JPS6014310B2 - Direction measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a Doppler azimuth measurement bag counterfeit in which antennas are arranged in a circular manner.

In particular, the present invention relates to improvements in digitizing the azimuth detector to improve measurement accuracy and response speed, as well as to correct for angular failure. A typical system diagram of a Doppler azimuth measuring device in which antennas are arranged in a circular manner is shown in FIG.

Incoming radio waves received by the receiving antenna 1 and the azimuth antenna 2 are converted into intermediate frequency signals by frequency converters 3 and 4, respectively. 5 is a local oscillator.

The two intermediate frequency signals are extracted by the mixer 6 as an intermediate frequency signal having only azimuth information, applied to the azimuth detector 7, detected, and the azimuth information is displayed on the display 8. In the conventional apparatus with such a configuration, an analog system using a discriminator or the like as the direction detector 7 was adopted.

FIG. 2 is a block diagram of the azimuth antenna 2, which is composed of N antenna elements (1) to (4) arranged at equal intervals on the circumference.

In such a conventional device, the detected signal has an N-step staircase waveform sine waveform as shown in Fig. 3, which is integrated to extract only the fundamental wave component, and the azimuth signal shown in Fig. 3 {b} is obtained. and the azimuth reference signal shown in FIG. 3'c) are obtained, and the azimuth of arrival is determined by changing the phase difference according to the azimuth of arrival.

Therefore, in order to obtain practically sufficient directional accuracy, it is necessary to narrow the bandwidth after detection, and the response time for azimuth detection is slow. In conventional equipment, the antenna switching frequency is several tens of Hz,
The response time for direction detection is about 1 second. Therefore, a direction measuring device using such an analog direction detector is not suitable for automatic measurements that require high-speed measurement.
It has the disadvantage that it cannot adequately follow rapid interruptions and changes in incoming radio waves. Furthermore, in a Doppler azimuth antenna, it is impossible in principle for the phase difference between adjacent antenna elements to exceed the lamp.

However, in the actual field, the phase of incoming radio waves is disturbed by various disturbances such as reflections from buildings, and the phase difference between adjacent antenna elements often exceeds the threshold. At this time, in the analog azimuth detector used as a follow-up, an abnormal notch appears in the detected waveform as shown in FIG. 4, the measured azimuth is disturbed, and sometimes the lateral angle becomes impossible. In order to solve this problem, there is no improvement in making the filter even narrower, and the result is that the response time for direction detection is further delayed. The present invention is a Doppler azimuth measurement device in which antennas are arranged in a circle, and improves the slow measurement time and weakness against various disturbances in the actual field, which are inherent in analog field angle methods such as secondary discriminators. The purpose is to provide a high-speed and highly accurate direction measuring device.

The present invention processes an incoming signal whose frequency has been converted to an intermediate frequency in a digital format, and performs phase detection, phase averaging, phase difference detection between adjacent antenna elements, correlation calculation, and azimuth calculation at high speed to calculate instantaneous azimuth. Then, the arrival direction is determined by adding the average value over a predetermined measurement time, and the phase difference between adjacent antenna elements in the process of calculation is stored in a storage device. A high-speed and highly accurate azimuth measurement device is provided by collating incoming signal interruption information, abnormal phase difference information between adjacent antenna elements, and antenna element failure information to correct the phase difference.

The present invention provides a direction measuring device that detects the direction of arrival of received radio waves based on the phase difference between signals obtained by scanning a plurality of antenna elements. a phase difference detection means for detecting as a signal; a memory means for storing the detection output of the phase difference detection means; a correlation calculation means for calculating the correlation between the stored contents of the memory means and the output of the phase difference detection means;
The present invention is characterized by comprising azimuth calculation means for calculating the direction of arrival of the received radio waves from the output of the correlation calculation means.

Furthermore, in addition to the above-mentioned configuration, a second invention provides that when the data obtained by any of the above-mentioned means is abnormal, this data is rejected and the outside of this data is replaced. The present invention is characterized by comprising a correction means for outputting data based on at least one of data of antenna elements adjacent to the element and data predicted from past data.

Next, an embodiment of the present invention employing the digital side kakumanshiki will be described with reference to the drawings.

The system diagram of the entire device is the same as that shown in FIG. 1 as a conventional device, and the configuration of the azimuth antenna 2 is the same as that shown in FIG. 2.

This Doppler direction measuring device is equipped with two antennas.
The first one is the reception antenna 1, which is omnidirectional in all directions on a plane, and the reception phase does not change depending on the arrival direction of radio waves. The second type is the azimuth antenna, and as shown in FIG. 2, N antennas are arranged at equal intervals on the circumference (for example, N is often 8 or 16).
) antennas ■ to ■ are electronically switched in sequence and connected to the receiver. As a result, the receiving position of the incoming radio wave changes in a circular manner, and the received radio wave is subjected to phase modulation according to the switching period around the N antenna elements. When this received radio wave is phase-difference-detected by the receiving device, the detected output has a phase angle that differs depending on the direction of arrival of the radio wave, with respect to the switching phase difference of one turn from the reference antenna element (2). This is the phase angle 8 shown in FIG. 3, and this is the direction in which the radio waves arrive from the reference antenna element (for example, ■). In Fig. 3, a shows how the phase of the received signal changes stepwise as the antenna element is switched;
Figure b is a waveform obtained by extracting the fundamental component of the signal shown in figure a.

