JP4962510B2 - Target search signal generation method and target search device - Google Patents

Description

  The present invention relates to a target search signal generation method and a target search device, and in particular, a target search signal generation method (radar signal generation method), a target search device (radar device) using a radar signal that is an electromagnetic wave as a target search signal, and a target The present invention relates to a target search signal generation method (a sonar signal generation method) and a target search device (a sonar device) that use a sonar signal that is an ultrasonic wave as a search signal. The present invention can be suitably applied to radar equipment fields such as search radar, tracking radar, synthetic aperture radar, and reverse synthetic aperture radar, and sonar fields such as search sonar and synthetic aperture sonar.

  Searches for targets by sending target search signals consisting of pulse waves toward the targets, such as aircraft flying in the air and submersibles sailing in the sea, and receiving target search signals reflected by the targets. As target search devices, radar devices and sonar devices are widely used. The radar device transmits a radar signal composed of radio waves in the air as a target search signal, and the sonar device transmits a sonar signal composed of ultrasonic waves in the water as a target search signal. With the development of science and technology, as described in Japanese Patent Laid-Open No. 2002-6031 “Pulse Compression Radar Device” of Patent Document 1, the radar device includes a distance debris (space debris). There is a growing demand for detection of high-speed moving targets. Alternatively, in order to improve the detection performance of a radar device or sonar device for a target having a small reflection cross section of a radar signal or sonar signal, an increase in the number of transmission pulses and an increase in resolution have been required.

JP 2002-6031 A (page 2-3)

  In general, in order to increase the detection distance and clutter suppression performance of a radar device, a plurality of pulses are transmitted to search for a target in one direction, and a plurality of pulses reflected from the target are received as received pulses. It is necessary to integrate the obtained received pulse. However, according to the method of integrating a plurality of received pulses as described above, when the target has a radar direction velocity that is a component moving in the same direction as the radar signal, the received pulse from the target is transmitted after the pulse is transmitted. The time until acquisition, that is, the time position of the received pulse changes with each received pulse. As a result, if the amount of movement of the target radar direction within the search time in one direction is larger than the distance resolution of the radar device, the loss when integrating the received pulse increases, and the detection performance etc. deteriorates. Arise.

  In the prior art, in order to deal with such problems, the distance resolution is lowered or the number of transmission pulses is reduced so that the target radar direction movement amount is smaller than the distance resolution. Was trying to shorten the search time. Alternatively, the time position of each received pulse is corrected by assuming a target speed before integrating the received pulse.

  However, in the case of the former measure, the basic performance of the radar such as detection performance and distance resolution is degraded. In the latter case, since it is necessary to assume many cases for the target speed, not only the signal processing amount for correcting the time position of each reception pulse becomes enormous, but also the assumed number. A problem that the false alarms of the radar increase in proportion will arise.

  The problem like this is exactly the same not only in the field of radar equipment but also in the field of sonar equipment. Instead of radar signals, ultrasonic sonar signals are transmitted and the target is in the same direction as the sonar signals. When the sonar velocity is a moving component, the time from when a pulse is transmitted until the reception pulse from the target is obtained changes depending on each reception pulse, and the detection performance of the sonar device deteriorates. Problems arise.

  The present invention has been made in view of such circumstances, and even when the target has a velocity component that moves in the same direction as the target search signal, the target search device has no degradation in detection performance or distance resolution, and An object of the present invention is to provide a target search signal generation method applied to this target search device.

  In order to solve the above-described problems, the target search signal generation method and target search device according to the present invention employ the following characteristic configuration. The following item numbers (1) and (7) respectively correspond to the item numbers of the claims in the claims.

  (1) In a target search signal generation method applied to a target search device that generates a target search signal composed of a plurality of pulses each of which is a chirp modulation signal and transmits the target search signal toward the target. By compensating at least one of the pulse width and the distance resolution of the pulses of the received pulses to compensate for the Doppler shift of the received pulses due to the velocity component of the target moving in the same direction as the target search signal, the received pulses A method for generating a target search signal in which the time positions to be compressed are the same.

