JP2001194449A - Radar system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a radar system which can prevent deterioration of pulse compression characteristics, reduce wrong targets, and improve target detection provability by correcting large Doppler shift due to a high-speed target. SOLUTION: A stalo signal, where the Doppler shift of a target 3 as an object is offset by a stabilized local oscillator 6 and an offset signal generator 7 is generated, and frequency conversion is performed. Thereby a transmitting radio wave is turned into a frequency offset by the Doppler shift. By canceling the Doppler shift caused by the movement of the target 3 and the amount of the offset, pulse compression process is possible by a pulse compressor 13 without generating mismatch of the frequency characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device, and more particularly to a pulse compression radar device for detecting a high-speed target.

[0002]

FIG. 19 is a functional system diagram showing an example of a conventional pulse compression radar device. In the figure, 1 is a transmitting / receiving antenna, 2 is a circulator, 3 is a target, 4 is a high power amplifier, 5a to 5c are mixers, 6 is a stabilized local oscillator (STALO), 8 is a pulse expander, and 9 is a coherent oscillator (COHO). ), 10 is a transmission pulse generator, 11
Is a low noise amplifier, 12 is a phase detector, 13 is a pulse compressor, 14 is a moving target detector (MTI), and 15 is a target detector.

FIG. 20 is an explanatory diagram of a linear frequency modulation type pulse compression radar shown in "Radar Technology" published by the Institute of Electronics, Information and Communication Engineers in 1996.

Next, the operation will be described. Here, a pulse compression by a linear frequency modulation method will be described as an example of the pulse compression method. The rectangular pulse having the pulse width T generated by the transmission pulse generator 10 is mixed with the coherent signal of the frequency fcoho generated by the coherent generator 9 by the mixer 5a, thereby obtaining the frequency fco.
It becomes the transmission pulse of ho. This transmission pulse is shown in FIG.
The pulse expander 8 that performs frequency modulation of the bandwidth Δf as shown in FIG. 20A produces a linear frequency-modulated pulse as shown in FIG. The modulated pulse is supplied to the mixer 5b together with the stray signal of the frequency fo generated by the stabilized local oscillator 6, and frequency-converted to the carrier frequency fo. Then, the output of the frequency-converted mixer 5b is amplified as required by the high power amplifier 4,
The signal is radiated from the transmitting / receiving antenna 1 to the space via the circulator 2 as a transmission radio wave.

[0005] The received radio wave reflected by the target 3 is received by the transmitting / receiving antenna 1, and is amplified by the low noise amplifier 11 through the circulator 2. The received signal is supplied to a mixer 5c together with a stray signal having a frequency fo from a stabilized local oscillator 6 and frequency-converted. Thereafter, the signal is supplied to a phase detector 12 together with a coherent signal having a frequency fcoho from a coherent oscillator 9. Is done. The output of the phase detector 12 is input to a pulse compressor 13 having a frequency versus delay time characteristic as shown in FIG. Then, in the pulse compressor 13, the frequency components dispersed in the pulse in this order are concentrated at one point, and the input signal becomes a rapid impulse shape as shown in FIG. Output as a signal. In this way,
Even if the pulse width of the transmission signal is long, a high-resolution reception signal can be obtained on the receiver side. The received signal is target detected by the moving target detector 14 and the target detector 15,
It is displayed on an indicator (not shown).

[0006]

However, since the conventional pulse compression radar apparatus is configured as described above,
There were the following problems. That is, in the conventional pulse compression radar device, the frequency characteristics of the pulse expander and the pulse compressor are configured to match. However, when the Doppler shift fdt accompanying the target shift shown in the following equation (1) is added to the received signal, the spectrum of the received signal does not match the frequency characteristic of the pulse compressor,
A mismatch occurs in the pulse compression processing.

F dt ≒ 2 · vt / λ (1) where, vt: relative speed with respect to the target radar device λ: wavelength of transmission radio wave

Due to this mismatch, for example, degradation of the side lobe of the compressed pulse as shown in FIG. 21 described in “Radar Handbook” by M. Skolink, or as shown in FIG. The signal-to-noise ratio (S / N) is degraded due to the decrease in the amplitude of the compressed pulse, and the range of the detection target is shifted.

As shown in FIGS. 21 and 22, the larger the Doppler shift, that is, the higher the target speed, the larger the deterioration tends to be. Therefore, in a pulse compression radar apparatus targeting a high-speed target, an erroneous target increases due to deterioration of the side lobe of the pulse after compression, a target detection rate decreases due to deterioration of a signal-to-noise ratio, and a range shift of a detection target occurs. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a radar apparatus capable of correcting a large Doppler shift caused by a high-speed target, thereby preventing deterioration of pulse compression characteristics. The purpose is to:

[0011]

According to a first aspect of the present invention, there is provided a radar apparatus which converts the frequency of a transmission pulse, extends the pulse width, radiates the pulse as a radio wave into space, and reflects the frequency of a radio wave reflected by a target. And a first frequency offset means for offsetting a frequency associated with transmission and reception of the transmission pulse by the target Doppler shift. .

According to a second aspect of the present invention, in the radar apparatus according to the first aspect, the first frequency offset means is configured to transmit the stray signal of the transmission system in which the frequency is offset in advance by the target Doppler shift. Is provided.

According to a third aspect of the present invention, in the radar apparatus according to the first aspect, the first frequency offset means includes a transmitting coherent signal whose frequency is offset in advance by the target Doppler shift. Is provided.

According to a fourth aspect of the present invention, in the radar apparatus according to the first aspect, the first frequency offset means includes a digital pulse expansion unit in which a center frequency is offset in advance by the target Doppler shift. It has offset means for generating coefficients.

According to a fifth aspect of the present invention, in the radar apparatus according to the first aspect, the first frequency offset means includes a stirrer signal of a transmission system whose frequency is offset in advance by the target Doppler shift. Is provided.

According to a sixth aspect of the present invention, in the radar apparatus according to the first aspect, the first frequency offset means performs pulse compression in which a center frequency is offset in advance by the target Doppler shift. It has offset means.

According to a seventh aspect of the present invention, the radar apparatus converts the frequency of a transmission pulse, expands the pulse width, radiates the pulse as a radio wave into space, and converts the frequency of a radio wave reflected by a target whose speed changes. And a second frequency offset means for offsetting a frequency related to transmission and reception of the transmission pulse by a Doppler shift corresponding to a plurality of speeds of the target in the radar apparatus for detecting the target by pulse compression. Things.

In a radar apparatus according to an eighth aspect of the present invention, in the invention according to the seventh aspect, the second frequency offset means includes a transmission system whose frequency is offset in advance so as to correspond to the target Doppler shift. And a means for generating a plurality of stirling signals and performing frequency conversion while switching the plurality of stirling signals.

According to a ninth aspect of the present invention, in the radar apparatus according to the seventh aspect of the present invention, the second frequency offset means is configured to transmit a basic stallow signal of a transmission system so as to correspond to the target Doppler shift. And offset means for offsetting the frequency while switching by the target Doppler shift.

According to a tenth aspect of the present invention, in the radar apparatus according to the seventh aspect, the second frequency offset means includes a transmission system whose frequency is offset in advance so as to correspond to the target Doppler shift. And an offset means for performing frequency conversion while switching the plurality of coherent signals.

According to an eleventh aspect of the present invention, in the radar apparatus according to the seventh aspect, the second frequency offset means converts the basic coherent signal of the transmission system so as to correspond to the target Doppler shift. And offset means for offsetting the frequency while switching by the target Doppler signal deviation.

According to a twelfth aspect of the present invention, in the radar apparatus according to the seventh aspect of the present invention, the second frequency offset means includes a plurality of frequency offset center frequencies which are previously offset so as to correspond to the target Doppler shift. And an offset means for performing pulse expansion while switching the digital pulse expansion coefficient.

According to a thirteenth aspect of the present invention, in the radar apparatus according to the seventh aspect, the second frequency offset means is provided with a basic coefficient of a digital pulse expander so as to correspond to the target Doppler shift. In contrast, there is provided an offset means for offsetting the frequency while switching by the target Doppler shift.

According to a fourteenth aspect of the present invention, in the radar apparatus according to the seventh aspect, the second frequency offset means includes a receiving system whose frequency is offset in advance so as to correspond to the target Doppler shift. And an offset means for performing frequency conversion while switching the plurality of starrow signals.

According to a fifteenth aspect of the present invention, in the radar apparatus according to the seventh aspect of the present invention, the second frequency offset means is adapted to transmit the basic starrow signal of the receiving system so as to correspond to the target Doppler shift. And offset means for offsetting the frequency while switching by the target Doppler shift.

According to a sixteenth aspect of the present invention, in the radar apparatus according to the seventh aspect, the second frequency offset means includes a pulse whose center frequency is offset in advance so as to correspond to the target Doppler shift. It has offset means for switching the compression.

According to a seventeenth aspect of the present invention, in the radar apparatus according to the seventeenth aspect, the second frequency offset means includes a plurality of frequency offset center frequencies which are offset in advance so as to correspond to the target Doppler shift. And an offset means for performing pulse compression while switching the digital pulse compression coefficient of the above.

