the two obtained results are added with the same time lag. Such a pair of binary code sequences having the same absolute value of the range side lobe and opposite signs is a complementary sequence (hereinafter, one of the pair of complementary sequences is referred to as CodeA and the other is referred to as CodeB).
And 2 × 2 ⁿ , 10 × 2 ⁿ , 26 × 2 ⁿ (n =
It is known that a code length M of (0, 1, 2,...) Exists. FIG. 18 shows a typical complementary sequence.

By using the complementary sequence in this way, the range side lobe when the received signal is not phase-modulated by the Doppler frequency is zero, that is, the peak range side lobe level (the size of the largest range side lobe relative to the main lobe). ) Can be -∞,
Pulse compression with a distance resolution of Ts (1 / M of the transmission pulse width T) can be realized.

However, when there is a relative speed between the pulse compression transmitting / receiving device and the target, the received signal is subjected to phase modulation by the Doppler frequency corresponding to the relative speed. If the received signal is phase-modulated by the Doppler frequency, the amplitude characteristics of the demodulated signal when performing pulse compression by the intra-pulse phase modulation method are not used for the autocorrelation function of the code sequence used for the modulation, but for the modulation. It is represented by the cross-correlation function between the code sequence that was phase-modulated by the Doppler frequency and the code sequence used for modulation, and the main lobe level decreased and the range side lobe level increased, that is, the peak range Side lobe level degradation occurs.

In particular, in pulse compression using a complementary sequence,
A pulse that is phase-modulated in a pulse by CodeA and CodeB is transmitted alternately, and a correlation value between a received pulse signal that is phase-modulated in a pulse by CodeA, a reference signal that is phase-modulated in a pulse by CodeA, and a phase modulation in a pulse that is CodeB. In order to obtain the sum of the correlation values between the received reception pulse signal and the reference signal that has undergone intra-pulse phase modulation by CodeB, the peak range sidelobe level is significantly degraded when the reception signal is phase-modulated by the Doppler frequency.

The reason is that, in the pulse compression using the complementary sequence, the correlation value at the time lag = 0 when there is no phase modulation by the Doppler frequency, that is, the main lobe is:
As shown in FIG. 19, the amplitude of the received pulse signal is 2M times (M is the code length of the modulation code sequence). If the received signal has phase modulation by the Doppler frequency, the time of 2PRI is determined by the Doppler frequency. The phase changes by an odd multiple of 2π, that is, if the Doppler frequency is 1 / (2
20 (in FIG. 20, 2 PRI) at an odd multiple of PRI).
At a time of 2π. ), When the time lag is tz = 0, the correlation value between the received pulse signal phase-modulated in pulse by CodeA, the reference signal phase-modulated in pulse by CodeA, and CodeB
A received pulse signal whose phase has been modulated in the pulse by
The correlation value with the reference signal subjected to intra-pulse phase modulation at B has the same magnitude and opposite signs, and the main lobe that is the sum thereof is zero, that is, the peak range side lobe level is ∞. Because.

As a conventional pulse compression transmission / reception apparatus of the phase modulation scheme using pulses using a complementary sequence, for example,
There is one described in -303135. In this apparatus, as a modulation code sequence used for intra-pulse phase modulation, a complementary sequence and a peak range side lobe level when there is no Doppler frequency are larger than a complementary sequence, but Barker whose peak range side lobe level is less deteriorated by the Doppler frequency is small. With other sequences such as sequences, if the received signal does not have phase modulation by Doppler frequency, use the pulse compression result using the complementary sequence, if the received signal has phase modulation by Doppler frequency,
It uses the result of pulse compression using another sequence such as the Barker sequence.

FIG. 21 is a configuration diagram in which the above-mentioned pulse compression transmission / reception apparatus is applied to a general pulse compression radar apparatus. 21, 1 is a stabilized local oscillator, 2 is a reference intermediate frequency signal generator, 3a and 3b are frequency mixers, 4
Is a pulse modulator A, 5 is a power amplifier, 6 is a duplexer,
7 is an antenna, 8 is an intermediate frequency amplifier, 9 is a 90-degree hybrid circuit, 10a and 10b are phase detectors, 11a,
11b is an A / D converter, 12a and 12b are correlators A and 3
3 is a modulation code switch B, 14 is an envelope detector, 15 is a changeover switch, 16 is a memory, 17 is an on-off switch, 18 is an adder, and 19 is a post-stage signal processing circuit.

The operation of the above conventional pulse compression transmitting / receiving apparatus will be described with reference to FIG. The signal generated by the stabilized local oscillator 1 and the signal generated by the reference intermediate frequency signal generator 2 are both input to the frequency mixer 3a.
The frequency mixer 3a generates a transmission carrier signal having the sum of the frequency of the signal generated by the stabilized local oscillator 1 and the reference intermediate frequency, and outputs the transmission carrier signal to the pulse modulator A4.

In the pulse modulator A4, the frequency mixer 3a
As shown in FIG. 22, pulse modulation is performed on the input signal from, and intra-pulse phase modulation is performed using three types of modulation code sequences. That is, the first pulse is subjected to pulse modulation of width T and then divided into M sub-pulses of width Ts. Based on information from the modulation code switch B33, CodeA (p1, p2,... Intra-pulse phase modulation is performed using pM). The second pulse is pulse-modulated with a width T, then divided into M sub-pulses with a width Ts, and based on information from the modulation code switch B33, CodeB (q1, q2,..., QM) of a complementary sequence. To perform intra-pulse phase modulation. The third pulse is pulse-modulated with a width T ′ and then divided into M ′ sub-pulses with a width Ts.
Intra-pulse phase modulation is performed using the ker sequence (r1, r2,..., rM ′). The fourth pulse is again pulse-modulated with a width T, then divided into M sub-pulses with a width Ts, and based on information from the modulation code switch B33, CodeA (p1, p2,... Intra-pulse phase modulation is performed using pM), and thereafter, the above operation is repeated. However, the pulse repetition interval (hereinafter referred to as PRI)
Takes a long enough time to not transmit the next pulse until a reflected pulse from the target for the transmitted pulse is received.

The output signal of the pulse modulator A4 is input to the power amplifier 5, where the power is amplified, passed through the transmission / reception switch 6, and radiated from the antenna 7 to space. The signal reflected from the target is received by the antenna 7 and is input to the frequency mixer 3b via the transmission / reception switch 6. The signal generated by the stabilized local oscillator 1 is also input to the frequency mixer 3b. The frequency mixer 3b generates a signal having a frequency that is the difference between the frequency of the carrier signal of the received signal and the signal generated by the stabilized local oscillator 1, that is, a signal of the intermediate frequency. The output signal of the frequency mixer 3b is input to the intermediate frequency amplifier 8, where power amplification is performed, and thereafter, the signal is divided into two and input to the phase detectors 10a and 10b, respectively. On the other hand, the signal generated by the reference intermediate frequency signal generator 2 is separated by a 90-degree hybrid circuit 9 into two signals having a phase difference of 90 degrees and input to the phase detectors 10a and 10b.
In the phase detectors 10a and 10b, the intermediate frequency amplifier 8
And an output signal of the 90-degree hybrid circuit 3 to generate an I-component and a Q-component video signal having a frequency of the difference between the intermediate frequency and the reference intermediate frequency and having a phase difference of 90 degrees from each other. The generated I and Q video signals are supplied to A / D converters 11a, 11 having a sampling frequency of 1 / Ts.
1b, converted into digital I and Q video signals, respectively, and input to correlators A12a and 12b. Since the operation of the correlators A12a and 12b is based on the difference between the input signal and the I video signal, the operation of the correlator A12a will be described in detail with reference to FIG.

