JPH0429030B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides the switching in the received signal obtained by receiving radio waves while scanning by sequentially switching omnidirectional antennas arranged at intervals on the circumference. A radio direction finding method that obtains a direction signal based on a signal that detects the phase difference of the phase change caused by the radio direction finding method, that is, a so-called stationary Doppler radio direction finding method, involves measuring the arrival angle of radio waves in a plane perpendicular to the horizon. The present invention relates to a method for adding a function to measure the distance from an antenna installation position to a radio wave emission point, and an apparatus for implementing the method.

[Conventional technology]

The stationary Doppler direction finding method is as follows:
To explain it using an implementation device, as shown in Fig. 1A, a large number of omnidirectional antennas A ₁ to A _o having the same characteristics are arranged at equal intervals on the circumference,
It is installed in the center of the antenna and led to an antenna switching scanning circuit, which is sequentially switched and scanned and connected to a receiver.

If we assume that the radio waves propagate horizontally to the horizon, the phase component φ _o of the received signal can be expressed as shown in equation (1) according to the arrival direction of the radio waves and the relative position of the antenna, and the first It changes in a sinusoidal stepwise manner as shown in Figure C.

φ _o = πD/λ・cos(nα−θ) ……(1) D: Antenna diameter λ: Wavelength of received radio waves α: Angle between adjacent antennas θ: Angle of incoming radio waves with respect to reference N n: Antenna element Number (1 to n) Here, m=πD/λ, where m is the amplitude itself of the azimuth signal obtained by what is called a modulation index.

Therefore, when this received signal is amplified and detected, a direction signal as shown in Fig. 1C is obtained, so the reference point N,
In other words, find the maximum amplitude point (or zero cross point t ₁ or t ₂ ) of this azimuth signal from the reference azimuth, and
Japanese Patent Publication No. 56-35828 and Japanese Patent Application Laid-Open No. 56-137169 disclose devices in which the direction of arrival of radio waves can be measured by counting up to 90 degrees (adding or subtracting 90 degrees).

In addition, the conventional method for measuring the angle of arrival of radio waves in a plane perpendicular to the horizon, so-called angle of incidence, using the angle of elevation or depression is the interferometer method, in which radio waves are measured using multiple antennas spaced apart in a line. A method of detecting the angle of incidence based on a change in the reception phase of each received signal is well known.

Then, the distance from the antenna to the emission point of the received radio waves is calculated based on the above incident angle and the height of the ionosphere, and the emission point of the radio waves is determined using this distance value and the azimuth value obtained by radio direction finding. You can know.

[Problem to be solved by the invention]

Devices using the stationary Doppler radio direction finding method as described above are already widely used.
Even in radio wave inspection facilities that have installed such devices,
It is desired to have equipment that can measure the above incident angle and determine the emission point of radio waves based on the measured incident angle.

Therefore, there is a method that can measure the above-mentioned angle of incidence and distance to the launch point using the existing stationary Doppler radio direction finding facility without adding a new interferometer system. If provided, equipment investment can be reduced and it is extremely convenient.

Furthermore, in the case of a parent-owned facility, there is an advantage in that it requires relatively low investment.

Therefore, there is a problem of how to configure and provide such a measurement method.

[Means to solve the problem]

The present invention obtains a received signal by receiving radio waves while scanning by sequentially switching the omnidirectional antennas arranged at equal intervals on the circumference as described above, and also detects the phase difference in the received signal caused by the switching. By obtaining a direction signal of a signal that has a SIN wave-like component that is related to the arrival direction of the radio wave due to change, that is, a SIN wave-like change component, the direction of arrival of the radio wave can be detected based on the direction signal, and the arrival direction of the radio wave can be detected. In the wireless direction distance measurement method that measures the position of the emission point of radio waves based on the direction, there is an amplitude measurement method in which the amplitude of the SIN wave-like change component included in the above-mentioned azimuth signal is obtained as the measured amplitude value m'; The amplitude value corresponding to the measured amplitude value m′ that should be obtained when the wave propagates through the horizon, that is,
By creating the equivalent amplitude value m, and using the above measured amplitude value m' and the equivalent amplitude value m, based on the relational expression m'/m=cosβ, in the plane perpendicular to the horizon, By measuring the arrival angle in the vertical plane to obtain the arrival angle of the radio wave, that is, the arrival incident angle β, and by determining the height h of the ionosphere and the earth radius f from the above arrival incidence angle β, 2 {cos ^-1 [r/r + hcos β] -β}r=Q A method for calculating the distance Q from the installation point of the omnidirectional antenna to a radio wave emission point based on the relational expression, and a device embodying the method are provided. This makes it possible to solve the above problems.

