JPH0516751B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention is used in a tracking device that tracks short wavelength electromagnetic waves generated by or reflected from a target. The present invention relates to a tracking receiver for extracting error signals of the elevation angle and azimuth angle of a target in a rosette scan receiver and a spiral scan receiver.

(Prior Art) An example of a rosette scan pattern 40 produced by a rosette scan antenna used in a rosette scan receiver is shown in FIG. 40 in the figure is a rosette scan pattern of 12 petals.

An example of a helical scan pattern 42 produced by a helical scan antenna used in a helical scan receiver is shown in FIG.

Rosette scan antennas and helical scan antennas consist of two antennas rotating at different angular frequencies ω ₁ and ω ₂ . Also, if an electronic scanning antenna is used, a rosette scan pattern 40 and a helical scan pattern 4 can be created.
2 can be easily made.

Coordinates (x, y) of point P on rosette scan pattern 40 and spiral scan pattern 42
Since is the sum of two rotating vectors, it can be expressed as follows (however, time is assumed to be t).

x=φ[sin0.5( _ω1 + _ω2 )t]cos0.5( _ω1 − _ω2 )
t = (φ/2) (sinω ₁ t + sinω ₂ t) ...(1) y = φ [sin0.5 (ω ₁ + ω ₂ ) t] sin0.5 (ω ₁ − ω ₂ )
t=(φ/2)(cosω ₁ t+cosω ₂ t) (2) The rosette scan pattern 40 in FIG. 2 is drawn with φ=1, ω ₂ =5, and ω ₁ =7. When the target P is located on the pattern shown in FIGS. 2 and 3, a sharp pulse-like signal is received, and therefore, conventional receivers have been broadband receivers.

FIG. 7 will be explained. Target P in Figures 2 and 3
FIG. 7 is an enlarged view showing the relationship between the target P and the scan. This is an example in which the antenna beam crosses the target from C to D. The center A of the target on the xy coordinates is (a, b).

Here, r=√( ² + ² )...(2a) θ=arctan(b/a)...(2b). The relationship between the target in Figure 7 and the scan has already been explained by the
-30431: JP-A No. 58-215574'', ``Rozetsu Scan Demodulator, JP-A No. 1-30432: JP-A-59-
No. 77372'', ``Rozetsu Scan Demodulator, Special Publication No. 1
-56389: Japanese Patent Application Laid-Open No. 1983-77371” and “Heral Scan Demodulator, Japanese Patent Publication No. 1-31148: Japanese Patent Application Laid-open No. 1983-
As shown in No. 100069, l=btanβ+a/(tan ² β+1) ^1/2 ...(2C) =√( ² + ² )cos{β-tan(b/a)}...(2d) Therefore, it has already been shown that the polarity of the signal can be reversed around the 0 point as shown in FIG. Therefore, conventionally, multiplication was performed using a signal of X=sign {sin0.5(ω ₁ +ω ₂ )t} (2e).

however sign(x)=1 1/2 -1 x>0 x=0 x<0...(2f) It is.

The signal waveform in FIG. 4 corresponds to the rosette shown in FIG.
Amplitude detector output 49, first and second phase oscillator second output 29b which is the output of first and second phase oscillator 28, or output of second and second phase oscillator 30 in a conventional example of a tracking receiver equipped with a scan antenna 2nd/2nd phase oscillator second output 31b, and demodulator first output 51a or demodulator second output 51
b. Amplitude detector output 4 in Figure 4
9, target P is rosette scan pattern 40
Alternatively, it is a part of the signal waveform when it is sufficiently small compared to the search angle of the helical scan pattern 42.
The first and second phase oscillator second output 29b, which is the output of the first and second phase oscillator 28, or the second and second phase oscillator output 31b, which is the output of the second and second phase oscillator 30, is a signal for phase detection. The azimuth error signal 23 or the elevation error signal 25 is obtained by multiplying the two signals 49, 29b or 31b. When the target P is off the center of the pattern, two signals 49, 29b or 31b
During this period, as shown in FIG. 4, the pulse center of the signal is shifted by l, so that an azimuth angle error signal 23 and an elevation angle error signal 25 are obtained.