The radar apparatus according to the eighteenth aspect of the present invention is the radar apparatus according to any one of the eighth to thirteenth aspects, wherein the radar apparatus responds to the corresponding target Doppler shift based on the beam azimuth and / or the elevation angle. And control means for selecting and controlling the switching of the offset means.

A radar apparatus according to a nineteenth aspect of the present invention is the radar apparatus according to any one of the fourteenth to seventeenth aspects, wherein the Doppler of the corresponding target is determined based on the directional azimuth or directional elevation angle of the beam, the target distance, or a combination thereof. It has a control means for selecting and controlling the switching of the offset means so as to correspond to the shift.

According to a twentieth aspect of the present invention, in the radar apparatus according to any one of the eighth to seventeenth aspects, the Doppler shift of the target is predicted from the tracking result of the target, and based on the prediction,
It has control means for selecting and controlling the switching of the offset means.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, taking a pulse compression radar apparatus as an example. In the following embodiments, pulse compression by a linear frequency conversion method will be described as an example of a pulse compression method, but the same applies to other pulse compression methods such as a phase modulation method. Embodiment 1 FIG. FIG. 1 is a functional system diagram showing the first embodiment of the present invention. In FIG. 1, portions corresponding to those in FIG. 19 are denoted by the same reference numerals, and redundant description thereof will be omitted. In the figure, 5d is a mixer provided between the mixer 5b and the stabilized local oscillator 6, and 7 is an offset signal for supplying the mixer 5d with an offset signal having a frequency equivalent to the Doppler shift fdt of the target 3 to be processed. Generator. Note that the mixer 5d and the offset signal generator 7 constitute offset means as first frequency offset means. Other configurations are the same as those in FIG.

Next, the operation will be described. The rectangular pulse having a pulse width T generated by the transmission pulse generator 10 is a frequency fco generated by the coherent oscillator 9.
By being mixed with the coherent signal of ho by the mixer 5a, it becomes a transmission pulse of the frequency fcoho. This transmission pulse is transmitted in the same manner as in the operation described with reference to FIG.
The pulse expander 8 that performs frequency modulation with a bandwidth Δf as shown in FIG. 20B produces a linear frequency-modulated pulse as shown in FIG.

Since the velocity Vt of a target which draws a ballistic trajectory can be predicted to be within a certain narrow range, the Doppler shift fdt of the target can be predicted in advance. Therefore, the offset signal generator 7 generates an offset signal having the frequency of the Doppler shift fdt, and the mixer 5d converts the frequency of the basic stray signal having the frequency fo generated by the stabilized local oscillator 6. The frequency of the offset signal generated by the offset signal generator 7 is -fdt.

As a result, at the output side of the mixer 5d, a stirling signal of the transmission system substantially offset to the frequency fo-fdt is obtained.
And frequency-converts the modulated pulse from the pulse expander 8 to the carrier frequency fo-fdt. The output of the mixer 5b is amplified by the high power amplifier 4 as required, and then radiated to the space from the transmission / reception antenna 1 through the circulator 2 as transmission radio waves. The frequency of this transmission radio wave is offset by the predicted Doppler shift of the target 3. The transmitted radio wave is reflected by the target 3, and the Doppler shift fdt accompanying the movement of the target 3 is added.
The frequency offset of the frequency offset of the transmission radio wave given in advance is cancelled, and the frequency of the reception radio wave reflected as a result is fo
And the received radio wave of this frequency fo is
Is received by

Therefore, the reception radio wave received by the transmission / reception antenna 1 can be subjected to reception processing in a form equivalent to the case where the Doppler shift fdt of the target 3 is not given. That is, the signal is amplified by the low-noise amplifier 11 via the circulator 2 and supplied to the mixer 5c together with the stray signal of the frequency fo from the stabilized local oscillator 6, where the frequency is converted and the center frequency fcoh
o, after being phase-detected by the phase detector 12 as a received signal of the band axis △ f, it is input to the pulse compressor 13. As described above, since the Doppler shift has already been cancelled, the signal input to the pulse compressor 13 is sequentially dispersed in the pulse without causing a mismatch, similarly to the operation described with reference to FIG. The frequency components are concentrated at one point, forming a steep impulse. The impulse reception signal from the pulse compressor 13 is detected by the moving target detector 14 and the target detector 15, and displayed on an indicator (not shown). Thus, it is possible to prevent the pulse compression characteristic from deteriorating irrespective of the Doppler shift due to the target.

As described above, in the present embodiment, the offset means for offsetting the frequency of the transmission signal by a target Doppler shift in advance to generate a transmission stirrer signal by offsetting the frequency of the basic stirrer signal is provided. By having this, the frequency offset at the time of transmission and the Doppler shift given by the target cancel each other, and it is possible to prevent deterioration of the pulse compression characteristic.

Embodiment 2 In the first embodiment, the case where the frequency of the stirrer signal of the transmission system is frequency-offset so that the frequency of the transmission signal is offset in advance by the target Doppler shift has been described. This is a case where the frequency of the coherent signal is offset. FIG. 2 is a functional system diagram showing Embodiment 2 of the present invention. In the figure, a mixer 5d provided between the mixer 5b and the stabilized local oscillator 6 in FIG. 1 is provided between the mixer 5a and the coherent oscillator 9, and a similar offset signal generator 7 is provided for the mixer 5d. . Other configurations are the same as those in FIG.

Next, the operation will be described. As in the first embodiment, when the target Doppler shift fdt can be predicted in advance, an offset signal having a frequency equivalent to the Doppler shift fdt is generated in the offset signal generator 7 and generated by the coherent oscillator 9. The mixer 5d converts the frequency of the basic coherent signal having the frequency fcoho. The coherent signal of the transmission system offset to the frequency fcoho-fdt is supplied to the mixer 5a, and the pulse width T generated by the transmission pulse generator 10 is calculated.
Is converted to a frequency. The frequency-converted signal is converted by the pulse expander 8 into a linear frequency-modulated pulse having a bandwidth Δf.

The modulated pulse from the pulse expander 8 is frequency-converted to a carrier frequency fc-fdt by a stray signal having a frequency fo generated by a stabilized local oscillator 6 in a mixer 5b. After a predetermined amplification is performed, the signal is radiated from the transmission / reception antenna 1 through the circulator 2 to the space as a transmission radio wave. The frequency of the transmission radio wave is offset by the predicted target Doppler shift as in the first embodiment.

The transmission radio wave is reflected by the target 3 and the Doppler shift fdt accompanying the movement of the target 3 is added. However, the transmission radio wave offsets the frequency offset of the transmission radio wave given in advance, and as a result, the frequency of the reflected reception radio wave Is fc, and the received radio wave of this frequency fc is received by the transmitting / receiving antenna 1. Therefore, similarly to the first embodiment, the received radio wave can be subjected to reception processing in a form equivalent to the case where the Doppler shift fdt of the target 3 is not given, and regardless of the Doppler shift due to the target, a pulse can be generated without causing a mismatch. Compression can be performed, and deterioration of pulse compression characteristics can be prevented.

As described above, in this embodiment, the offset means for offsetting the frequency of the transmission signal by the target Doppler shift in advance to generate the stirl signal of the transmission system by frequency offsetting the basic coherent signal is provided. By having, frequency offset at the time of transmission,
The Doppler shift given by the target is canceled out, and it is possible to prevent the pulse compression characteristics from deteriorating.

Embodiment 3 Also, in the first embodiment, the case has been described where the frequency of the stirrer signal of the transmission system is offset so that the frequency of the transmission signal is offset in advance by the target Doppler shift. This is a case where the center frequency of the device is frequency offset. FIG. 3 is a functional system diagram showing Embodiment 3 of the present invention. In the figure, reference numeral 8a denotes a pulse extender whose center frequency is frequency-offset by adding a frequency offset of fdt in advance to a modulation coefficient for performing pulse modulation, and constitutes offset means as first frequency offset means. I do. Other configurations are the same as those in FIG. 1 except that the mixer 5d and the offset signal generator 7 are omitted.

Next, the operation will be described. As in the first embodiment, a rectangular pulse having a frequency fcoho from the mixer 5a is input to the pulse expander 8a. Here, when the pulse expander 8a is of a digital type, the frequency offset of the center frequency can be easily made by adding a frequency offset of fdt in advance to a modulation coefficient for performing pulse modulation. By such a pulse expander 8a, a linear frequency-modulated pulse having a bandwidth Δf offset by fdt is generated, as in the first embodiment.
It is radiated from the transmitting / receiving antenna 1 to space as a transmission radio wave.

Since the frequency of the transmission radio wave is offset by the predicted Doppler shift of the target 3 as in the first embodiment, the Doppler shift fdt accompanying the movement of the target 3 is canceled. The received radio wave can be processed in a form equivalent to the case where the Doppler shift fdt of the target 3 is not given, and the pulse can be compressed without causing a mismatch regardless of the Doppler shift due to the target 3, and the pulse compression characteristic deteriorates. Can be prevented.