  (2) In a target search device that generates a target search signal composed of a plurality of pulses each of which is a chirp modulation signal and transmits the target search signal toward the target, the pulse width and the distance resolution of the plurality of pulses By making at least one of them different from each other, the Doppler shift of the received pulse due to the velocity component of the target moving in the same direction as the target search signal is compensated, and the time position where each received pulse is compressed is made the same. A target search apparatus having target search signal generation means for performing.

  According to the target search signal generation method and target search device of the present invention, when generating a target search signal composed of a plurality of pulses, at least one of the pulse width and the distance resolution in the plurality of pulse signals is different from each other. By using the obtained chirp modulation signal as the target search signal, the target moves in the same direction as the target search signal even when the target has a directional velocity component that moves in the same direction as the target search signal. Compensating for the Doppler shift of the received pulse due to having the velocity component, the time position where each received pulse is compressed can be made the same, and the compressed received pulse can be integrated without loss. Thus, according to the present invention, even when the target has a direction velocity component that moves in the same direction as the target search signal, the basic performance of the target search device such as detection performance and distance resolution is not degraded. An apparatus can be realized.

It is a block block diagram which shows an example of the block configuration of the radar apparatus by this invention. It is a block block diagram which shows the detailed structure of the radar signal generation part 1 in the radar apparatus of FIG.

(Features of the present invention)
Prior to the description of the embodiments of the present invention, an outline of the features of the present invention will be described first. The present invention generates a target search signal composed of a plurality of pulses, each of which is a chirp modulation signal, and transmits the target search signal toward the target, and a target search signal applied to the target search device In the generation method, by making at least one of the pulse width and the distance resolution different from each other in the plurality of pulses, for example, the relationship of the following formula (A) is satisfied, and the target is in the same direction as the target search signal. The main feature is that the Doppler shift of the received pulse due to the moving velocity component is compensated to keep the time position where each received pulse is compressed the same. The following formula (A) is the transmission of the first transmission pulse and the i-th (i: 1, 2,..., N) where n is the number of transmission pulses of one target search signal. This is an equation showing the relationship between the pulse width and distance resolution of a pulse, using the time interval Ti of both pulses and the wavelength λ of the transmission radio wave as parameters. Expression (A) is an example, and the time position where each received pulse is compressed is kept the same by changing at least one (one or both) of the pulse width and distance resolution of a plurality of pulses of the target search signal. If it is possible to do this, it is not limited to the formula (A).

Pw (i) · Dr (i) = Pw (1) · Dr (1) ± Ti · (λ / 2) ... (A)
Where Pw (i): pulse width of the i-th transmission pulse
Dr (i): Distance resolution of the i-th transmission pulse
Pw (1): Pulse width of the first transmission pulse
Dr (1): Distance resolution of the first transmission pulse
Ti: Time interval between the first transmission pulse and the i-th transmission pulse
λ: wavelength of the target search signal
i ： 1,2, ... ・ ・ ・ n
Note that (+) of the sign (±) on the right side indicates a case where the chirp modulation signal is down-chap modulation, and (−) indicates a case where the chirp modulation signal is up-chap modulation.
(Embodiment of the present invention)

  When the target search signal in the present invention is a radar signal, the target search signal generation method and the target search device of the present invention are a radar signal generation method and a radar device, respectively. Similarly, when the target search signal in the present invention is a sonar signal, the target search signal generation method and target search device of the present invention are a sonar signal generation method and a sonar device, respectively. Hereinafter, a preferred embodiment of a radar signal generation method and a radar apparatus obtained by using a target search signal in the present invention as a radar signal will be described with reference to the drawings, but also for a sonar signal generation method and a sonar apparatus, The signal format of the generated chirp modulation signal is only a sonar signal for transmission, and is exactly the same as the embodiment of the radar signal generation method and radar apparatus described below.

  FIG. 1 is a block configuration diagram showing an example of a block configuration of a radar apparatus according to the present invention. The radar apparatus of FIG. 1 includes a radar signal generation unit 1, a transmission unit 2, an antenna unit 3, a reception unit 4, a signal processing unit 5, and a display / control unit 6. The radar apparatus of FIG. 1 operates as follows.