〔Example〕

Examples will be described below with reference to the drawings.

In Figure 1 B, if a radio wave arriving from the sky with an elevation angle β is received by the antenna group in Figure 1 A, which has omnidirectional antennas arranged on the circumference of a circle with a diameter D, then The antenna diameter D in equation (1) in the direction of arrival of the radio wave apparently becomes smaller, and therefore φn also becomes smaller, so the amplitude m of the azimuth signal in FIG. 1C also becomes smaller accordingly.

In other words, in Figure 1B, when a radio wave arrives at an angle β with respect to the horizontal plane, the wavefront of the radio wave becomes
A 180° in the opposite direction after reaching the ₄ antenna
The distance that the A _o-2 antenna reaches, ie, the effective antenna diameter D', is D'=D·cosβ (2), and decreases in proportion to cosβ.

Therefore, the phase change φ′ _o caused by the Dobra effect of radio waves received with an elevation angle is φ′ _o = (π/λD′)・cos(nα−θ) = (π/λD・cosβ)・cos (nα−θ) = (m・cosβ・cos(nα−θ) ……(3) The modulation index m′ in equation (3) is m′=m・cosβ ……(4) and the elevation angle β of the radio wave modulation index proportional to the cosine of
Since m' becomes smaller and therefore the phase change φ' _o also becomes smaller, the amplitude of the azimuth signal in FIG. 1C also becomes smaller.

Therefore, find the amplitude m of the azimuth signal when the ground wave is received at zero elevation angle, store it in memory as a reference value, and measure the azimuth signal amplitude m' of the radio wave that arrives at the elevation angle β. Then (4)
The elevation angle β of the radio wave can be found from the formula.

In other words, based on the trigonometric function of the amplitude m that should be obtained when the radio wave propagates through the horizon and the amplitude m' that is actually measured, the radio wave in a plane perpendicular to the horizon is calculated. The angle of arrival β is found.

Next, the principle of estimating the radio wave emission point using the elevation angle determined above will be explained. FIG. 2 is a diagram showing the principle of estimating distance based on the elevation angle β of the arriving radio wave and the height h of the ionosphere.

Arc P is the earth's surface, O is the center of the earth, r is the radius of the earth, S is the radio wave emission point, R is the radio wave reception point, Q
is the length of the arc with S, Y is the angle between S and R, h is the height of the ionosphere, and β is the angle of elevation (angle of incidence) of the incoming radio wave with respect to the ground, and the height of the ionosphere when the radio wave is emitted from point S is The figure shows how the signal is reflected at point H and received at point R. The ionospheric reflected wave has an elevation angle of 0 at point R.
The height of the ionosphere at the time of reception is _H0 , and the angle of elevation of the radio wave becomes H as the height of the ionosphere increases is β.

Therefore, the elevation angle β of the radio wave reflected wave, the height h of the ionosphere,
Since there is a relationship as shown in equation (5) between the radio wave emitting point S and the radio wave receiving point R as seen from the center point O of the earth, the relationship shown in equation (5) can be modified as shown in equation (6). A good relationship can be obtained.

SIN(90°+β)/r+h=SIN(90°−β−Y/2)
/r...(5) cosβ/r+h=cos(β+Y/2)/rcos(β+Y/
2) =r/r+hcosβ+Y/2=cos ^-1 [r/r+hcos
β]Y =2cos ^-1 [r/r+hcosβ] -2β ...(6) Furthermore, the following relationship exists between the length Q of the circular arc and the angle Y sandwiching S and R.

Q=Y/2π・2πr=Yr=2{cos ^-1 [r/r+hcosβ]−β}r...(7) r is the radius of the earth, approximately 6378 km (according to the Science Chronology),
Since h is the height of the ionosphere actually measured at the measurement point and is a known value, by finding β, the distance Q to the radio wave emission point can be found.

That is, the distance Q to the emission point of the radio wave is determined based on a trigonometric function of the arrival angle β of the radio wave in a plane perpendicular to the horizon, the radius r of the earth, and the height h of the ionosphere.

Next, an example of an implementation apparatus of the present invention will be described.

FIG. 3 is a system diagram showing an implementation apparatus embodying the above measurement method. Figure 4 shows the DAC (DIGITAL)
TO ANALOG CONVERTER) circuit example,
FIG. 5 shows one embodiment of a frequency correction circuit according to the invention. FIG. 6 is a diagram showing details of the phase comparator circuit 8 shown in FIG. 3, and FIGS. 7 and 8 are operational waveform diagrams of each part. Figure 9 is a diagram showing the calculated data value of the amplitude m' of the azimuth signal for each elevation angle of the radio wave reflected at the ionosphere height of 300 km, the distance to the radio wave emission source, and the memory arrangement for storing this data value in memory. It is.

