JPH0418274B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention irradiates radio waves from a radar to a moving target such as an aircraft or a flying object, and the frequency of the reflected wave from the target is higher than that of the transmitted wave. Continuous-wave Doppler radar or pulsed-wave radar distinguishes between fixed targets and moving targets by utilizing the characteristics that the frequency is high when the target is approaching and low when the target is moving away, depending on the speed of the target. Dotsupura・
The present invention relates to a phase-locked tracking radar that improves target detection performance by improving the ability to discriminate between moving and fixed targets and increasing sensitivity by combining dual frequency conversion and a phase-locked loop.

(Prior Art) First, a conventional example of the Doppler radar shown in FIG. 2 will be described. In this figure, a transmission source output 21, which is an output of a transmission source 20, is input to a power divider 22 and becomes a power divider first output 23a and a second power divider output 23b, one of which is a power divider second output 23b.
is input to the second mixer 26, and the other power divider first output 23a is input to the transmission antenna 12 and becomes the transmission signal 13.

A received signal 11, which is a reflected wave from a moving target, is received by a receiving antenna 14 and output from the receiving antenna 1.
5, the reception antenna output 15 is frequency-converted in the first mixer 16 using the first local oscillator output 25, which is the output of the first local oscillator 24, as a reference signal, and becomes the first mixer output 17, which is the first intermediate frequency. The signal is input to an amplifier 18 and becomes a first intermediate frequency amplifier output 19.

The power divider second output 23b is mixed with the first local oscillator output 25 in the second mixer 26 to become the second mixer output 27, which is input to the second intermediate frequency amplifier 28 and becomes the second intermediate frequency amplifier 29. .

The outputs of the first intermediate frequency amplifier 19 and the second intermediate frequency amplifier 29 are respectively input to a third mixer 30 and mixed, resulting in a third mixer output 31, which becomes a Doppler signal of the target reflected wave.

(Problem to be Solved by the Invention) By the way, when an aircraft or flying object with a small radar reflection area moves at a low altitude, a moving target and a fixed target such as the ground or sea surface may be included in the main beam of the radar antenna. to be mixed together,
The Doppler frequency, which is the frequency difference between the transmitting frequency and the receiving frequency, exists only in reflected waves from moving targets, which is used to distinguish moving targets from Kuratsuta reflected waves, which are unnecessary reflected waves from fixed targets. .

Various improvement measures have been proposed to improve the performance of target detection when targets with small radar reflected waves move at low speeds and low altitudes. They can be summarized as follows.

(a) Distinguish between moving targets and fixed targets by using the Doppler frequency, (b) Narrowing the band of the intermediate frequency amplifier in the previous stage improves the ability to discriminate between moving targets and fixed targets, (b) ) that the transmitter and local transmitter have,
By combining circuits, we can reduce the inherent phase noise that causes a decrease in sensitivity. e) Distinguish between positive and negative Doppler frequencies to distinguish between approaching targets and receding targets, (i) Increase sensitivity by performing synchronous detection when detecting signals, (i) Necessary for signal demodulation. To avoid deteriorating the signal-to-noise ratio, set the center frequency of the reference oscillator to
(x) It does not require a highly selective filter in the high frequency section. If it is possible to simultaneously realize the above measures, it should be possible to significantly improve the performance compared to the existing Dotsupura radar, and if it can be realized by a simpler method, the economic effect should further increase. .

(Means for Solving the Problems) In view of the above points, the present invention provides continuous wave Doppler
In radar or pulsed Doppler radar, phase synchronization improves target detection performance by improving the ability to discriminate between moving and fixed targets and increasing sensitivity by combining dual frequency conversion and phase synchronization loops. The aim is to provide a tracking radar.