  First, the operation until the radar apparatus of FIG. 1 transmits a radar signal to space will be described. A radar signal generation unit 1 (corresponding to the above-described target search signal generation means) generates a radar signal 101 composed of a plurality of pulses each of which is a chirp modulation signal. Since the radar signal 101 is a baseband signal, it is hereinafter referred to as a baseband radar signal. In the baseband radar signal 101, if at least one of the pulse width and the distance resolution of the plurality of pulses is different from each other with respect to the plurality of pulses so as to maintain the relationship represented by the following formula (A), Although the radar apparatus of the invention can be realized, in the present embodiment, for the sake of simplicity of explanation, it is assumed that only the pulse widths of a plurality of pulses are different from each other with respect to the plurality of pulses. The transmission unit 2 modulates a high frequency carrier wave having a wavelength λ with the baseband radar signal 101, generates a high frequency radar signal, amplifies the high frequency radar signal, and transmits the amplified high frequency radar signal 102 to the antenna unit 3. To do. The antenna unit 3 transmits the high-frequency radar signal 102 transmitted from the transmission unit 2 in a designated direction in space.

  Next, the radar apparatus of FIG. 1 receives the high-frequency radar signal reflected from the target, generates a high-frequency reception signal, converts the high-frequency reception signal into a baseband reception signal, and pulses the baseband reception signal. An operation until compression processing is performed and a target signal is generated will be described. The antenna unit 3 receives a high-frequency reflected signal from the target and outputs it as a high-frequency received signal 103. The reception unit 4 amplifies the high frequency reception signal 103 obtained by the antenna unit 3, removes the carrier wave component, generates a baseband reception signal 104, and outputs the reception signal 104 to the signal processing unit 5. It is the same as the radar signals 101 and 102 that the received signals 103 and 104 are composed of a plurality of pulses.

  In the present embodiment, as described above, only the pulse width of the pulse widths of the plurality of pulses and the distance resolution in the radar signal 102 is related to the plurality of pulses so as to maintain the relationship represented by the following formula (A). They are different from each other. Since the pulse widths of a plurality of pulses in the radar signal 102 are in the relationship (A), a plurality of received signals 104 caused by a Doppler shift caused by a velocity component in which the target moves in the same direction as the radar signal (ie, radar direction velocity). The shift (shift) of the time position between the pulses is compensated in the pulse compression process in the signal processing unit 5, and the time positions of the plurality of pulses after the pulse compression obtained by the pulse compression process are the same.

  The signal processing unit 5 performs a pulse compression process for compressing the pulse width of the plurality of pulses in the reception pulse 104 in synchronization with the timing 111 signal to generate a plurality of compressed pulses. This pulse compression processing is performed by FFT processing (matched filter). In the present embodiment, as described above, the time positions of a plurality of pulses after pulse compression are arranged to be the same. The plurality of pulses after pulse compression are integrated, and the integrated pulse is subjected to processing such as making the false alarm probability constant, and a pulse after compression of peak power exceeding a predetermined value is output as the target signal 105. Since the time positions of the plurality of pulses after pulse compression are arranged to be the same, there is little loss in the integration process, and the peak power of the target signal 105 obtained by the integration process can be increased. Therefore, the present embodiment provides a radar device with excellent search capability that has a large target detection distance and a large distance resolution.

  The display / control unit 6 displays the target signal 105 obtained by the signal processing unit 5 on the screen. Further, the display / control unit 6 performs necessary control on the entire radar apparatus.

  FIG. 2 is a block configuration diagram showing a detailed configuration of the radar signal generator 1 in the radar apparatus of FIG. 2 includes a timing generator 11, a waveform memory 12, a pulse data selector 13, and a digital / analog converter (hereinafter abbreviated as “D / A”) 14. The timing generator 11 generates a timing signal 111 and sends the timing signal 111 to the pulse data selector 13 and the signal processing unit 5. The waveform memory 12 is a memory for storing a plurality of chirp waveform data. Assuming that the radar signal 101 in the radar according to the present embodiment is composed of n transmission pulses up to the first,..., I,. At least n chirp waveform data are stored. In the present embodiment, the pulse width Pw (i) of the transmission pulse is different for each transmission pulse, and the distance resolution Dr (i) is constant in any transmission pulse. Therefore, the pulse width of the chirp waveform in each chirp waveform data Pw (i) satisfies the formula (A) described later. The waveform memory 12 stores n chirp waveform data in which only the pulse widths Pw (i) of transmission pulses are different from each other.

