JPH10160813A - Apparatus for monitoring bearing of tacan antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a monitoring apparatus which reduces the constitution of a high-frequency module and of an analog circuit and which simplifies a circuit constitution when the bearing of an electronic scanning TACAN antenna is monitored. SOLUTION: When the bearing of an electronic scanning TACAN antenna is monitored, e.g. a change in the phase of variable bearing signals (15Hz, 135Hz) and a change in the phase of carrier waves are monitored. When the change in the phase of the variable gearing signals is monitored, pickup signals (pulse signals) from 36 array antennas are detected, and transmission levels of the repsective array antennas are detected by peak hold circuits 3. Then, their transmission level signals (peak level signals) are phase-corrected digitally so as to be synthesized, the waveform of the variable bearing signals is analyzed, and the change in the bearing (the phase) is monitored. When the change in the phase of the carrier waves is monitored, the pickup signals from the array antennas are mixed with a local signal, and the change in the phase is monitored by a phase detector 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an azimuth monitoring device for monitoring the azimuth of an antenna of a Takan device, and more particularly to an azimuth monitoring device of an electronic scanning antenna.

[0002]

2. Description of the Related Art A Takan device is a device for providing the direction and distance of a Takan station as viewed from an aircraft with reference to magnetic north. A direction signal (Takan signal) of Takan can be expressed by the following equation (1).

[0003]

(Equation 1) Here, ω = 2πf, f: 15 Hz, A: modulation degree of 15 Hz, B: modulation degree of 135 Hz.

The azimuth information of the Takan device includes a reference burst (north azimuth, 40-degree azimuth) and a variable azimuth signal (15 Hz, 1 azimuth).
As shown in FIG. 9, the north direction reference burst is transmitted when the maximum value of the variable direction signal is east at t = 0 (0 degree) in the Takan direction reference as shown in FIG. At this time, the aircraft in the south (indicating magnetic north; the direction of Takan is opposite to the direction seen from the aircraft) is 15
A north azimuth reference burst is received at the rising zero crossing point of the Hz variable azimuth signal. The angle measurement is counterclockwise from the north azimuth reference burst and is expressed as an electrical angle up to the zero crossing point in the rising direction of the 15 Hz variable azimuth signal. Therefore, the azimuth indicates 0 degree.

The relationship between the Takan north azimuth reference burst and the 40 degree azimuth reference burst is such that the north azimuth reference burst is 15 Hz.
The variable azimuth signal is transmitted at an electrical angle of 0 degrees, and the 40-degree azimuth reference signal is an electrical angle of 40 degrees (1
35 Hz). 15Hz variable direction signal and 1
The relationship with the 35 Hz variable azimuth signal starts at the same phase at t = 0, and 9 times higher accuracy than the 15 Hz angle measurement accuracy is obtained. Therefore, the 135 Hz variable azimuth signal has a vernier function with respect to the 15 Hz variable azimuth signal.
As a result, the aircraft located north of the Takan station will show an azimuth of 180 degrees, and the aircraft located east of it will show 270 degrees. Similarly, the west indicates 90 degrees.

The above is the principle of the Takan device. Next, the direction monitoring of the Takan device will be described.

FIGS. 6 and 7 are views for explaining a conventional direction monitoring device. Referring to FIG. 6, an electronic scanning type Takan antenna 41 shown in FIG. 6 (a) is a cylindrical antenna and has 36 array antennas 41a arranged along the circumference thereof. Monitor pickup 1
Is connected to the signal processing unit 42 via the. The signal processing unit 42 is connected to the monitoring circuit 26.

When the direction of the electronic scanning type Takan antenna 41 is monitored, an integral monitor system is conventionally employed, thereby monitoring 36 directions. In the integral monitor system, as shown in FIG. 8, the pattern characteristics of the array-type antenna 41a and the phase difference between the path difference with respect to the equal phase plane are corrected and combined to thereby combine the electric field received by the far-field monitor antenna. This is a method of generating an equivalent signal and monitoring the direction.