As described above, in the present embodiment, a digital pulse expander is provided as offset means for offsetting the center frequency so that the frequency of the transmission signal is offset in advance by the target Doppler shift. , The frequency offset at the time of transmission and the Doppler shift given by the target cancel each other out, and it is possible to prevent deterioration of the pulse compression characteristic.

Embodiment 4 FIG. Also, in the first embodiment, the case where the frequency of the stirrer signal of the transmission system is frequency-offset so that the frequency of the transmission signal is offset by the target Doppler shift in advance has been described. This is a case where the stray signal of the reception system is frequency-offset so that the frequency of the reception signal is offset by the deviation. FIG. 4 shows Embodiment 4 of the present invention.
FIG. In the figure, a mixer 5 provided between a mixer 5b and a stabilized local oscillator 6 in FIG.
d is provided between the stabilized local oscillator 6 and the mixer 5c,
A similar offset signal generator 7 is provided for the mixer 5d. Other configurations are the same as those in FIG.

Next, the operation will be described. Figure 1 above
As in 9, first, without considering the Doppler shift of target 3,
A linear frequency-modulated pulse having a carrier frequency fc and a bandwidth Δf is radiated from the transmission / reception antenna 1 to space as a transmission radio wave. The transmission radio wave is reflected by the target 3 and the Doppler shift fdt accompanying the movement of the target 3 is added. Therefore, the frequency of the reflected reception radio wave is fc + fdt, which is received by the transmission / reception antenna 1.

This received radio wave is amplified by the low-noise amplifier 11 through the circulator 2. As in the first embodiment, when the target Doppler shift fdt can be predicted in advance, the offset signal generator 7 An offset signal of this Doppler shift fdt frequency is generated, and the mixer 5d converts the frequency of the basic stalo of the frequency fo generated by the stabilized local oscillator 6. This frequency f
By supplying the stirling signal of the receiving system offset to o-fdt to the mixer 5c and frequency-converting the receiving signal from the low-noise amplifier 11, the Doppler shift accompanying the movement of the target 3 and the stray signal of the receiving system are reduced. The frequency offset amount is cancelled, and is input to the phase detector 12 as a linear frequency modulation pulse having a frequency fcoho and a bandwidth Δf. Accordingly, the subsequent reception processing is performed in a form equivalent to the case where the Doppler shift of the target 3 is not given. Thus, also in this case, regardless of the Doppler shift due to the target, pulse compression can be performed without causing a mismatch, and deterioration of pulse compression characteristics can be prevented.

As described above, in the present embodiment, there is provided an offset means for offsetting the frequency of the received signal by the target Doppler shift to generate the stray signal of the receiving system by frequency offsetting the basic starrow signal. Thus, the Doppler shift given by the target is canceled by the frequency offset at the time of reception, and it is possible to prevent the pulse compression characteristics from deteriorating.

Embodiment 5 In the first embodiment, the case has been described where the frequency of the stirrer signal of the transmission system is offset in advance so that the frequency of the transmission signal is offset by the target Doppler shift in advance. This is a case where the center frequency of the pulse compression of the receiving system is frequency offset so that the frequency of the received signal is offset by the Doppler shift. FIG. 5 is a functional system diagram showing Embodiment 5 of the present invention. In the figure, 1
Reference numeral 3a denotes a pulse compressor for performing frequency-offset of the center frequency by a target Doppler shift fdt to perform pulse compression, and constitutes offset means as first frequency offset means. Other configurations are the same as those in FIG. 1 except that the mixer 5d and the offset signal generator 7 are omitted.

Next, the operation will be described. As in the method described in the fourth embodiment, first, a linear frequency modulated pulse having a carrier frequency fo and a bandwidth △ f is transmitted from the transmitting / receiving antenna 1 to space as a transmitting radio wave without considering the Doppler shift of the target 3. Radiate. The transmission radio wave is reflected by the target 3 and the Doppler shift fdt accompanying the movement of the target 3 is added. Therefore, the frequency of the reflected reception radio wave is fc + fdt, which is received by the transmission / reception antenna 1.

The received radio wave is amplified by the low-noise amplifier 11 through the circulator 2 and is mixed with the stray signal of the frequency fo generated by the stabilized local oscillator 6 by the mixer 5.
After being supplied to c and frequency-converted, it is phase-detected by the phase detector 12. Then, as in the first embodiment,
If the target Doppler shift fdt can be predicted in advance, the pulse compressor 13a frequency-offsets the center frequency by the Doppler shift fdt to compress the pulse, thereby obtaining the Doppler shift accompanying the movement of the target 3 and the pulse compression. The frequency offset amount is canceled, and pulse compression can be performed without causing a mismatch. Thus, also in this case, regardless of the Doppler shift due to the target, it is possible to prevent the pulse compression characteristics from deteriorating.

As described above, in the present embodiment, by providing the pulse compressor as the offset means for offsetting the center frequency so as to offset the frequency of the received signal by the target Doppler shift, the pulse width is given by the target. The obtained Doppler shift is canceled by the frequency offset at the time of reception, so that it is possible to prevent the deterioration of the pulse compression characteristic.

Embodiment 6 FIG. In addition, the first embodiment
In 5, the target speed of interest is within a certain narrow range,
Although the case where the Doppler shift can be predicted in advance has been described, in the present embodiment, the speed of the target target can be predicted in advance within a certain narrow range. However, when there are a plurality of target speeds, In this case, the offset is performed while switching the stirrer signal of the transmission system so as to offset the frequency of the transmission signal by the amount of the Doppler shift.

FIG. 6 is a functional system diagram showing Embodiment 6 of the present invention. In the figure, reference numerals 6a to 6c denote stabilizing local oscillators each generating a stall signal having a predetermined frequency in accordance with the Doppler shift of the target 3 to be processed, and 16 denotes a plurality of speeds Vt1, Vt2, Vt3 of the target 3. This is an offset switching device that switches the starrow signals from the stabilized local oscillators 6a to 6c and supplies the signals to the mixer 5b. Note that the stabilized local oscillators 6a to 6c and the offset switch 1
6 constitutes an offset means as a second frequency offset means. Other configurations are the same as those in FIG. 1 except that the mixer 5d and the offset signal generator 7 are omitted.

Next, the operation will be described. For example, the Doppler shift of target 3 is fdt1, fdt2, fdt
In the case of 3, the frequencies of the starrow signals generated in the stabilized local oscillators 6a to 6c are respectively fo-fdt1, fo
−fdt2, fo−fdt3. The mixer 5b frequency-converts the linear frequency-modulated pulse of the transmission system while switching the stallow signals from the stabilized local oscillators 6a to 6c corresponding to the respective speeds of the target 3 by the offset switch 16. Since the frequency of the transmission radio wave radiated from the transmitting / receiving antenna 1 to the space is offset by the target Doppler shift at each speed, the frequency can be offset by the Doppler shift added when reflected by the target 3 and reflected. The frequency of the received radio wave becomes fc for any target at any speed, and the received radio wave of this frequency fc is received by the transmitting / receiving antenna 1.

Therefore, even when the speed of the target 3 is plural, the received radio wave is received in a form equivalent to the case where the Doppler shift fdt of the target 3 is not given, as in the other embodiments. Processing can be performed and pulse compression can be performed without causing a mismatch, regardless of the Doppler shift due to the target 3, and deterioration of pulse compression characteristics can be prevented.

As described above, in the present embodiment, a plurality of starrow signals of the transmission system are frequency offset so as to correspond to a plurality of speed targets and offset the frequency of the transmission signal by the target Doppler shift in advance. The frequency offset at the time of transmission with respect to the target of each speed and the Doppler shift given by the target cancel each other out, and it is possible to prevent pulse compression characteristics from deteriorating. Become.

Embodiment 7 FIG. Further, in the sixth embodiment, the case where the offset is performed while switching the stirrer signal of the transmission system so as to offset the frequency of the transmission signal by the amount of the target Doppler shift having a plurality of velocities,
In the present embodiment, there is a case where a frequency offset amount corresponding to a target Doppler shift of each speed is given to a basic stray signal of a transmission system serving as a reference while switching.

FIG. 7 is a functional system diagram showing Embodiment 7 of the present invention. In the figure, 7a to 7c are mixers 5
A plurality of offset signal generators 16 for supplying offset signals having frequencies corresponding to the respective Doppler shifts of the target 3 of interest with respect to d, these offset signal generators 7a to 7c correspond to the target 3 And an offset switch 16 for supplying the output to the mixer 5d. Note that the offset signal generators 7a to 7c, the offset switch 16 and the mixer 5d constitute offset means as second frequency offset means. In other configurations, except that the offset signal generator 7 is deleted,
It is the same as FIG.

Next, the operation will be described. For example, the Doppler shift of target 3 is fdt1, fdt2, fdt
3, the frequency of the offset signal generated in the offset signal generators 7a to 7c is -fdt1,-
fdt2 and -fdt3. And the offset switch 1
6, while switching these offset signal generators 7a to 7c corresponding to the respective target speeds, first, the mixer 5d
The reference frequency fo from the stabilized local oscillator 6
The frequency of the starrow signal is converted. As a result, a starrow signal corresponding to the target Doppler shift at each speed is generated, and the linear frequency modulated pulse of the transmission system is frequency-converted by the mixer 5b using this starrow signal as in the sixth embodiment.