  The pulse data selector 13 sequentially reads chirp waveform data from the waveform memory 12 in accordance with the timing signal 111, and outputs each read chirp waveform data to the D / A. Since each radar signal 101, 102 in this embodiment is composed of n transmission pulses, the pulse data selector 13 outputs n chirp waveform data corresponding to one radar signal at the timing of the timing signal 111. Output to A. A signal composed of n chirp waveform data sequentially transmitted at the timing of the timing signal 111 is illustrated as a digital radar signal 113 in FIG. The D / A 14 receives the digital radar signal 113, sequentially converts n chirp waveform data constituting the digital radar signal 113 into an analog signal, and outputs the analog signal as a baseband radar signal 101.

  Next, a method for generating the transmission pulse 102 of the radar apparatus of FIG. 1 will be further described.

  As described above, the radar signal generation unit 1 in this radar apparatus is a chirp modulation signal generator and outputs the radar signal 101 composed of a plurality of pulses (chirp modulation signals). In the chirp modulation signal generated as the radar signal 101 by the radar signal generator 1, the pulse widths of the plurality of pulses are made different with respect to the plurality of pulses so as to maintain the relationship represented by the following equation (A). Compensation is performed for Doppler shift between received pulses due to a velocity component (that is, radar direction velocity) at which the target moves in the same direction as the radar signal, and control is performed so as to keep the time position where each received pulse is compressed the same.

Pw (i) · Dr (i) = Pw (1) · Dr (1) ± Ti · (λ / 2) ... (A)
Where Pw (i): pulse width of the i-th transmission pulse
Dr (i): Distance resolution of the i-th transmission pulse
Pw (1): Pulse width of the first transmission pulse
Dr (1): Distance resolution of the first transmission pulse
Ti: Time interval between the first transmission pulse and the i-th transmission pulse
λ: wavelength of the transmission radio wave (high frequency radar signal 102) of the radar device
i ： 1,2, ... ・ ・ ・ n

  In Formula (A), in the case of down-chirp modulation where the frequency is lowered with time, the calculation between the first term and the second term is performed so that the second term is added to the first term on the right side. The child is (+), and on the other hand, in the case of up-chirp modulation where the frequency is increased with time, the second term is subtracted from the first term on the right side so that the second term is subtracted from the first term. The operator is (-).

  Here, the characteristics of the chirp modulation signal when the expression (A) is satisfied will be described first. When the chirp modulation signal is subjected to Doppler shift (Doppler shift), the time position of the compressed pulse is shifted. The shift amount is not only proportional to the Doppler shift amount but also proportional to the pulse width before and after compression.

  The amount of shift by the Doppler shift is, for example, the time width from the peak value of the pulse after compression to the first null point when a period of Doppler shift is received within the pulse width before compression. Become. The signal shift direction is a direction away from the radar in the case of a down chirp modulation signal when the Doppler shift amount is (+), and vice versa in the case of an up chirp modulation signal.

  Note that the time width from the peak value of the pulse after compression to the first null point is a time corresponding to the distance resolution capable of separating the two targets. For this reason, the post-compression pulse width of the transmission pulse is used here.

  Hereinafter, the relationship between the pre-compression and post-compression pulse width and distance resolution for making the time position where the reception pulse is compressed the same for the first transmission pulse and the i-th transmission pulse will be described.

The time position Pt (1) where the reception pulse obtained by the first transmission pulse is compressed is expressed by the following equation (1).
Pt (1) = Rto ± fd ・ Pw (1) ・ Dt (1) (1)
Where Pt (1): Time position where the first transmission pulse is compressed
Rto: Target distance equivalent time when the first transmission pulse is reflected
fd: Doppler frequency
Pw (1): Pulse width of the first transmission pulse
Dt (1): Pulse width after compression of the first transmission pulse

  However, (±) of the operator between the first term and the second term of Equation (1) is (+) when the down-chirp modulation signal is used, and conversely when the up-chirp modulation signal is used. (-).

  Each term on the right side of Equation (1) represents the following meaning. The first term represents the time required for the radio wave to travel back and forth the distance from the radar to the target, and the second term represents the Doppler shift of the transmission signal by the velocity component (radar direction velocity) in the same direction as the target radar signal. The amount of shift of the compression time position due to the reception is shown.

