JPH05240949A - Mti radar device - Google Patents

Abstract

PURPOSE:To fast modify a transmission frequency as the detection function of a moving target is held by extracting the frequency deviation component of the moving target without any dependence on the frequency of a local signal. CONSTITUTION:Within a subpulse former 22 a local signal (fo) is distributed to a plurality of systems, with linear frequency modulation performed by means of different modulation functions, a plurality of pulse signal sequences are formed and time sharing output is performed. The amplitude of another local signal (carrier wave) (fx) is modulated by means of the pulse signal sequences and a transmission RF signal is generated. Transmission RF is emitted from an antenna 1, its reflection wave is transmitted to a receiving part 3 as a receiving RF signal and, with the reflection wave mixed with the local signal (fx), a receiving IF signal is generated to supply to an MTI processor 36. Within the processor 36 the signals are separated every receiving signal corresponding to each transmission pulse performing time sharing and after, with the signals aligned on a same time, subtraction processing is performed and amplitude detection is conducted, phase detection is performed by means of the local signal (fo). Within a moving target display 4 a Doppler frequency component for timely performing phase change is extracted to show thereon. The control accompanying transmission frequency modification is conducted by the use of a control part 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MTI radar device capable of changing the transmission frequency at high speed without losing the function of a moving target display device and having a function of removing an unnecessary signal due to reflection from a stationary target. Regarding

[0002]

2. Description of the Related Art As is well known, as shown in FIG. 13, an MTI radar device has an antenna section 1, a transmitting section 2, and a receiving section 3.
And a moving target display device 4.

First, in the transmitter 2, the second local signal (frequency f0) generated by the second local oscillator 21 is mixed with the first local signal (frequency fx) generated by the first local oscillator 23 in the mixer 22. Then, the frequency is converted, and unnecessary frequency components are removed by the frequency filter 24 to form a transmission RF signal. The transmission RF signal is pulsed by the pulse modulator 25, amplified by the high power amplifier 26, and sent to the antenna unit 1.

In the antenna section 1, a transmission RF signal from the transmission section 2 is transmitted via the transmission / reception switch 11 to the transmission / reception antenna 1
2 and is radiated as a transmitted wave. When the transmitted wave is reflected by various fixed or moving targets, the reflected wave is received by the transmission / reception antenna 12 and is sent to the receiving unit 3 via the transmission / reception switch 11 as a received RF signal.

In the receiving section 3, the RF signal received from the antenna section 1 is amplified by the low noise amplifier 31, and then the mixer 32 produces a first local signal (frequency) coherent with the transmission system generated by the first local oscillator 23. fx),
It is converted to an intermediate frequency and becomes a reception IF signal. The received IF signal is amplified by the intermediate frequency amplifier 33 and then amplified by the second local oscillator 21 to generate a second coherent signal with the transmission system.
Phase detection is performed based on the local signal. This phase detection signal is converted into a digital signal by an A / D (analog / digital) converter 35 and sent to the moving target display device 4.

In the moving target display device 4, the digital signal from the receiver 3 is input, and the signal component whose phase changes with time is extracted by digital signal processing. This component is the Doppler frequency component due to the moving target.
Then, the position of the moving target is appropriately displayed together with other radar information.

As described above, in the conventional MTI radar device, the frequency shift component changed by the moving target is extracted for each transmission pulse with reference to the transmission frequency. That is, in order to detect the moving target, the moving target display device 4
Since the Doppler frequency is detected based on the transmission frequency by, the frequency of the transmission signal is constant.

However, when the transmission signal has a constant frequency, it is easy to detect the radar radio wave, and the radio wave is easily disturbed particularly in the electronic warfare. Therefore, it is strongly desired to be able to change the transmission frequency at high speed in response to radio wave interference and the like.

[0009]

As described above, in the conventional MTI radar device, if the transmission frequency is changed in response to radio wave interference or the like, the Doppler frequency corresponding to the moving target cannot be detected, and the moving object is not detected. There was a problem that the mark could not be detected and displayed.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an MTI radar device capable of changing the transmission frequency at high speed without losing the function of detecting a moving target.