Since the frequency of the transmission radio wave radiated from the transmission / reception antenna 1 to the space is offset by the target Doppler shift at each speed, the frequency is offset by the Doppler shift added when reflected by the target 3. The frequency of the reflected received radio wave is fc for any speed target, and this is received by the transmitting / receiving antenna 1. Therefore, similarly to the sixth embodiment, the received radio wave can be subjected to reception processing in a form equivalent to the case where the Doppler shift fdt of the target 3 is not given, and no mismatch occurs regardless of the Doppler shift due to the target. Pulse compression can be performed, and deterioration of pulse compression characteristics can be prevented.

As described above, this embodiment corresponds to a plurality of Doppler shifts so as to correspond to a target having a plurality of speeds and offset the frequency of the transmission signal by the target Doppler shift in advance. By providing offset means for generating a stirling signal of the transmission system by frequency offsetting the basic stirling signal while generating and switching the signal, the frequency offset at the time of transmission for each speed target and the Doppler deviation given by the target are provided. The transfer is offset,
Deterioration of the pulse compression characteristics can be prevented.

Embodiment 8 FIG. Further, in the sixth embodiment, the case where the offset is performed while switching the stirrer signal of the transmission system so as to offset the frequency of the transmission signal by the amount of the target Doppler shift having a plurality of velocities,
In the present embodiment, the offset is performed while switching the coherent signal of the transmission system.

FIG. 8 is a functional system diagram showing an eighth embodiment of the present invention. In the figure, reference numerals 9a to 9c denote coherent oscillators for generating coherent signals corresponding to the respective Doppler shifts of the target 3 to be processed. These coherent oscillators 9a to 9c are offset switches corresponding to the target 3. The output is supplied to the mixer 5a by switching by 16. Note that the coherent oscillators 9a to 9c and the offset switch 16 constitute offset means as second frequency offset means. Other configurations are the same as those in FIG. 1 except that the mixer 5d and the offset signal generator 7 are omitted.

Next, the operation will be described. For example, the Doppler shift of target 3 is fdt1, fdt2, fdt
3, the frequencies of the coherent signals generated in the coherent oscillators 9a to 9c are respectively fcoho-fdt
1, fcoho-fdt2 and fcoho-fdt3. And
While the coherent signals from the coherent oscillators 9a to 9c are switched by the offset switch 16 corresponding to each speed of the target 3, the transmission pulse generator 1 is switched by the mixer 5a.
After frequency conversion of the rectangular pulse generated by 0, a frequency modulation with a bandwidth Δf is given. Since the frequency of the transmission radio wave radiated from the transmitting / receiving antenna 1 to the space is offset by the Doppler shift of the own target at each speed,
The Doppler shift added when reflected by the target 3 can be canceled out, and the frequency of the reflected received radio wave becomes fc for any speed target, which is received by the transmitting / receiving antenna 1.

Therefore, even in the case where there are a plurality of target velocities, similarly to the other embodiments, the reception radio wave is subjected to reception processing in a form equivalent to the case where the target Doppler shift fdt is not given. Yes, regardless of the Doppler shift due to the goal,
Pulse compression can be performed without causing a mismatch, and deterioration of pulse compression characteristics can be prevented.

As described above, in the present embodiment, a plurality of coherent signals of the transmission system are frequency-shifted so as to correspond to a target having a plurality of velocities and offset the frequency of the transmission signal by the target Doppler shift in advance. By having an offset means that generates an offset and switches this, the frequency offset at the time of transmission with respect to the target of each speed and the Doppler shift given by the target cancel each other, and it is possible to prevent the deterioration of the pulse compression characteristic Becomes

Embodiment 9 Also, in the above-mentioned Embodiment 8, a case has been shown in which the coherent signal of the transmission system is offset while switching the coherent signal so as to offset the frequency of the transmission signal by the amount of the target Doppler shift having a plurality of velocities. In this embodiment, a frequency offset amount corresponding to a target Doppler shift of each speed is given to a basic coherent signal of a transmission system serving as a reference while switching.

FIG. 9 is a functional system diagram showing Embodiment 9 of the present invention. In the figure, a plurality of offset signal generators 7a to 7c for supplying offset signals having frequencies corresponding to the respective Doppler shifts of the target 3 to be processed as in FIG.
a to 7c are switched by the offset switch 16 corresponding to each speed of the target 3, and the output is supplied to the mixer 5d provided between the mixer 5a and the coherent oscillator 9. The coherent oscillators 9a to 9c, the offset switch 16 and the mixer 5d constitute offset means as second frequency offset means. Other configurations are the same as those in FIG. 1 except that the mixer 5d and the offset signal generator 7 are omitted.

Next, the operation will be described. For example, the Doppler shift of the target 3 is fdt1, fdt2, fdt
3, the frequency of the offset signal generated by the offset signal generators 7a to 7c is -fdt1,
-Fdt2 and -fdt3. Then, while the outputs of the offset signal generators 7a to 7c are switched by the offset switch 16 corresponding to each speed of the target 3, the mixer 5
The frequency of the coherent signal of the reference frequency fcoho is converted by d.

As a result, a coherent signal corresponding to the target Doppler shift of each speed is generated.
Similarly, after the frequency of the rectangular pulse generated by the transmission pulse generator 10 is converted by the mixer 5a, the bandwidth Δf
Frequency modulation. Since the frequency of the transmission radio wave radiated from the transmitting / receiving antenna 1 to the space is offset by the target Doppler shift at each speed, the frequency can be offset by the Doppler shift added when reflected by the target 3 and reflected. The frequency of the received radio wave becomes fc for any target at any speed, and the received radio wave of this frequency fc is received by the transmitting / receiving antenna 1.

Accordingly, similarly to the eighth embodiment, the received radio wave can be received in a form equivalent to the case where the Doppler shift fdt of the target 3 is not given, and a mismatch is generated regardless of the Doppler shift due to the target. Thus, pulse compression can be performed without deterioration, and deterioration of pulse compression characteristics can be prevented.

As described above, this embodiment corresponds to a plurality of Doppler shifts so as to correspond to a target having a plurality of speeds and offset the frequency of the transmission signal by the target Doppler shift in advance. By providing offset means for generating a coherent signal of the transmission system by frequency offsetting the basic coherent signal while generating and switching the signal, the frequency offset at the time of transmission with respect to each speed target and the Doppler deviation given by the target are provided. The shift is cancelled, and it is possible to prevent the pulse compression characteristic from deteriorating.

Embodiment 10 FIG. Embodiment 6
In the above, the offset is performed while switching the stirrer signal of the transmission system so as to offset the frequency of the transmission signal by the amount of the target Doppler shift having a plurality of velocities. This is a case where the offset is performed while switching the center frequency of the coefficient.

FIG. 10 is a functional system diagram showing an embodiment of the present invention. In the figure, reference numerals 17a to 17c denote pulse expansion coefficient generators each generating a pulse expansion coefficient of a predetermined frequency in accordance with the Doppler shift of the target 3 to be processed. To the vessel 8. The pulse expansion coefficient generators 17a to 17c and the offset switch 16
Constitutes offset means as second frequency offset means. Other configurations are the same as those in FIG. 1 except that the mixer 5d and the offset signal generator 7 are omitted.

Next, the operation will be described. For example, the Doppler shift of target 3 is fdt1, fdt2, fdt
In the case of 3, the pulse expansion coefficients generated in the pulse expansion coefficient generators 17a to 17c are respectively represented by the frequencies fcoho-f
dt1, fcoho-fdt2, and fcoho-fdt3. Then, the pulse expansion coefficient generators 17a to 17c corresponding to the respective speeds of the target 3 by the offset switch 16
Are supplied to the pulse expander 8 while switching the output, and the pulse expander 8 gives the frequency modulation of the bandwidth Δf.

Since the frequency of the transmission radio wave radiated from the transmitting / receiving antenna 1 to the space is offset by the target Doppler shift at each speed, the frequency is offset by the Doppler shift added when reflected by the target 3. The frequency of the reflected received radio wave is fc for any target at any speed, and the received radio wave of this frequency fc is received by the transmitting / receiving antenna 1.

Therefore, even when the speed of the target 3 is plural, the received radio wave is received in a form equivalent to the case where the Doppler shift fdt of the target 3 is not given, as in the other embodiments. Processing can be performed, and pulse compression can be performed without causing a mismatch, regardless of the Doppler shift due to the target, and deterioration of pulse compression characteristics can be prevented.

As described above, in the present embodiment, a plurality of digital signals each having a center frequency offset so as to correspond to a target having a plurality of velocities and offset the frequency of a transmission signal by the target Doppler shift in advance. By having an offset means for switching the pulse extension coefficient,
The frequency offset at the time of transmission with respect to the target of each speed and the Doppler shift given by the target cancel each other, so that it is possible to prevent deterioration of the pulse compression characteristic.

