JP2685759B2 - Direction measurement device - Google Patents

Description

The present invention relates to an azimuth measuring device that measures the arrival direction of an electromagnetic wave, transmits the arrival direction information, and then displays the arrival direction. (Prior Art) As a device for measuring the arrival direction of an electromagnetic wave, transmitting the obtained information, and then displaying the information, there is a conventional device configured as shown in FIG. That is, in FIG. 4, the azimuth measuring beam formed in the antenna 11 and the goniometer 12 is received by the receiver 13, converted into an IF (intermediate frequency) signal, and supplied to the detector 14 as an output IF signal. This detector 14
Is for envelope detection of the IF signal and extracts the detection signal. The detection signal extracted by the detector 14 is supplied to the modulator 15. The modulator 15 modulates a carrier wave having an optimum frequency on the transmission line 17 with a detection signal and supplies the band filter 16 with the modulated detection signal. The band filter 16 limits the output signal of the modulator 15 to a predetermined band and then sends it to the transmission line 17. The modulated detection signal transmitted via the transmission line 17 is demodulated by the demodulator 18 and returned to the detection signal. This detection signal is supplied to the indicator 19, converted into a video signal, and the arrival direction of the target radio wave is displayed on the cathode ray tube, and the direction is measured. When the azimuth measurement of the target radio wave is based on the ad-coc azimuth measurement method, as the antenna 11, for example, four antennas 111 to 114 installed in four directions as shown in FIG. 5A are used. This is a basic adcoc azimuth measuring antenna. The goniometer 12 uses the output of each antenna to generate an 8-shaped beam 20 as shown in FIG. 5 (b) every second.
It forms a rotating beam that rotates about 30 times. The receiver 13 shown in FIG. 4 receives the rotating beam as the azimuth measuring beam transmitted from the goniometer 12 and converts it into an IF signal. The output IF signal has a waveform as shown in FIG. 6 (a), and the position where the waveform has the minimum amplitude is the arrival direction of the radio wave. The detector 14 of FIG. 4 detects the output IF signal of the receiver 13 as shown in FIG. 6 (a) and obtains the detection signal as shown in FIG. 6 (b). The carrier wave is amplitude-modulated or frequency-modulated by this detection signal, the band is limited by the band filter (16) and then transmitted, and then the demodulator 18 demodulates the detection signal. The demodulated detection signal is supplied to the indicator 19. The indicator 19 is, for example, as shown in FIG. 7, a polarity inverter 21 that inverts the polarity of the detection signal, an adder 22 and an adder 22 that add the output signal voltage of the polarity inverter 21 and the constant voltage Vo.
Multipliers 23 and 24 for multiplying the output signal of the sine wave signal and the cosine wave signal, and a CRT2 that indicates the arrival direction of the target radio wave
Equipped with 5. In the indicator 19, the detection signal is inverted in polarity, and then a constant voltage Vo is added to the detection signal, as shown in FIG.
Is converted into a video signal as shown in. This video signal is multiplied by the rotation signal (sine wave signal and cosine wave signal) supplied from the goniometer 12 separately from the azimuth measurement beam, and the target radio wave indication as shown in FIG. 8 (a) is displayed on the CRT 25. The waveform is displayed. The direction indicated by the maximum amplitude portion of this instruction waveform is the arrival direction of the target radio wave. Since the maximum amplitude part is located at two positions on the plus side and the minus side, there is an azimuth uncertainty of 180 degrees as the arrival azimuth. In the device shown in FIG. 4, when an ordinary leased line (3.4K line, etc.) is taken as an example of the transmission line 17 for transmitting the modulated detection signal, the detection signal to be transmitted from a remote place is shown in FIG. 9 (a). As shown, it is similar to the full-wave rectified waveform of a sine wave and contains high frequency components in addition to the fundamental wave. This high frequency component e.g. 3.
When the 4 kHz line is used, frequency components higher than 3.4 kHz are removed by the band filter 16 and then transmitted. Therefore, the transmitted detection signal has a high frequency component removed as shown in FIG. 9 (b), and that portion becomes a distorted signal, so the waveform displayed on the indicator 19 is shown in FIG. 8 (a). ), The maximum amplitude part has a rounded and distorted waveform, resulting in a measurement error. (Problems to be Solved by the Invention) As described above, in the conventional azimuth measuring device, since the detection signal is transmitted after the high frequency component of the detection signal is removed, the detection signal is transmitted from the transmission source at the transmission destination. However, there was a problem that the display waveform in the direction of arrival of the electromagnetic wave was distorted without being demodulated and the measurement error was large and the measurement performance deteriorated. Therefore, the present invention has been made in order to solve such a problem, and transmits a detection signal without removing high frequency components to reduce measurement error and improve measurement performance. The purpose is to provide a device. [Structure of the Invention] (Means for Solving the Problems) The azimuth measuring apparatus according to the present invention squares the detected signal and then transmits the squared signal, and at the transmission destination, square-root processes the demodulated signal to display the arrival direction of the electromagnetic wave. Configured to do. (Operation) With such a configuration, the detection signal is band-compressed and transmitted without being affected by the band limitation by the band filter, and at the transmission destination, the original detection signal can be easily obtained by expanding the band. This makes it possible to improve the measurement performance. (Embodiment) An embodiment of the azimuth measuring apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram for explaining an embodiment of an azimuth measuring apparatus according to the present invention. The same parts as those shown in FIG. 4 are designated by the same reference numerals as those in FIG. 4 and different parts are mainly explained. To do. That is, as shown in FIG. 1, the output IF signal of the receiver 13 is band-compressed by the band compressor 30 and then the signal is transmitted, and at the transmission destination, the signal after transmission is band-compressed by the band expander 31. It is configured to be extended and then supplied to the indicator 19. The band compressor 30, for example, as shown in FIG. 2, is composed of a detector 301, a parallel processor 302, a modulator 303, and a band filter 304. That is, the detector 301 introduces the IF signal from the receiver 13, detects the envelope, and supplies the detected output to the square processor 302. The square processor 302 narrows the frequency band by squaring the detection output, and supplies the signal having the narrowed frequency band to the modulator 303. Modulator 303