The present invention provides a first mixer for performing a first frequency conversion, and a first mixer for performing a first frequency conversion, in a phase-locked tracking radar that irradiates radio waves from a transmitting antenna to a moving target and tracks reflected radio waves. a narrow-band intermediate frequency amplifier for amplifying the output of the intermediate frequency amplifier; a second mixer for performing a second frequency conversion on the output signal of the downstream side of the intermediate frequency amplifier; The receiver is equipped with a receiver using a dual or more frequency conversion method, which has at least a video amplifier that amplifies the output. Then, the phase of the first reference signal used for the first frequency conversion, which is generated from the signals of the reference signal _oscillator and the two-phase voltage controlled oscillator, is expressed as follows: (However, ωc: angular frequency of the transmitted signal, φc(t):
Phase noise of transmitted signal, ωr: Angular frequency of reference signal oscillator, φr: Phase noise of reference signal oscillator, ωd:
angular frequency of the two-phase voltage controlled oscillator, φv: phase control amount, t: time); to obtain an output signal including a Doppler signal, and convert the Doppler signal into a phase detector using a third reference signal using the output of the two-phase voltage controlled oscillator. The phase detection output is used as an input signal to the two-phase voltage controlled oscillator.
Here, the phase difference when the input signal is in synchronization is Δφ + φz - φv (where Δφ = φc (t - T) - φc (t), T: delay time from transmission to reception, φz: target phase noise). Then, the positive and negative polarities of the angular frequency ωd included in the phases of the first and second reference signals used for the first and second frequency conversions are switched by a polarity switch to track the approaching and receding Doppler signals. This method solves the problems of the prior art.

(Operation) Since FIG. 3 is a mathematical representation of the signal flow of the embodiment of the present invention shown in FIG. 1, the operation of the present invention will be described using FIG.

In FIG. 3, the two-phase oscillator first output 59a (X ₅₉ a) and the two-phase oscillator second output 59b (X ₅₉ b), which are the outputs of the two-phase oscillator 58 (working as a reference signal oscillator), are as follows. can be expressed as

X ₅₉ a=sin (ωrt+φr) (1) X ₅₉ b=cos (ωrt+φr) (2) where ωr is the angular frequency of the two-phase oscillator 58, φr is its phase noise, and t is time.

The two-phase voltage controlled oscillator first output 55a (X ₅₅ a) which is the output of the two-phase voltage controlled oscillator 54 and
The phase voltage controlled oscillator second output 55b (X ₅₅ b) is as follows: X ₅₅ a=sin (ωdt±φv) (3) X ₅₅ b=cos (ωdt±φv) (4). However, ωd is the two-phase voltage controlled oscillator 54
The first output 55a (X ₅₅ a) and the second output 55b of
(X ₅₅ b) is the angular frequency, and φv is the phase control amount. Multiple signs are in the same order. In the following description, the symbols above the denominator relate to the case of approaching target signals, and the symbols below the denominator relate to signals of a receding target.

Switch output 6 which is the output of the third polarity switch 60
1(X ₆₁ ) is expressed as follows from equation (1): X ₆₁ =±sin(ωrt+φr) (5).

_The modulator output ₅₇ ( _{X 57} ) is calculated by the following _arithmetic operation _: ±φv) = cos[ωrt+φr〓(ωdt±φv)] =cos(ωrt+φr〓ωdt−φv) …(6).

The transmission signal 13 (X ₁₃ ) and the power divider second output 23b (X ₂₃ b) are as follows: X ₁₃ =X ₂₃ b=sin[ωct+φc(t)] (7). However, ωc is the angular frequency of the transmission signal 13 (X ₁₃ ), and φc(t) is its phase noise. Therefore, _the received signal 11 (X ₁₁ ) and the receiving antenna output 15 (X ₁₅ ) _are as follows: T)]...(8). However, T is the delay time from transmission to reception. In addition, +ωd of the double sign of ωd in equation (8) is the Doppler angular frequency when the target is approaching, -ωd is the negative angular frequency when the target is moving away, and φz is the Doppler angular frequency when the radio wave is reflected. This is phase noise generated from

The fourth mixer output 33 (X ₃₃ ) is the second mixer output
Output 23b (X ₂₃ b) and modulator output 57 (X ₅₇ )
X ₃₃ = sin[ωct−ωrt ±ωdt+φc(t)−φr+φv] (9).

The fifth mixer output 35 (X ₃₅ ) and the third intermediate frequency amplifier output 37 (X ₃₇ ) are the receiving antenna output 15
(X ₁₅ ) and the fourth mixer output 33 (X ₃₃ ), so X ₃₅ =X ₃₇ =sin(ωrt+φz+Δφ+φr−φv) (10). However, Δφ=φc(t-T)−φc(t) (11).

Since the phase term in equation (10) does not include the angular frequency ωd of the Doppler signal, it is a narrowband signal, indicating that the third intermediate frequency amplifier 36 can be made narrowband.