Embodiment 11 FIG. Embodiment 1
In the case of 0, offset is performed while switching the center frequency of the digital pulse expansion coefficient so as to offset the frequency of the transmission signal by the amount of the target Doppler shift having a plurality of velocities. In this case, a frequency offset amount corresponding to a target Doppler shift at each speed is given to a basic coefficient of a digital pulse expander as a reference while switching.

FIG. 11 is a functional system diagram showing Embodiment 11 of the present invention. In the figure, reference numerals 18a to 18c denote offset coefficient generators each generating an offset coefficient corresponding to the Doppler shift of the target 3 to be processed,
The output is switched by the offset switch 16 and supplied to the pulse expander 8. The offset coefficient generators 18a to 18c and the offset switch 16
, An offset means as a frequency offset means. Other configurations are the same as those in FIG. 1 except that the mixer 5d and the offset signal generator 7 are omitted.

Next, the operation will be described. For example, the Doppler shift of the target 3 is fdt1, fdt2, fdt
In the case of 3, the offset coefficients generated in the offset coefficient generators 18a to 18c are each represented by a frequency -fdt.
1, -fdt2 and -fdt3. Then, while the outputs of the offset coefficient generators 18a to 18c are switched according to the respective speeds of the target 3 by the offset switch 16, the frequency expansion of the bandwidth Δf is given by the pulse expander 8. Since the frequency of the transmission radio wave radiated from the transmitting / receiving antenna 1 to the space is offset by the target Doppler shift at each speed, the frequency can be offset by the Doppler shift added when reflected by the target 3 and reflected. The frequency of the received radio wave obtained is fc for any speed target, and the received radio wave of this frequency fc is received by the transmitting / receiving antenna 1.

Therefore, similarly to the tenth embodiment, the received radio wave can be received in a form equivalent to the case where the Doppler shift fdt of the target 3 is not given. Pulse compression can be performed without occurrence, and deterioration of pulse compression characteristics can be prevented.

As described above, in the present embodiment, a digital signal corresponding to a plurality of Doppler shifts is set so as to correspond to a target having a plurality of speeds and offset the frequency of the transmission signal by the target Doppler shift in advance. By having offset means for frequency offsetting the basic coefficient of the digital pulse expander while switching the pulse expansion coefficient, the frequency offset at the time of transmission for each speed target and the Doppler shift given by the target are offset, Deterioration of the pulse compression characteristics can be prevented.

Embodiment 12 FIG. Embodiment 6
In the above, the case where the offset is performed while switching the stirrer signal of the transmission system so as to offset the frequency of the transmission signal by the amount of the target Doppler shift having a plurality of speeds has been described. For the signal
This is a case where the frequency offset amount for each target of each speed is given while being switched.

FIG. 12 is a functional system diagram showing a twelfth embodiment of the present invention. In the figure, FIG.
, The stabilized local oscillators 6a1 to 6c provided to the mixer 5c instead of the stabilized local oscillators 6a to 6c provided for the mixer 5c.
c1 is provided, and these outputs are switched by the offset switch 16 and supplied to the mixer 5c. The stabilized local oscillators 6a1 to 6c1 and the offset switch 16
Constitutes offset means as second frequency offset means. Other configurations are the same as those in FIG. 1 except that the mixer 5d and the offset signal generator 7 are omitted.

Next, the operation will be described. First, similarly to the method described in the fourth embodiment, a linear frequency modulation pulse having a carrier frequency fc and a bandwidth Δf is radiated from the transmitting / receiving antenna 1 to space as a transmission radio wave without considering the target Doppler shift. . For example, when the Doppler shift of the target 3 is fdt1, fdt2, fdt3, the transmitted radio wave is reflected by the target 3, and the Doppler shift accompanying the movement of the target 3 is added. The frequencies of the radio waves are fc + fdt1, fc + fdt2, fc + fdt3, and the received radio waves having these frequencies are received by the transmitting / receiving antenna 1.

In the receiving process, the stabilized local oscillator 6a
The frequencies of the starrow signals generated in 1 to 6c1 are fo + fdt1, fo + fdt2, and fo + fdt3, respectively. The received signal is frequency-converted by the mixer 5c while the outputs of the stabilized local oscillators 6a to 6c are switched in accordance with the respective speeds of the target 3 by the offset switch 16 to reduce the Doppler shift accompanying the movement of the target 3. The frequency offset amount of the stirrer signal of the receiving system is canceled, and is input to the phase detector 12 as a linear frequency modulation pulse having a frequency fcoho and a bandwidth Δf. Therefore, the subsequent reception processing is performed in a form equivalent to the case where the target Doppler shift is not given.

Therefore, even in the case where there are a plurality of target velocities, similarly to the other embodiments, the received radio wave is subjected to reception processing in a form equivalent to the case where the Doppler shift fdt of the target 3 is not given. Thus, regardless of the Doppler shift due to the target, pulse compression can be performed without causing a mismatch, and deterioration of pulse compression characteristics can be prevented.

As described above, in the present embodiment, a plurality of starrow signals of the receiving system are frequency-offset so as to correspond to a target having a plurality of velocities and offset the frequency of the received signal by the target Doppler shift. And the offset means for switching between them, the Doppler shift given by the target is canceled by the frequency offset at the time of reception with respect to the target of each speed, and it becomes possible to prevent the deterioration of the pulse compression characteristic. .

Embodiment 13 FIG. Embodiment 1
In FIG. 2, the case where the offset is performed while switching the stirrer signal of the receiving system so as to offset the frequency of the received signal by a plurality of target Doppler shifts is described. This is a case in which the frequency offset amount for each target of each speed is given to the basic stirling signal while switching.

FIG. 13 is a functional system diagram showing Embodiment 13 of the present invention. In the figure, the mixer 5b in FIG.
5d provided between the power supply and the stabilized local oscillator 6
Is provided between the stabilized local oscillator 6 and the mixer 5c, and a plurality of offset signal generators 7 are provided to the mixer 5d.
a to 7c are provided, and these outputs are connected to the offset switch 16
To switch to supply to the mixer 5c. The offset signal generators 7a to 7c, the offset switch 16 and the mixer 5d constitute offset means as second frequency offset means. Other configurations are the same as those in FIG.

Next, the operation will be described. First, similarly to the method described in the twelfth embodiment, a linear frequency modulated pulse having a carrier frequency fc and a bandwidth Δf is radiated from the transmitting / receiving antenna 1 to space as a transmitting radio wave without considering the target Doppler shift. I do. For example, when the Doppler shift of the target 3 is fdt1, fdt2, fdt3, the transmitted radio wave is reflected by the target 3, and the Doppler shift accompanying the movement of the target 3 is added. The frequencies of the radio waves are fc + fdt1, fc + fdt2, fc + fdt3, and the received radio waves having these frequencies are received by the transmitting / receiving antenna 1.

In the receiving process, the frequencies of the offset signals generated by the offset signal generators 7a to 7c are respectively fdt1, fdt2, and fdt3. Then, while switching the outputs of the offset signal generators 7a to 7c corresponding to the respective speeds of the target 3 by the offset cut detector 16, first, the mixer 5d converts the frequency of the stallow signal of the reference frequency fo by the mixer 5d. As a result, a starrow signal corresponding to the target Doppler shift at each speed is generated. The received signal is frequency-converted by the mixer 5c in the same manner as in the twelfth embodiment, so that the Doppler shift accompanying the movement of the target 3 is obtained. Then, the frequency offset amount of the stirrer signal of the receiving system is canceled, and is input to the phase detector 12 as a linear frequency modulation pulse having a frequency fcoho and a bandwidth Δf.

Accordingly, the subsequent reception processing is performed in a form equivalent to the case where the Doppler shift of the target 3 is not given. Therefore, even when there are a plurality of target velocities, similarly to the other embodiments, the received radio wave can be subjected to reception processing in a form equivalent to the case where the Doppler shift fdt of the target 3 is not given. Irrespective of the Doppler shift due to the target, the pulse pressure width can be increased without causing a mismatch, and deterioration of the pulse compression characteristic can be prevented.

As described above, in the present embodiment, a signal corresponding to a plurality of Doppler shifts is offset so as to correspond to a target having a plurality of velocities and offset the frequency of the received signal by the target Doppler shift. By generating a stirling signal of the receiving system by frequency offsetting the basic stirling signal while switching, so that the Doppler shift given by the target is the frequency offset at the time of reception with respect to the target at each speed. Thus, the pulse compression characteristics can be prevented from deteriorating.

Embodiment 14 FIG. Embodiment 6
In the above, a case has been described in which the offset of the transmission signal is offset while switching the stirrer signal of the transmission system so as to offset the frequency of the transmission signal by the amount of the target Doppler shift having a plurality of velocities. This is a case in which a plurality of offsets of the center frequency are provided for each target of each speed while switching.