FIG. 6 shows a conventional example of a tracking receiver equipped with a rosette scan antenna 2. The received signal 1 from the target P has a rosette scan pattern 40.
The signal is received by antenna 2, which is generating the signal. The antenna output 3 is mixed in the fourth mixer 44 using the local oscillator output 15 which is the output of the local oscillator 14, and is mixed into the fourth mixer output 4 which is an intermediate frequency signal.
5, is amplified by the fourth intermediate frequency amplifier 46 to become the fourth intermediate frequency amplifier output 47, is amplitude detected by the amplitude detector 48 to become the amplitude detector output 49, and is input to the demodulator 50. . The pattern generator 26 receives the first and second phase oscillators from the first and second phase oscillators 28.
2-phase oscillator first output 29a and 2nd/2nd phase oscillator first output 31 from 2nd/2nd phase oscillator 30
Create a rosette scan pattern 40 using a. In the demodulator 50, the first and second phase oscillator second outputs 29b and the second and second phase oscillator outputs 31b
are used to become the demodulator first output 51a and demodulator second output 51b, respectively, and the first low-pass filter 22
and a second low-pass filter 24, respectively, and become an azimuth angle error signal 23 and an elevation angle error signal 25.

(Problems to be Solved by the Invention) By the way, when tracking a target such as an aircraft, ship, or vehicle, it is necessary to first detect the target by pointing the antenna of the tracking device in that direction or by searching the vicinity of the target. Follow the steps to start tracking. In order to improve target tracking accuracy, a tracking device with a narrow antenna beam width is used that uses high frequencies such as millimeter waves, but in this case, the narrow beam width naturally causes the target to go from a search state to a tracking state. The retraction width becomes narrower. For this reason, rosette scan and spiral scan tracking systems, which have a wide pull-in width, are attracting attention. If possible, these tracking receivers would be even better.

(Means for Solving the Problems) In view of the above-mentioned points, the present invention aims to provide an economical tracking receiver that can improve sensitivity by narrowing the bandwidth of an intermediate frequency amplifier. It is something to do.

For example, when the target P is a small circular target with a radius R, and the circular target is shifted from the center of the rosette scan pattern 40 by coordinates (a, b), the antenna output 3 in FIG.
(x ₃ ) becomes as follows.

x ₃ = v(t) cosωct ...(3) where ωc is the angular frequency of the received signal 1, and v
(t) is v(t)=k・sgn{R ² −[(x−a) ² +(y−b)
² ]} =k・sgn{R ² −[2cos(ω ₁ +ω ₂ )t −4r・sinαt・cos(βt−θ)+r ² +2]}
...(4) becomes. However, k is a proportional constant, α and β are α=0.5(ω ₁ +ω ₂ ) …(5) β=0.5(ω ₁ −ω ₂ ) …(6), and r=√( ² + ² ) θ=arctan(b/a) agn(x)=1 1/2 −1 x>0 x=0 x<0 (7). Here, the relationship between the target and the scan in FIG. ^2β +1) ^1/2 ...(7a) =√( ² + ² )cos{β-tan(b/a)}...(7b). Since the 0 point on the xy coordinates corresponds to the 0 point in Figure 5, the formula (4) shown in the received signal 1
The purpose is achieved by outputting r and θ contained in the signal.

Antenna 2 generating a rosette scan pattern 40 or a spiral scan pattern 42
By biphasically modulating the switching signal to the mixer for conversion to an intermediate frequency, the signals received at the It is an attempt to realize a tracking receiver by the same means as a monopulse receiver (commonly used) which obtains an azimuth error signal and an elevation angle error signal by synchronously detecting an intermediate frequency signal.

Antenna output 3 and switching signal (two-phase modulator output) 1 in the embodiment of the present invention shown in FIG.
1, 13, and the synchronous detector outputs 83, 85 are shown in FIG.

As shown in FIG. 7, when the target is shifted from the center of the antenna 2 by (a, b), the center of the antenna output 3 and the first and second
There is a phase shift of l from the center of phase switching of the phase modulator output 11 or the second/second phase modulator output 13. Therefore, since the center of the pulse of the second intermediate frequency amplifier output 19 and the center of phase switching of the first intermediate frequency amplifier output 17 or the third intermediate frequency amplifier output 21 are shifted by l, the azimuth error signal 23 Alternatively, an elevation angle error signal 25 can be obtained.