In FIG. 23, a correlator A12a uses a variable-stage number shift register 24 for sequentially storing an input digital I video signal one sample at a time, and a code A of a complementary sequence used for intra-pulse phase modulation during transmission. A reference signal storage memory 25a that stores a phase-modulated digital reference signal, and a reference signal that stores a digital reference signal that has been phase-modulated using a complementary sequence CodeB used for phase modulation in a pulse during transmission. Storage memory 2
5b, Bark used for intra-pulse phase modulation during transmission
A reference signal storage memory 25c for storing a digital reference signal phase-modulated using the er sequence, a number of multipliers 26 and changeover switches 27 as many as the number of stages of the variable stage number shift register 24, and one adder 28 Is done. However, the number of stages of the variable shift register 24 is the same as the code length M of the complementary sequence when the modulation code sequence using the intra-pulse phase modulation is a complementary sequence, and the code length of the Barker sequence when the modulation sequence is the Barker sequence. It is the same as the length M '.

The digital I input to the correlator A12a
The video signal is sequentially input to the variable-stage-number shift register 24 on a sample-by-sample basis. Each time one sample of the digital I video signal is input, the value stored in each register and the value of the digital reference signal stored in the reference signal storage memories 25a, 25b, and 25c corresponding to each register are read. Is multiplied by the multiplier 26. At that time, 25
Which of the reference signal storage memories a, 25b, and 25c is to be used depends on whether the received pulse is subjected to intra-pulse phase modulation by CodeA of a complementary sequence, or by intra-pulse phase modulation by CodeB from the modulation code switch B33. Or whether the received pulse is a complementary sequence CodeA, using the changeover switch 27, if the received pulse is a complementary sequence CodeA, the received signal is stored in the reference signal storage memory 25a.
If the received pulse is B in the reference signal storage memory 25b,
If it is an arcer sequence, it is determined by switching to the reference signal storage memory 25c. The output signal of the multiplier 26 is input to the adder 28, the sum of which is calculated, and the envelope detector 14
Output the result. As described above, the correlator A12b performs the same operation as the correlator A12a only by replacing the digital I video signal with the digital Q video signal.

The envelope detector 14 calculates the sum of the square of the output signal of the correlator A12a and the square of the output signal of the correlator A12b, or the square root of the sum, and outputs the sum to the changeover switch 15. The changeover switch 15 determines whether the modulation code used for intra-pulse modulation during transmission is a complementary sequence of CodeA or CodeA.
It is switched depending on whether it is B or Barker series. Also, o
The n-off switch 17 determines whether the modulation code used for intra-pulse modulation during transmission is a complementary sequence of CodeA or CodeB.
It is switched depending on whether or not. For example, at the time of transmission, when a pulse subjected to phase modulation within a pulse using CodeA of a complementary sequence is transmitted first, the changeover switch 15 and the on-off switch 17 switch the received pulse from the modulation code switch B33 to the complementary sequence. Upon receiving the information that the intra-pulse phase modulation is performed by CodeA, the changeover switch 15 is connected to X, and the on-off switch 17 is turned off.
Therefore, the output signal of the envelope detector 14 is output to the memory 16, and the output signal of the envelope detector 14 is stored in the memory 16 in the order in which the samples are input one by one. 1
When the PRI time has elapsed, the changeover switch 15 and the on-o
When the information that the received pulse is phase-modulated in the pulse by the code B of the complementary sequence is input from the modulation code switch B33 to the ff switch 17, the changeover switch 15 is connected to Y, and the switch of the envelope detector 14 The output signal is output to the adder 18. Further, the on-off switch 17 is turned on, and the signal stored in the memory 16 becomes
The samples are output to the adder 18 one by one in the order of input. The adder 18 adds the output signal of the memory 16 and the output signal of the envelope detector 14 and outputs the result to the subsequent signal processing circuit 19. Further, when the time of 1 PRI has elapsed and the pulse received by the changeover switch 15 is
When the information that the intra-pulse phase modulation is performed in the r-sequence is input, the changeover switch 15 is connected to Z, and the output signal of the envelope detector 14 is output to the subsequent signal processing circuit 19 as it is. The subsequent signal processing circuit 19 performs signal processing such as signal detection and distance measurement. Further, information indicating that the received pulse is subjected to intra-pulse phase modulation by the complementary code A from the modulation code switch B33 is input to the changeover switch 15 and the on-off switch 17 after the elapse of one PRI. Again, the changeover switch 15 is set to X
And the on-off switch 17 is turned off, and the above operation is repeated thereafter.

It is not generally known whether the received signal has phase modulation by the Doppler frequency or not. Therefore, either the pulse compression result using the complementary sequence or the pulse compression result using the Barker sequence is used for the range side lobe. Use the one with good low characteristics.

By using such an apparatus, the range side lobe when the received signal has no phase modulation by the Doppler frequency is zero, that is, the peak range side lobe level (the size of the largest range side lobe with respect to the main lobe). Can be −∞, and even when the received signal has phase modulation by the Doppler frequency,
Pulse compression with less degradation of the peak range side lobe level can be realized.

[0020]

As described above, in the conventional pulse compression transmission / reception device, a device such as a changeover switch is required to perform pulse compression by switching between a complementary sequence and a sequence such as a Barker sequence. There is a problem that the structure of the pulse compression transmission / reception device is complicated. In addition, in order to use three types of modulation code sequences (two types of complementary sequences and a sequence in which the peak range sidelobe level is less degraded due to the Doppler frequency such as the Barker sequence), the time of 3PRI is required to obtain one pulse compression result. Is required.

[0021] The present invention has been made to solve the above-described problems. When the received signal has no phase modulation based on the Doppler frequency, the range side lobe is set to zero, and the phase modulation based on the Doppler frequency is performed on the received signal. An object of the present invention is to provide a pulse compression transmission / reception device and a pulse compression transmission / reception method which reduce deterioration of a peak range side lobe level in a certain case, have a simple structure, and have a short time required to obtain a single pulse compression result. I do.

[0022]

According to a first aspect of the present invention, there is provided a pulse compression transmission / reception apparatus using a complementary sequence. A pulse having a width T that is phase-modulated in a pulse in a series is transmitted, and this transmission pulse is not waited for reception of a reflected pulse reflected at a target, but is successively separated by a time interval w equal to or more than the width T of the transmission pulse. Transmitting a pulse of the same width T, which has been subjected to intra-pulse phase modulation with the other sequence of the complementary sequence, and receiving the two reflected pulses reflected by the target at the pulse repetition period. A transmission device that repeats transmission of two transmission pulses, and a first time interval T of a received signal at a time interval of 2T + w
, A reference signal that has been subjected to intra-pulse phase modulation with one of the complementary sequences used for intra-pulse phase modulation of the first transmission pulse, and the last time interval T of the received signal at a time interval of 2T + w. And a correlator for obtaining a correlation between the reference signal and the reference signal that has been subjected to intra-pulse phase modulation with the other of the complementary sequences. The two correlation results obtained by the correlator are input and both the correlation results are 0. Otherwise, the sum of two input correlation results is output, and if at least one of them is 0, 0 is output.
And a receiving device having a determiner for outputting a signal.

A pulse compression transmission / reception apparatus according to a second aspect of the present invention is a pulse compression transmission / reception apparatus using a complementary sequence. After transmitting, without waiting for the reception of the reflected pulse reflected by the target, the pulse is phase-modulated in the pulse by the other sequence of the complementary sequence with a time interval w longer than the width T of the transmission pulse. A transmission device that transmits a pulse having the same width T and repeats the transmission of the two transmission pulses at each pulse repetition period after receiving the two reflected pulses in which the two transmission pulses are reflected at the target; A signal at the first time interval T of the received signal at the time interval of 2T + w, and a reference signal intra-pulse phase modulated with one of the complementary sequences used for the intra-pulse phase modulation of the first transmission pulse And a correlator for obtaining a correlation between the signal of the last time interval T of the received signal of the time interval of 2T + w and a reference signal subjected to intra-pulse phase modulation with the other of the complementary sequences, When the two obtained correlation results are input and both of the two correlation results are greater than a predetermined threshold value, the sum of the two input correlation results is output, and at least one of the input results is a predetermined threshold value. And a receiving device having a determiner that outputs 0 when the value is smaller than the threshold value.