[0011]

In order to achieve the above object, the present invention is a coherent sine wave signal, and local signal generating means for generating first and second local signals having different frequencies, and The first local signal is distributed to a plurality of systems, pulse signal train generating means for generating a plurality of time division pulse signal trains by giving different modulation function characteristics to each other, and pulse signal trains output from this means 2 amplitude-modulating means for amplitude-modulating the local signal, transmitting / receiving means for pulse-transmitting the output signal of the amplitude-modulating means, and receiving the reflected signal thereof, and the received signal obtained by the transmitting / receiving means for each transmission pulse. Signal separation means for separating the signals into two parts, and the signals separated by this means are given characteristics opposite to the modulation function characteristics given at the time of transmission, and the same timing is obtained. As described above, weighted addition means for removing the reflected signal component from the stationary target that does not move by delaying and adding, and shift for detecting the frequency component shifted by the moving target from the signal obtained by this means It comprises a component detection means and a display means for displaying the moving target based on the detection output of this means.

[0012]

In the MTI radar device having the above-mentioned configuration, a plurality of pulse trains are transmitted at equal intervals at the same frequency by applying different modulation function characteristics within the repetition period of the transmission signal, and the received reflected signal is transmitted for each transmission pulse. The signal is separated, the delay is controlled at the same timing, and the characteristics opposite to the modulation function characteristics are applied to perform addition processing to remove the frequency component due to the stationary target that does not move, and detect the frequency shift component to detect the moving target. indicate.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the basic configuration of the MTI radar device according to the present invention, which includes the antenna section 1, the transmitting section 2,
In addition to the receiving unit 3 and the moving target display device 4, a control unit 5 is further provided.

First, in the transmitter 2, the second local signal (frequency f0) generated by the second local oscillator 21 is supplied to the sub-pulse former 27. The sub-pulse shaper 27 distributes the input second local signal to a plurality of systems and linearly frequency-modulates it with different modulation functions such as up-chirp and down-chirp to form a plurality of pulse signal trains. After giving a predetermined delay time so as to have the same phase, the time-division output is performed. The pulse signal train generated by the sub-pulse generator 27 is the amplitude modulator 2
8 are supplied.

The amplitude modulator 28 includes a first local oscillator 23.
The first local signal (frequency fx) generated in 1 is input as a carrier wave, and the carrier wave is amplitude-modulated by the pulse signal train from the sub-pulse former 27 to generate a transmission RF signal. The transmission RF signal is supplied to the pulse modulator 25, pulsed, amplified by the high-power amplifier 26, and sent to the antenna unit 1.

In the antenna section 1, the transmission RF signal from the transmission section 2 is transmitted via the transmission / reception switch 11 to the transmission / reception antenna 1
2 and is radiated as a transmitted wave. When the transmitted wave is reflected by various fixed or moving targets, the reflected wave is received by the transmission / reception antenna 12 and is sent to the receiving unit 3 via the transmission / reception switch 11 as a received RF signal.

In the receiving section 3, the RF signal received from the antenna section 1 is amplified by the low noise amplifier 31, and then the mixer 32 produces a first local signal (frequency) coherent with the transmission system generated by the first local oscillator 23. fx),
It is converted to an intermediate frequency and becomes a reception IF signal. The received IF signal is amplified by the intermediate frequency amplifier 33 and then MTI.
It is supplied to the processor 36.

This MTI processor 36 receives the received IF
The signal is separated for each received signal corresponding to each transmission pulse that is time-divided at the time of transmission, and the time-divided signal is subtracted according to the same time. The output of the MTI processor 36 is supplied to the amplitude demodulator 37 for amplitude detection, and then phase detected by the phase detector 34 by the second local signal (frequency f0) coherent with the transmission system. This phase detection signal is converted into a digital signal by the A / D converter 35,
It is sent to the moving target display device 4.

In the moving target display device 4, the digital signal from the receiver 3 is input and the signal component whose phase is temporally changed is extracted by digital signal processing. This component is the Doppler frequency component due to the moving target.
Then, the position of the moving target is appropriately displayed together with other radar information.

First when changing the frequency of the transmitter 2
The frequency control of the local oscillator 21, the delay time control of the sub pulse former 27, the pulse timing control of the pulse modulator 25, and the delay time control of the MTI processor 36 of the receiving unit 3 are
It is performed by the control unit 5.

2 and 3 show specific configurations of the sub-pulse former 27 and the MTI processor 36, which are essential parts of the present invention, respectively.