Figure c is a periodic signal for switching. For example, if the standard for switching is set to the north of the absolute direction of the antenna element, and 00 is the north, 36 pins are assigned in the direction of north → east → south → west → north. ,
The angle shown in FIG. 3 indicates the absolute direction. 1st
The device shown in the figure is a device for accurately determining the azimuth angle 8, and this operation is performed by the azimuth detector 7 of the devices shown in FIG.

The obtained angle is displayed on the display 8. By the way, if the arriving radio signal itself is a signal that does not include a phase modulation component, the azimuth angle a can be determined as described above. However, when the incoming radio signal itself is phase modulated, this phase modulation component ingredients must be removed.

In general, even if a radio wave is amplitude modulated but not phase modulated, or is unmodulated, if it propagates over a certain distance and is received, there will be many propagation paths, and the received radio wave will contain a phase modulated component. included. Direction detector 7 with the device shown in Figure 1
The two systems of circuits and their mixer 6 provided in the front stage are circuits for removing this phase modulation component. That is, the radio signals received by the above-mentioned receiving antenna 1 and azimuth antenna 2 are converted into intermediate frequency signals by the output of one local oscillator 5 by frequency converters 3 and 4 having the same characteristics, respectively.

These intermediate frequency signals are mixed in one mixer 6 such that their phase components are opposite to each other. As a result, the phase modulation component of the incoming radio wave itself is canceled out, and only the phase modulation component generated by switching the orientation antenna 2 is input to the azimuth detector 7. Here, the feature of the present invention is the configuration of the direction detector 7.

Details of the direction detector 7 are shown in a block diagram in FIG. Fifth
In the configuration shown in the figure, an input signal is applied to a phase detector 12 via a pulse converter 11.

Here, it is compared with the output of the reference generator 13, and the phase averager 1
given to 4. This world power is sequentially applied to a phase difference detector 15, a correlation calculator 16, an azimuth calculator 17, and an azimuth processor 18. Each element 15-18 is all coupled with memory 19. The operation of the device configured in this way is explained in the sixth section.
This will be explained with reference to the waveform diagram shown in the figure.

In FIG. 6, a is a control signal for the antenna element, b is an input intermediate frequency signal, c is an output waveform of the pulse converter 11, and d is a reference phase signal. Figures 6 a to d are shown in Figure 5, respectively.
It is a waveform diagram of points ~d. The intermediate frequency signal shown in FIG. 6b is converted by the pulse converter 11 into the pulse shown in FIG. 6c, and the phase is compared with the reference phase signal shown in FIG. 6d by the phase detector 12.

Here, the phase difference of the intermediate frequency signal with respect to the reference phase is counted digitally. Next, the phase averager 14 calculates the average phase when the antenna element is closed by referring to the control signal for the antenna element shown in FIG. 6a. Here, the phase difference detector 15, phase calculator 16, azimuth calculator 17, and azimuth processor 18 can be functionally illustrated as shown in FIG. Each of the elements 15 to 18 is realized by its software.

Memory 19 is a memory connected to this microprocessor. In order to clarify the contents of the processing executed by this microprocessor, the contents of the processing or calculation will be explained for each block.

Now, if the average phase of the i-th antenna element is 8i, then
In the phase difference detector 15, the phase difference between the i-th and i-1th is △8
i is △ai=01-Ko-1......'1)
This is then stored in the calculation memory 19.

When the number of elements of the azimuth antenna 2 is N, the phase difference between adjacent antenna elements becomes a step-wave trigonometric function as shown in Fig. 3a, so as explained above, it becomes the reference for the azimuth antenna 2. The azimuth angle 8 of the arriving radio wave from the azimuth of the antenna can be found by calculating the correlation function with a trigonometric function whose period is the reference antenna switching frequency. Therefore, the phase difference data is appropriately calculated from the memory 19, and the correlation calculator 16 calculates that RX=
Mother △8i●Sin2 band i ……■iko1N Ry:i≧,△8,. COS usurpation i.・・・．・・【
31 is executed by the direction calculator 17.

At the foot of the mountain. ...--'4), the instantaneous bearing 8 at the time of switching one antenna can be obtained.
Next, the azimuth processor 18 averages the instantaneous azimuth 81 over a given measurement time, and outputs the final azimuth ■@:3,j斗j...■.

Here, n is the number of instantaneous orientation data within the measurement time.
Here, the reason why the orientation is determined by the above equation (2) will be quantitatively explained.

The signal obtained by the azimuth antenna 2 is f.

= pine in (t+0) ...[6' (however,
8' Azimuth angle of the arrival signal with respect to the reference antenna element) The reference signal is fR = t of Sin and fR = t of COS...{
71, and calculate the correlation between the two signals, RX; main's f.