Here, the Doppler frequency (fd) is expressed by the following equation (2).
fd = 2 · Vt / λ (2)
Where Vt: Target radar speed
λ: wavelength of transmission radio wave by radar signal 102 Note that Vt is (+) in the direction in which the target approaches the radar apparatus.

Substituting equation (2) into equation (1) yields the following equation (3).
Pt (1) = Rto ± 2, Vt, Pw (1), Dt (1) / λ (3)

Next, the time position where the received pulse obtained by the i-th transmission pulse is compressed will be described. The time position is the same as the radar signal during the period from the first transmission pulse to the i-th transmission pulse with respect to the time position where the reception pulse obtained by the first transmission pulse is compressed. The following equation (4) is obtained by adding the time corresponding to the distance traveled with the direction velocity component (radar direction velocity).
Pt (i) = Rto-2 ・ Vt ・ Ti / C ± 2 ・ Vt ・ Pw (i) ・ Dt (i) / λ (4)
Where Pt (i): time position where the i-th transmission pulse is compressed
Ti: Time difference between the first transmission pulse and the i-th transmission pulse
C: speed of light
Dt (i): Compressed pulse width of the i-th transmission pulse
i ： 1,2, ... ・ ・ ・ n

  The reason why the movement distance (distance change amount) of the second term is set to (−) is that when the target radar direction velocity Vt is (+), the target movement direction approaches the radar apparatus. Depending on the direction.

Here, the relations for setting the time positions Pt (1) and Pt (i) where the first and i-th signals are compressed to the same time position are the above-described expressions (3) and (4). Then, the following equation (5) is obtained.
Pw (i) · Dt (i) = Pw (1) · Dt (1) ± Ti · λ / C (5)

  However, with regard to (±) of the operator between the first term and the second term on the right side of Equation (5), in the case of the down-chirp modulation signal, the second term is (+) with respect to the first term. When the up-chirp modulation signal is used, the second term becomes (−) on the contrary to the first term.

  As shown in Expression (5), for example, when a down-chirp modulated signal is used as a radar signal, the product of the pulse width before and after compression of the i-th transmission pulse on the left side is expressed as the first term on the right side. If the setting is made such that (Ti · λ / C) in the second term on the right side is added to the product of the pulse width before and after compression of the first transmission pulse of It can be seen that the time positions to be compressed are the same.

  When an up-chirp modulation signal is used as a radar signal, the product of the pulse width before and after compression of the i-th transmission pulse on the left side is the compression of the first transmission pulse in the first term on the right side. If the value obtained by subtracting (Ti · λ / C) in the second term on the right side from the product of the pulse width before and after compression is set to a value, the time positions where both received pulses are compressed are the same. I understand that.

Furthermore, if the pulse width (Dt) after compression of Expression (5) is expressed by distance resolution (Dr),
Dt = 2 ・ Dr / C (6)
It can be expressed as.

Therefore, when equation (6) is substituted into equation (5), the speed of light (C) is eliminated, and the following equation (7), that is, the above-described equation (A) is obtained.
Pw (i) · Dr (i) = Pw (1) · Dr (1) ± Ti · λ / 2 (7)

  Thus, according to the equation (7), that is, the above-described equation (A), there is no performance degradation by directly using the values of the distance resolutions Dr (i) and Dr (i) representing the performance specifications of the radar. Radar signals can be generated. In the present embodiment, as described above, only the pulse width Pw (i) is different from each other, and n-th chirp waveform data from the first to the n-th satisfying the relationship of the formula (A) is stored in the waveform memory 12. In addition, these n chirp waveform data are sequentially read out, and n chirp modulation transmission pulses (1st to nth) are sequentially generated based on these chirp waveform data.

  The basic configuration and operation of the radar apparatus according to this embodiment described above may be the same as those of a conventional radar apparatus using a chirp modulation signal with a constant pre-compression pulse width and the like.

(Description of the effect of this embodiment)
In the radar apparatus shown in the present embodiment, when the radar signal is generated by the radar signal generation unit 1, the pulse width Pw (i) and the distance resolution of each radar signal i (i = 1, 2,..., N). By changing one or both of Dr (i) so as to maintain the relationship represented by the above-mentioned equation (A), the target has a velocity component (radar direction velocity) in the same direction as the radar signal. However, it is possible to compensate for the moving distance between the received pulses depending on the target radar direction velocity, and to make the time position where each received pulse is compressed the same, thus integrating the compressed received pulse without loss. be able to.