Referring to FIG. 6B, specifically, 36
The signals are picked up by the monitor pickups 1 coupled to the array type antennas 41, respectively, and supplied to the switch 21 as pickup signals. The switch 21 selects ten pickup signals from the azimuth to be monitored in accordance with the control signal from the card module 22 and outputs the selected signals as a selection signal. The phase shifter 23 performs the phase control according to the control signal from the card module 22. As a result, the selection signal is subjected to the phase correction of the path difference with respect to the equal phase plane, and then the signal is added by the synthesizer 24 to obtain the synthesized signal Is output as Then, the combined signal is detected by the detector 25 and supplied to the monitoring circuit 26 as a detected signal.

Referring to FIG. 7, FIG. 7 (a) shows a configuration of a monitoring circuit, and detection signal a is a variable azimuth signal (1
A first generation circuit (15 Hz filter 31 and 135 Hz filter 3) for generating 5 Hz and 135 Hz)
5) and a second generation circuit (north azimuth reference burst detection 33 and 4) for generating a reference signal (north azimuth and 40 degree azimuth)
0 ° azimuth reference burst detection 37). The reference signals (north azimuth reference signal and 40-degree azimuth reference signal) are supplied to relative phase difference detection circuits 34 and 38, respectively, and the variable azimuth signals (15 Hz and 135 Hz) are phase-shifted to zero the phase difference with the reference signal. After being phase-shifted by the shifters 32 and 36, they are input to the relative phase difference detection circuits 34 and 38.

Referring to FIG. 6 (b), when there is no failure in the Takan device, the azimuth error of the relative phase difference detection circuits 34 and 38 is adjusted to a minimum value (0.2 degrees or less). . On the other hand, when a failure occurs in the Takan device, the outputs of the relative phase difference detection circuits 34 and 38 generate an azimuth error corresponding to the change in the azimuth angle. Upon detection, the wave breaking of the takan device is performed.

The outputs of the relative phase difference detection circuits 34 and 38 are pulses of the time difference between the reference signal and the zero-cross point in the rising of the variable azimuth signal. The relationship between this pulse width and the azimuth error is that the pulse width is 185 μs = 1 degree. is there.

The output pulses (azimuth errors) of the relative phase difference detection circuits 34 and 38 are given to an azimuth error counting circuit 39.
Counted and averaged for seconds. Then, the determination circuit 40 determines whether the count average result is 1 or more or 1 or less, and if it is 1 or more, the control / display circuit 41 performs a wave stop of the takan device and an alarm display.

Using this method, one round of monitoring is sequentially performed in 36 directions. This required time is 36 seconds. However, since the alarm detection time is limited to 4 seconds, one round is quickly made by monitoring every 50 degrees, but ultimately all 36 directions are monitored.

[0015]

By the way, in the conventional Takan antenna azimuth monitoring apparatus, a signal processing unit includes a switch for switching 36 pickup signals, a 10 phase shifter, and a switch and a phase shifter. Controlling card module, and 10
Considering that the operating frequency is in the 1 GHz band, there is a problem that the number of high-frequency modules is large, the circuit configuration is complicated and large in view of the fact that a synthesizer for synthesizing the outputs of the plurality of phase shifters is provided.

Furthermore, in the conventional Takan antenna monitoring device, the monitoring circuit uses a variable heading signal (15 Hz and 135 Hz).
And a generating circuit for generating a reference azimuth signal (north azimuth and 40-degree azimuth), a relative phase difference detecting circuit, and an azimuth error counting circuit, and there are many circuits for processing analog signals. However, there is a problem that is complicated and large.

An object of the present invention is to provide a small and lightweight azimuth monitoring device.

[0018]

SUMMARY OF THE INVENTION A Takan antenna direction monitoring apparatus according to the present invention comprises a variable direction signal (15 Hz, 135H).
The phase change of z) and the phase change of the carrier are monitored.