・Sin's tdt...'8': Te'kichi ASin
Kunot+8)-Sin's tdt=sha. S8
‐‐‐‐‐‐It becomes '9'. Similarly, Ry=kai ino
Since the skin o0 is obtained, the azimuth angle can be obtained from formulas 9 and 00 as 8 = fence 1 foundation.

In this way, this azimuth detector 7 digitally processes the intermediate frequency signal having azimuth information, executes phase detection, phase averaging, phase difference detection, correlation calculation, and azimuth calculation at high speed, and calculates the instantaneous direction of arrival. At the same time, it is possible to calculate an average direction that is averaged every predetermined measurement time.

Since the device of the present invention performs processing digitally, there is no response delay caused by the signal passing through a narrow band filter, and the scale and speed of arithmetic processing are reduced by taking into account the necessary precision and response time. Can be set.

Another feature of digitally performing arithmetic processing is that the results of each process can be memorized and various corrections can be executed at high speed.

This is effective against various disturbances in the real field,
Here, as an example, correction will be described in the case where there is a momentary interruption in the '1' signal, (2) where the phase difference between adjacent elements exceeds 180 degrees, and where a failure occurs in the '3' element.

Above [1] is based on signal presence/absence detection information from other receivers, etc., ■ is based on information that the phase difference between adjacent antenna elements in the azimuth detector itself exceeds the threshold, '31 is based on the azimuth antenna This is based on the failure information of the antenna elements.

When there is no incoming signal, when the phase difference between adjacent antenna elements exceeds the threshold, or when an antenna element malfunctions, an abnormal value is output to the phase difference detector 12 in FIG. increases, and in some cases, lateral angle loss may occur. In such a case, based on the detection information of each abnormality, phase difference data showing the corresponding abnormal value is rejected, and instead of this, the value between the antenna elements one scan ago or the value between the antenna elements is used. By inserting the immediately preceding value or inserting a value predicted from values between a series of past antenna elements, stable and accurate azimuth measurement can always be achieved.

As a result, even if phase disturbances occur due to rapid interruptions or changes in incoming radio waves in the actual field, or various disturbances such as reflections from buildings, the measurement display will not be affected immediately, and unnecessary transmission of signals will be avoided. be able to. Furthermore, since the instantaneous direction string is stored, various statistical processing such as calculation of standard deviation is also possible. As described above, according to the present invention, the measurement response time and measurement accuracy are improved compared to the conventional analog shelf angle method azimuth measurement device, and measurement abnormalities that occur and recover in a short period of time can be resolved. It has an excellent feature that enables correction processing.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a circular array Doppler azimuth measuring device in which the present invention is implemented. FIG. 2 is a configuration diagram of an azimuth antenna made up of N antenna elements arranged at equal intervals on the circumference. FIG. 3 shows each detected waveform of the azimuth detector, a azimuth signal immediately after detection, b integrated azimuth signal, and c azimuth reference signal. FIG. 4 is a diagram showing an example of a detected waveform when the phase difference between adjacent antenna elements exceeds a threshold. FIG. 5 is a system diagram of the digital side angle type azimuth detector of the present invention. FIG. 6 is an operational waveform diagram of the digital side angle type azimuth detector of the present invention. a Control signal for the antenna element. b input intermediate frequency signal, c pulse converter output waveform, d reference phase signal. 1... Receiving antenna, 2... Direction antenna, 3,
4... Frequency converter, 5... Local oscillator, 11...
- Pulse converter, 12... Phase detector, 13... Reference phase generator, 14... Phase averager, 15... Phase difference detector, 16... Correlation calculator, 17... - Direction calculator, 18...Direction processor, 19...Memory. XI figure rare 2 figure girder 3 figure rare 4 figure boat 5 figure and 6 figure

Claims (1)

[Claims] 1. In an azimuth measuring device that detects the arrival direction of received radio waves based on the phase difference between signals obtained by scanning a plurality of antenna elements, the position of the induced voltage of each antenna element relative to a reference signal is determined. A phase difference detection means for detecting the phase difference as a digital signal, a memory means for storing the detection output of the phase difference detection means, and a correlation calculation for calculating the correlation between the contents stored in the memory means and the output of the phase difference detection means. 1. An azimuth measuring device comprising: a means for calculating a correlation; and an azimuth calculating means for calculating the direction of arrival of a received radio wave from the output of the correlation calculating means. 2. In an azimuth measurement device that detects the arrival direction of received radio waves based on the phase difference between signals obtained by scanning multiple antenna elements, the phase difference of the induced voltage of each antenna element with respect to a reference signal is detected as a digital signal. a phase difference detecting means for detecting a phase difference, a memory means for storing a detection output of the phase difference detecting means, a calculating means for calculating a correlation between the stored content of the memory means and an output of the phase difference detecting means, and a correlation calculating means for azimuth calculating means for calculating the direction of arrival of the received radio waves from the output of; and when the data obtained by any of the above means is abnormal, this data is rejected and replaced with this data, the data from one scan ago, An azimuth measuring device comprising: correction means for outputting data based on at least one of data of an antenna element adjacent to the antenna element and data predicted from past data.