(Operation) Since the rosette scan pattern 40 and the spiral scan pattern 42 are essentially the same as shown in FIGS. 2 and 3, the case of the rosette scan pattern 40 will be explained.

1st and 2nd phase oscillator first output 29a in FIG.
(x ₂₉ a) and second/two-phase oscillator first output 31a
(x ₃₁ a) are defined as follows.

x ₂₉ a=-cosω ₁ t...(8) x ₃₁ a=cosω ₂ t...(9) The first output 29a of the first and second phase oscillators and the second
The two-phase oscillator second output 31a is the pattern generator 2
6, the antenna 2 generates a rosette scan pattern 40.

The first adder output 33 (x ₃₃ ) is x ₃₃ =x ₂₉ a+x ₃₁ a =2(sinαt)sinβt (10).

Since the first waveform shaping circuit output 37 (x ₃₇ ) is a binary signal, x ₃₇ = sign {(sin αt) sin βt} ...(11) where sign (x) = 1 1/2 -1x>0 x = 0 x<0...(12)

The second/second phase modulator output 13 (x ₁₃ ) is 0,
It is a two-phase modulated signal of π _{radians ,} and the local _oscillator output ₁₅ (x ₁₅ ) is ≒{(sinαt)sinβt}cosω _Q t) ...(14). However, ω _Q is the angular frequency of the local oscillator output 15.

The first and second phase oscillator second outputs 29b (x ₂₉ b) and the second and second phase oscillator second outputs 31b (x ₃₁ b) are as follows.

x ₂₉ b＝sinω ₁ t ……(15) x ₃₁ b＝sinω ₂ t ……(16) The second adder output 35 (x ₃₅ ) is x ₃₅ = x ₂₉ b＋x ₃₁ b = 2(sinαt) cosβt … …(17) becomes.

Since the second waveform shaping circuit output 39 (x ₃₉ ) is a binary signal, x ₃₉ =sign {(sinαt)cosβt} (18). Since the first and second phase modulator outputs 11 (x ₁₁ ) are two-phase modulated signals of 0 and π radians, x ₁₁ = sign [(sinαt) cosβt] cosω _Q t (or ≒ {(sinαt) cosβt }cosω _Q t) ...(19).

The first mixer output 5 (x ₅ ) and the first intermediate frequency amplifier output 19 (x ₁₉ ) are the antenna output 3 (x ₃ ) and the first and second phase modulator outputs 11 (x ₁₁ ) mixed together. ₅ =kv(t)sign[(sinαt)cosβt]cosωit...(20). However, ωi=ωc−ω _Q ……(21).

The second mixer output 7 (x ₇ ) and the second intermediate frequency amplifier output 19 (x ₁₉ ) are the antenna output 3 (x ₃ ) and the local oscillator output 15
(X ₁₅ ) is mixed and becomes x ₇ =x ₁₉ =kv(t)cosωit...(22).

The third mixer output 9 (x ₉ ) is the antenna output 3
(X ₃ ) and second/second phase modulator output 13 (X ₁₃ )
are mixed x ₉ = kv(t)sign[(sinαt)sinβt]cosωit
...(23) becomes.

Therefore, the azimuth error signal 23 (x ₂₃ ) is synchronously detected using the second intermediate frequency amplifier output 19 (x ₁₉ ) as a switching signal, and is further filtered to obtain x ₂₃ = ₅ · ₁₉ = ^{2 2} () [( )
] ≒ ^{2 2} () () ≒ {(-)} ≒ a ...(24), and the height angle error signal 25 (x ₂₅ ) is expressed as x ₂₅ = ₉・₁₉ = ^{2 2} ( ) [()
] ≒ ^{2 2} () () ≒ {(-)} ≒ b ...(25). However, is the average of one period,
From equation (4), kv(t)≧0 (26).

Note that the calculations of equations (24) and (25) are almost the same as the demodulation principle of the conventional example.