FIG. 14 is a functional system diagram showing a fourteenth embodiment of the present invention. In the figure, reference numerals 13a to 13c denote a plurality of pulse compressors for performing pulse compression by frequency offsetting the center frequency by a target Doppler shift fdt. An offset switch 16a for switching the input side of the pulse compressors 13a to 13c is provided between the pulse compressors 13a to 13c and the phase detector 12.
An offset switch 16b for switching the output side of the pulse compressors 13a to 13c is provided between the moving target detector 14 and the moving target detector 14. The pulse compressors 13a to 13c and the offset switches 16a and 16b constitute offset means as second frequency offset means. Other configurations are the same as those in FIG. 1 except that the mixer 5d and the offset signal generator 7 are omitted.

Next, the operation will be described. First, similarly to the method described in the twelfth embodiment, a linear frequency modulated pulse having a carrier frequency fc and a bandwidth Δf is radiated from the transmitting / receiving antenna 1 to space as a transmitting radio wave without considering the target Doppler shift. I do. For example, when the Doppler shift of the target 3 is fdt1, fdt2, fdt3, the transmitted radio wave is reflected by the target 3, and the Doppler shift accompanying the movement of the target 3 is added. The frequencies of the radio waves are fc + fdt1, fc + fdt2, fc + fdt3, and the received radio waves having these frequencies are received by the transmitting / receiving antenna 1.

In the receiving process, up to phase detection is performed in the same manner as in the method described in the fifth embodiment. The center frequencies of the pulse compressors 13a to 13c are respectively fo + fdt1 and fo +
fdt2, fo + fdt3. Then, the phase detector 1 corresponding to each speed of the target 3 is set by the offset switch 16a.
2 is switched by the pulse compressors 13a to 13c while the output of each pulse compressor is switched by the offset switch 16b.
In this way, the Doppler shift due to the movement of the target 3 and this frequency offset amount are canceled out, and regardless of the Doppler shift due to the target, pulse compression can be performed without causing a mismatch and deterioration of pulse compression characteristics can be prevented. it can.

As described above, in the present embodiment, a plurality of pulse compressors whose center frequencies are offset so as to correspond to a target having a plurality of velocities and offset the frequency of the received signal by the target Doppler shift. , The Doppler shift given by the target is canceled by the frequency offset at the time of reception with respect to the target at each speed, and it is possible to prevent the pulse compression characteristic from deteriorating.

Embodiment 15 FIG. Embodiment 1
In FIG. 4, a case is shown in which a plurality of pulse compressors are provided so as to offset the frequency of the received signal by a target Doppler shift having a plurality of speeds.
A configuration may be adopted in which the coefficient of the pulse compressor is given while being switched for each target of each speed. FIG. 15 is a functional system diagram showing Embodiment 15 of the present invention. In the figure, 19a-
Reference numeral 19c denotes a pulse compression coefficient generator that generates a compression coefficient for performing pulse compression. The output of the pulse compression coefficient generator 19c is switched by the offset switch 16 and supplied to the pulse compressor 13. Note that the pulse compression coefficient generators 19a to 19c and the offset switch 16 constitute offset means as second frequency offset means. Other configurations are the same as those in FIG. 1 except that the mixer 5d and the offset signal generator 7 are omitted.

Next, the operation will be described. First, similarly to the method described in the fourteenth embodiment, a linear frequency modulation pulse having a carrier frequency fo and a bandwidth Δf is radiated from the transmitting / receiving antenna 1 to space as a transmitting radio wave without considering the target Doppler shift. I do. For example, when the Doppler shift of the target 3 is fdt1, fdt2, fdt3, the transmitted radio wave is reflected by the target 3, and the Doppler shift accompanying the movement of the target 3 is added. The frequencies of the radio waves are fc + fdt1, fc + fdt2, fc + fdt3, and the received radio waves having these frequencies are received by the transmitting / receiving antenna 1.

In the receiving process, up to phase detection is performed in the same manner as in the method described in the fourteenth embodiment. When the pulse compressor 13 is of a digital type, it is easy to perform frequency offset switching of a compression coefficient for performing pulse compression. The center frequencies of the pulse compression coefficient generators 19a to 19c are respectively fo + fdt1, fo + fdt2, fo + fdt
3 is assumed. The target 3 is set by the offset switch 16.
Pulse compression coefficient generators 19a to 19 corresponding to respective speeds of
By performing pulse compression by the pulse compressor 13 while switching the output of c, the Doppler shift accompanying the movement of the target 3 and this frequency offset amount are canceled out, and no mismatch occurs regardless of the Doppler shift due to the target 3. Pulse compression can be performed, and deterioration of pulse compression characteristics can be prevented.

As described above, in the present embodiment, an offset for switching a plurality of digital pulse compression coefficients corresponding to a target having a plurality of velocities and offsetting the frequency of the received signal by the amount of the target Doppler shift. By having the means, the Doppler shift given by the target is canceled by the frequency offset at the time of reception with respect to the target of each speed, and it becomes possible to prevent the pulse compression characteristic from deteriorating.

Embodiment 16 FIG. Embodiment 6
In No. to No. 15, the case where the speed of the target target can be predicted in a narrow range in advance, and when there are a plurality of target speeds, the case where the frequency offset amount is switched and selected according to the target Doppler shift has been described. Although the speed of the target changes, the trajectory of the target is predicted in advance, and if the Doppler shift of the target can be predicted in advance by the azimuth and elevation angle seen from the radar, based on the beam azimuth or azimuth elevation angle or both, This is a case where a frequency offset amount is selected and controlled so as to correspond to a target Doppler shift.

FIG. 16 is a functional system diagram showing a sixteenth embodiment of the present invention. In the drawing, reference numerals 3a and 3b denote targets having different speeds, azimuths, and elevation angles, and reference numeral 20 denotes a beam pointing controller as a control means, which corresponds to the Doppler shift of the target based on the azimuth and / or azimuth of the beam. Next, the offset switch 16 is switched to select and control the outputs of the stabilized local oscillators 6a and 6b, and to control the direction of the transmitting / receiving antenna 1. In addition,
Stabilized local oscillators 6a and 6b and offset switch 1
6 constitutes an offset means as a second frequency offset means. Other configurations are the same as those in FIG.

Next, the operation will be described. For example, if the Doppler shift of the target 3a having the speed Vt1 can be predicted to be fdt1, and the Doppler shift of the target 3b having a different azimuth, elevation angle, and speed Vt2 can be predicted to be fdt2, the beam pointing controller 20 controls the beam. Is switched so as to select the stabilized local oscillator 6a having the frequency fo-fdt1 when pointing in the direction of the target 3a, and to select the stabilized local oscillator 6b having frequency fo-fdt2 when pointing in the direction of the target 3b. The device 16 is selected and controlled.

The above selection by the beam pointing controller 20,
By the control, the Doppler shift due to the movement of the target and the frequency offset amount are offset, and regardless of the Doppler shift due to the target, pulse compression can be performed without causing a mismatch and deterioration of pulse compression characteristics can be prevented. Although the present embodiment shows the case where the stirrer signal of the transmission system is selected and controlled, the same applies to other embodiments.

As described above, in the present embodiment, the Doppler deviation of the corresponding target is determined based on the beam azimuth and / or directional elevation angle so as to correspond to the case where the Doppler shift differs depending on the azimuth or elevation of the target. By having control means for selecting and controlling the switching of the offset means so as to correspond to the shift, the Doppler shift given by the target is canceled by the frequency offset which is selected and controlled for each individual target, and the pulse compression Deterioration of characteristics can be prevented, and it is possible to reliably cope with the case where the Doppler shift differs depending on the target azimuth or elevation angle.

Embodiment 17 FIG. Embodiment 1
In FIG. 6, the case where the frequency offset amount is selected and controlled so as to correspond to the target Doppler shift according to the beam azimuth and / or the directional elevation angle or both is shown. In the present embodiment, the above embodiments 12 to 15 are used. When the frequency offset is performed in the receiving system shown in (1), the frequency offset amount is selected and controlled so as to correspond to the target Doppler shift based on the target distance or the combination thereof in addition to the beam azimuth or directional elevation angle. is there.

FIG. 17 is a functional system diagram showing a seventeenth embodiment of the present invention. In the figure, FIG.
In place of the stabilized local oscillators 6a, 6b provided for b, the stabilized local oscillators 6a1, 6a1,
6b1 is provided, and these outputs are switched by the offset switch 16 based on the control of the beam pointing controller 20 and the target distance controller 21 and supplied to the mixer 5c. The stabilized local oscillators 6a1 and 6b1 and the offset switch 16 constitute offset means as second frequency offset means, and the beam pointing controller 20 and the target distance controller 21 constitute control means. Other configurations are
This is the same as FIG. The target distance controller 21 detects a target distance from the output of the target detector 15 or another sensor (not shown).

Next, the operation will be described. For example, if the Doppler shift of the target 3a can be predicted to be fdt1 and the Doppler shift of the target 3b of another azimuth, elevation or distance can be predicted to be fdt2, the beam pointing controller 20 and the target distance controller 21 The stabilizing local oscillator 6a1 having the frequency fo + fdt1 is selected when the beam is directed in the direction of the target 3a and the reception processing is performed at the corresponding distance. The offset switch 16 is selected and controlled so as to select the stabilized local oscillator 6b1.