That is, in the sub pulse former 27, as shown in FIG. 2, the second local signal from the second local oscillator 21 is divided into n systems by the signal divider 271. The n-system second local signals are supplied to the frequency modulators 2721 to 272n having different modulation functions, and are linearly frequency-modulated. The modulated signals of the respective systems are given a predetermined delay time by delay elements 2731 to 273n to have their phases aligned, and are sequentially switched out by a signal switch 274 to be a time division pulse signal train.

The modulation function is arbitrary, and examples thereof include up-chirp (linear frequency modulation pulse whose frequency increases with time) and down-chirp (linear frequency modulation pulse whose frequency decreases with time). The frequency vs. time characteristics of each chirp are shown in FIGS. In this case, two lines are enough. The delay times of the delay elements 2731 to 273n and the signal switching timing of the signal switch 274 are controlled for each transmission pulse repetition period (PRI).

Further, in the MTI processor 36, as shown in FIG. 3, the reception IF signal from the intermediate frequency amplifier 33 is distributed by the signal distributor 361 into n systems. The received IF signals of the n systems are respectively frequency demodulators 3621 to 362.
n. These demodulators 3621 to 362n are distributed delay lines having a demodulation function corresponding to the modulation function of the frequency modulators 2721 to 272n of the transmission system, and pulse-compress the input reception IF signal. When the modulation function of the transmission system is up-chirp or down-chirp having the characteristics shown in FIGS. 4 and 5, the demodulation function of the reception system is shown in FIGS.
The characteristics are shown in.

The compressed pulse signals obtained by the demodulators 3621 to 362n are delayed by delay elements 3631 to 363n, and the weights W1 to
Wn is multiplied and addition processing is performed by the adder 365.

The first local oscillator 23 is specifically constructed as shown in FIG. That is, the oscillator 23 includes a plurality of (here, m) local oscillator signal generation circuits 2311 to 231m, and each of the circuits 2311 to 23m.
To generate signals of different frequencies, and the signal switch 2
By appropriately controlling the switching of 32 according to the control signal from the control unit 5 and selectively outputting an arbitrary frequency signal, the first local signal whose frequency is arbitrarily changed is obtained.

The operation of the above configuration will be described below.

First, as shown in FIG. 9, the transmission signal radiates n pulse trains at the same frequency and at equal intervals within a repetition period. The second local signal component (modulation signal component of frequency f0) for each pulse train within the repetition period is controlled to have the same phase. That is, the modulation signal components of the amplitude-modulated transmission signal are controlled so as to have the same phase within the pulse of each pulse train. Further, the carrier frequency and the time interval of the pulse train are switched for each repetition period. Figure 9
, Fx1 is different from fx2, and dt1 is different from dt2.

Here, an example will be described in which up-chirp and down-chirp are used for the modulation function and two transmission pulse signals are radiated within the repetition period.

First, in the transmission system, one transmission pulse signal has an up-chirp having the characteristic shown in FIG. 4, and the other transmission pulse signal has a down-chirp having the characteristic shown in FIG.
Send in time division within the repetition period.

In this case, in the receiving system, the received signal is first set to 2
To divide. Each divided reception signal is a composite signal of a reflection signal component corresponding to the up-chirp transmission pulse signal and a reflection signal component corresponding to the down-chirp transmission pulse signal. Then, by demodulating one of the received signals with the characteristic shown in FIG. 6, a compressed pulse of only the reflected signal component corresponding to the up-chirp transmission pulse signal is formed, and the other received signal is shown in FIG. By performing the demodulation processing with the above characteristics, the compressed pulse of only the reflected signal component corresponding to the down-chirp transmission pulse signal is formed. This separates the two signal components.

Specifically, the transmission wave in the transmission system is (1)
It is shown as an expression. Tx (t) = A (t) ・ cos (2πf0 ・ t) ・ exp (j2πfx ・ t) + A (t-dt) ・ cos {2πf0 ・ (t-dt)} ・ exp (j2πfx ・ t)… ( 1) where Tx (t) is the transmission signal, A (t) is the pulse modulation function, dt is the pulse delay time, fx is the frequency of the first local signal, and f0 is the frequency of the second local signal.