The carrier most suitable for the transmission line 17 is modulated by the output signal of the square processor 302, and the modulated signal is output to the band filter 304. The band filter 304 sends a signal in a predetermined band corresponding to the transmission band of the transmission line 17 to the transmission line 17. Here, the band of the band filter 304 is the band filter 16 in FIG.
It is almost the same as the band. On the other hand, the band expander 31 comprises a demodulator 311 and a square root processor 312 as shown in FIG. 3, for example. That is, the demodulator 311 extracts the modulated signal of the signal transmitted from the transmission line 17, and supplies it to the square root processor 312. The modulated signal extracted by the demodulator 311 corresponds to the output signal of the square processor 302, and the square root processor 312 derives the square root of this signal and outputs a signal corresponding to the detection output of the detector 301. In this case, the output signal of the demodulator 311 is a band-compressed signal, while the output signal of the square root processor 312 is a band-decompressed signal. The output signal of the square root processor 312 is supplied to the indicator 19, and the arrival direction of the electromagnetic wave is displayed on the CRT as in the case of FIG. In the configuration shown in FIG. 1, the detection output obtained by envelope-detecting the receiver output is squared to eliminate the effect of band limitation by the band filter 304, and after transmission, square root processing is performed to obtain the original detection signal. As a result, the measurement error generated in the case of FIG. 4 is eliminated. That is, the signal to be transmitted is a detection output obtained by envelope-detecting the receiver output, and is a signal as shown in FIG. 9 (a). Letting V (t) be the detection signal to be transmitted, V (t) = | cosωgt | (1) Here, ωg = 2πfg (2) However, fg is the rotation frequency of the goniometer and is about 30 Hz. Expanding equation (1) by Fourier series Becomes here, Moreover, ω ₀ = 2ωg (5) Becomes From the expressions (3) to (6), the detection signal V (t) to be transmitted is
It can be seen that there is a high-order frequency component in the. In the configuration shown in FIG. 4, since at least a part of this high-order frequency component is cut off by the band filter 16,
As shown in FIG. 9 (b), the detection signal V (t) is not transmitted in the manner to be transmitted, which causes the display waveform on the indicator 19 to show the measurement error as shown in FIG. 8 (a). It will be big. On the other hand, when the detection signal V (t) is squared and band-compressed, the squared detection signal V ′ (t) is And similarly, if Fourier series expansion Becomes here, Becomes In the configuration shown in FIG. 1, the detection signal V'of formula (7) is used.
Although (t) is transmitted, the detected signal V ′ (t) has a frequency component of 2ω as can be seen from the equations (8) and (9).
g, that is, only twice the rotation frequency of the goniometer 12, resulting in a signal as shown in FIG. 9 (c). Therefore, the signal V '(t) is transmitted in the band filter 304 without damaging the frequency component, and after the signal V' (t) is square-root processed, the detection signal (V) t of the equation (1) is obtained. Can be easily obtained, and the display waveform on the indicator 19 has a sharp pointing direction and a small measurement error as shown in FIG. 8 (b). As a result, it is possible to improve the measurement performance of the arrival direction of the electromagnetic wave at a remote place. [Advantages of the Invention] As described above, according to the azimuth measuring apparatus of the present invention, it is possible to transmit a detection signal without removing high frequency components, reduce measurement errors, and improve measurement performance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 3 are configuration diagrams illustrating an embodiment of an azimuth measuring device according to the present invention, FIG. 4 is a configuration diagram illustrating a conventional azimuth measuring device, and FIG. FIG. 6 is a diagram for explaining the operation of the ad-hoc antenna and the goniometer, FIG. 6 is a signal waveform diagram for explaining the operation of the device shown in FIG. 4, FIG. 7 is a configuration diagram for explaining the indicator, and FIG. 8 is an indicator. FIG. 9 is a display waveform diagram of the arrival direction of the electromagnetic wave in FIG. 9, and FIG. 9 is a signal waveform diagram for explaining the detection signal. 11 …… antenna, 12 …… goniometer, 13 …… receiver,
30 …… Band compressor, 301 …… Detector, 302 …… Square processor, 303 …… Modulator, 304 …… Band filter, 17 …… Transmitter, 31 …… Band expander, 311 …… Demodulator , 312 …… Square root processor, 19 …… Indicator.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hiroshi Sunohara               1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa               Company Toshiba Komukai factory                (56) References JP-A-60-82984 (JP, A)                 JP-A-60-93363 (JP, A)

Claims (1)

(57) [Claims] Capture means for rotating the beam in the circumferential direction and capturing an electromagnetic wave coming from the outside, a receiver for receiving the output signal of the capture means, a detector for detecting the output signal of the receiver, and the detector The square processor for performing band compression while maintaining the point where the voltage of the output signal becomes zero by squaring the output signal of, the modulating means for modulating the carrier wave with the output signal of the square processor, and the modulating means of the modulating means. Transmission means for transmitting the output signal, demodulation means for receiving the output signal of the transmission means and demodulating the output signal of the square processor, and deriving the square root of the output signal of the demodulation means to obtain the output signal of the detector. A square root processor for band expanding the corresponding signal,
An azimuth measuring apparatus comprising: an instruction means for displaying an arrival direction of the electromagnetic wave supplied with the output signal of the square root processor.