In Figure 3, 1 has the auxiliary antenna A ₀ in the center,
It is also an antenna group in which omnidirectional antennas 1 to n are arranged at equal intervals on the circumference. 2 is a reference signal generating circuit which generates a clock pulse, which is frequency-divided to generate pulses of each desired frequency.

Reference numeral 3 denotes an antenna switching scanning circuit for switching each antenna element provided at the center of the antenna group, which controls the current flowing through the diode to sequentially switch the output of each antenna, and connects the output to the receiver 4.
4 is by operating one frequency knob,
A two-channel receiver consisting of a main receiver and a sub-receiver that can adjust the receiving frequency of both channels simultaneously, connects the output of the auxiliary antenna A ₀ to one channel and the output of the antenna switching circuit to the other channel. Amplify each.

5 is an azimuth signal detection circuit consisting of an FM component removal circuit and a frequency discrimination circuit, which frequency-converts the outputs from the main and sub-receivers, and further converts the frequency of the output by a mixing circuit to detect received radio waves with frequency changes. The modulation component is removed to create a signal containing only the component due to the Dobra effect based on antenna switching.

The purpose of this FM component removal circuit is that when a frequency-modulated radio wave is received, a large modulated wave originally attached to the radio wave is superimposed on the azimuth signal generated by antenna switching scanning, and the direction of the incoming radio wave becomes unstable. It is used to indicate a stable direction through the FM component removal circuit, and the received radio waves are
By passing the signal through this circuit even when it is not undergoing FM modulation, it is possible to extract only the signal component resulting from the intended antenna switching scan without causing any inconvenience.

Next, the azimuth signal due to the Dobra effect caused by the front antenna switching scan is detected through a frequency discrimination circuit, such as a disk drive or PLL circuit, which is the output of the FM component removal circuit.

Reference numeral 6 denotes a frequency correction circuit, which inputs the azimuth signal whose amplitude increases in inverse proportion to the frequency, that is, the output of the azimuth signal detection circuit 5, and outputs the received frequency signal F1.
When the frequency becomes lower due to (a binary digital signal composed of a plurality of bits), the amplification degree of the frequency compensating circuit 6 is increased so that the azimuth signal output a becomes a constant value regardless of the frequency.

The correction by this frequency correction circuit 6 is performed by the above-mentioned
As explained using equation (1), as the wavelength λ of the received radio wave increases, that is, as the frequency decreases, the modulation index m (amplitude of the azimuth signal) decreases proportionally. In addition to the amount that decreases with frequency, the amount that decreases with frequency is added, so when direction finding is performed over a wide frequency band, the condition of equation (4) above holds as it is. This was created to save people from losing their lives.

The direction signal in Figure 7a is the same as the signal in Figure 1C, but for simplicity, the step change is omitted and it is expressed as an average SIN wave, and by passing it through a frequency correction circuit, the frequency can be changed. It is a signal of constant amplitude regardless. Figure 4 shows general information for explanation.
An example of a circuit for a DAC is shown in FIG. 5, and an embodiment of a frequency correction circuit according to the present invention is shown in FIG.

In the figure, 61 is a multi-bright DAC IC such as AD7523J, and 62 is an operational amplifier with two inputs. 4th DAC IC
When a digital signal F1 of multiple bits (e.g. 8 bits or 12 bits) is applied to the data input terminal T1 of the 61, and an analog reference voltage F2 is applied to the reference input terminal T2 (VREF), the input F1 is input to the terminal T3 (RF). It operates so that the product F3 of F2 is output, so if F1 increases, the output F3 also increases,
The following relationship exists between F1, F2, and F3.

F1×F2=F3...(8) Therefore, as shown in FIG. 5, input the multi-bit reception frequency DIGITAL signal F1 to the input T1,
When an azimuth signal whose amplitude changes depending on the reception frequency, that is, the output of the azimuth signal detection circuit 5 is added to the terminal T3, the signal F2 outputted to the terminal T2 becomes F2=F3/F1 from equation (8). F1 is DIGITAL proportional to the receiving frequency
Since it is a signal, if the proportional constant is k, it can be expressed as F1=kf.

Also, the signal F3 at terminal T3 is an azimuth signal, and the amplitude similarly changes in proportion to the reception frequency, so if the proportionality constant is k', then it can be expressed as F3 = k'f, and F2 = F3 / F1 = k'f/kf=k'/k (constant constant), so that an azimuth signal with a constant amplitude is obtained at the terminal T2 regardless of the reception frequency.