With respect to this transmission wave, a reflection signal reflected by a fixed or moving target is received as a reception RF signal. The received wave at this time is shown in Eqs. (2) to (6). Rx (t) = Rx1 (t) + Rx2 (t)… (2) Rx1 (t) = A (t-ta) ・ Pa ・ cos {2πf0 ・ (t-ta) + f0a ・ t} ・ exp [j2π {fx ・ (t-ta) + fxa ・ t}] + A (t-tb) ・ Pb ・ cos {2πf0 ・ (t-tb)} ・ exp {j2πfx ・ (t-tb)… (3) Rx2 ( t) = A (t-dt-ta ') ・ Pa ・ cos {2πf0 ・ (t-dt-ta') + f0a ・ (t-dt)} ・ exp [j2π {fx ・ (t-dt-ta ' ) + fxa ・ (t-dt)}] + A (t-dt-tb) ・ Pb ・ cos {2πf0 ・ (t-dt-tb)} ・ exp {j2πfx ・ (t-dt-tb)… (4 ) ta = 2Ra / c, ta '= 2 (Ra-v ・ dt) / c, tb = 2Rb / c… (5) f0a = (2v / c) ・ f0, fxa = (2v / c) ・ fx… (6) where Rx (t); received signal, Rx1 (t); received signal corresponding to the first pulse signal, Rx2 (t); received signal corresponding to the second pulse signal, Pa, Pb; target A And the reception intensity of the reflected signal of the target B, fxa; the Doppler frequency at the frequency fx, f0a; the Doppler frequency at the frequency f0, ta; the signal delay time by the target A of the first pulse, ta '; the target of the second pulse Signal delay time due to A, tb; first and second pulse objects Signal delay time by B, c; is the speed of light.

When the received signal is mixed with the first local signal and converted into the intermediate frequency, the equations (7) to (9) are obtained. IF (t) = Rx1 (t) ・ exp (-j2πfx ・ t) + Rx2 (t) ・ exp {-j2πfx ・ (t-dt)} = IF1 (t) + IF2 (t)… (7) IF1 ( t) = A (t-ta) ・ Pa ・ cos {2πf0 ・ (t-ta) + f0a ・ t} ・ exp {j2π (fxa ・ t-fx ・ ta} + A (t-tb) ・ Pb ・ cos {2πf0 ・ (t-tb)} ・ exp (-j2πfx ・ tb)… (8) IF2 (t) = A (t-dt-ta ') ・ Pa ・ cos {2πf0 ・ (t-dt-ta') + f0a ・ (t-dt)} ・ exp [j2π {fxa ・ (t-dt) -fx ・ ta '}] + A (t-dt-tb) ・ Pb ・ cos {2πf0 ・ (t-dt-tb )} ・ Exp (-j2πfx ・ tb) (9) This received IF signal is separated into the first received IF signal corresponding to the first pulse signal and the second received IF signal corresponding to the second pulse signal by the method described above. Then, the delay time dt is given to the first reception IF signal, and the difference S (t) from the second reception IF signal is obtained as shown in equation (10): S (t) = IF1 (t-dt )-IF2 (t) = A (t-dt-ta) ・ Pa ・ cos {2πf0 ・ (t-dt-ta) + f0a ・ (t-dt)} ・ (exp [j2π {fxa ・ (t-dt ) -fx ・ ta}] -exp [j2π {fxa (t-dt) -fx ・ ta '}]) (10) However, the frequency f0 of the second local signal is the first low. Since the frequency is extremely smaller than the frequency fx of the cull signal and the signal delay time difference between the first pulse signal and the second pulse signal of the target A is small, the approximate expression of the equation (11) can be used. = f0 · ta '(11) From equation (10), the received signal component (clutter component) of the fixed target B is removed, and the frequency f of the first local signal is f.
When x is changed, the difference signal component fluctuates, but also in this case, the clutter component can be removed, as is apparent from the equation (10).

Next, when the difference signal is amplitude-detected and time-corrected, it becomes as shown in equation (12).

