JPH0359481A - Azimuth measuring instrument - Google Patents

Abstract

PURPOSE:To take a high-accuracy measurement without being affected by frequency nor a delay signal by finding the difference in arrival time between pulse radio waves obtained by receiving radio waves, acquired by two antennas arranged in the same direction at a constant interval, by two receivers individually. CONSTITUTION:A pulse radio wave which arrives in some direction is acquired by the two antennas 20A and 20B which are provided in the same direction at the constant interval and received by the two receivers 30A and 30B individually. Those radio waves have the arrival time difference according to the arrival angle. An angle measurement processing circuit 10 measures the difference and calculates the arrival angle from the interval between the antennas and the propagation speed. Therefore, the measurement accuracy is affected by none of characteristic variation of the antennas and receivers with frequency, and variation in gain and a shift in phase with temperature and time and only the rising time of pulses is measured for reflection by a peripheral structure to eliminate the influence of the delay signal upon the measurement accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an azimuth measuring device, and particularly to a azimuth measuring device suitable for measuring the direction of arrival of pulse-modulated radio waves.

[Conventional technology]

A conventional example is shown in FIGS. 6 and 7. Among these, the conventional example shown in Fig. 6 has two antennas 2OA and 20B installed at a certain distance apart, and two
receivers 30A and 30B, and an amplitude comparison circuit 50 for determining the arrival angle of radio waves from the amplitude difference between the radio waves received by each receiver.

Furthermore, the conventional example shown in FIG. 7 includes two antennas 2OA and 20B installed at a certain distance apart, two receivers 30A and 30B for capturing radio waves with each antenna, and each receiver. A phase comparison circuit 60 is provided for determining the arrival angle of radio waves from the phase difference of the received radio waves.

Each of the above conventional examples utilizes the fact that the amplitude and phase of radio waves differ depending on the distance traveled.

(Problem to be Solved by the Invention) However, in the above conventional example, when determining the arrival angle of radio waves from the amplitude difference of each received signal, the gain of each antenna and the gain of each receiver are measured in advance with high precision. Moreover, since each gain must be kept constant at all times, the equipment becomes expensive.Also, when determining the arrival angle of radio waves from the phase difference of each received signal, However, since the propagation phase of the receiving system up to the phase comparator circuit must always remain constant, the equipment becomes expensive.Furthermore, since the amplitude and phase change depending on the receiving frequency, it is difficult to achieve a wide band. There have been problems in that it is difficult to perform measurements, and that measurement accuracy is reduced due to distortion of the antenna pattern and phase disturbance due to reflections around the antenna.

[Purpose of the invention]

The purpose of the present invention is to improve the disadvantages of the conventional example, and in particular, to overcome the problems of the antenna and the receiver even if there are changes in characteristics of the antenna and receiver due to frequency, changes in temperature, changes over time, and changes in gain and phase caused by these changes. It is an object of the present invention to provide an azimuth measuring device whose measurement accuracy is not affected by

[Means to solve the problem]

Therefore, in the present invention, two antennas are installed facing the same direction with a certain distance apart, two receivers each receive the radio waves captured by each antenna, and the radio waves received by each receiver are provided. The configuration includes an angle measurement processing circuit for determining the arrival angle of the pulse radio waves from the arrival time difference of the pulse radio waves. This aims to achieve the above-mentioned purpose.

[Effect]

When pulse radio waves arriving from a certain direction are received by a plurality of antennas installed at a certain distance interval, a difference in arrival time occurs depending on the arrival angle of the pulse radio waves.

Conversely, by measuring the arrival time difference of the pulsed radio waves using an angle measurement processing circuit, it is possible to calculate the arrival angle of the pulsed radio waves from the antenna spacing and the propagation speed of the radio waves.

[Embodiments of the invention]

A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

The embodiment shown in Fig. 1 has two antennas A20A and 820B installed facing the same direction at a certain distance apart, and two receivers A (30A) for capturing radio waves with each antenna.
, B (30B), and an angle measurement processing circuit 10 for determining the arrival angle of the pulse radio waves from the arrival time difference of the pulse radio waves received by each receiver.

For example, if the arrival time difference of pulse radio waves received through antenna A (20A) and antenna B (20B) is Δt, as shown in FIG.
20B), the following relationship holds true.

cos θ = Δti/L...■ Here, θ is the arrival angle of the pulse radio wave, and f is the propagation speed of the pulse radio wave.

Therefore, the arrival angle of the pulse radio wave can be determined from the following equation based on equation (2).

θ cos-'(Δt-f/L)...■ Then, the process shown by equation (2) is performed in the angle measurement processing circuit 10.

Next, a second embodiment of the present invention will be described based on FIGS. 3 to 5. The embodiment shown in FIG. 3 has eight antennas a-h (20a
=h), eight receivers a-h (20a-h) for capturing radio waves with each antenna, and a system for determining the arrival angle of pulse radio waves from the arrival time difference of pulse radio waves received by each receiver. The configuration includes an angle measurement processing circuit 11.

As shown in FIG. 4, pulse radio waves 40a and 40b
When pulse radio waves arrive from different directions as shown in FIG. It varies depending on the direction of arrival. This positional shift corresponds to Δθ in FIG. Therefore, the arrival angle of pulsed radio waves can be measured over the entire circumferential direction.

〔Effect of the invention〕

As described above, according to the present invention, there are a plurality of antennas installed at a certain distance interval, a plurality of receivers for receiving radio waves from each antenna, and the arrival of pulse radio waves received by each receiver. Because it has a configuration that includes an angle measurement processing circuit for determining the arrival angle of pulse radio waves from the time difference,
Measurement accuracy is not affected by changes in the characteristics of the antenna and receiver due to frequency, or changes in gain and phase due to temperature changes or aging, and only the rise time of the pulse is measured despite reflections from surrounding structures. Therefore, the measurement accuracy is not affected by the signal via the reflection path, that is, the delayed signal. Therefore, it is possible to provide an unprecedented and excellent azimuth measuring device capable of high-precision azimuth measurement at low cost.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing the first embodiment of the present invention;
1 is a schematic diagram for explaining the operation of FIG. 1, FIG. 3 is a schematic configuration diagram showing a second embodiment of the present invention, FIG. 4 is a schematic diagram for explaining the operation of FIG. 3, FIG. 5 is an envelope showing the relationship between the antenna direction and time difference in FIG. 3, FIG. 6 is a schematic configuration diagram showing the first conventional example, and FIG. 7 is a schematic configuration diagram showing the second conventional example. be. 10.11...Angle measurement processing circuit, 2OA, B, 2
0 a -b ------- Antenna, 3 Q, A,
B, 30 a ~ O...Receiver.

Claims (1)

[Claims] (1) Two antennas placed a certain distance apart and pointing in the same direction, two receivers that separately receive the radio waves captured by each antenna, and pulse radio waves received by each receiver. An azimuth measurement device comprising: an angle measurement processing circuit for determining the arrival angle of a pulse radio wave from the arrival time difference of the pulse radio waves.