If a signal 1 with the opposite polarity to the frequency signal F1 is obtained, by making the connection shown in Figure 4 and adding the output of the azimuth signal detection circuit 5 to the terminal T2, the azimuth signal with a constant amplitude is always output to the terminal T3 regardless of the frequency. I get a signal.

7 is a double-wave rectifier circuit composed of an operational amplifier and a diode, and the output of the frequency correction circuit 6.
At the same time, a rectangular wave having the same period as the azimuth signal a as shown in c is generated.

8 is a phase comparator circuit that includes an internal signal generator 81, a multiplier 82, a semiconductor switch 83,
ADC (ANALOG TO DIGITAL)
CONVERTER) 84, latch circuit 85,
Consists of EXCLUSIVE OR GATE86. As mentioned above, in order to find the radio wave arrival direction from the detected direction signal a, find the maximum amplitude point of the direction signal (or find the 0 cross point and add or subtract 90 degrees to it to determine the direction) It is sufficient to use the direction of arrival of the radio waves, but as shown in Figure 2, in the case of far-off radio waves that propagate by being reflected from the ionosphere, the direction signal contains many noise signals, , the direction tends to fluctuate, making measurement difficult.

Therefore, an internal signal generation circuit is installed to generate a double rectified SIN wave with the same period as the direction signal (Fig. 7e), and the area of the waveform obtained by multiplying this signal by the direction signal b is calculated and averaged. The process is performed, and the phase of the output of the internal signal generation circuit is controlled based on the result, thereby making it possible to obtain a more accurate and stable heading.

In addition, the direction signal is not always a relatively clean SIN wave as shown in Figure 7a, but depending on the radio wave situation, it becomes a complicated waveform and contains high-order harmonics, and if it becomes an internal signal. When using a rectangular wave, the phase difference component between the harmonics of both signals (e.g. 3rd harmonic, 5th harmonic, etc.) will be superimposed on the output, so when the internal signal is a SIN wave (fundamental wave), the direction will be different. This will result in an error. Therefore, as mentioned above, one of the two signals, that is, the internal signal, is
When multiplied by the azimuth signal as a SIN wave using ROM, even if the azimuth signal has a waveform that includes harmonics, the average value of the multiplication results for frequency components other than the fundamental wave will be 0, so this will affect the azimuth error. This means that the correct direction can be pointed out.

Here, we will summarize the relationship between the azimuth signal a, the SIN wave of the internal signal, the signal e, and the phase control.
To explain with a diagram, when a radio wave arrives from the direction of the reference direction N, the SIN wave-like signal of the direction signal a appears as a waveform of V corresponding to θ ₀ in FIG. The direction signal b obtained by rectifying both waves appears as a waveform V in FIG. 7b.

On the other hand, the SIN wave of the internal signal is initially the azimuth signal a
is generated as a SIN wave with a phase difference of 90° with respect to the waveform when the radio wave arrives from the direction of the reference direction N, that is, the waveform of V, but the rectified wave of both SIN waves of this internal signal The waveform of signal e appears as a waveform of V corresponding to θ ₀ in FIG. 7e.

The arrival direction of the radio wave changes to the direction of θ ₁ or θ ₂ , and the azimuth signal a becomes a waveform of U or W corresponding to θ ₁ or θ ₂ .

Therefore, the average value of the signal obtained by multiplying the signal e and the azimuth signal b, that is, the average value of the signal obtained by multiplying the signal e and the azimuth signal b, that is, the
Create a signal with the average value of the signals explained with the waveform, and use this average value signal to shift the phase of the SIN wave of the internal signal so that it has a phase difference of 90 degrees with the SIN wave signal of the direction signal a. When controlled, the SIN wave of the internal signal shifts to the phase point θ ₁ or θ ₂ , and the amount of phase shift during this time, that is, θ ₁ or θ ₂ is the arrival direction of the radio wave.

FIG. 6 shows an embodiment of the phase comparator circuit of the present invention.

Reference numeral 811 is a presettable up-down binary counter which applies a preset input F4 to a preset terminal consisting of multiple bits, performs down counting using the clock CLK applied from the antenna reference signal generation circuit 2, and obtains a multi-bit counter output on the output side. It will be done.

812 is ROM (READ ONLY MEMORY)
A half cycle or one cycle of the SIN wave is stored in the input side of the SIN ROM, and the output of the presettable up-down binary counter 812 changes the SIN wave e stored at address L.
DIGITAL signal can be obtained.