  The above-described embodiment has been described with respect to the case of the radar device. However, the same applies to the case of the sonar device. By simply replacing the radar signal of the above-described embodiment with a sonar signal for transmission for the sonar device, it remains as it is. Can be applied.

The configuration of the preferred embodiment of the present invention has been described above. However, it should be noted that such embodiments are merely examples of the present invention and do not limit the present invention. Those skilled in the art will readily understand that various modifications and changes can be made according to a specific application without departing from the gist of the present invention. For example, the embodiment of the present invention can be expressed as the following configuration in addition to the configurations (1) and (7) in the means for solving the problems. The following item numbers (2) to (6) and (8) to (12) correspond to the item numbers of the claims in the claims.
(2) The chirp modulation signal to be generated is expressed by the following equation (A)
Pw (i) · Dr (i) = Pw (1) · Dr (1) ± Ti · (λ / 2) ... (A)
Where Pw (i): pulse width of the i-th transmission pulse
Dr (i): Distance resolution of the i-th transmission pulse
Pw (1): Pulse width of the first transmission pulse
Dr (1): Distance resolution of the first transmission pulse
Ti: Time interval between the first transmission pulse and the i-th transmission pulse
λ: wavelength of the target search signal
i ： 1,2, ... ・ ・ ・ n
The target search signal generation method according to (1) above, wherein:
(3) (+) of the sign (±) on the right side of the equation (A) indicates that the chirp modulation signal is down-chap modulation, and (−) indicates that the chirp modulation signal is up-chirp modulation. The target search signal generation method according to (2), which shows a case where
(4) When receiving a plurality of transmission pulses generated as the chirp modulation signal in one direction and receiving a plurality of reflected pulses, each reception after compression obtained as a result of correlation processing with each transmitted transmission pulse 4. The target search signal generation method according to any one of (1) to (3), wherein the pulse is integrated and a signal having a predetermined magnitude is extracted as a target signal.
(5) The target search signal generation method according to any one of (1) to (4), wherein the target search signal is a radar signal.
(6) The target search signal generation method according to any one of (1) to (5), wherein the target search signal is a sonar signal.
(8) The chirp modulation signal to be generated is expressed by the following formula (A):
Pw (i) · Dr (i) = Pw (1) · Dr (1) ± Ti · (λ / 2) ... (A)
Where Pw (i): pulse width of the i-th transmission pulse
Dr (i): Distance resolution of the i-th transmission pulse
Pw (1): Pulse width of the first transmission pulse
Dr (1): Distance resolution of the first transmission pulse
Ti: Time interval between the first transmission pulse and the i-th transmission pulse
λ: wavelength of the target search signal
i ： 1,2, ... ・ ・ ・ n
The target search device according to (7), which satisfies the above.
(9) (+) of the sign (±) on the right side of the equation (A) indicates that the chirp modulation signal is down-chap modulation, and (−) indicates that the chirp modulation signal is up-chirp modulation. The target search device according to (8), which shows a case where
(10) When receiving a plurality of transmission pulses generated as the chirp modulation signal in one direction and receiving a plurality of reflection pulses, each reception after compression obtained as a result of correlation processing with each transmission pulse transmitted The target search device according to any one of (7) to (9), wherein the pulse is integrated to extract a signal having a predetermined magnitude as a target signal.
(11) The target search device according to any one of (7) to (10), wherein the target search signal is a radar signal.
(12) The target search device according to any one of (7) to (11), wherein the target search signal is a sonar signal.

  In the above embodiment, only the pulse width Pw (i) of the plurality of pulses and the pulse width Pw (i) of the distance resolution Dr (i) are different from each other. ) And distance resolution Dr (i) or only distance resolution Dr (i) with respect to multiple pulses, the Doppler shift of the received pulse due to the velocity component that the target moves in the same direction as the target search signal And the time position where each received pulse is compressed can be kept the same. If the method of changing only the transmission pulse distance resolution Dr (i) for each transmission pulse is adopted, the waveform memory 12 stores n chirp waveforms whose transmission pulse distance resolutions Dr (i) are different from each other. It is enough if only the data is stored. Further, when adopting a method in which both the pulse width Pw (i) and the distance resolution Dr (i) are different, the waveform memory 12 has the pulse width Pw (i) and the distance resolution Dr (i) of the transmission pulse. It is sufficient to store only n different chirp waveform data. Of course, it is necessary to satisfy the formula (A) in any of the methods.