The sixth mixer output 39 is a Doppler signal.
(X ₃₉ ) and video amplifier output 41 (X ₄₁ )
Intermediate frequency amplifier output 37 (X ₃₇ ) and modulator output 5
7 (X ₅₇ ), so X ₃₉ =X ₄₁ =cos(±ωdt+Δφ+φz)...(12). Here, the video amplifier 40 has the necessary Doppler signal bandwidth.

The two-phase voltage controlled oscillator first output 55a is input to the second polarity switch 50, and the second polarity switch output 55a is input to the second polarity switch 50.
1(X ₅₁ ) becomes X ₅₁ =〓sin(ωdt±φv) (13). In the phase detector 44, the video amplifier output 41 (X _{41 ) is phase detected using the second polarity switch output 51 (X 51 )} as a reference signal to obtain a phase detector output 45 (X ₄₅ ).

X ₄₅ =sin(Δφ+φz−φv) (14) The two-phase voltage controlled oscillator 54 controls the phase detector output 45 (X ₄₅ ) in equation (14) so that it becomes zero. In equation (14), Δφ is a small amount of high-frequency phase noise corresponding to the distance to the target out of the phase noise possessed by the transmission source 20, and φz is the phase noise from the target itself when the radio wave is reflected. Since this is the generated phase noise, equation (14) shows that the transmitter/receiver has extremely low phase noise. Furthermore, one of the excellent features of the present invention is that equation (14) does not include the phase noise of the two-phase oscillator 58.

In the synchronous detector 42, the video amplifier output 41 (X ₄₁ ) is synchronously detected using the two-phase voltage controlled oscillator second output 55b (X ₅₅ b) as a reference signal to obtain a synchronous detector output 43 (X ₄₃ ).

X ₄₃ = cos (Δφ + φz − φv) ... (15) From equation (15), the synchronous detector output 43 (X ₄₃ ) can be used to detect the presence or absence of a signal, so the sweep oscillator 52
It can be used as a stop and start signal (if a signal is present and cos0 = 1, the sweep will stop).

The basic signal flow has been explained, and the equivalent block shown in FIG. 4, which will be described later, is created from this signal flow.

From the above explanation, we have been able to explain in principle that the Doppler frequency of an approaching target and the Doppler frequency of a receding target can be tracked by using two polarity switchers 48 and 50 even though the amplifier has one channel.

Next, FIG. 6, which shows the signal flow of the second embodiment shown in FIG. 5, which is a modification of the first embodiment according to the present invention shown in FIG. 1, will be described.

The third polarity switch output 61 (X' ₆₁ ) is as follows, similar to equation (5): X' ₆₁ =±sin(ω'rt+φ'r) (16). Two-phase oscillator second output 59b (X' ₅₉ b)
As in equation _{( 2} ) _, (ω′rt+φ′r〓ωdt−φv) …(18) The third reference signal oscillator output 83 (X ₈₃ ), which is the output of the third reference signal oscillator 82, becomes X ₈₃ =cos(ω〓t+φ〓) (19). However, ω〓 is the third reference signal oscillator output 8
3 (X ₈₃ ), and φ〓 is the phase noise.

10th mixer output 8 which is the output of the 10th mixer 80
1 is generated by mixing the modulator output 57 (X ₅₇ ) and the third reference signal output 83 (X ₈₃ ), so X ₈₁ =cos(ωrt+φr〓ωdt−φv) (20). However, ωr＝ω′r−ω〓…(21) φv＝φ′r−φ〓…(22). Since the modulator output 57 (X ₅₇ ) in equation (6) and the 10th mixer output 81 (X ₈₁ ) in equation (20) have the same format, the following explanation is the same as in the case of Fig. 1. be.

Furthermore, FIG. 8, which is a signal flow diagram of the third embodiment shown in FIG. 7, will be explained. Since the third embodiment shown in FIG. 7 is a modification of the first embodiment shown in FIG. I will only explain the differences between the two.

The second reference signal oscillator 71 (X ₇₁ ), which is the output of the second reference signal oscillator 70, becomes X ₇₁ =sin(ωmt+φm) (23). However, ωm is the second reference signal oscillator output 7
1 (X ₇₁ ), and φm is the phase noise. The seventh mixer output 63 (X ₆₃ ), which is the output of the seventh mixer 62, is mixed with the modulator output 57 (X ₅₇ ) so that X ₆₃ =cos(ωrt±ωmt +φr〓ωdt−φv±φm)...( 24) However, when mixing in the seventh mixer 62, ωm can be decoded using either the sum frequency term or the difference frequency term between the modulator output 57 and the second reference signal oscillator output 71. It shows that there is.

