JPS61294380A - Direction detector - Google Patents

Abstract

PURPOSE:To improve the detection precision of an inter-ruptedly coming radio wave by operating the amplitude difference between signal outputs of two receivers which demodulate a difference signal and a sum signal respectively to output an audio signal which rises quickly when antennas are directed to the coming direction of the radio wave. CONSTITUTION:Two reception signals received by antennas 1 and 2 are inputted to a hybrid 2 to obtain the sum signal output and the difference signal output. These sum and difference signals are demodulated by receivers 3a and 3b and are inputted to a differential amplifier 5. Since the output of the differential amplifier 5 is obtained by using the difference signal which has a sharp null characteristic for the antenna rotation angle, this output has a sharp peak characteristic for the rotation angle. This output is inputted to an audio amplifier 6 to extract and amplify only the signal having a polarity required for detection of the coming direction. An operator detects the coming direction of the received radio wave in accordance with rotation angle information from an angle detector at the time when the audio output is maximum for the antenna rotation angle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an azimuth detection device that detects the direction of radio waves by arranging two directional antennas on a horizontal plane.

[Prior Art] Fig. 3 is a schematic configuration diagram showing a conventional direction finding device. Rotate on a horizontal plane while keeping the angle constant.

(2) is a hybrid that outputs the difference signal and sum signal of the received signals from antennas (la) and (lb); (3a) (
3b) is a receiver that receives and demodulates the difference signal and sum signal from the hybrid (2), and (4) is the antenna (la).
This is an angle detector that usually consists of a synchro generator that detects the rotation angle of (lb).

Next, its operation will be explained. Antenna (1a) (1
The signal captured by b) is transferred to the hybrid (2) using the antenna (
The signal from antenna (1a) and the signal from antenna (1b) are output as a difference signal (difference signal) and a sum signal (sum signal).

Since the directions of the antennas (la) and (lb) differ by a small angle, the radio wave arrival direction is clearly shown in Figure 2a, which shows the received signal amplitude by these antennas with respect to the rotation angle of the antennas (la) and (lb). It becomes symmetrical with the same amplitude. Therefore, when the difference signal and sum signal of these signals are demodulated by the receivers (3a) and (3b), the output is as shown in FIG. In other words, the time difference signal with two antennas (la) and (lb) facing the radio wave arrival direction is O(Nu
ll), and the sum signal becomes maximum. Difference signal is Null
Since the point where is very sensitive to the rotation angle of the antenna, the difference signal is used for angle detection. The angle information from the angle detector (4) when the difference signal is Null is taken as the arrival direction of the arriving radio wave.

[Problems to be solved by the invention] Since the conventional direction finding device is configured as described above, it has the advantage of detecting the direction of arrival with high accuracy for radio waves that arrive continuously, but For radio waves that arrive at
It is unclear whether there is no output signal at the null point. Therefore, it becomes necessary to determine the presence or absence of incoming radio waves based on the output of the sum signal.

The operator not only operates the direction-finding device but also operates other devices, and in cases where the operator has no choice but to judge these output signals by voice, conventional direction-finding devices use the same signal source as described above. There was a problem in that it was necessary to distinguish between the part sounds of the sum signal and the difference signal, making it extremely difficult.

This invention was made to solve the above-mentioned problems, and it is an object of the present invention to provide a direction finding device that can inform an operator of the direction of an incoming radio wave with a single signal tone.

[Means for Solving the Problems] The direction finding device according to the present invention includes a differential amplifier that takes the difference between the signal outputs of two receivers that demodulate the difference signal and the sum signal, respectively, and the differential amplifier. The device is equipped with an audio amplifier that outputs an audio signal according to the output signal level.

[Operation] In this invention, by taking the difference in amplitude between the difference signal and the sum signal, the steep N with respect to the rotation angle of the difference signal is calculated.
The ull characteristic is changed to a signal that has a steep maximum value for one rotation angle, and this signal is converted into an audio signal to inform the operator. The operator can easily detect the direction of arrival of radio waves by the sound that rises sharply when the antenna is directed toward the direction of arrival of radio waves.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a schematic diagram showing one embodiment of this invention.

(la) (lb) (2) (3a) (3b) (
4) is the same as the conventional example in Fig. 3, and (5) is the receiver (3a
) (3b), a differential amplifier that takes the amplitude difference of the output signals of (6
) is an audio amplifier connected to this differential amplifier (5).

Next, the operation will be explained with reference to FIG. Antenna (l)
a) (lb) outputs a received signal as shown in FIG. 2a. When these two signals are input to the hybrid (2), a sum signal output and a difference signal output as shown in FIG. 2 are obtained. The sum signal and difference signal are sent to the receiver (3a) (3
After demodulating in step b), the signal is input to the differential amplifier (5) to obtain the output shown in FIG. 2C. Since this output is obtained using a difference signal that has a steep null characteristic with respect to the antenna rotation angle, it has a steep peak characteristic with respect to the rotation angle. The output of the differential amplifier (5) becomes a signal whose polarity is inverted in accordance with the antenna rotation angle, as shown in FIG. 2C. Only the polarity signal necessary for detecting the direction of arrival in the audio amplifier (6),
That is, only the signal near the direction of arrival is extracted and audio amplified. This output is shown in Figure 2d, and this audio output signal is sent to the operator. The operator can know the direction of arrival of the received radio waves based on the rotation angle information from the angle detector when the audio output is at its maximum with respect to the antenna rotation angle.

C. Effects of the Invention As described above, according to this invention, the difference between the sum signal and the difference signal is taken and converted into an audio signal by the audio amplifier, so an audio signal that rises sharply only near the direction of arrival can be obtained. This has the effect of allowing highly accurate direction detection even for intermittent arriving radio waves.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention. FIG. 2 is an explanatory diagram of its operation, and FIG. 3 is a schematic configuration diagram showing a conventional direction finding device. In the figure, (la) and (lb) are antennas, (2) is a hybrid, (3a) and (3b) are receivers, (4) are angle detectors, (5) are differential amplifiers, and (6) are audio amplifiers. be. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] Two directional antennas are placed on a horizontal plane facing in the same direction at a slight angle to each other, and rotate on the horizontal plane while keeping this angle constant, outputting the sum signal and difference signal of the received signal output of both antennas. An azimuth finding device comprising: a hybrid which receives and demodulates a sum signal and a difference signal from the hybrid, and an angle detector which detects the direction in which both of the antennas are facing,
A direction finding device comprising: a differential amplifier that takes the difference between demodulated signals from the two receivers; and an audio amplifier that outputs an audio signal according to the output signal level of the differential amplifier.