The above selection and control by the beam pointing controller 20 and the target distance controller 21 cancel out the Doppler shift due to the movement of the target and the amount of this frequency offset, and the mismatch is reduced regardless of the Doppler shift due to the target. It can be said that pulse compression can be performed and deterioration of pulse compression characteristics can be prevented. FIG. 17 shows a case where the stirrer signal of the receiving system is selected and controlled, but the same applies to other cases.

As described above, in the present embodiment, based on the beam azimuth, the directional elevation angle, the target distance, or a combination thereof, in order to cope with the case where the Doppler shift varies depending on the azimuth, elevation, or distance of the target. Having a control means for selecting and controlling the switching of the offset means so as to correspond to the Doppler shift of the corresponding target, so that the Doppler shift given by the target is selected and controlled for each individual target. Offset by the offset,
It is possible to prevent pulse compression characteristics from deteriorating.
It is possible to reliably cope with the case where the Doppler shift differs depending on the azimuth, elevation, or distance of the target.

Embodiment 18 FIG. Embodiment 1
6 and 17, the speed of the target changes, but the trajectory of the target is predicted in advance, and the Doppler shift of the target can be predicted in advance by the azimuth and the elevation angle as viewed from the radar. In the present embodiment, In the case where the target speed changes arbitrarily, the target Doppler shift is predicted from the target speed data based on the target tracking result, and the frequency offset amount is selected and controlled accordingly.

FIG. 18 is a functional system diagram showing an embodiment 18 of the invention. In the figure, reference numeral 22 denotes a target tracking circuit as control means for tracking the target 3, predicting the Doppler shift of the target 3 from the speed data, and selecting and controlling the frequency offset amount by the offset switch 16 corresponding to the target. is there. Other configurations include the beam pointing controller 20
Is the same as FIG. 16 except that is deleted.

Next, the operation will be described. First, the target 3 is detected while the stirrer signal of the transmission system is arbitrarily switched by the offset switch 16. Then, the target 3 is tracked by the target tracking circuit 22 and its speed data (Vt
1, Vt2), the Doppler shift of the target 3 is predicted, and the frequency offset amount is selected and controlled by the offset switch 16 correspondingly. By the above selection and control based on the target tracking circuit 22, the Doppler shift accompanying the movement of the target 3 and this frequency offset amount are offset, and the pulse can be compressed without generating a mismatch irrespective of the Doppler shift due to the target 3. Deterioration of compression characteristics can be prevented. In the present embodiment, a case is shown in which a stirling signal of a transmission system is selected and controlled, but the same applies to other cases.

As described above, in this embodiment, the Doppler shift of the target is predicted from the tracking result of the target so as to cope with the case where the Doppler shift of the target is arbitrarily changed. By having the control means for selecting and controlling the switching, the Doppler shift given by the target is canceled by the frequency offset which is selected and controlled for each target, and it is possible to prevent the deterioration of the pulse compression characteristic. Also, it is possible to reliably cope with a case where the target Doppler shift changes arbitrarily.

[0121]

As described above, according to the first aspect of the present invention, the frequency of the transmission pulse is converted, the pulse width is extended, the radio wave is radiated to space as a radio wave, and the frequency of the radio wave reflected by the target is changed. In the radar apparatus for converting and pulse-compressing and detecting the target, the first frequency offset means for offsetting the frequency related to the transmission and reception of the transmission pulse by the target Doppler shift is provided. In this case, it is possible to prevent the pulse compression characteristic from deteriorating due to the Doppler shift, thereby reducing erroneous targets and improving the target detection probability.

According to the second aspect of the present invention, the first
Since the frequency offset means has offset means for generating a stirling signal of the transmission system in which the frequency is offset in advance by the target Doppler shift, the frequency offset at the time of transmission and the Doppler shift given by the target Are offset, and there is an effect that deterioration of the pulse compression characteristic can be prevented.

According to the third aspect of the present invention, the first type
Since the frequency offset means has offset means for generating a coherent signal of the transmission system in which the frequency is offset in advance by the target Doppler shift, the frequency offset at the time of transmission and the Doppler shift given by the target Are offset, and there is an effect that deterioration of the pulse compression characteristic can be prevented.

According to the fourth aspect of the present invention, the first
Since the frequency offset means has an offset means for generating a digital pulse expansion coefficient whose center frequency is offset in advance by the target Doppler shift, the frequency offset at the time of transmission and the Doppler shift given by the target are obtained. There is an effect that the shift is canceled and deterioration of the pulse compression characteristic can be prevented.

According to the fifth aspect of the present invention, the first
Since the frequency offset means has offset means for generating a stirling signal of the transmission system in which the frequency is offset in advance by the target Doppler shift, the Doppler shift given by the target is the frequency offset at the time of reception. This has the effect of canceling out each other and preventing deterioration of the pulse compression characteristics.

According to the sixth aspect of the present invention, the first type
Since the frequency offset means has offset means for performing pulse compression in which the center frequency is offset in advance by the target Doppler shift, the Doppler shift given by the target is offset by the frequency offset at the time of reception, There is an effect that deterioration of the pulse compression characteristic can be prevented.

According to the seventh aspect of the present invention, the frequency of the transmission pulse is converted, the pulse width is extended, the radio wave is radiated into space as a radio wave, and the frequency of the radio wave reflected by the target whose speed changes is converted. And a second frequency offset means for offsetting a frequency related to transmission and reception of the transmission pulse by a Doppler shift corresponding to a plurality of speeds of the target in the radar apparatus for detecting the target by pulse compression. Therefore, it is possible to prevent the pulse compression characteristic from deteriorating due to the Doppler shift of the high-speed target whose speed changes, and it is possible to reduce the erroneous target and improve the target detection probability.

Further, according to the invention of claim 8, the second
Frequency offset means generates a plurality of stirling signals of a transmission system in which the frequency is offset in advance so as to correspond to the target Doppler shift, and an offset means for performing frequency conversion while switching the plurality of stray signals. Therefore, there is an effect that the frequency offset at the time of transmission with respect to the target of each speed and the Doppler shift given by the target cancel each other, and deterioration of the pulse compression characteristic can be prevented.

Further, according to the ninth aspect of the present invention, the second
Frequency offset means has offset means for offsetting the frequency while switching by the target Doppler shift with respect to the basic stray signal of the transmission system so as to correspond to the target Doppler shift. The frequency offset at the time of transmission with respect to the target and the Doppler shift given by the target are canceled out, so that there is an effect that deterioration of pulse compression characteristics can be prevented.

According to the tenth aspect of the present invention, the second frequency offset means switches a plurality of coherent signals of a transmission system whose frequency is offset in advance so as to correspond to the target Doppler shift. However, since the offset means for frequency conversion is provided, the frequency offset at the time of transmission with respect to the target of each speed and the Doppler shift given by the target are cancelled, and there is an effect that deterioration of pulse compression characteristics can be prevented.

According to the eleventh aspect of the present invention, the second frequency offset means applies the target Doppler signal polarization to the basic coherent signal of the transmission system so as to correspond to the target Doppler deviation. Since there is an offset means for offsetting the frequency while switching by the transfer, the frequency offset at the time of transmission with respect to the target of each speed and the Doppler shift given by the target cancel each other out, and deterioration of the pulse compression characteristic can be prevented. effective.

According to the twelfth aspect of the present invention, the second frequency offset means generates a plurality of digital pulse expansion coefficients whose center frequencies are offset in advance so as to correspond to the target Doppler shift. Since there is an offset means for performing pulse elongation while switching, the frequency offset at the time of transmission with respect to the target of each speed and the Doppler shift given by the target are cancelled, and there is an effect that deterioration of pulse compression characteristics can be prevented. .

According to the thirteenth aspect of the present invention, the second frequency offset means sets the target Doppler relative to the basic coefficient of the digital pulse expander so as to correspond to the target Doppler shift. Since it has offset means to offset the frequency while switching by the amount of deviation,
The frequency offset at the time of transmission with respect to the target of each speed and the Doppler shift given by the target are offset, and there is an effect that deterioration of pulse compression characteristics can be prevented.

According to the fourteenth aspect of the present invention, the second frequency offset means switches a plurality of starrow signals of a receiving system whose frequency is offset in advance so as to correspond to the target Doppler shift. However, since the offset means for frequency conversion is provided, the Doppler shift given by the target is offset by the frequency offset at the time of reception with respect to the target of each speed, and there is an effect that deterioration of pulse compression characteristics can be prevented.

According to the fifteenth aspect of the present invention, the second frequency offset means converts a basic stray signal of a receiving system into a signal corresponding to the target Doppler shift.
Since there is an offset means for offsetting the frequency while switching by the target Doppler shift, the Doppler shift given by the target is canceled by the frequency offset at the time of reception with respect to the target of each speed, thereby preventing deterioration of the pulse compression characteristic. There is an effect that can be.