X (t) = | S (t + dt) | ² = A (t-ta) ² · Pa ² · cos ² {2πf0 · (t-ta) + f0a · t} · [Real (t) ² + Imag (t) ² ] = 4 ・ A (t-ta) ²・ Pa ²・ cos ² {2πf0 ・ (t-ta) + f0a ・ t} ・ sin ² {2πfx (ta'-ta)} = 4 ・ A (t-ta) ²・ Pa ²・ cos ² {2πf0 ・ (t-ta) + f0a ・ t} ・ sin ² {4πfx ・ v ・ dt ・ fx / c) = 2 ・ cons ・ cos ² { 2πf0 ・ (t-ta) + f0a ・ t} = const ・ [1 + cos {4πf0 ・ (t-ta) + f0a ・ t}]… (12) Real (t) = cos {2π (fxa ・ t- fx ・ ta)}-cos {2π (fxa ・ t-fx ・ ta ')} = -2sin [2π {fxa ・ 2t-fx (ta + ta')}] ・ sin {2πfx (ta'-ta)} (13) Imag (t) = sin {2π (fxa ・ t-fx ・ ta)}-sin {2π (fxa ・ t-fx ・ ta ')} = 2 cos [2π {fxa ・ 2t-fx (ta + ta ')}] ・ sin {2πfx (ta'-ta)}… (14) const = 2 ・ A (t-ta) ²・ Pa ²・ sin ² (4πfx ・ v ・ dt / c)… (15 ) Here, assuming that the speed of the target A is constant, if dt and fx are made constant, const shown in the equation (15) becomes constant,
The amplitude detection output is a signal output that does not depend on the frequency fx of the first local signal.

As is clear from the above relational expression, since the frequency shift component due to the moving target that does not depend on the first local signal can be obtained, the first local oscillator 2 can cope with the radio interference.
Even if the oscillation frequency of No. 3 is changed for each transmission pulse, the movement target indicating device 4 can be operated. Also, (1
As is clear from the equation (2), the phase detection using the second local signal makes it possible to detect the Doppler frequency component corresponding to f0.

Therefore, the MTI radar device having the above-described structure can change the transmission frequency at high speed without losing the function of detecting the moving target. The moving target can be detected and displayed by detecting the Doppler frequency corresponding to.

By the way, in the above embodiment, the method of using different modulation functions as means for separating the pulse signal train has been described, but there is another method of switching the polarization. The structure is shown in FIG. However, in FIG.
The same parts as those in FIG. 1 are designated by the same reference numerals, and different parts will be described here.

First, in the antenna section 1, the transmission RF signal from the transmission section 2 is supplied to the signal switch 13 and selectively derived to one of the n systems according to the control signal from the control section 5. Transmission / reception switchers 111 to 11n and transmission / reception antennas 121 to 12n are provided in each system. The transmission / reception switchers 111 to 11n are switching-controlled by a control signal from the control unit 5, guide the transmission RF signal from the transmission unit 2 to the antennas 121 to 12n, and the antennas 121 to 12n.
The received RF signal received in 3 is sent to the receiving unit 3. The antennas 121 to 12n have polarization directions different from each other, for example, vertical polarization and horizontal polarization are used. In this case, two lines are enough.

In the receiving section 3, n from the antenna section 1
The received RF signals of the system are low noise amplifiers 311 to 311 respectively.
Amplified by 1n, mixed with the first local signal from the first local oscillator 23 by the mixers 321 to 32n, converted to an intermediate frequency, further amplified by the intermediate frequency amplifiers 331 to 33n, and supplied to the MTI processor 36. ..

The sub-pulse former 27 of the transmitter 2 and the MTI processor 36 of the receiver 3 are shown in FIG. 11 and FIG. 12, respectively.
It is configured as shown in. That is, as can be seen by comparing with FIG. 2 and FIG. 3, the sub-pulse former 27 in this case is
Uses the frequency modulators 2721 to 272n and directly outputs the respective distribution outputs of the signal distributor 271 to the delay elements 2731 to 2731.
73n, and the MTI processor 36 supplies the signal distributor 361.
Also, the reception IF signals of n systems are directly supplied to the delay elements 3631 to 363n without using the frequency demodulators 3621 to 362n.

In the above structure, the characteristic operation, that is, the means for separating the pulse signal train from the signal will be described below.

First, in the transmission system, the transmission signal is as shown in FIG.
As shown in, the n pulse trains are radiated at the same frequency and at equal intervals within the repetition period. The second local signal component (modulation signal component of frequency f0) for each pulse train within the repetition period is controlled to have the same phase. That is, the modulation signal components of the amplitude-modulated transmission signal are controlled so as to have the same phase within the pulse of each pulse train. Further, the carrier frequency and the time interval of the pulse train are switched for each repetition period.

Here, the antenna section 1 has two systems, and uses vertical polarization and horizontal polarization as polarizations, and the polarization is 2 in the repetition period.
The case where the individual transmission pulse signals are emitted will be described as an example.