According to a third aspect of the present invention, there is provided a pulse compression transmission / reception apparatus using a complementary sequence, wherein a pulse having a width T whose pulse is phase-modulated in one of the complementary sequences is first transmitted. After transmitting, without waiting for the reception of the reflected pulse reflected by the target, the pulse is phase-modulated in the pulse by the other sequence of the complementary sequence with a time interval w longer than the width T of the transmission pulse. A transmitting device that transmits a pulse having the same width T and repeats the transmission of the two transmission pulses every pulse repetition period after receiving the two reflected pulses in which the two transmission pulses are reflected at the target; A signal of the first time interval T of the received signal of the time interval of 2T + w, a reference signal that has been subjected to intra-pulse phase modulation with one of the complementary sequences used for intra-pulse phase modulation of the first transmission pulse, and A correlation for obtaining a correlation and a correlation between a signal at the last time interval T of a received signal at a time interval of 2T + w and a reference signal subjected to intra-pulse phase modulation with the other of the complementary sequences, and taking the sum of the correlation results. And a receiving device having a receiver.

Further, the pulse compression transmission / reception method of the invention according to claim 4 has the following steps. (A) First, a pulse having a width T that has been subjected to phase modulation within a pulse in one of the complementary sequences is transmitted, and the transmission pulse is continuously transmitted without waiting for reception of a reflected pulse reflected at a target. With a time interval w greater than the pulse width T,
A transmitting step of transmitting a pulse of the same width T, which has been subjected to intra-pulse phase modulation with the other of the complementary sequences, (b) a signal of a first time interval T of a received signal of a 2T + w time interval, and a pulse of the first transmission pulse Correlation with a reference signal that has been subjected to intra-pulse phase modulation with one of the complementary sequences used for internal phase modulation, the signal at the last time interval T of the received signal with a time interval of 2T + w, and the other sequence of the complementary sequence The correlation with the reference signal that has been subjected to intra-pulse phase modulation is obtained, and when the obtained two correlation results are both other than 0, the sum of the two correlation results is used as the final correlation result, and at least one of them is 0 Is a receiving step in which the final correlation result is set to 0, and (c) When the receiving step is executed, the procedure proceeds to step (a) and is repeated.

The pulse compression transmission / reception method according to the fifth aspect of the invention is characterized by including the following steps. (A) First, a pulse having a width T that has been subjected to phase modulation within a pulse in one of the complementary sequences is transmitted, and the transmission pulse is continuously transmitted without waiting for reception of a reflected pulse reflected at a target. With a time interval w greater than the pulse width T,
A transmitting step of transmitting a pulse of the same width T, which has been subjected to intra-pulse phase modulation with the other of the complementary sequences, (b) a signal of a first time interval T of a received signal of a 2T + w time interval, and a pulse of the first transmission pulse Correlation with a reference signal that has been subjected to intra-pulse phase modulation with one of the complementary sequences used for internal phase modulation, the signal at the last time interval T of the received signal with a time interval of 2T + w, and the other sequence of the complementary sequence The correlation with the reference signal that has been subjected to intra-pulse phase modulation is obtained. When both of the obtained two correlation results are larger than a predetermined threshold value, the sum of the two correlation results of the input is calculated as the final correlation value. As a result, if at least one of them is smaller than a predetermined threshold value, the receiving step of setting the final correlation result to 0, and (c) when the receiving step is executed, the process proceeds to step (a) and is repeated.

The pulse compression transmission / reception method according to the invention according to claim 6 is characterized by comprising the following steps. (A) First, a pulse having a width T that has been subjected to phase modulation within a pulse in one of the complementary sequences is transmitted, and the transmission pulse is continuously transmitted without waiting for reception of a reflected pulse reflected at a target. With a time interval w greater than the pulse width T,
A transmitting step of transmitting a pulse of the same width T, which has been subjected to intra-pulse phase modulation with the other of the complementary sequences, (b) a signal of a first time interval T of a received signal of a 2T + w time interval, and a pulse of the first transmission pulse Correlation with a reference signal that has been subjected to intra-pulse phase modulation with one of the complementary sequences used for internal phase modulation, the signal at the last time interval T of the received signal with a time interval of 2T + w, and the other sequence of the complementary sequence In step (a), a correlation is obtained with the reference signal that has been subjected to intra-pulse phase modulation, and the sum of the correlation results is obtained.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a block diagram showing Embodiment 1 of a pulse compression transmitting / receiving apparatus of the present invention. In FIG.
1 is a stabilized local oscillator, 2 is a reference intermediate frequency signal generator, 3a and 3b are frequency mixers, 5 is a power amplifier, 6 is a duplexer, 7 is an antenna, 8 is an intermediate frequency amplifier, 9
Is a 90-degree hybrid circuit, 10a and 10b are phase detectors, 11a and 11b are A / D converters, 13 is a modulation code switcher A, 14 is an envelope detector, 19 is a post-stage signal processing circuit, and 20 is pulse modulation. Units B, 22a and 22b are correlators C, and 23a and 23b are judgment units A.

Embodiment 1 of this pulse compression transmitting / receiving apparatus
Will be described with reference to FIGS. FIG.
, The signal generated by the stabilized local oscillator 1 and the signal generated by the reference intermediate frequency signal generator 2 are both input to the frequency mixer 3a. The frequency mixer 3a generates a transmission carrier signal having the sum of the frequency of the signal generated by the stabilized local oscillator 1 and the reference intermediate frequency, and outputs the transmission carrier signal to the pulse modulator B20.

In the pulse modulator B20, the frequency mixer 3
As shown in FIG. 2, the input signal from a is subjected to pulse modulation having a width T, and the pulse having the width T is divided into M sub-pulses having a width Ts. , And performs intra-pulse phase modulation using the complementary sequence CodeA. Further, at the same time interval w as the width T, pulse modulation of the width T is performed, and the pulse of the width T is divided into M sub-pulses of the width Ts. In this case, the intra-pulse phase modulation is performed using CodeB. The time interval w may be equal to or longer than the pulse width T. Here, for the sake of specific description, w = T. Thereafter, at intervals of PRI− (2T + w),
The above operation is repeated again. However, in the PRI, two transmission pulses, ie, a transmission pulse whose pulse is phase-modulated by CodeA of a complementary sequence and a transmission pulse whose phase is pulse-modulated by CodeB of a complementary sequence at a time interval w, are reflected at the target. Until a series of reflected pulses is received, a sufficiently long time is taken so as not to transmit the next transmission pulse.

The output signal of the pulse modulation B20 is input to the power amplifier 5, where the power is amplified, passed through the transmission / reception switch 6, and radiated from the antenna 7 to space. The signal reflected from the target is received by the antenna 7 and is input to the frequency mixer 3b via the transmission / reception switch 6. The signal generated by the stabilized local oscillator 1 is also input to the frequency mixer 3b. The frequency mixer 3b generates a signal having a frequency that is the difference between the frequency of the carrier signal of the received signal and the signal generated by the stabilized local oscillator 1, that is, a signal of the intermediate frequency. The output signal of the frequency mixer 3b is input to the intermediate frequency amplifier 8, where power amplification is performed, and thereafter, the signal is divided into two and input to the phase detectors 10a and 10b, respectively. On the other hand, the signal generated by the reference intermediate frequency signal generator 2 is separated by a 90-degree hybrid circuit 9 into two signals having a phase difference of 90 degrees and input to the phase detectors 10a and 10b.
In the phase detectors 10a and 10b, the intermediate frequency amplifier 8
And the output signal of the 90-degree hybrid circuit 3 to generate I- and Q-component video signals having a frequency of the difference between the intermediate frequency and the reference intermediate frequency and having a phase difference of 90 degrees from each other. The generated I and Q video signals are supplied to A / D converters 11a, 11 having a sampling frequency of 1 / Ts.
1b, converted into digital I and Q video signals, respectively, and input to correlators C22a and 22b. Operation of correlators C22a and 22b, and decision devices A23a and 2
The operation of 3b is the difference between the input signal and the I-video signal or the Q-video signal. Here, the operation of the correlator C22a is described with reference to FIG. This will be described in detail with reference to FIG.