82 is a multiplication circuit composed of a DAC IC and an operational amplifier as shown in Fig. 4, and one input terminal has the above-mentioned
Apply the SIN wave DIGITAL signal, add the above-mentioned double-wave rectified wave b of the azimuth signal to the other input terminal, multiply both inputs, create an analog output as shown in Figure 7j, and send this to the semiconductor switch. through 83
Input to ADC84. The ADC84 starts conversion at the rising edge of the SC (start conversion) signal,
At the end of conversion, an EOC (end of convergence) signal is generated, which turns on the semiconductor switch and applies the multiplication circuit output (Fig. 7j) to the input terminal of the ADC. The above SC sequentially switches the antennas arranged on the circumference and takes the time to make one rotation as T=1/fa (fa: frequency of one antenna rotation), and if the number of antennas is n, then T/n=1/nfa. Use periodic pulses.

In other words, the value of the flat portion in which the amplitude of the azimuth signal shown in FIG. Note that at the same time as the AD conversion is started, the EOC signal becomes "L" and the semiconductor switch 83 is turned off so that the data does not change during the conversion. A.D.
The converted multi-bit output is latched in a latch circuit 85 and then transferred to the next circuit.

86 is an EXCLUSIVE OR GATE which inputs a rectangular wave c synchronized with the azimuth signal b and the uppermost bit of the internal signal, that is, the uppermost bit output d of the presettable up-down counter 811, and calculates the polarity shown in FIG. 7 k. The signal is output and transferred together with the output of the latch circuit 85 described above to the next DIGITAL averaging circuit 9.

9 is a DIGITAL averaging circuit with memory, 8
The area of the waveform shown in FIG. 7j is cumulatively averaged according to the polarity signal k using the output of the phase comparator circuit of FIG. This average result is temporarily stored in the memory in the averaging circuit, and is added as the preset input F4 of the presettable up-down binary counter 811 of the phase comparator circuit to output the output signal of the presettable up-down binary counter. By advancing or delaying the phase of the direction signal and the internal signal, the phase difference between the direction signal and the internal signal is
Gradually move the phase so that it becomes 90°, and finally the waveform of j is symmetrical, that is, the integration result for one period is 0.
It is controlled until it becomes stable.

As mentioned above, the preset values are temporarily accumulated and stored in the memory, so the summation is the internal signal that has a phase difference of 90° from the azimuth signal from the reference point N, that is, the phase point corresponding to the reference azimuth. This corresponds to the amount of phase shift until the phase shift reaches the phase point, and ultimately becomes the arrival direction of the radio wave from the reference direction. This is transferred to the display 12 and displayed according to an appropriate display cycle. 11 is an amplitude comparator, and 10 is a memory that measures the amplitude m for the elevation angle of the radio wave,
m' and the distance Q to the radio wave emission source are stored. Measuring the amplitude m' of the direction signal of the received radio wave and calculating the magnitude of the elevation angle β each time using m stored in memory requires a calculation device and is time-consuming. Not on point. Also, the elevation angle β, the reference amplitude m, and the measured amplitude
As mentioned above, there is a relationship between m' and equation (4), but the height of the ionosphere itself has a large spread, and its state is constantly changing. Since there is no point in calculating and looking at β in too much detail, it is practical to calculate it every few degrees.

Therefore, if the amplitude value m when the elevation angle is 0 degrees is set to a certain value, for example 2560 mV (decimal), r is already known, so in the embodiment of the present invention, h is set to a certain value, for example 300 Km.
By calculating the amplitude m' and distance Q for the angle β, the data values shown in FIG. 9 are obtained, and these are stored in the memory 10 for each address as shown in the memory arrangement in FIG.

When a radio wave is measured and a direction signal is obtained, the amplitude m' of the direction signal and m' stored in the memory 10 according to the memory arrangement shown in FIG. amplitude of the direction signal
β when the value matches or is closest compared to m′
and Q is the elevation angle and distance to the radio wave emission source when the ionosphere height is 300 km. For example, if the amplitude of the direction signal when the radio wave was just received was 2557 mV, then if we compare the m' values of the data values in Figure 9 in order, we will find the one closest to the second m' = 2558 mV. Therefore, the elevation angle and distance at this time are β = 0002 degrees and Q = 3838 km, which are read out and transferred to the next display 12, which instantly displays the arrival direction and elevation angle of the radio wave and the distance to the radio wave emission source at the same time. .

Next, the overall operation will be explained.

The outputs received by the antennas _A1 to _Ao are sent to one RF input of the two-channel receiver 4 by sequentially switching each antenna in the antenna switching scanning circuit 3 using the switching signal obtained from the antenna scanning reference signal generation circuit 2. , and the outputs of the auxiliary antenna _A0 are respectively applied to the other RF input terminals and amplified, and the IF outputs thereof are applied to the inputs of the azimuth signal detection circuit 5, respectively.

The two IF inputs are frequency-converted to remove the frequency modulation components given to the radio waves, leaving only the modulation components due to antenna rotation, and then the azimuth signal is extracted by a frequency discrimination circuit.