First, in the transmission system, one transmission pulse signal is vertically polarized and the other transmission pulse signal is horizontally polarized, and is transmitted in a time division manner within a repetition period. Antenna 121
Is for vertical polarization, and the antenna 122 is for horizontal polarization.

A signal transmitted by vertical polarization is reflected from a moving or fixed target. This reflected signal is a combined signal of the vertically polarized component and the horizontally polarized component. However, the amplitude level of the vertically polarized component is considerably larger than that of the horizontally polarized component, and the vertically polarized component is mainly received by the transmitting / receiving antenna 121.

The signal transmitted in the horizontal polarization is exactly the same as in the case of the vertical polarization, and is reflected from the moving or fixed target. This reflected signal is a composite signal of the vertical polarization component and the horizontal polarization component, but the amplitude level of the horizontal polarization component is considerably larger than that of the vertical polarization component.
It is mainly received by the horizontally polarized transmission / reception antenna 122. Therefore, the two signal components can be separated.

The present invention is not limited to the above embodiment, and it is not always necessary to make the time intervals of the pulse trains in the repetition period equal intervals, as in the above embodiment. That is, it can be applied even when the intervals are not equal.

As a method of separating each pulse train within the repetition period, the case where the modulation function of linear frequency modulation is changed has been described in the above embodiment, but modulation is performed by any of amplitude, phase, frequency or a combination thereof. It can also be applied in cases. It can also be applied to code modulation methods such as coded phase modulation using Barker codes.

Further, as a method of separating each pulse train within the repetition period, the case where the modulation function of the linear frequency modulation is changed has been shown in the above embodiment, but it can be applied to the case where the right-handed and left-handed circularly polarized waves are used. .. Of course, it can also be applied to the case of separating each pulse train by combining with the case where the modulation function is changed.

Further, in the above embodiment, the case where the pulse signal train within the repetition period is separated by the MTI processor by the analog signal is shown. However, it is digitally converted by the A / D (analog / digital) converter. It can also be applied to a case where signal separation is performed later by a digital signal.

Further, in the above embodiment, the case where the pulse modulator is used to perform the pulse modulation has been described, but the present invention can also be applied to the case where the signal is switched within the repetition period and the CW (continuous wave) is transmitted.

In addition to the above, it is needless to say that various modifications can be made without departing from the scope of the present invention.

[0056]

As described above, according to the present invention, it is possible to provide an MTI radar device capable of changing the transmission frequency at high speed without losing the function of detecting a moving target.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram showing an embodiment of an MTI radar device according to the present invention.

FIG. 2 is a block diagram showing a specific configuration of a sub pulse former of the embodiment.

FIG. 3 is a block diagram showing a specific configuration of the MTI processor of the embodiment.

FIG. 4 is a characteristic diagram showing characteristics of an up-chirp used as a transmission system modulation function in the embodiment.

FIG. 5 is a characteristic diagram showing characteristics of a down-chirp used as a transmission system modulation function in the example.

6 is a characteristic diagram showing characteristics of a demodulation function used in a reception system when the up-chirp of FIG. 4 is used for a modulation function in the embodiment.

7 is a characteristic diagram showing characteristics of a demodulation function used in a reception system when the downchirp of FIG. 5 is used for a modulation function in the embodiment.

FIG. 8 is a block diagram showing a specific configuration of a first local oscillator of the same embodiment.

FIG. 9 is a time chart for explaining a pulse signal time division transmission method of the same embodiment.

FIG. 10 is a block diagram showing a configuration when a method of switching polarization is used as a means for separating a pulse signal train from another embodiment according to another embodiment of the present invention.

FIG. 11 is a block diagram showing a specific configuration of a sub pulse former in the embodiment of FIG.

12 is a block diagram showing a specific configuration of an MTI processor in the embodiment of FIG.