In FIG. 3, a correlator C22a includes a 3M-stage (M is the code length of a modulation code) shift register 29 for sequentially storing an input digital I video signal one sample at a time, and a pulse phase during transmission. A reference signal storage memory 25a storing a digital reference signal phase-modulated using CodeA of a complementary sequence used for modulation, and phase-modulated using CodeB of a complementary sequence used for phase modulation in a pulse during transmission. A reference signal storage memory 25b storing a digital reference signal, and 2M multipliers 26
And adders 31a and 31b.

Digital I input to correlator C22a
The video signal is sequentially input to the 3M-stage shift register 29 one sample at a time. Each time one sample of the digital I video signal is input, M multipliers 26 multiply the respective values of the first to Mth registers of the shift register 29 by the corresponding values of the reference signal storage memory 25a. And outputs the result to the adder 31a. Adder 31
In a, the sum of the M input signals is obtained, and the result is output to the decision unit A23a. At the same time, shift register 29
Are multiplied by the values of the 2M + 1-th to 3M-th registers and the corresponding values in the reference signal storage memory 25b by M multipliers 26, and the result is output to the adder 31b.
The adder 31b calculates the total sum of the M input signals, and outputs the result to the determiner A23a.

Further, as shown in the flowchart of FIG. 4, the determiner A23a determines in step S50a that
It is determined whether both the output signal of the adder 31a and the output signal of the adder 31b are greater than zero.
If both the output signal of the adder 31b and the output signal of the adder 31b are greater than zero, the process proceeds to step S50b, and outputs the sum of the output signal of the adder 31a and the output signal of the adder 31b to the envelope detector 14. When at least one of the output signal of the adder 31a and the output signal of the adder 31b is zero,
Proceeding to step S50c, zero is output to the envelope detector 14.

In the correlator C22b and the determiner A23b,
As mentioned earlier, the correlator C22 only replaces the digital I video signal with the digital Q video signal.
a and the same operation as that of the judgment unit A23a.

The envelope detector 14 calculates the sum of the square of the output signal of the decision unit A23a and the square of the output signal of the decision unit A23b, or the square root of the sum, and outputs the result to the post-stage signal processing circuit 19. . The subsequent signal processing circuit 19 performs signal processing such as signal detection and distance measurement.

Next, the transmitting / receiving operation of the pulse compression transmitting / receiving apparatus according to the first embodiment of the present invention will be described with reference to the flowchart of FIG. In step S60a, a pulse having a width T whose pulse is phase-modulated by CodeA of the complementary sequence is transmitted, and the transmission pulse is continuously transmitted without waiting for the reception of the reflected pulse reflected at the target. With the same time interval w as T, the complementary sequence C
A pulse having the same width T that has been subjected to intra-pulse phase modulation by modeB is transmitted, and the process proceeds to step S60b. In step S60b, the first time interval T of the received signal at the time interval of 2T + w
, A reference signal that has been subjected to intra-pulse phase modulation with Code A of a complementary sequence, a signal of the last time interval T of a received signal with a time interval of 2T + w, and CodeB of a complementary sequence
The correlation with the reference signal that has been subjected to intra-pulse phase modulation is obtained, and when the obtained two correlation results are both other than 0, the sum of the two correlation results is used as the final correlation result, and at least one of them is 0 Sets the final correlation result to 0, and returns to step S60a again. Thereafter, step S60a and step S60b are repeated.

The flowchart for explaining the transmitting and receiving operation of the first embodiment of the pulse compression transmitting and receiving apparatus shown in FIG. 5 defines the pulse compression transmitting and receiving method of the present invention. This has been described in the description of the operation of the first embodiment of the present invention.

Hereinafter, in the embodiment of the pulse compression transmitting / receiving apparatus of the present invention, the principle that the range side lobe becomes zero when the received signal does not have the phase modulation by the Doppler frequency will be described with reference to FIGS. This will be described with reference to FIGS. In the above-described embodiment, the time interval w is described as w = T for the sake of specific description, but here, w ≧ T will be described for general description.
Reception of a pulse of width T transmitted with phase modulation in the pulse by CodeA of the complementary sequence in correlator C22a and a pulse of width T transmitted in phase modulation with pulse in CodeB with a time interval w longer than pulse width T As shown in FIG. 6, the correlation between the pulse signal (digital I video signal), the reference signal phase-modulated in pulse by CodeA, and the reference signal phase-modulated in pulse by CodeB is as shown in FIG.
There are nine cases, case (a) to (i). Here, the time lag tz is such that the received pulse signal phase-modulated in pulse by CodeA completely overlaps the reference signal phase-modulated in pulse by CodeA, and the received pulse signal phase-modulated in pulse by CodeB and the pulse signal in CodeB When the internal phase-modulated reference signals completely overlap, ie, cas
e (e) is set to 0.

In case (a), (tz ≧ (2T +
w)) are both the received pulse signal subjected to intra-pulse phase modulation with CodeA and the received pulse signal subjected to intra-pulse phase modulation with CodeB, the reference signal subjected to intra-pulse phase modulation with CodeA, and the intra-pulse phase modulation with CodeB. Since it does not overlap with the reference signal thus obtained, 0 is output from both the adder 31a and the adder 31b in the correlator C22a.
3a, and both inputs are 0 in the decision unit A23a.
Therefore, 0 is output to the envelope detector 14 by the processing according to the flowchart shown in FIG.

In case (b) ((2T + w)> t)
z> w), the received pulse signal subjected to intra-pulse phase modulation using CodeA does not overlap with the reference signal subjected to intra-pulse phase modulation using CodeA and the reference signal subjected to intra-pulse phase modulation using CodeB. Since the phase-modulated received pulse signal overlaps with the reference signal that has been subjected to intra-pulse phase modulation with CodeA, 0 is output from the adder 31a in the correlator C22a, and from the adder 31b,
A cross-correlation value of CodeA and CodeB at a certain time lag is output. Therefore, in the decision unit A23a,
By the processing according to the flowchart shown in (1), since one of the inputs is 0, 0 is output to the envelope detector 14.

In case (c) (w ≧ tz ≧ T)
Are both the received pulse signal subjected to intra-pulse phase modulation with CodeA and the received pulse signal subjected to intra-pulse phase modulation with CodeB, the reference signal subjected to intra-pulse phase modulation using CodeA, and the reference subjected to intra-pulse phase modulation using CodeB. Since the signal does not overlap, 0 is output from the adder 31a and the adder 31b in the correlator C22a to the decision unit A23a, and both inputs are 0 in the decision unit A23a. By processing by
0 is output to the envelope detector 14.

In case (d) (T>tz> 0)
Is that the received pulse signal subjected to intra-pulse phase modulation with CodeA overlaps with the reference signal subjected to intra-pulse phase modulation with CodeA, and the received pulse signal subjected to intra-pulse phase modulation with CodeB is referred to as the reference pulse subjected to intra-pulse phase modulation with CodeB. Since the signal overlaps with the signal, the adder 31a in the correlator C22a outputs the autocorrelation value at a certain time lag tz of CodeA and CodeA, and the adder 31b outputs the autocorrelation value of CodeB and CodeB at the same time lag tz. Is done. Therefore, in the decision unit A23a, according to the processing in the flowchart shown in FIG. 4, 0 is set when both inputs are 0, and when the absolute values of both inputs are larger than 0,
The sum of the adder 31b and the adder 31a is output to the envelope detector 14, and the adder 31b and the adder 31a are output due to the characteristic of the range side lobe level of the complementary sequence shown in FIG.
Is 0, so that 0 is output to the envelope detector 14.