Since the amplitude of this signal increases in proportion to the frequency, an output with a constant amplitude is always obtained regardless of the frequency using the frequency information F1 through the next frequency correction circuit 6. A part of this signal is amplified to form the rectangular wave signal shown in FIG.
The signal is applied to the phase comparator circuit 8 along with the azimuth signal shown in FIG.

This direction signal b, presettable up-down binary counter 811, and SINROM 81
If the signal shown in FIG. 7e obtained in step 2 is multiplied by the multiplication circuit 82, an analog product output as shown in FIG. 7j can be obtained.

A necessary value F4 is preset from the next DIGITAL averaging circuit to the preset input of this presettable up-down binary counter, and the phase of the internal signal output is controlled to advance or lag forward or backward.

The output of the multiplication circuit 82 is output by the ADC circuit 84.
According to the sign of the polarity signal in addition to the average circuit along with the polarity signal (Fig. 7k) described above as the DIGITAL value,
Accumulate and average over one cycle or several cycles.

Now, if the areas of the sections , , in Fig. 7j are =A ₁ , =A ₂ , =A ₁ , =A ₂ , then
If we take the sum and difference of the area of each section according to the polarity signal k, we get +++=2(A ₁ −A ₂ ) ...(9) −+−=2(A ₁ +A ₂ ) ...(10) ( Equation 9) is the area difference in FIG. 7j, that is, the phase error component, and Equation (10) is the sum of the areas, that is, the average amplitude value.

Therefore, when the azimuth signal a-V and the internal signal e-V have a completely 90° phase difference, the areas _A1 and _A2 are equal, so
The result of equation (9) becomes zero, and the phase of the internal signal also stabilizes at that point, becoming the phase θ ₀ from the reference N.

At the moment when the azimuth signal changes like a-U, the phases of internal signals d and e are not controlled at all, so they remain as they were, that is, d-V, e-V, so the multiplication circuit 82 Since the output is the product of the azimuth signal b-U and the internal signal e-V, it becomes a signal like f, which is the output of EXCLUSIVE OR GATE, that is, c-
The product of U and d-V is g. Also, when the azimuth signal changes like a-W, at the moment the azimuth changes, the output of the multiplication circuit and
The output of EXCLUSIVE OR GATE becomes h, i.

This output is integrated by the next averaging circuit 9 for one cycle or several cycles, and when averaged, if the azimuth signal is a-U, the signal of f is integrated, so the average value becomes (-), and the azimuth signal is h in case of a-W
Since the signals are integrated, the average value is (+).

When this average value is added to the preset input terminal of the presettable up-down binary counter described above and preset at the time of reference N and frequency division is performed, the phase of the output changes back and forth by the preset value.

FIG. 8 is an explanatory diagram showing the relationship between the preset input and counter output of the presettable up-down binary counter. 1 indicates the total sum of the output of the presettable up-down counter, and the maximum point indicates that the counter has reached the maximum, and the total sum of the counter decreases sequentially until the minimum point is when the contents of the counter become 0.
2 to 4 indicate the maximum bit output of the counter.

If the current azimuth signal is in the state shown in Figure 7 a-V and the internal signal is controlled to have a phase difference e-V of exactly 90 degrees from the azimuth signal, then at time N, the preset value F4 is determined by the result of integration by the averaging circuit 9. If it is preset as θ ₀ , the waveform of the maximum output bit of the preset binary counter will be as shown in FIG. 8.

Next, if the azimuth signal changes as shown in Figure 7 a-U, the internal signal e-V is not controlled at all, so the product output of the azimuth signal b-U and internal signal e-V and EXCLUSIV The output of OR GATE 86, that is, the polarity signal which is the product output of c and d in Figure 7, becomes f and g, respectively, and if the area of f is integrated and averaged according to the polarity signal of g, the (-) portion will remain. , this is accumulated in the memory mentioned above, and this total _θ1 is preset in the presettable up-down counter at time N. As a result, the output of the counter becomes as shown by curve U in Fig. 8 1, and the maximum output bit of the counter gradually lags in phase as shown in Fig. 8 3, and finally reaches d-U, e in Fig. 7. -U,j-
U, k-U, and the phase is delayed by Δθ from the initial point and stabilizes at the point θ ₁ from the reference N.

Next, when the azimuth signal becomes a-W, the phase advances by Δθ by the same operation and becomes stable at a point θ ₂ from the reference N. In this way, the phase of internal signals d and e follows the phase of the azimuth signal, and the preset value F
The sum of 4 is the direction of the incoming radio wave.