The pattern created by the first adder output 33 (x ₃₃ ) and the second adder output 35 (x ₃₅ ) is the rosette pattern shown in FIG. 2 or the spiral pattern shown in FIG. 3.

Here, x ₃₃ = 0 ... (27) x ₃₅ = 0 ... (28) Or x ₃₇ = 0 regarding the first waveform shaping circuit output 37 (x ₃₇ ) and the second waveform shaping circuit output 39 (x ₃₉ ) ...(29) x ₃₉ =0 ...(30) The point that simultaneously satisfies each equation is the center (0,0) of FIGS. 2 and 3. Also, that point is the seventh
This is the 0 point on the xy coordinates of the figure, and corresponds to the 0 point in FIG. From this, the first and second phase modulator outputs 11 and the first waveform shaping circuit output 37 necessary for demodulating the error voltage can be obtained from the same type of signal forming the pattern. The first adder output 33 and the second
The method of adjusting the adder output 35 is to adjust the azimuth error signal 2 when the target is at the pattern center (a=0, b=0).
The phases of the first adder output 33 and the second adder output 35 may be adjusted so that the height angle error signal 25 and the height angle error signal 25 are zero.

(Example) Hereinafter, an example of a tracking receiver according to the present invention will be described with reference to the drawings.

In FIG. 1, the received signal 1 from the target P is
It is received by the antenna 2 which generates the rosette scan pattern 40, and becomes the antenna output 3. The antenna output 3 is branched and input to the second mixer 6, where it is frequency-converted using the local oscillator output 15, which is the output of the local oscillator 14, as a switching signal, and becomes the second mixer output 7, which is then input to the second intermediate frequency amplifier 18. is amplified by the second intermediate frequency amplifier output 1
9 and becomes the reference signal for the first synchronous detector 82 and the second synchronous detector 84.

In the first mixer 4, the first and second phase modulator outputs 1
1 as a switching signal, the antenna output 3 is frequency-converted to obtain the first mixer output 5. This first
The mixer output 5 is amplified by the first intermediate frequency amplifier 16 to become the first intermediate frequency amplifier output 17, is synchronously detected by the first synchronous detector 82, becomes the first synchronous detector output 83, and becomes the first synchronous detector output 83. 1 is input to a low-pass filter 22 and becomes an azimuth error signal 23.

In the third mixer 8, the second/second phase modulator output 1
3 as a switching signal, the antenna output 3 is frequency converted to obtain a third mixer output 9. This third mixer output 9 is transmitted to a third intermediate frequency amplifier 20
It is amplified to become the third intermediate frequency amplifier output 21, and synchronously detected by the second synchronous detector 84 to become the third intermediate frequency amplifier output 21.
The signal becomes the synchronous detector output 85, is input to the second low-pass filter 24, and becomes the elevation angle error signal 25.

The first and second outputs of the first and second phase oscillators 28
The phase oscillator first output 29a and the second and second phase oscillator first outputs 31a, which are the outputs of the second and second phase oscillators 30, are branched and sent to the pattern generator 2.
6 to generate a rosette scan pattern 40. The other branched first output 29a of the first and second phase oscillators and the first output 31a of the second and second phase oscillators are respectively input to the first adder 32 and become the first adder output 33. The first waveform shaping circuit output 37 is waveform-shaped into a binary signal in the waveform shaping circuit 36, and this is the second waveform shaping circuit output 37.
It becomes the modulation signal of the two-phase modulator 12, phase-modulates the local oscillator output 15, and becomes the second/two-phase modulator output 13. Further, the first and second phase oscillator second outputs 29b, which are the outputs of the first and second phase oscillators 28, and the second and second phase oscillator outputs 31b, which are the outputs of the second and second phase oscillators 30, are the second and second phase oscillator outputs, respectively. It is input to the adder 34 and becomes the second adder output 35, and it is input to the second waveform shaping circuit 38 and becomes the second waveform shaping circuit output 39, which is a binary signal, and becomes the modulation signal of the first and second phase modulator 10. becomes, local oscillator output 15
becomes the first and second phase modulator output 11.

This completes the explanation of the tracking receiver that detects the azimuth angle error signal or the elevation angle error signal.

A supplementary explanation of the example will be provided.