In case (e) (tz = 0), C
The received pulse signal subjected to intra-pulse phase modulation by mode A is
Since the received pulse signal that has been subjected to intra-pulse phase modulation with CodeA completely overlaps with the reference signal that has undergone intra-pulse phase modulation with CodeB, it completely overlaps with the reference signal that has undergone intra-pulse phase modulation with CodeB. Container 31
From a, the time lag between CodeA and CodeA tz = 0
Is output from the adder 31b.
The autocorrelation value at the time lag tz = 0 between eB and CodeB is output. Therefore, in the decision unit A23a, the absolute value of both inputs is greater than 0 by the processing according to the flowchart shown in FIG.
The sum of a is output to the envelope detector 14. Time lag tz
The sum of the adder 31b and the adder 31a when = 0 becomes 2M (M is the code length of the complementary sequence) times the range side lobe level characteristic of the complementary sequence shown in FIG.

In case (f) (0>tz> -T)
Is the same as case (d), and 0 is output to the envelope detector 14.

In case (g) (-T ≧ tz ≧ −
w) is the same as case (c), and the envelope detector 1
0 is output to 4.

In case (h) (-w>tz>-
(2T + w)) is the reverse of case (b) and Cod
The received pulse signal subjected to intra-pulse phase modulation with eB is Co
Both the reference signal phase-modulated in the pulse by deA and Cod
Although it does not overlap with the reference signal subjected to phase modulation inside the pulse by eB, the received pulse signal subjected to phase modulation inside the pulse by CodeA overlaps with the reference signal subjected to phase modulation inside the pulse by CodeB, so that the adder 31b in the correlator C22a is added. From 0
Are output, and CodeA and Code are output from the adder 31a.
A cross-correlation value at a certain time lag of eB is output. Therefore, in the decision unit A23a, 0 is output to the envelope detector 14 because one of the inputs is 0 by the processing according to the flowchart shown in FIG.

In case (i), (-(2t + w) ≧
Tz) becomes the same as case (a), and 0 is output to the envelope detector 14.

The operation of the decision unit A23a has been described above, but the same applies to the decision unit A23b.
For the above reason, the correlation value other than the time lag tz = 0, that is, the range side lobe can be set to zero.

The reason why the deterioration of the peak range side lobe level in the pulse compression transmitting / receiving apparatus shown in the present embodiment when the received signal has phase modulation by the Doppler frequency is reduced will be described with reference to FIGS. This will be described with reference to FIGS.

In the conventional pulse compression transmission / reception apparatus using a complementary sequence, when there is phase modulation by a Doppler frequency, as shown in FIG. 20, the phase of a received signal at a time interval of 2PRI is 2π depending on the Doppler frequency. When the phase modulation that changes by an odd multiple of the above occurs, that is, when the Doppler frequency is an odd multiple of 1 / (2PRI), the peak range sidelobe level becomes ∞ and becomes the largest, whereas in the first embodiment In the pulse compression transceiver shown,
As shown in FIG. 7, the Doppler frequency is 1 / (2PR
Phase modulation occurs at an odd multiple of 1 / (2 (T + w)) higher than I), that is, the phase of the received signal at an interval of 2 (T + w) changes by an odd multiple of 2π depending on the Doppler frequency. At the time, CodeA at time lag = 0
The correlation value between the I or Q digital video signal of the received pulse signal phase-modulated in the pulse with the reference signal phase-modulated in the pulse with CodeA, and the I or Q digital signal of the received pulse signal with the phase-modulated pulse in the CodeB The correlation value between the video signal and the reference signal subjected to intra-pulse phase modulation with CodeB has the same magnitude and opposite signs, and the main lobe that is the sum of them is zero, ie, the peak range side lobe level Becomes ∞ and becomes the largest.

Since the Doppler frequency of the peak range sidelobe deteriorates as the Doppler frequency approaches the Doppler frequency at which the peak range sidelobe level becomes ∞, the Doppler frequency at which the peak range sidelobe level becomes ∞ becomes smaller than that of the conventional pulse compression. In the transmission / reception device, the pulse compression transmission / reception device according to the first embodiment, which is higher than in the case of using a complementary sequence, has less degradation of the peak range sidelobe level at the same Doppler frequency.

FIG. 8 shows that the Doppler frequency is changed from 0 Hz to 30.
Hz, pulse compression using a complementary sequence (code length M = 10) in the conventional pulse compression transmission / reception apparatus, and Ba in the conventional pulse compression transmission / reception apparatus.
Peak range side lobe level of pulse compression using rker sequence (code length M '= 11) and pulse compression using complementary sequence (code length M = 10) in Embodiment 1 of pulse compression transmitting / receiving apparatus of the present invention 3 shows the simulation results of the change of. However, PRI = 10 msec, T /
PRI is set to 0.1. Although not shown, when the range of the above simulation is expanded, in the conventional pulse compression transmitting / receiving apparatus using the complementary sequence, the peak range sidelobe level becomes ∞ when the Doppler frequency is 50 Hz, and the Doppler frequency approaches 50 Hz. The peak range side lobe level deteriorates as
In the first embodiment of the pulse compression transmitting / receiving apparatus of the present invention, when the Doppler frequency is 250 Hz, the peak range sidelobe level becomes ∞, and the Doppler frequency becomes 25.
Since the peak range side lobe level deteriorates as the frequency approaches 0 Hz, the peak range side lobe level in the case where there is phase modulation by the Doppler frequency is less deteriorated than in the conventional pulse compression transmitting / receiving apparatus using the complementary sequence. I understand.

According to FIG. 8, in the conventional pulse compression transmission / reception device, even if the Doppler frequency is changed to the Barker sequence modulation code sequence from the complementary sequence when the Doppler frequency is around 10 Hz, for example, the Doppler frequency becomes 25 Hz.
In the case of the conventional pulse compression transmitting / receiving apparatus, Ba
While the peak range side lobe level when the rker sequence is used is -20.4 dB, the pulse compression transmitting and receiving apparatus according to the first embodiment of the present invention has -25.4 dB.
B, and the peak range side lobe level of about 5 dB can be reduced.

Further, in the first embodiment of the pulse compression transmission / reception device of the present invention, the changeover switch 15, the on-off switch 17, the memory 16, and the memory 16 shown in FIG. The changeover switch 27 of the component of the correlator A shown is not required, and the configuration can be simplified.

Further, in the conventional pulse compression transmission / reception apparatus, in order to obtain one pulse compression result, as shown in FIG. Since it is necessary to transmit three pulses, ie, a pulse subjected to phase modulation within the pulse and a pulse subjected to phase modulation within the Barker sequence, 3P
While the time required for RI is required, in the embodiment of the pulse compression transmission / reception apparatus of the present invention, only the transmission pulse whose pulse is phase-modulated by CodeA and the transmission pulse whose pulse is phase-modulated by CodeB are used. This 2
To transmit one pulse during one PRI, only one PRI time is required to obtain one pulse compression result.

As described above, according to the first embodiment of the pulse compression transmitting / receiving apparatus of the present invention, the range side lobe when the received signal does not have the phase modulation by the Doppler frequency is set to zero, and the phase of the received signal is changed by the Doppler frequency. The degradation of the peak range side lobe level in the presence of modulation can be reduced, the configuration is simple, and the time required to obtain one pulse compression result can be shortened.