Once the direction of arrival of the radio wave is determined, the amplitude m' of the azimuth signal is determined at the next point in time by calculating the integration of equation (10), that is, the sum of the sections . As described above, this m' is compared with the contents of the memory 10, and when the values match or are the closest value, the elevation angle and the distance to the radio wave emission source are read out and the azimuth/elevation angle/distance is instantaneously determined by the azimuth indicator 12. It is displayed.

Normally, the height of the ionosphere is determined by transmitting short-duration impulse waves from a transmitter at regular intervals (for example, 1/50 (SEC)).
Normally, the time difference between the direct wave and the reflected wave from the ionosphere is measured using an oscilloscope by emitting it vertically upward and using a nearby receiver to measure the time difference between the direct wave and the reflected wave from the ionosphere, but this value is the average value for the ionosphere. The width of the ionosphere is relatively wide, generally over 100 km, and this width changes from moment to moment. Therefore, it is meaningless to measure the height of the ionosphere in too small sections.

The height of the ionosphere is usually said to be between 100km and 500km, so it would be sufficient to measure it in units of 100km, so the data in Figure 9 was calculated for each ionosphere by dividing the range from the ground to about 500km in units of 100km. Create a value and memory arrangement and store this value in the memory circuit 10.
It is practical to input the necessary ionospheric height, search and collate the contents of the memory circuit corresponding to the ionospheric height, read out the contents, and instruct the user.

Specifically, the adjustment is extremely simple, as it only requires emitting and receiving radio waves from near the antenna using a small oscillator, and adjusting the amplitude of the azimuth signal at that time to the reference value m, that is, 2560 mV in this embodiment. Note that this reference value m can be freely selected within a range in which the ADC 84 is not saturated.

It is also possible to perform the signal processing after 6 in FIG. 3 in an analog manner using a special function generator, but it is more practical to digitize the signal and perform it using a digital microcomputer or the like.

〔Effect of the invention〕

According to the present invention, as described above, in a method using a stationary Doppler wireless direction finding method, a) the amplitude of the direction signal when radio waves propagate horizontally to the ground is known in advance; The measurement method is extremely simple, as the angle of incidence of the radio wave and the distance to the emission point can be measured simply by adding a function to measure the amplitude value and a calculation function.

b. By simply providing a memory that stores the angle of incidence and distance in correspondence with the amplitude value of the azimuth signal, an extremely simple configuration that does not require arithmetic functions can be provided.

c. For direction finding using wide frequency radio waves,
By simply providing a function to increase the amplitude of the azimuth signal in inverse proportion to the frequency, it is possible to provide something that can ensure the accuracy of the incident angle and distance.

It has the following features.

[Brief explanation of drawings]

FIG. 1A is a diagram showing the arrangement of antennas, B is a diagram showing how radio waves arrive at an elevation angle β, and C is a waveform diagram showing a phase change component generated by switching antennas for reception. Fig. 2 is an explanatory diagram of the elevation angle of radio waves due to ionospheric reflection, Fig. 3 is a system diagram showing one embodiment of the present invention, and Fig. 4 is a DAC (DIGITAL TO ANALOG) diagram.
FIG. 5 shows an example of a frequency correction circuit according to the present invention. FIG. 6 is a detailed explanatory diagram of the phase comparator circuit, and FIGS. 7 and 8 are operational waveform diagrams of each part. FIG. 9 shows the calculated data values of the amplitude m' with respect to the elevation angle and the distance to the radio wave emission source, and the address arrangement for storing the results in the memory circuit. 1: Antenna group, 2: Antenna scanning reference signal generation circuit, 3: Antenna switching scanning circuit, 4: Receiver, 5: Direction signal detection circuit, 6: Frequency correction circuit, 7: Double wave rectification circuit, 8: Phase comparison Circuit, 9:
DIGITAL averaging circuit, 10: Memory circuit, 11: Amplitude comparison circuit, 12: Direction indicator, F1: Reception frequency digital signal, F2: ADC IC terminal signal, F3: ADC IC terminal signal, F4: Preset value to presettable up-down counter 811, D: Antenna diameter, N: Reference (true north) D': Effective antenna diameter, β: Elevation angle (incident angle) of incoming radio waves relative to the ground, r: Radius of the earth ( about
6387Km), O: center point of the earth, h: height of the ionosphere,
S: radio wave emitting point, R: radio wave receiving point, Y: angle surrounding radio wave emitting point S and radio wave receiving point R, P: earth surface,
Q: Distance of arc S/R, m: Modulation index.