Eighth mixer output 6 which is the output of the eighth mixer 64
₅ (X ₆₅ ) and the fourth intermediate frequency amplifier output 67 (X ₆₇ ), which is the output of the fourth intermediate frequency amplifier ₆₆ , are as follows: The output signal contains the signal.

The ninth mixer output 6 is the output of the ninth mixer 68
9 (X ₆₉ ) and _the video amplifier 41 (X _{41 )} are as follows:
(X ₄₁ ), the following explanation is the same as the embodiment shown in FIG.

FIG. 4, which is an equivalent block diagram of FIG. 1, will be explained. The phase 85 (X ₈₅ ) _of the video amplifier output 41 (X ₄₁ ) _is as follows: become.

X ₇₃ = Δφ + φz − φv … (28) Sine generator output 75 which is the output of sine generator 74
(X ₇₅ ) becomes X ₇₅ =sin(Δφ+φz−φv) (29), which is the same as the phase detector output 45 (X ₄₅ ). The sine generator output 75 (X ₇₅ ) is input to the convolution integrator 76 and becomes the convolution integrator output 77, and is input to the integrator 78 and becomes the integrator output 79, thereby closing the negative feedback loop. This loop has been shown to function well as a phase-locked loop.

(Example) Hereinafter, an example of the phase-locked tracking radar according to the present invention will be described with reference to the drawings.

The principle explanation of the first embodiment shown in FIG. 1 has already been explained in the third embodiment.
The first embodiment shown in FIG. 1 will be further described, although some of the explanation will be made with reference to the drawings.

The modulator 56 includes a two-phase voltage controlled oscillator first output 55a which is the output of the two-phase voltage controlled oscillator 54.
and a signal whose polarity has been switched by the third polarity switch 60 of the two-phase voltage controlled oscillator second output 55b and the two-phase oscillator first output 59a which is the output of the two-phase oscillator 58 (working as a reference signal oscillator). 3-polarity switch output 61 and 2-phase oscillator second output 5
9b is input and becomes the modulator output 57, and the fourth
The signal is input to the mixer 32 and the sixth mixer 38 as a reference signal.

A transmission source output 21, which is an output of the transmission source 20, is input to a power divider 22 and outputted as a power divider first output 2.
3a, and is transmitted by the transmitting antenna 12 toward the target. The power divider second output 23b is mixed with the modulator output 57 in the fourth mixer 32 to become the fourth mixer output 33.

The received signal 11 is received by the receiving antenna 14, becomes the receiving antenna output 15, is mixed with the fourth mixer output 33 in the fifth mixer 34, becomes the fifth mixer output 35, and is sent to the third intermediate frequency amplifier 3.
6 to become the third intermediate frequency amplifier output 37, mixed with the modulator output 57 in the sixth mixer 38 to become the sixth mixer output 39, and input to the video amplifier 40 to become the video amplifier output 41.
becomes.

The other output of the two-phase voltage controlled oscillator first output 55a is input to the second polarity switch 50 and is switched to the second polarity switch 50.
It becomes the polarity switch output 51. Video amplifier output 4
1 is phase-detected using the second polarity switch output 51 as a reference signal, becomes the phase detector output 45, is input to the low-pass filter 46, and becomes the low-pass filter output 4.
7, which is input to the first polarity switch 48 and the first
This becomes the polarity switch output 49 and is input to the two-phase voltage controlled oscillator 54.

The other video amplifier output 41 is synchronously detected by a synchronous detector 42 using the two-phase voltage controlled oscillator second output 55b as a reference signal, and the synchronous detector output 4
3 and is input to the sweep oscillator 52, but when a DC signal is output to the synchronous detector output 43 because the frequency and phase match, the sweep oscillator 5
The second sweep is stopped, and the DC signal of the sweep oscillator output 53 is held and input to the two-phase voltage controlled oscillator 54.

The second embodiment shown in FIG. 5 will be described (the same parts as in FIG. 1 are given the same numbers). Fig. 6, which is a principle diagram of the second embodiment shown in Fig. 5, has already been explained, and since Fig. 5 is a modification of Fig. 1, only the differences from the first embodiment shown in Fig. 1 will be described. .