Embodiment 2 FIG. 9 is a configuration diagram showing a second embodiment of the pulse compression transmitting / receiving apparatus of the present invention. In FIG. 9, reference numerals 32a and 32b denote decision units B having a different configuration from that of the first embodiment, and the other components are the same as those of the first embodiment.

Embodiment 2 of this pulse compression transmitting / receiving apparatus
A description will be given of a decision unit B having a configuration different from that of the first embodiment, together with a correlator C at the preceding stage, with reference to FIGS. 9, 3, and 4. FIG.

In FIGS. 9 and 3, the correlator C22a includes:
Phase modulation using a 3M (M is the code length of a modulation code) stage shift register 29 for sequentially storing the input digital I video signal one sample at a time, and a complementary sequence CodeA used for phase modulation in a pulse during transmission. And a reference signal storage memory 25a for storing a digital reference signal obtained from the base station, and a CodeB of a complementary sequence used for phase modulation in a pulse during transmission.
A reference signal storage memory 25b for storing a digital reference signal phase-modulated by using a 2M multiplier 26
And adders 31a and 31b.

The digital I video signal input to the correlator C22a is input to the 3M-stage shift register 29 one sample at a time. Each time one sample of the digital I video signal is input, the shift register 2
9 is multiplied by each value of the first to Mth registers and the corresponding value of the reference signal storage memory 25a by M multipliers 2
6 and outputs the result to the adder 31a. The adder 31a calculates the sum of the M input signals, and outputs the result to the determiner B32a. At the same time, the multiplication of the values of the 2M + 1th to 3Mth registers of the shift register 29 and the corresponding values of the reference signal storage memory 25b is performed by M multipliers at 26, and the result is output to the adder 31b. . The adder 31b calculates the sum of the M input signals,
The result is output to the determiner B32a.

As shown in the flowchart of FIG. 10, the determiner B 32a determines in step S51a that the adder 3
It is determined whether the absolute value of the output signal of the adder 31a and the absolute value of the output signal of the adder 31b are both greater than a predetermined threshold Tr, and the absolute value of the output signal of the adder 31a and the output signal of the adder 31b are determined. Together with the absolute value of
If the threshold Tr is larger than the threshold Tr, step S
51b, the output signal of the adder 31a and the adder 31b
Is output to the envelope detector 14. Also,
At least one of the absolute value of the output signal of the adder 31a and the absolute value of the output signal of the adder 31b is equal to the threshold T.
If it is smaller than r, the process proceeds to step S51c, and outputs zero to the envelope detector 14.

In the correlator C22b and the determiner B32b,
As mentioned earlier, the correlator C22 only replaces the digital I video signal with the digital Q video signal.
a and the same operation as that of the decision unit A32a.

The envelope detector 14 calculates the sum of the square of the output signal of the determiner B 32 a and the square of the output signal of the determiner B 32 b, or the square root of the sum, and outputs the result to the post-stage signal processing circuit 19. . The subsequent signal processing circuit 19 performs signal processing such as signal detection and distance measurement.

Next, the transmitting / receiving operation of the pulse compression transmitting / receiving apparatus according to the second embodiment of the present invention will be described with reference to the flowchart of FIG. In step S61a,
First, a pulse having a width T that is phase-modulated in a pulse with CodeA of a complementary sequence is transmitted, and the transmission pulse does not wait for reception of a reflected pulse reflected at a target. At the same time interval w, a pulse of the same width T that has been subjected to intra-pulse phase modulation with CodeB of the complementary sequence is transmitted, and the process proceeds to step S61b. Step S61
In b, the correlation between the signal of the first time interval T of the received signal of the time interval of 2T + w, the reference signal subjected to intra-pulse phase modulation with the complementary sequence CodeA, and the last time interval of the received signal of the time interval of 2T + w T signal and the complementary sequence Cod
A correlation with a reference signal subjected to intra-pulse phase modulation by eB is obtained. When both the obtained two correlation results are larger than a predetermined threshold value, the sum of the two input correlation results is finally calculated. If at least one of the correlation results is smaller than a predetermined threshold value, the final correlation result is set to 0, and the process returns to step S61a. Thereafter, step S61a
And step S61b are repeated.

As described above, according to the second embodiment of the pulse compression transmitting / receiving apparatus of the present invention, similarly to the first embodiment, the range side lobe when the received signal does not have the phase modulation by the Doppler frequency is set to zero. When the received signal has phase modulation by the Doppler frequency, the deterioration of the peak range side lobe level is small, the structure is simple, and the time required to obtain one pulse compression result can be shortened. Further, by making a determination using the threshold Tr for the operation of the above-described determiner B, the output from the adder 31a and the adder 31b is theoretically 0 in the correlator C22a or 22b due to the influence of noise or the like. Even when a value other than 0 occurs where it should be, correct judgment can be made.

The flow chart for explaining the transmission / reception operation of the pulse compression transmission / reception apparatus of FIG. 11 defines the pulse compression transmission / reception method of the present invention. This is described in the description of the operation of the first and second embodiments.

Embodiment 3 FIG. 12 is a block diagram showing Embodiment 3 of the pulse compression transmitting / receiving apparatus of the present invention.
12, 1 is a stabilized local oscillator, 2 is a reference intermediate frequency signal generator, 3a and 3b are frequency mixers, 5 is a power amplifier, 6 is a transmission / reception switch, 7 is an antenna, 8 is an intermediate frequency amplifier, 9 Is a 90-degree hybrid circuit, 10a, 1
0b is a phase detector, 11a and 11b are A / D converters, 1
3 is a modulation code switch A, 14 is an envelope detector, 19 is a subsequent signal processing circuit, 20 is a pulse modulator B, 21a, 21
b is a correlator B. The difference from the configuration of the first embodiment is
The configuration of the correlator B is different from that of the first embodiment, and no correlator is provided. Other configurations and operations are the same as those of the first embodiment.

Embodiment 3 of this pulse compression transmitting / receiving apparatus
The correlator B having a different configuration from the first embodiment will be described with reference to FIGS.

12 and 13, the correlator B21a
Uses a 3M-stage (M is the code length of a modulation code) shift register 29 for sequentially storing input digital I video signals one sample at a time, and a complementary sequence CodeA used for intra-pulse phase modulation during transmission. Reference signal storage memory 25a storing a phase-modulated digital reference signal
And Co of the complementary sequence used for phase modulation in the pulse during transmission.
It comprises a reference signal storage memory 25b storing a digital reference signal phase-modulated using deB, 2M multipliers 26, and an adder 30.

The digital I input to the correlator B21a
The video signal is sequentially input to the 3M-stage shift register 29 one sample at a time. Each time one sample of the digital I video signal is input, M multipliers 26 multiply the respective values of the first to Mth registers of the shift register 29 by the corresponding values of the reference signal storage memory 25a. And outputs the result to the adder 30. At the same time, M multipliers 26 multiply the values of the 2M + 1-th to 3M-th registers of the shift register 29 with the corresponding values of the reference signal storage memory 25b, and add the result to the adder 30.
Output to The adder 30 calculates the sum of the output signals of the 2M multipliers 26 and outputs the result to the envelope detector 14. The correlator B21b performs the same operation as the correlator B21a only by replacing the digital I video signal with the digital Q video signal.

The envelope detector 14 calculates the sum of the square of the output signal of the correlator B21a and the square of the output signal of the correlator B21b, or the square root of the sum, and outputs the result to the post-stage signal processing circuit 19. . The subsequent signal processing circuit 19 performs signal processing such as signal detection and distance measurement.