In monitoring the phase change of the variable azimuth signal, 36 monitor pickup signals (pickup signals) are detected, and the transmission level transmitted from the array antenna is detected by a peak hold circuit. Waveform analysis (15 Hz and 135 Hz) by discrete Fourier transform (DFT) or fast Fourier transform (FFT) processing by a processor
Of 0 to 360 degrees (equal angle) while performing phase correction for vector synthesis by performing
And a waveform analysis (15 Hz and 13 Hz) by discrete Fourier transform (DFT) or fast Fourier transform (FFT) processing on a composite wave from data values of 0 to 360 degrees.
(5 Hz modulation degree, phase) and monitor the phase change.

The sampling timing of the discrete Fourier transform (DFT) or the fast Fourier transform (FFT) is as follows.
Starting from a 15 Hz reference trigger for generating a north azimuth reference burst, sampling is performed at equal intervals, for example, every two times for one cycle of 15 Hz. by this,
The north reference azimuth burst can be adjusted to zero in the variable azimuth signal.

When monitoring the phase change of the carrier, 36
After mixing the monitor pickup signals with the local signal, a change in phase is monitored by a phase detector.

The phase change of the carrier caused by the failure of a mechanical object such as a cable is extremely small, and generally the phase change of the carrier is not monitored (that is, the phase change of the carrier need not be performed). In addition, since a failure of an active element used for modulation or the like also appears in a variable direction signal, it is generally performed by monitoring the variable direction signal.

As described above, the processing after sampling the transmission level of the array-type antenna and performing analog-to-digital conversion is a program processing / calculation by a signal processor, so that the high-frequency module (switches, plural phase shifters) And a combiner).

The self-function can be included in the program of the signal processor, so that the maintenance person can easily confirm the operation of the signal processor.

As described above, monitoring of the phase change of the carrier wave can be omitted because the number of failures is extremely small. However, when the local oscillator frequency is mixed near the carrier frequency, the phase detection is performed at a frequency of 10 MHz or less. A circuit can be configured. Since the frequency is low, no special technique is required, the circuit configuration is easy, and the size can be reduced.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

Referring to FIG. 1, the azimuth monitoring apparatus for a Takan antenna according to the present invention includes a first monitoring unit (FIG. 1A) for monitoring a variable azimuth signal and a second monitoring unit for monitoring a carrier wave. A first monitor monitors the phase change of the variable azimuth signal, and the second monitor monitors a phase change of the carrier.

The first monitoring unit includes 36 detectors 2, 36
A peak hold circuit 3, 36 sampling circuits 4, 36 data latch circuits 5, a chip select circuit 6, a signal processor 7, and a control / display circuit 8 are provided. 1 to detect the pickup signal, and generate a detection signal. The peak hold circuit 3 peak-holds the detection signal and outputs a peak hold signal. The sampling circuit 4 samples the peak hold signal at a predetermined sampling period, performs analog / digital conversion, and outputs a digital signal. The data latch circuit 5 data latches the digital signal according to the chip enable signal and outputs a latch signal. The chip select circuit 6 sends a chip enable signal to the data latch circuit. The signal processor 7 processes the latch signal as described later and outputs a signal processing result. The control / display circuit 8 displays the signal processing result and controls the sampling circuit 4 and the chip select circuit 6 according to the signal processing result.

On the other hand, the second monitoring unit comprises 36 mixers 1
1, local oscillator 12, phase detector 13, determination circuit 1
6 and a control / display circuit 17, and the mixer 11
Mixes pickup signals in accordance with local signals from the local oscillator 12 to generate respective mixing signals. The phase detector 13 includes phase reference circuits 14 and 3
The phase reference circuit 14 includes six phase detectors 15.
Receives one of a plurality of mixing signals and uses this mixing signal as a reference phase signal. The phase detection circuit 15 detects a phase from each of the mixing signals according to the reference phase signal, and outputs a phase detection signal. The determination circuit 16 determines whether or not the phase detection result indicated by the phase detection signal is equal to or less than a predetermined value, and outputs a determination signal. Then, the control / display circuit 17 displays the judgment result according to the judgment signal.

Here, the operation of the Takan antenna monitoring apparatus according to the present invention will be described with reference to FIG.