According to the sixteenth aspect of the present invention, the second frequency offset means has an offset means for switching the pulse compression in which the center frequency is offset in advance so as to correspond to the target Doppler shift. Therefore, the Doppler shift given by the target is canceled by the frequency offset at the time of reception with respect to the target of each speed, and there is an effect that deterioration of the pulse compression characteristic can be prevented.

According to the seventeenth aspect of the present invention, the second frequency offset means includes a plurality of digital pulse compression coefficients whose center frequencies are offset in advance so as to correspond to the target Doppler shift. Since there is an offset means for performing pulse compression while switching, the Doppler shift given by the target is offset by the frequency offset at the time of reception with respect to the target of each speed, and there is an effect that deterioration of pulse compression characteristics can be prevented.

According to the eighteenth aspect of the present invention, the switching of the offset means is selected and controlled based on the beam azimuth and / or the elevation angle so as to correspond to the Doppler shift of the corresponding target. With the control means, the Doppler shift given by the target is canceled by the frequency offset selected and controlled for each individual target, so that the pulse compression characteristics can be prevented from deteriorating. Therefore, it is possible to reliably cope with the case where the Doppler shift is different.

Further, according to the nineteenth aspect of the present invention, based on the directional azimuth or azimuth of elevation of the beam, the target distance, or a combination thereof, the offset means of the offset means is adapted to correspond to the Doppler shift of the corresponding target. Select switching,
With the control means for controlling, the Doppler shift given by the target is canceled by the frequency offset which is selected and controlled for each target, so that the pulse compression characteristic can be prevented from deteriorating. Alternatively, it is possible to reliably cope with the case where the Doppler shift differs depending on the elevation angle or the distance.

Further, according to the twentieth aspect of the present invention, there is provided control means for predicting the Doppler shift of the target from the tracking result of the target and selecting and controlling the switching of the offset means based on the prediction. The Doppler shift given by is canceled out by the selected and controlled frequency offset for each target, and the pulse compression characteristic can be prevented from deteriorating.Also, when the target Doppler shift changes arbitrarily, This has the effect that it is possible to reliably cope with the situation.

[Brief description of the drawings]

FIG. 1 is a functional system diagram showing a first embodiment of the present invention.

FIG. 2 is a functional system diagram showing a second embodiment of the present invention.

FIG. 3 is a functional system diagram showing a third embodiment of the present invention.

FIG. 4 is a functional system diagram showing a fourth embodiment of the present invention.

FIG. 5 is a functional system diagram showing a fifth embodiment of the present invention.

FIG. 6 is a functional system diagram showing a sixth embodiment of the present invention.

FIG. 7 is a functional system diagram showing a seventh embodiment of the present invention.

FIG. 8 is a functional system diagram showing Embodiment 8 of the present invention.

FIG. 9 is a functional system diagram showing Embodiment 9 of the present invention.

FIG. 10 is a functional system diagram showing Embodiment 10 of the present invention.

FIG. 11 is a functional system diagram showing an eleventh embodiment of the present invention.

FIG. 12 is a functional system diagram showing Embodiment 12 of the present invention.

FIG. 13 is a functional system diagram showing a thirteenth embodiment of the present invention.

FIG. 14 is a functional system diagram showing Embodiment 14 of the present invention.

FIG. 15 is a functional system diagram showing Embodiment 15 of the present invention.

FIG. 16 is a functional system diagram showing Embodiment 16 of the present invention.

FIG. 17 is a functional system diagram showing a seventeenth embodiment of the present invention.

FIG. 18 is a functional system diagram showing Embodiment 18 of the present invention.

FIG. 19 is a functional system diagram of a conventional pulse compression radar device.

FIG. 20 is an explanatory diagram of a linear frequency modulation type pulse compression radar.

FIG. 21 is an explanatory diagram of degradation of a side lobe of a compressed pulse due to a target Doppler shift.

FIG. 22 is an explanatory diagram of degradation of a signal-to-noise ratio (S / N) due to a target Doppler shift.

[Explanation of symbols]

1 transmitting / receiving antenna, 3, 3a, 3b target, 5a
~ 5d mixer, 6,6a ~ 6c, 6a1 ~ 6c1
Stabilized local oscillator, 7, 7a to 7c Offset signal generator, 8, 8a Pulse expander, 9, 9a to 9c
Coherent oscillator, 10 transmit pulse generator,
13, 13a to 13c pulse compressor, 14 moving target detector, 15 target detector, 16, 16a to 16
b offset switcher, 17a-17c pulse expansion coefficient generator, 18a-18c offset coefficient generator,
19a to 19c pulse compression coefficient generator, 20 beam pointing controller, 21 target distance controller, 22 is a target tracking circuit.

Claims (20)

[Claims] 1. A radar apparatus for converting the frequency of a transmission pulse, extending the pulse width, radiating the pulse as a radio wave into space, converting the frequency of a radio wave reflected by a target, compressing the pulse, and detecting the target. 2. The radar apparatus according to claim 1, further comprising first frequency offset means for offsetting a frequency related to transmission and reception of the transmission pulse by the target Doppler shift. 2. The apparatus according to claim 1, wherein said first frequency offset means includes an offset means for generating a transmission stirrer signal whose frequency is previously offset by the target Doppler shift. Radar equipment. 3. The apparatus according to claim 1, wherein said first frequency offset means has offset means for generating a coherent signal of a transmission system in which the frequency is offset in advance by the target Doppler shift. Radar equipment. 4. The apparatus according to claim 1, wherein said first frequency offset means has an offset means for generating a digital pulse extension coefficient whose center frequency is previously offset by the target Doppler shift. The described radar device. 5. The apparatus according to claim 1, wherein said first frequency offset means includes an offset means for generating a transmission stirrer signal whose frequency is offset in advance by the target Doppler shift. Radar equipment. 6. A radar apparatus according to claim 1, wherein said first frequency offset means has offset means for performing pulse compression in which a center frequency is offset in advance by the target Doppler shift. . 7. The frequency of a transmission pulse is converted, the pulse width is extended, the radio wave is emitted to space as a radio wave, the frequency of the radio wave reflected by a target whose speed changes is converted, and the target is compressed by a pulse compression. A radar apparatus for detecting, comprising: second frequency offset means for offsetting a frequency related to transmission and reception of the transmission pulse by a Doppler shift corresponding to the plurality of target velocities. 8. The second frequency offset means generates a plurality of stall signals of a transmission system whose frequency is offset in advance so as to correspond to the target Doppler shift, and switches the plurality of starrow signals. The radar apparatus according to claim 7, further comprising offset means for performing frequency conversion. 9. The second frequency offset means for offsetting a frequency while switching by a target Doppler shift with respect to a basic stray signal of a transmission system so as to correspond to the target Doppler shift. 8. The radar device according to claim 7, further comprising: means. 10. The second frequency offset means,
8. The radar apparatus according to claim 7, further comprising offset means for performing frequency conversion while switching a plurality of coherent signals of a transmission system whose frequency is offset in advance so as to correspond to the target Doppler shift. 11. The second frequency offset means,
8. The apparatus according to claim 7, further comprising offset means for offsetting the frequency while switching the basic coherent signal of the transmission system by the target Doppler signal shift so as to correspond to the target Doppler shift. Radar equipment. 12. The second frequency offset means,
8. The radar apparatus according to claim 7, further comprising offset means for switching a plurality of digital pulse expansion coefficients whose center frequencies are offset in advance so as to correspond to the target Doppler shift, and for performing pulse expansion. 13. The second frequency offset means,
8. An offset means for offsetting a frequency while switching the basic coefficient of the digital pulse expander by the target Doppler shift so as to correspond to the target Doppler shift. Radar equipment. 14. The second frequency offset means,
8. The radar apparatus according to claim 7, further comprising an offset unit for performing frequency conversion while switching a plurality of starrow signals of a receiving system whose frequency is offset in advance so as to correspond to the target Doppler shift. 15. The second frequency offset means,
8. The radar according to claim 7, further comprising offset means for offsetting a frequency with respect to a basic stray signal of a receiving system by switching by the target Doppler shift so as to correspond to the target Doppler shift. apparatus. 16. The second frequency offset means,
8. The radar apparatus according to claim 7, further comprising offset means for switching pulse compression in which a center frequency is offset in advance so as to correspond to the target Doppler shift. 17. The second frequency offset means,
8. The radar apparatus according to claim 7, further comprising offset means for switching a plurality of digital pulse compression coefficients whose center frequencies are offset in advance so as to correspond to the target Doppler shift, and for performing pulse compression. 18. Selecting switching of said offset means based on the beam azimuth and / or elevation angle or both to correspond to a corresponding target Doppler shift;
9. A control device for controlling a vehicle.
14. The radar device according to any one of 13. 19. A control means for selecting and controlling the switching of the offset means based on the beam azimuth or azimuth elevation and / or the target distance or a combination thereof so as to correspond to the Doppler shift of the corresponding target. The radar device according to any one of claims 14 to 17, comprising: 20. The apparatus according to claim 8, further comprising control means for predicting a Doppler shift of the target from a result of tracking the target, and selecting and controlling switching of the offset means based on the prediction. A radar device according to any of the above.