Next, the transmitting / receiving operation of the pulse compression transmitting / receiving apparatus according to the third embodiment of the present invention will be described with reference to the flowchart of FIG. In step S62a, first, a pulse having a width T that has been subjected to intra-pulse phase modulation with CodeA of a complementary sequence is transmitted, and the transmission pulse continues without waiting for reception of a reflected pulse reflected at the target.
At the same time interval w as the transmission pulse width T, a pulse having the same width T that has been subjected to intra-pulse phase modulation with the complementary sequence CodeB is transmitted, and the process proceeds to step S62b. Step S
In 62b, the correlation between the signal of the first time interval T of the received signal of the time interval of 2T + w, the reference signal phase-modulated in the pulse by CodeA of the complementary sequence, and the last time interval of the received signal of the time interval of 2T + w T signal and the complementary sequence C
The correlation with the reference signal that has been subjected to intra-pulse phase modulation at mode B is obtained, the sum of the correlation results is obtained, and the process returns to step S6
Return to 2a. Thereafter, step S62a and step S6
2b is repeated.

As described above, according to the third embodiment of the pulse compression transmission / reception apparatus of the present invention, the pulse of width T transmitted by phase-modulating the pulse in the pulse with CodeA of the complementary sequence shown in FIG. Correlation between a received pulse signal corresponding to a pulse of width T transmitted by performing phase modulation in a pulse at CodeB with an interval of w, a reference signal phase-modulated in a pulse with CodeA, and a reference signal phase-modulated in a pulse with CodeB , The time lag tz is case (b)
((2T + w)>tz> w) and case (h) (-w>
Since the range side lobe level in the case of tz>-(2T + w) is not 0, the same as in the first and second embodiments,
Time lag tz range in which the effect of reducing the range side lobe when the received signal does not have phase modulation by the Doppler frequency to zero and reducing the deterioration of the peak range side lobe level when the received signal has phase modulation by the Doppler frequency is reduced. Is limited to the range of ((2T + w)>tz> w) and (−w>tz> − (2T + w)). However, since the judgment device is not required, the configuration is simpler than in the first and second embodiments. can do. Also, the time required to obtain one pulse compression result is the same as in the first and second embodiments.
Similarly to the above, the length can be made shorter than in the conventional example.

The flow chart for explaining the transmission / reception operation of the pulse compression transmission / reception apparatus of FIG. 14 defines this pulse compression transmission / reception method. Each step of the flow chart is described in the first embodiment of the present invention. , 3 are described.

In the first, second, and third embodiments of the pulse compression transmission / reception apparatus, the demodulation processing is performed on the digital signal obtained by A / D converting the received signal. However, the A / D converter is eliminated. The present invention can also be applied to a case where demodulation processing is performed on an analog signal by performing the demodulation processing.

[0077]

As described above, according to the first aspect of the present invention, the range side lobe when the received signal does not have phase modulation by the Doppler frequency is set to zero, and when the received signal has phase modulation by the Doppler frequency. In this case, it is possible to obtain a pulse compression transmission / reception apparatus in which the deterioration of the peak range side lobe level is reduced, the configuration is simple, and the time required to obtain one pulse compression result is reduced.

According to the second aspect of the present invention, the range side lobe when the received signal does not have phase modulation due to the Doppler frequency is zero, and the peak range side lobe when the received signal has phase modulation due to the Doppler frequency is zero. It is possible to obtain a pulse compression transmission / reception device that reduces the deterioration of the level, has a simple configuration, and shortens the time required to obtain a single pulse compression result. It is possible to obtain a pulse compression transmission / reception device with reduced erroneous judgment factors.

According to the third aspect of the present invention, the range side lobe when the received signal does not have phase modulation due to the Doppler frequency is zero, and the range side lobe when the received signal has phase modulation due to the Doppler frequency is zero. Although the range of the time lag tz in which the effect of reducing the level deterioration is obtained is limited, it is possible to obtain a pulse compression transmission / reception device with a simple configuration and a short time required to obtain one pulse compression result. it can.

According to the fourth aspect of the present invention, the range side lobe when the received signal does not have phase modulation due to the Doppler frequency is set to zero, and the peak range side lobe when the received signal has phase modulation due to the Doppler frequency is set to zero. It is possible to obtain a pulse compression transmission / reception method in which the deterioration of the level is reduced and the time required to obtain one pulse compression result is shortened.

According to the invention of claim 5, the range side lobe when the received signal does not have phase modulation due to the Doppler frequency is zero, and the peak range side lobe when the received signal has phase modulation due to the Doppler frequency. It is possible to obtain a pulse compression transmission / reception method in which the deterioration of the level is reduced, the time required to obtain a single pulse compression result is reduced, and the factors for erroneously determining the correlation value due to the influence of noise and the like are reduced. .

According to the invention of claim 6, the range side lobe when the received signal does not have phase modulation due to the Doppler frequency is zero, and the peak range side lobe when the received signal has phase modulation due to the Doppler frequency. Although the range of the time lag tz in which the effect of reducing the level deterioration is obtained is limited, it is possible to obtain a pulse compression transmission / reception method in which the configuration is simple and the time required to obtain one pulse compression result is shortened. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a pulse compression transmitting / receiving apparatus according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram of a transmission pulse signal and a transmission pulse signal common to the first, second, and third embodiments of the pulse compression transmission / reception device of the present invention.

FIG. 3 is an internal configuration diagram of the correlator of FIG. 1;

FIG. 4 is a flowchart illustrating the operation of the decision unit in FIG. 1;

FIG. 5 is a flowchart illustrating a pulse transmission / reception operation according to the first embodiment of the pulse compression transmission / reception device of the present invention.

FIG. 6 is a diagram illustrating a correlation between a received pulse signal and a reference signal, which is common to the first, second, and third embodiments of the pulse compression transmission / reception device of the present invention.

FIG. 7 is a diagram illustrating a pulse compression transmitting / receiving apparatus according to the first, second, and third embodiments of the present invention.
FIG. 4C is a diagram for explaining the correlation characteristic when the time lag is tz = 0 when phase modulation by the Doppler frequency of w)) is performed.

FIG. 8 is a diagram illustrating the effect of suppressing the peak range side lobe level when the received signal has a phase modulation of a Doppler frequency of 0 to 30 Hz in the pulse compression transmitting / receiving apparatus according to the first embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a pulse compression transmitting / receiving apparatus according to a second embodiment of the present invention.

FIG. 10 is a flowchart illustrating the operation of the decision unit in FIG. 9;

FIG. 11 is a flowchart illustrating a pulse transmission / reception operation according to a second embodiment of the pulse compression transmission / reception device of the present invention.

FIG. 12 is a block diagram showing a configuration of a pulse compression transmitting / receiving apparatus according to a third embodiment of the present invention.

FIG. 13 is an internal configuration diagram of the correlator of FIG.

FIG. 14 is a flowchart illustrating a pulse transmission / reception operation of the pulse compression transmission / reception device according to the third embodiment of the present invention.

FIG. 15 is a diagram illustrating a transmission pulse signal waveform of the pulse compression transmission / reception device of the intra-pulse phase modulation system.

FIG. 16 is a diagram illustrating amplitude characteristics (main lobe and range side lobe) after demodulation of a received signal in a pulse compression transmission / reception device using a binary code sequence alone as a modulation code sequence.

FIG. 17 is a diagram illustrating amplitude characteristics (main lobe and range side lobe) after demodulation of a received signal in a pulse compression transmission / reception device using a complementary sequence as a modulation code sequence.

FIG. 18 is a diagram showing a representative complementary sequence.

FIG. 19 is a diagram illustrating a correlation characteristic when a time lag tz = 0 when there is no phase modulation by a Doppler frequency in a received signal when a complementary sequence is used for intra-pulse phase modulation in a conventional pulse compression transmission / reception device. It is.

FIG. 20 shows a correlation characteristic when a time lag tz = 0 when a received signal has a phase modulation by a Doppler frequency of 1/2 PRI when a complementary sequence is used for phase modulation in a pulse in a conventional pulse compression transmitting / receiving apparatus. FIG.

FIG. 21 is a configuration block diagram showing a conventional pulse compression transmission / reception device.