In the tenth mixer 80, the modulator output 57 and the third
The third reference signal oscillator output 83, which is the output of the reference signal oscillator 82, is mixed to produce the tenth mixer output 81.
becomes. Hereinafter, the explanation is the same as in FIG. 1.

The third embodiment shown in Fig. 7 (the same parts as in Fig. 1 are given the same numbers) will be explained, but Fig. 8, which is a principle diagram of the third embodiment shown in Fig. 7, has already been explained. Since the third embodiment shown in FIG. 7 is a modification of the second embodiment shown in FIG. 1, only the differences from the first embodiment shown in FIG. 1 will be described.

In the seventh mixer 62, the modulator output 57 and the second reference signal oscillator output 71 are mixed, and the seventh mixer output 62 can be either a sum or a difference frequency.
3 and is used as a reference signal for frequency converting the third intermediate frequency amplifier output 37. Third
The intermediate frequency amplifier output 37 and the seventh mixer output 63 are mixed in the eighth mixer 64 to become the eighth mixer output 65, and are amplified in the fourth intermediate frequency amplifier 66 to become the fourth intermediate frequency amplifier output 67. The second reference signal oscillator output 71 is used as a reference signal and mixed in the ninth mixer 68 to become the ninth mixer output 69. The following explanation is the same as in FIG.

Next, a supplementary explanation of the embodiment will be given. Although the transmitting antenna 12 and the receiving antenna 14 have been described separately in each embodiment shown in FIG. 1, the transmitting antenna 12 and the receiving antenna 14 may be used in common.

When the target makes a U-turn, for example from approaching to separating, the Doppler frequency of the approaching target approaches 0, and if the polarity of the switch is changed at that point, the Doppler frequency of the separating target appears again, and the synchronous loop becomes unable to track it. It becomes possible. Radar is used in such a way that targets enter the radar coverage area from outside the radar coverage area, so even if the device itself cannot simultaneously determine whether the target is approaching or moving away, By switching the switch, you can realize whether the target you are currently tracking is approaching or moving away, then you can essentially achieve your purpose as a radar.

(Effects of the Invention) Various excellent effects of the present invention are summarized as follows.

(A) Since the third intermediate frequency amplifier 36 is a narrow band Doppler gate, the resolution of the target velocity is high.

(b) The combination of circuits reduces the inherent phase noise of the oscillator, and it is constructed without using an expensive local oscillator that is close to the frequency of the transmission source.

(C) The video amplifier output 41 returns the positive and negative Clutter/Doppler signals from the moving target and the fixed target, but only the moving target signal is filtered in the narrow band third intermediate frequency amplifier 36. It has high sensitivity and high resolution.

(e) Since the positive and negative speeds of a moving target can be detected with one channel, the economical effect is great.

(E) Since the signal is detected by the synchronous detector 42, it is less susceptible to noise and has high sensitivity.

(l) Because of the filtering effect of the video amplifier 40 and the fact that the two-phase voltage controlled oscillator 54 does not oscillate near zero frequency, a self-synchronization phenomenon occurs due to the direct wrap-around of the transmitted signal 13, which tends to occur in this type of receiver. Hateful.