In general, the radiated electric field of an array-type antenna is shown in Equation 2.

[0032]

(Equation 2) Here, ω = 2πf, f; 15 Hz, a _i ; modulation degree of 15 Hz, b _i ; modulation degree of 135 Hz, φ _i : angle at which an array antenna is placed from magnetic north.

Monitor pickup 1 from array type antenna
The transmission output thus combined is detected by the detector (linear detector) 3 and input to the peak hold circuit 3 as described above. The peak hold circuit 3 discharges instantly (1 μs or less) when a transmission pulse (detection signal) is input, and holds the peak of the input pulse. As a result, a peak hold signal corresponding to the peak of the input pulse is always obtained.

The sampling circuit 4 samples the peak hold signal in accordance with a sampling pulse of a predetermined cycle from the signal processor 16, converts the sampled signal from analog to digital, and outputs a digital signal. The data latch circuit 5 updates the digital signal and sends the digital signal to the signal processor 17 by the chip enable signal, and the digital signal is taken into the signal processor 17 as data.
That is, the signal processor 7 sequentially takes in 36 pieces of data as first to 36th data.

As shown in FIG. 1A, the signal processor 17
Is provided with a 15 Hz reference trigger for generating a north reference burst, whereby the signal processor 17 determines the timing of sampling using the 15 Hz reference trigger. In other words, the position of the north azimuth reference burst is set to the start of sampling, that is, zero electrical angle,
The end of sampling is one of the next 15 Hz reference triggers.
It is said to be before. That is, a 15-Hz electrical angle of 360 degrees is equally spaced at a constant period (a fixed frequency; for example, twice, basically, a frequency 360 / (9 *
2) = 20 degree to average period of transmission pulse of Takan 1/2
Sampling is performed at 700/185 E-6 = 2 degrees, that is, at a fixed period between 20 and 2 degrees.

The signal processor 17 analyzes the waveforms of the first to thirty-sixth data (DC component, modulation rates at 15 Hz and 135 Hz, phase) to calculate a transmission waveform (Equation 3) (step 1).

[0037]

(Equation 3) Here, j is the number of the monitor pickup, D _{j is the} DC component (standard; 1.0).

Next, the signal processor 17 synthesizes K waveforms (step 2).

Referring also to FIG. 3A, the radius R of the antenna is
k; the number of left and right combining, P _k; k-th pattern factor of the half-wavelength antenna, lambda; wavelength, (basically, 3-17) a composite number such as 11 when the synthetic type E _0, the number 4 (for example, in FIG. 3B, when n = −2, the angle is −2 × 10 ° = −20 °. −20 ° = −20)
× π / 180 (rad), and E ₀ is obtained from the vector synthesis of −5 to 0-5. Note that the left and right signals of ysin 左右 cancel each other out, and basically become zero.) This is t
(0 to 360 degrees) in one or two steps.

[0040]

(Equation 4) This composition is calculated for 36 directions. And E ₀ ,
Find E ₁ ,..., E ₃₅ .

Since equi-period data of ₀ to 360 degrees was obtained for E _{0 to} E ₃₅ , this was subjected to waveform analysis (DC component, 1
(5 Hz modulation degree, 135 Hz modulation degree, phase) to obtain an analysis (Equation 5) (step 3).

[0042]

(Equation 5) Here, l is a number corresponding to 36 directions, D _{l is a} DC component (standard; 1.0).

As a result, the phase of the variable azimuth signal in the normal state is obtained and temporarily stored (step 4) and stored in a phase reference value storage area (not shown) (step 5). In operation, the azimuth error data (phase) that changes every moment is compared with a phase reference value (step 6), and when it is determined that the comparison result is 1 degree or more (step 7), an alarm is controlled. The comparison result is output to the display circuit.

Next, the second monitoring section will be described with reference to FIG.