FIG. 13 is a block diagram showing a configuration of a conventional MTI radar device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Antenna part, 11 ... Transmission / reception switcher, 12 ... Transmission / reception antenna, 13 ... Signal switcher, 2 ... Transmission part, 21 ... 2nd local oscillator, 22 ... Mixer, 23 ... 1st local oscillator, 231
1 to 231 m ... Local signal generation circuit, 232 ... Signal switcher, 24 ... Frequency filter, 25 ... Pulse modulator, 26
... High-power amplifier, 27 ... Sub-pulse former, 271 ... Signal distributor, 2721-272n ... Frequency modulator, 273
1-273n ... Delay element, 274 ... Signal switcher, 28 ...
Amplitude modulator, 3 ... Receiving unit, 31, 311 to 31n ... Low noise amplifier, 32, 321 to 32n ... Mixer, 33, 33
1 to 33n ... Intermediate frequency amplifier, 34 ... Phase detector, 35
... A / D converter, 36 ... MTI processor, 361 ... Signal distributor, 3621-362n ... Frequency demodulator, 3631-
363n ... Delay elements, 3164 to 364n ... Multipliers, 3
65 ... Adder, 37 ... Amplitude demodulator, 4 ... Moving target display device, 5 ... Control unit.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Seiichi Maeda 1-9-2 Fujimachi, Hoya-shi, Tokyo 203 Heimsquae 203 (72) Inventor Tsutomu Watanabe 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Stock company Inside the Toshiba Komukai Plant (72) Inventor Mitsuyoshi Shinonaga 1 Komukai Toshiba-cho, Komu-ku, Kawasaki-shi, Kanagawa Stock Company Toshiba Komukai Plant

Claims (9)

[Claims] 1. A local signal generating means for generating first and second local signals that are coherent sine wave signals and have different frequencies, and the first local signal is distributed to a plurality of systems for different modulation. Pulse signal train generating means for giving a function characteristic to generate a plurality of time-division pulse signal trains, amplitude modulating means for amplitude-modulating the second local signal with the pulse signal train output from the means, and the amplitude A transmission / reception means for converting the output signal of the modulation means into a pulse and transmitting the reflected signal, a signal separation means for separating the reception signal obtained by this transmission / reception means for each transmission pulse, and a separation means The characteristics that are opposite to the modulation function characteristics given at the time of transmission are given to each signal, and the signals do not move by delaying and adding at the same timing. Weighted addition means for removing the reflected signal component from the target, shift component detection means for detecting the frequency component shifted by the moving target from the signal obtained by this means, and based on the detection output of this means And a display means for displaying a moving target. 2. The local signal generating means comprises:
2. The MTI radar device according to claim 1, further comprising frequency changing means for changing one of the frequencies of one of the second local signals in a unit of a transmission repetition period. 3. The pulse signal train generating means delays a plurality of systems of first local signals to which different modulation function characteristics are applied, and delays the plurality of time division pulse signals in phase. The MTI radar device according to claim 1, further comprising: 4. The local signal generating means comprises frequency changing means for changing one of the frequencies of the first and second local signals in units of a transmission repetition period, and the pulse signal sequence generating means respectively. 2. The MTI radar device according to claim 1, further comprising delay means for changing a delay time of the first local signals of a plurality of systems given different modulation function characteristics according to the frequency change. 5. The MTI according to claim 1, wherein the modulation function is up-chirp or down-chirp.
Radar equipment. 6. A local signal generating means which is a coherent sine wave signal and generates first and second local signals having different frequencies, and a plurality of systems for distributing the first local signal to a plurality of systems. Pulse signal train generation means for generating a time-division pulse signal train, amplitude modulation means for amplitude-modulating the second local signal with the pulse signal train output from this means, and pulsed output signal of this amplitude modulation means After that, transmitting / receiving means for receiving the reflected signals by repeatedly transmitting the polarized waves with different polarizations at a constant period, and signal separating means for separating the received signals obtained by the transmitting / receiving means for each transmission pulse, And a weighted addition means for removing the reflection signal component from the stationary target that does not move by delaying and adding the signals separated in step 1 to have the same timing. An MTI radar apparatus comprising a shift component detecting means for detecting a frequency component shifted by a moving target from a signal obtained by this means, and a display means for displaying a moving target based on a detection output of this means. .. 7. The local signal generating means comprises:
7. The MTI radar device according to claim 6, further comprising frequency changing means for changing one of the frequencies of one of the second local signals in units of a transmission repetition period. 8. The pulse signal train generating means comprises delay means for delaying a plurality of first local signals of a plurality of systems to align respective phases of the plurality of time division pulse signals. 6. The MTI radar device according to item 6. 9. The local signal generating means comprises frequency changing means for changing one of the frequencies of the first and second local signals in units of a transmission repetition period, and the pulse signal train generating means respectively. 7. The MTI according to claim 6, further comprising delay means for changing a delay time of the first local signals of a plurality of systems according to the frequency change.
Radar equipment.