(i) Since the video amplifier 40 is in the loop, the effect of removing noise around zero Doppler is great.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of a phase-locked tracking radar using a phase-locked loop according to the present invention, FIG. 2 is a block diagram of a conventional Doppler radar, and FIG. 3 is a block diagram of a conventional Doppler radar. 4 is an equivalent diagram that is a mathematical expression of the explanatory diagram in FIG. 3, FIG. 5 is a block diagram of the second embodiment, and FIG. 6 is a diagram of the diagram in FIG. FIG. 7 is an explanatory diagram showing the flow of signals in the block diagram. FIG. 7 is a block diagram of the third embodiment. FIG. 8 is an explanatory diagram showing the flow of signals in the block diagram of FIG. 11...Received signal ( _X11 ), 12...Transmission antenna, 13...Transmission signal ( _X13 ), 14...Reception antenna, 15...Reception antenna output ( _X15 ),
16...first mixer, 17...first mixer output,
18...First intermediate frequency amplifier, 19...First intermediate frequency amplifier output, 20...Transmission source, 21...Transmission source output, 22...Power divider, 23a...Power divider first output, 23b ...Power divider 2nd output,
24...First local oscillator, 25...First local oscillator output, 26...Second mixer, 27...Second mixer output, 28...Second intermediate frequency amplifier, 29...
Second intermediate frequency amplifier output, 30...Third mixer,
31...Third mixer output, 32...Fourth mixer,
33...Fourth mixer output (X ₃₃ ), 34...Fifth
Mixer, 35...Fifth mixer output (X ₃₅ ), 36
...Third intermediate frequency amplifier, 37...Third intermediate frequency amplifier output, 38...Sixth mixer, 39...Sixth
Mixer output (X ₃₉ ), 40...Video amplifier, 4
1... Video amplifier output (X ₄₁ ), 42... Synchronous detector, 43... Synchronous detector output (X ₄₃ ), 44
... Phase detector, 45 ... Phase detector output (X ₄₅ ), 46 ... Low pass filter, 47 ... Low pass filter output, 48 ... First polarity switch, 49
...First polarity switch output, 50...Second polarity switch, 51...Second polarity switch output (X ₅₁ ), 52
...Sweep oscillator, 53...Sweep oscillator output, 54
...2-phase voltage controlled oscillator, 55a...2-phase voltage controlled oscillator first output (X ₅₅ a), 55b...2
Phase voltage controlled oscillator second output (X ₅₅ b), 56...
...Modulator, 57...Modulator output (X ₅₇ ), 58...
...Two-phase oscillator, 59a...Two-phase oscillator first output (X ₅₉ a), 59b... Two-phase oscillator second output (X ₅₉ b), 60... Third polarity switch, 61... Third polarity Switcher output (X ₆₁ ), 62...7th mixer,
63...Seventh mixer output ( _X63 ), 64...Eighth
Mixer, 65... 8th mixer output, 66... 4th
Intermediate frequency amplifier, 67... Fourth intermediate frequency amplifier output (X ₆₇ ), 68... Ninth mixer, 69... Ninth
mixer output (X ₆₉ ), 70... second reference signal oscillator, 71... second reference signal oscillator output (X ₇₁ ),
72... Adder, 73... Adder output (X ₇₃ ),
74...Sine generator, 75, Sine generator output (X ₇₅ ), 7
6... Convolution integrator, 77... Convolution integrator output, 78... Integrator, 79... Integrator output, 8
0...10th mixer, 81...10th mixer output ( _X81 ), 82...3rd reference signal oscillator, 83...
Third reference signal oscillator output ( _X83 ), 85... Phase of video amplifier output ( _X85 ), ANT...Antenna, MIX...Mixer, IF...Intermediate frequency amplifier,
V.AMP...Video amplifier, SDET...Synchronous detector, PSD...Phase detector, LPF...Low pass filter, 〓...Polarity switch, SWEEP...Sweep oscillator, VCO...2 phase Voltage controlled oscillator, MOD...
Modulator, OSC...oscillator.

Claims (1)

[Claims] 1. Irradiating radio waves from a transmitting antenna to a moving target,
A phase-locked tracking radar that tracks reflected radio waves includes: a first mixer for performing a first frequency conversion; a narrow-band intermediate frequency amplifier that amplifies the output of the first mixer; A dual- or more-multiplex system comprising at least a second mixer for performing second frequency conversion on the output signal of the downstream side of the intermediate frequency amplifier, and a video amplifier for amplifying the output of the second mixer. The receiver is equipped with a frequency conversion type receiver, and the phase of the first reference signal used for the first frequency conversion, which is generated from the signals of the reference signal oscillator and the two- _phase voltage controlled oscillator, is expressed as follows: ±ωdt+φc(t)−φr+φv] (where ωc: angular frequency of the transmitted signal, φc(t):
Phase noise of transmitted signal, ωr: Angular frequency of reference signal oscillator, φr: Phase noise of reference signal oscillator, ωd:
angular frequency of the two-phase voltage controlled oscillator, φv: phase control amount, t: time); Performing the second frequency conversion using
A third oscillator using the output of the two-phase voltage controlled oscillator
The Doppler signal is phase-detected by a phase detector using a reference signal of The relationship is Δφ+φz-φv (where Δφ=φc(t-T)-φc(t), T: delay time from transmission to reception, φz: phase noise generated by the target), and the first and second The angular frequency ωd included in the phase of the first and second reference signals used for frequency conversion of
A phase synchronized tracking radar characterized in that the positive and negative polarities of the signal are switched by a polarity switch to enable tracking of approaching and receding Doppler signals.