The pickup signal (carrier signal) is originally transmitted at the same phase (± 5 degrees or less), and a phase difference occurs if the mechanical length changes due to a failure or the like. The pickup signal (carrier signal: 1 GHz band) is
After being set to an intermediate frequency signal of 0 MHz or less, phase detection is performed as a reference of the phase of one intermediate frequency signal as described above. That is, upon receiving the reference phase signal and the intermediate frequency signal from the phase reference circuit 14, the phase detection circuit 15 outputs a DC output corresponding to the phase difference between the input signals (intermediate frequency signals).

For example, the phase detection circuit has S-curve characteristics such as DCOV when the phase difference is 0 degree, DC5V when the phase difference is 90 degrees, and DC-5V when the phase difference is -90 degrees. The determination circuit 16 determines whether each DC output is equal to or smaller than a standard value (for example, ± 20 degrees), and outputs an alarm to the control / display circuit 17 if the DC output is equal to or larger than the standard value.

Referring to FIG. 1, for example, a microcomputer is used as signal processor 7 described above.
This microcomputer has a CPU, ROM, RA
M, a serial interface, a timer, an interrupt controller, and the like. Then, the number of microcomputers increases according to the processing speed.

Data from the data latch circuit 5 is taken in through the input / output port of the signal processor 7. The sampling pulse is, for example, programmed by a timer,
The program is written in a read-only memory (ROM). A random access memory (RAM) is used for the calculation and the processing.

Here, the conditions and calculation formulas for waveform analysis by the discrete Fourier transform (DFT) are shown in equations (6) to (12). Here, conditions: m; the number of divisions, n; the nth harmonic (in the case of the TACAN device, the fundamental wave 15 Hz and the ninth harmonic 135H)
z), A _0; DC component, a _{n; n-th} harmonic sin component of, b
_n : cos of the n-th harmonic, x: data numbers 1 to m divided by m.

[0050]

(Equation 6)

[0051]

(Equation 7)

[0052]

(Equation 8)

[0053]

(Equation 9)

[0054]

(Equation 10)

[0055]

[Equation 11]

[0056]

(Equation 12) The calculated result is averaged for one second.

Under the above-described conditions, a detector capable of detecting a 1 GHz band by linear detection is used as the detector 2 in the first monitoring unit. The peak hold circuit 3 charges a capacitor with a peak corresponding to a pulse width of 1 to 10 μs and a pulse amplitude of 2 to 10 V of a Gaussian waveform. The hold time is 10 ms or more. The discharge by the pulse input is performed at the pulse rising 50% point or less and the pulse width is 1 μs or less.

The sampling circuit 4 performs analog / digital conversion every time a sampling pulse is input. The input is 0 to 5 V and the output is 8 bits or more. A 3-state D-type is used as the data latch circuit 5, and a shift register is used as the chip select circuit 6.

The signal processor 7 is a 16 / 8-bit microcomputer having a clock frequency of 5 MHz.
A self-test of the program is detected by detecting an external input pulse for self-test, and a signal for displaying the result to the outside is generated.

On the other hand, in the second monitoring section, the phase detector 15
And a phase detector of 10 MHz or less is used. In this phase detector, the output S-curve phase difference is 0 at input 2 to 5 V.
DCOV at 90 degree, DC5V at 90 degree, DC-5 at -90 degree
A phase discrimination method of V is used.

FIG. 4 shows the result of simulation performed by the signal processor 7 when the array-type antenna having a azimuth of 0 ° fails and the signal is lost. In this case, except for the 0 degree direction, the 15 Hz modulation degree 21.0% and the 135 Hz modulation degree 2
Calculate as 3.7%.

The characteristic of 135 Hz azimuth error shown in FIG. 4 is a point object with respect to 0 degrees, and it can be seen that there is a failure at 0 degrees. Also, it can be seen that the azimuth error is also equal to or greater than the standard value of 1 °.

Referring to FIG. 5, another example of the second monitoring section will be described. In the illustrated example, the mixer 11, the local oscillator 12, and the phase reference circuit 13 are removed from the example shown in FIG. In the illustrated example, the phase detector 1
Numeral 8 receives a 1 GHz band pickup signal as input and performs phase detection using another pickup signal (the 36th pickup signal in the illustrated example) as a reference signal.