Claims (1)

[Scope of Claims] 1. Omnidirectional antennas arranged at equal intervals on the circumference are sequentially switched and scanned while receiving radio waves to obtain a received signal, and the received signal generated by the switching is By obtaining a signal having a SIN wave-like component (hereinafter referred to as a SIN wave-like change component) that is related to the direction of arrival of the radio wave due to a phase change as an azimuth signal, the direction of arrival of the radio wave can be determined based on the azimuth signal. A radio direction distance measuring method (hereinafter referred to as the method) for detecting and measuring the position of the emission point of the radio wave based on the direction of arrival, the method comprising: a) measuring the amplitude of the SIN waveform change component included in the direction signal; (b) An amplitude value corresponding to the measured amplitude value m' that should be obtained when the radio wave propagates through the horizon (hereinafter referred to as equivalent amplitude value); c. Create an equivalent amplitude value to create m, and c. From the measured amplitude value m' and the equivalent amplitude value m, based on the relational expression m'/m=cosβ, the radio wave in a plane perpendicular to the horizon 2 {cos ^-1 [r/r+hcosβ ]-β}r=Q A method comprising: calculation of a distance Q from the installation point of the omnidirectional antenna to the emission point of the radio wave based on the relational expression: -β}r=Q. 2. Omnidirectional antennas arranged at equal intervals on the circumference are sequentially switched and scanned to receive radio waves to obtain a received signal, and the phase change in the received signal caused by the switching causes the radio waves to change. By obtaining a signal having a component that changes like a SIN wave in association with the direction of arrival (hereinafter referred to as a SIN wave change component) as a direction signal, the direction of arrival of the radio wave relative to a reference direction is detected based on the direction signal, and A wireless direction distance measuring device (hereinafter referred to as the device) that measures the position of the emission point of the radio wave based on the direction of arrival, comprising: a) measuring the amplitude of the SIN waveform change component included in the azimuth signal; an amplitude measuring means for obtaining a signal of the measured amplitude value m' as a measured amplitude value signal; b. an amplitude value corresponding to the measured amplitude value m' that should be obtained when the radio wave propagates through the horizon The arrival angle of the radio wave in a plane perpendicular to the horizon (hereinafter referred to as the arrival incident angle) is calculated based on the relational expression m'/m=cosβ using The installation point of the omnidirectional antenna is calculated based on the relational expression: 2 {cos ^-1 [r/r + hcos β] - β} r = Q, using the angle (referred to as angle) β, the height h of the ionosphere and the radius r of the earth. amplitude-corresponding angle-distance-distance means for storing calculated values of the measured amplitude value m', the arrival angle of incidence β, and the distance Q in correspondence with each other from among the data of the distance Q from to the emission point of the radio wave; and c. The measured amplitude value is retrieved from the memory by a readout signal based on the measured amplitude value signal.
By reading the memory contents corresponding to m′,
An apparatus characterized by comprising measurement readout means for obtaining a signal of the distance value Q or a signal of the arrival angle of incidence β and the distance value Q as a measurement readout signal. 3 Omnidirectional antennas placed at equal intervals on the circumference are sequentially switched and scanned to receive radio waves to obtain a received signal, and the phase change in the received signal caused by the switching causes the radio waves to be By obtaining a signal having a component that changes like a SIN wave in association with the direction of arrival (hereinafter referred to as a SIN wave change component) as a direction signal, the direction of arrival of the radio wave relative to a reference direction is detected based on the direction signal, and A radio direction distance measuring device (hereinafter referred to as the device) that measures the position of the emission point of the radio wave based on the direction of arrival, comprising: a) detecting the direction signal by using a signal obtained based on the frequency of the radio wave; an amplitude correction means for obtaining a corrected azimuth signal, a signal in which the amplitude of the SIN wave-like change component is increased in inverse proportion to the frequency; b) measuring the amplitude of the SIN wave-like change component included in the corrected azimuth signal; c) an amplitude measuring means for obtaining a signal with a measured amplitude value m' as a measured amplitude value signal; The arrival angle of the radio wave in a plane perpendicular to the horizon (hereinafter referred to as the equivalent amplitude value) and the measured amplitude value m' is calculated based on the relational expression m'/m=cosβ (hereinafter referred to as the equivalent amplitude value).
of the omnidirectional antenna, which is calculated based on the relational expression 2{cos ^-1 [r/r + hcos β] - β} r = Q, using the ionosphere height h and the earth's radius r. The measured amplitude value is determined from among the data regarding the distance Q from the installation point to the emission point of the radio wave.
an amplitude-corresponding angle-distance means for storing the calculated values of m', the arrival angle of incidence β, and the distance Q in correspondence; d. The measured amplitude value
By reading the memory contents corresponding to m′,
An apparatus characterized by comprising measurement readout means for obtaining a signal of the distance value Q or a signal of the arrival angle of incidence β and the distance value Q as a measurement readout signal.