FIG. 22 is a waveform diagram of a transmission pulse signal and a transmission pulse signal of a conventional pulse compression transmission / reception device.

FIG. 23 is an internal configuration diagram of the correlator of FIG. 21.

[Explanation of symbols]

1 stabilized local oscillator, 2 reference intermediate signal generator,
3a, 3b frequency mixer, 4 pulse modulator A,
5 power amplifier, 6 duplexer, 7 antenna,
8 Middle frequency amplifier, 9 90 degree hybrid circuit, 10a, 10b Phase detector, 11a, 11b
A / D converter, 12a, 12b Correlator A, 13
Modulation code switch A, 14 Envelope detector, 15
Changeover switch, 16 memories, 17 on-off
Switch, 18 adder, 19 post-stage signal processing circuit, 20a, 20b pulse modulator B, 21a, 2
1b correlator B, 22a, 22b correlator C, 23
a, 23b Judge A, 24 Variable stage number shift register, 25a, 25b, 25c Reference signal storage memory,
26 multiplier, 27 changeover switch, 28 adder, 29 3M-stage shift register, 30 adder,
31a, 31b adder, 32a, 32b determiner B, 33 modulation code switch B.

Claims (6)

[Claims] 1. A pulse compression transmission / reception apparatus using a complementary sequence, wherein a pulse having a width T which is phase-modulated in a pulse in one of the complementary sequences is transmitted, and the transmission pulse is reflected by a target. Without waiting for the reception of the pulse, the pulse having the same width T that is phase-modulated in the pulse by the other of the complementary sequences is transmitted at a time interval w equal to or longer than the width T of the transmission pulse. A transmission device that repeats transmission of the two transmission pulses for each pulse repetition period after receiving two reflection pulses whose pulses have been reflected at the target; and a signal of the first time interval T of the reception signal of the 2T + w time interval. And a reference signal that has been subjected to intra-pulse phase modulation with one of the complementary sequences used for intra-pulse phase modulation of the first transmission pulse, and the last time interval of the received signal at a time interval of 2T + w And signal, a correlator for obtaining a correlation between the pulse in the phase-modulated reference signal in the other series of complementary sequences,
When the two correlation results obtained by the correlator are input and the two correlation results are both other than 0, the sum of the two input correlation results is output, and when at least one of them is 0, 0 is output. A pulse compression transmission / reception device, comprising: a reception device having a determination unit; 2. A pulse compression transmission / reception apparatus using a complementary sequence, wherein a pulse having a width T which is phase-modulated in a pulse in one of the complementary sequences is transmitted, and the transmitted pulse is reflected by a target. Without waiting for the reception of the transmission pulse, successively, with a time interval w longer than the width T of the transmission pulse, a pulse having the same width T that is subjected to intra-pulse phase modulation with the other of the complementary sequences is transmitted. A transmission device that repeats the transmission of the two transmission pulses at each pulse repetition period after receiving the two reflected pulses reflected by the target at the first time interval T of the received signal at a time interval of 2T + w , The correlation between the reference signal that is intra-pulse phase-modulated by one of the complementary sequences used in the intra-pulse phase modulation of the first transmission pulse, and the last time of the received signal at a time interval of 2T + w A signal interval T, a correlator for obtaining a correlation between the pulse in the phase-modulated reference signal in the other series of complementary sequences,
When the two correlation results obtained by the correlator are input and both of the two correlation results are larger than a predetermined threshold, the sum of the two correlation results of the input is output, and at least one of the two is output in advance. A pulse compression transmission / reception device, comprising: a reception device having a decision unit that outputs 0 when the value is smaller than a predetermined threshold value. 3. A pulse compression transmission / reception apparatus using a complementary sequence, first, transmits a pulse having a width T that is phase-modulated in a pulse in one of the complementary sequences, and the transmission pulse is a reflected pulse reflected by a target. Without waiting for the reception of the transmission pulse, successively, with a time interval w longer than the width T of the transmission pulse, a pulse having the same width T that is subjected to intra-pulse phase modulation with the other of the complementary sequences is transmitted. A transmission device that repeats the transmission of the above-mentioned two transmission pulses every pulse repetition period after receiving the two reflected pulses reflected by the target at the first time interval T of the received signal at the time interval of 2T + w , The correlation between the reference signal that is subjected to intra-pulse phase modulation with one of the complementary sequences used for intra-pulse phase modulation of the first transmission pulse, and the last time of the received signal at a time interval of 2T + w And a receiver having a correlator for obtaining a correlation between the signal of T and a reference signal subjected to intra-pulse phase modulation with the other of the complementary sequences, and taking the sum of the correlation results. Pulse compression transceiver. 4. A pulse compression transmission / reception method comprising the steps of: (a) transmitting a pulse having a width T, which is phase-modulated in a pulse by one of a complementary sequence, and transmitting the pulse; Without waiting for the reception of the reflected pulse reflected by the target, successively, at a time interval w equal to or more than the width T of the transmission pulse,
A transmission step of transmitting a pulse of the same width T, which is intra-pulse phase-modulated by the other of the complementary sequences, (b) a signal of a first time interval T of a reception signal of a time interval of 2T + w, and a pulse of the first transmission pulse Correlation with a reference signal that has been subjected to intra-pulse phase modulation with one of the complementary sequences used for internal phase modulation, the signal at the last time interval T of the received signal at a time interval of 2T + w, and the other sequence of the complementary sequence The correlation with the reference signal that has been subjected to intra-pulse phase modulation is obtained. When both the obtained two correlation results are other than 0, the sum of the two correlation results is used as the final correlation result.
In the case of (1), a receiving step in which the final correlation result is set to 0; (c) When the receiving step is executed, the process proceeds to step (a) and is repeated. 5. A pulse compression transmission / reception method comprising the following steps: (a) transmitting a pulse having a width T, which is phase-modulated in a pulse in one of complementary sequences, and transmitting the pulse; Without waiting for the reception of the reflected pulse reflected by the target, successively, at a time interval w equal to or more than the width T of the transmission pulse,
A transmission step of transmitting a pulse of the same width T, which is intra-pulse phase-modulated by the other of the complementary sequences, (b) a signal of a first time interval T of a reception signal of a time interval of 2T + w, and a pulse of the first transmission pulse Correlation with a reference signal that has been subjected to intra-pulse phase modulation with one of the complementary sequences used for internal phase modulation, the signal at the last time interval T of the received signal at a time interval of 2T + w, and the other sequence of the complementary sequence The correlation with the reference signal that has been subjected to intra-pulse phase modulation is obtained. When both of the obtained two correlation results are larger than a predetermined threshold value, the sum of the two correlation results of the input is calculated as the final correlation value. As a result, if at least one of them is smaller than a predetermined threshold value, a receiving step of setting the final correlation result to 0, (c) When the receiving step is executed, the procedure proceeds to step (a) and is repeated. 6. A pulse compression transmission / reception method comprising the following steps: (a) transmitting a pulse having a width T that is phase-modulated in a pulse in one of a complementary sequence and transmitting the pulse; Without waiting for the reception of the reflected pulse reflected by the target, successively, at a time interval w equal to or more than the width T of the transmission pulse,
A transmission step of transmitting a pulse of the same width T, which is intra-pulse phase-modulated by the other of the complementary sequences, (b) a signal of a first time interval T of a reception signal of a time interval of 2T + w, and a pulse of the first transmission pulse Correlation with a reference signal that has been subjected to intra-pulse phase modulation with one of the complementary sequences used for internal phase modulation, the signal at the last time interval T of the received signal with a time interval of 2T + w, and the other sequence of the complementary sequence (C) a receiving step of obtaining a correlation with the intra-pulse phase-modulated reference signal and calculating the sum of the correlation results. (C) When the receiving step is executed, the process proceeds to step (a) and is repeated.