In the example shown in FIG. 5, high frequency technology is required, but the structure can be simplified.

[0065]

As described above, according to the present invention, a signal is analyzed by using a (discrete) Fourier transform for analyzing a signal wave without using a high-frequency module in the 1 GHz band which requires advanced technology and adjustment techniques. Since the vector calculation is introduced into the synthesis of the waves, there is an effect that the azimuth error can be easily calculated. That is, not only can the number of high frequency modules be significantly reduced, but also the circuit configuration can be simplified by digital signal processing.

Further, according to the present invention, it is possible to eliminate maintenance such as adjustment which has been conventionally performed by an analog circuit.
Since the digital signal processing (signal processor) is provided with a program self-test function, the maintainability is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a Takan antenna azimuth monitoring device according to the present invention, wherein (a) is a diagram showing a first monitoring unit, and (b) is a diagram showing a second monitoring unit.

FIG. 2 is a diagram for explaining the operation of the signal processor shown in FIG.

FIG. 3 is a diagram for explaining signal synthesis.

FIG. 4 is a diagram showing a simulation result at the time of failure by the signal processor shown in FIG. 1;

FIG. 5 is a block diagram showing another example of the second monitoring unit according to the present invention.

FIG. 6 is a diagram for explaining a conventional Takan antenna direction monitoring apparatus.

FIG. 7 is a diagram for explaining the monitoring device shown in FIG. 6;

FIG. 8 is a diagram for explaining an integral monitor method.

FIG. 9 is a diagram for explaining a relationship between a reference burst of Takan and a variable azimuth signal.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 monitor pickup 2 detector 3 peak hold circuit 4 sampling circuit 5 data latch circuit 6 chip select circuit 7 signal processor 8 control / display circuit 11 mixer 12 local oscillator 13 phase detector 14 phase reference circuit 15 phase detection circuit 16 judgment circuit 17 Control / display circuit

Claims (5)

[Claims] An azimuth monitoring device for monitoring the azimuth of an antenna of a Takan device, comprising a plurality of pickup elements coupled to a plurality of antenna elements arranged at predetermined intervals along a predetermined circumference. First means for detecting and peak-holding a pickup signal from each of the first and second signals to obtain a plurality of peak-hold signals, and sampling a plurality of digital signals by sampling the plurality of peak-hold signals at regular intervals of one cycle at a predetermined sampling period. A second means for calculating the azimuth shift in accordance with the plurality of digital signals to obtain a calculation result; and a display means for displaying the calculation result and based on the calculation result. 4th to control
And a means for monitoring the direction of a Takan antenna. 2. The Takan antenna azimuth monitoring apparatus according to claim 1, wherein the predetermined sample period is one cycle from a reference burst to a next reference burst. 3. The Takan antenna direction monitoring apparatus according to claim 2, wherein the sampling is performed at equal intervals in the one cycle. 4. The Takan antenna azimuth monitoring apparatus according to claim 1, wherein the third means calculates a formula relating to the plurality of pickup signals as a calculation formula based on the plurality of digital signals, and calculates the calculation. A vector synthesis of a plurality of the above-mentioned calculation expressions is performed at equal angles from 0 to 360 degrees symmetrically with respect to the direction to be monitored using the expression, and an expression of a synthesis signal is obtained from the data value obtained by the vector synthesis as a synthesis signal expression A Takan azimuth azimuth monitoring device, wherein the azimuth change is calculated. 5. The Takan antenna direction monitoring apparatus according to claim 1, further comprising: a mixing unit that mixes the plurality of pickup signals as predetermined local signals to obtain a plurality of intermediate frequency signals; Phase detecting means for obtaining a plurality of phase detection signals by phase-detecting each of the intermediate frequency signals using one of the intermediate frequency signals as a phase reference, and determining a phase shift according to the phase detection signals to obtain a determination result A Takan antenna azimuth monitoring device, comprising: a judging means; and a control display means for displaying the judgment result and controlling the Takan device according to the judgment result.