  In the above embodiment, the pulse compression processing is performed by FFT processing (matched filter), but may be performed by a distributed delay line.

DESCRIPTION OF SYMBOLS 1 Radar signal generation part 2 Transmission part 3 Antenna part 4 Reception part 5 Signal processing part 6 Display / control part 11 Timing generator 12 Pulse data selector 13 Waveform memory 14 Digital / analog converter 101 Baseband radar signal 102 Radar signal 103 High frequency received signal 104 Baseband received signal 105 Target signal 111 Timing signal 112 Digital pulse data 113 Digital radar signal

Claims (12)

  In a target search signal generation method applied to a target search device that generates a target search signal composed of a plurality of pulses each of which is a chirp modulation signal and transmits the target search signal toward the target, By making at least one of the pulse width and the distance resolution different from each other, the Doppler shift of the received pulse due to the velocity component in which the target moves in the same direction as the target search signal is compensated, and each received pulse is compressed. The target search signal generation method characterized by making the time positions to be the same. The chirp modulation signal has the following formula (A):
Pw (i) · Dr (i) = Pw (1) · Dr (1) ± Ti · (λ / 2) ... (A)
Where Pw (i): pulse width of the i-th transmission pulse
Dr (i): Distance resolution of the i-th transmission pulse
Pw (1): Pulse width of the first transmission pulse
Dr (1): Distance resolution of the first transmission pulse
Ti: Time interval between the first transmission pulse and the i-th transmission pulse
λ: wavelength of the target search signal
i ： 1,2, ... ・ ・ ・ n
The target search signal generation method according to claim 1, wherein:   (+) Of the sign (±) on the right side of the equation (A) indicates a case where the chirp modulation signal is down-chain modulation, and (-) indicates a case where the chirp modulation signal is up-chain modulation. The target search signal generation method according to claim 2, wherein:   Integrating each received pulse after compression obtained by compression of each received pulse, and extracting a pulse having a predetermined size as a target signal from the integrated pulses obtained by the integration. A method for generating a target search signal according to any one of claims 1 to 3.   5. The target search signal generation method according to claim 1, wherein the target search signal is a radar signal.   5. The method for generating a target search signal according to claim 1, wherein the target search signal is a sonar signal.   In a target search device that generates a target search signal composed of a plurality of pulses each of which is a chirp modulation signal and transmits the target search signal toward the target, at least of the pulse width and the distance resolution of the plurality of pulses By making one of them different from each other, a target search for compensating the Doppler shift of the received pulse due to the velocity component of the target moving in the same direction as the target search signal so that the time position where each received pulse is compressed is the same. A target search device comprising a signal generating means. The chirp modulation signal has the following formula (A):
Pw (i) · Dr (i) = Pw (1) · Dr (1) ± Ti · (λ / 2) ... (A)
Where Pw (i): pulse width of the i-th transmission pulse
Dr (i): Distance resolution of the i-th transmission pulse
Pw (1): Pulse width of the first transmission pulse
Dr (1): Distance resolution of the first transmission pulse
Ti: Time interval between the first transmission pulse and the i-th transmission pulse
λ: wavelength of the target search signal
i ： 1,2, ... ・ ・ ・ n
The target search device according to claim 7, wherein:   (+) Of the sign (±) on the right side of the equation (A) indicates a case where the chirp modulation signal is down-chain modulation, and (-) indicates a case where the chirp modulation signal is up-chain modulation. The target search device according to claim 8, wherein:   Integrating each received pulse after compression obtained by compressing each received pulse, and extracting a signal having a predetermined magnitude as a target signal from the integrated pulses obtained by the integration The target search device according to any one of claims 7 to 9.   The target search device according to claim 7, wherein the target search signal is a radar signal.   The target search device according to claim 7, wherein the target search signal is a sonar signal.

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