In the embodiments shown in FIGS. 1 and 5, the case of the rosette scan antenna 2 has been explained, but no explanation is necessary in the case of the helical scan antenna 2 as the only difference is the sign of ω ₁ and ω ₂ . .

(Effects of the Invention) As explained above, according to the tracking receiver of the present invention, the following effects can be obtained.

(A) In addition to using synchronous detectors 82 and 84 that do not require dropping the azimuth error signal 23 and the elevation angle error signal 25 to the base band, the first intermediate frequency amplifier 16 and the second intermediate frequency amplifier Since it is possible to narrow the frequency bandwidth of the 18 and third intermediate frequency amplifier 20 (as long as the phase information is accurate), the tracking receiver has extremely high sensitivity.

(b) The configuration of the receiver is very similar to that of a monopulse receiver, so when the monopulse receiver is used as a means of searching for a target, it has a small economic burden and is highly effective.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a tracking receiver according to the present invention, FIG. 2 is an explanatory diagram showing an example of a rosette scan pattern produced by a rosette scan antenna, and FIG. 3 is a spiral scan antenna. FIG. 4 is a signal waveform diagram of a conventional example of a radar receiver, FIG. 5 is a signal waveform diagram of an embodiment of the present invention, and FIG. 6 is a diagram of a signal waveform of a radar receiver. FIG. 7 is a block diagram showing a conventional example, and is an explanatory diagram showing the relationship between a target and a scan. P...Target, 1...Received signal, 2...Antenna, 3...
Antenna output (x ₃ ), 4...first mixer, 5...first
Mixer output, 6... Second mixer, 7... Second mixer output, 8... Third mixer, 9... Third mixer output, 10
...First and second phase modulator, 11...First and second phase modulator output ( _x11 ), 12...Second and second phase modulator, 13
... Second/second phase modulator output (X ₁₃ ), 14... Local oscillator, 15... Local oscillator output, 16... First intermediate frequency amplifier, 17... First intermediate frequency amplifier output, 1
8... Second intermediate frequency amplifier, 19... Second intermediate frequency amplifier output, 20... Third intermediate frequency amplifier, 21... Third intermediate frequency amplifier output, 22... First low pass filter, 23... Azimuth error Signal, 24... Second low pass filter, 25... Height angle error signal, 26... Pattern generator, 28... First and second phase oscillator, 29a... First and second phase oscillator first output (x ₂₉ a ), 29b... 1st/2nd phase oscillator second output (x ₂₉ b), 30... 2nd/2nd phase oscillator, 31a... 2nd/2nd phase oscillator first output (x ₃₁ a), 31b... 2nd/2nd phase oscillator 2-phase oscillator second output (x ₃₁ b), 32... first adder, 33... first adder output (x ₃₃ ), 34... second adder, 35...
Second adder output ( _x35 ), 36...first waveform shaping circuit, 37...first waveform shaping circuit output ( _x37 ), 38...
Second waveform shaping circuit, 39... Second waveform shaping circuit output (x ₃₉ ), 40... Rosette scan pattern,
42... Helical scan pattern, 44... Fourth mixer, 45... Fourth mixer output, 46... Fourth intermediate frequency amplifier, 47... Fourth intermediate frequency amplifier output, 48...
Amplitude detector, 49... Amplitude detector output, 50... Demodulator, 51a... Demodulator first output, 51b... Demodulator second output, 82... First synchronous detector, 83... First synchronous detector output, 84 ...Second synchronous detector, 85...Second
Synchronous detector output.

Claims (1)

[Claims] 1. An electromagnetic wave from a target is received by an antenna capable of generating a rosette scan pattern or a spiral scan pattern, and a switching signal expressed by the following formula () or () is generated in a first mixer. X ₁₃ = sign [(sinαt) sinβt _] cosω _{l t} or = {(sinαt) sinβt} cosω _l t ... () _l t...() (However, α, β: constants determined by the antenna,
ω _l : angular frequency of local oscillator output, t: time) is used to convert the frequency into the first intermediate frequency signal, and in the second mixer, the angular frequency and phase are An azimuth error signal or A tracking receiver characterized by detecting an elevation angle error signal.