JPH0245782A - Detecting method for radio wave arrival direction - Google Patents

Abstract

PURPOSE:To detect the direction of radio wave arrival without analyzing the frequency nor being affected by variation in antenna characteristics by recording and comparing received pulse waveforms. CONSTITUTION:Antennas 3a and 3b are arranged at points A and B and when the pulse input of an arrival radio wave is received at the point A, it is recorded and the time (t) up to the input point of a pulse with a similar waveform to the point B is measured. This time (t) is calculated from t=d.cosphi (where d is the distance between the antennas and phi is the angle of the arrival wave to the axis connecting the points A and B), so when the distance (d) is accurately grasped, reverse calculation is carried out to obtain the radio wave arrival direction phi. Waveforms are compared by calculating the similarity of the whole. In this case, similarity is calculated as to the amplified in the form of not an absolute value, but a relative value, so the influence of variation of the characteristics of the antenna is eliminated. A frequency analysis is not necessary and antenna characteristics and connection line characteristics are not limited.

Description

[Detailed description of the invention] [Industrial application field 1 The present invention relates to a method for detecting the direction of arrival of radio waves.

[Prior art j Figure 8 is a block diagram showing a phase comparison method, which is a type of conventional detection method. In the figure, (3a) and (3h) are antennas with the same characteristics, and (4) is a receiving frequency measuring device. ,(5)
is a comparator.

FIG. 9 is an IJI diagram explaining the principle of the phase comparison method, and FIG. 10 is a waveform diagram showing arriving waves in the phase comparison method.

Next, the operation will be explained.

The antennas are installed at points A and B in FIG. 4, and the distance 111d between them is accurately measured. Now, assuming that the arriving wave arrives at an angle ψ shifted from the axis connecting points A and B, the arriving wave at point B will be delayed by a cos ψ from the arriving wave at point A. If the speed of the arriving wave is C, then at point B there will be a delay of t=dcosψ/C time compared to point A. At this time, the wavelength λ of the arriving wave and the phase at points A and B -A, 1iB
The situation is shown in Figure 1O. Therefore, d, c, λ, φ
When A and -B are given, it is possible to calculate ψ.

[Problem to be solved by the invention 1 The conventional phase comparison method was configured as described above, so the phase must be detected, and it is vulnerable to changes in the amplitude of arriving waves, etc. This method is greatly affected by variations in characteristics and requires analysis of one frequency (or wavelength), which poses problems such as limitations on frequency bands and the like.

This invention was made to solve the above-mentioned problems, and provides a method for detecting the direction of arrival of radio waves that is not affected by changes in the characteristics of antennas, etc., which can detect the direction of arrival of radio waves without frequency analysis. [Means for Solving the Problem 1] The radio wave arrival direction detection method according to the present invention records and compares received pulse waveforms to determine the reception delay time without phase comparison, This allows for direction finding.

[Function 1] In the recording and comparison of pulse waveforms in this invention, time can be measured without frequency analysis, and by determining the similarity of waveforms with respect to the head width of the arriving wave, restrictions on frequency bands etc. can be avoided. It disappears.

[Embodiment 1] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1st
The figure is a block diagram showing a radio wave arrival direction detection method according to an embodiment of the present invention. In the figure, (1) is a processor, and (2) is a process! A comparator follows (1) and compares the pulse waveforms, (3a) and (3b) are antennas.

FIG. 2 is an explanatory diagram of the principle of the radio wave arrival direction detection method of the present invention, and FIG. 3 is a tlfli! of the present invention. FIG. 3 is a waveform diagram showing arriving waves according to a direction of arrival detection method.

Next, the operation will be explained. The principle is similar to the conventional phase comparison method, and the direction of arrival of radio waves is calculated by determining the delay time of received signals from multiple antennas.

In this method, when a pulse input as shown in FIG. 3 is received at point A, this is recorded and the time t until a pulse with a similar waveform is input at point B is measured. This time t
As mentioned earlier, is given by t = d - cos ψ, so if you know the distance d between the antennas accurately, you can calculate the direction of arrival of the radio wave (ψ) by calculating backwards. Comparison of waveforms is performed by calculating the overall similarity. On this occasion,
Regarding the amplitude, if the similarity is calculated based on relative values rather than absolute values, it will not be affected by changes in characteristics of the antenna or the like.

In the above embodiment, the method of determining the angle ψ of the antenna with respect to the A-B axis was described, but as shown in FIGS. By adding 3C, it becomes possible to determine the direction on the plane. Further, as shown in FIGS. 6 and 7, the plane A-B-C
By providing a point on the outside, it has easy expandability such as being able to determine the angle in three dimensions.

Further, although the above embodiment shows a case where the comparator and the processor are separated, depending on the performance of the processor and memory, it is possible to combine them into one, and the same effects as in the above embodiment can be obtained.

[Effect of the invention 1] As described above, according to this invention, the method of detecting the direction of arrival of radio waves is the simplest method of comparing waveforms and measuring time, so there is no need for frequency analysis, unlimited antenna characteristics, and similar connections. It has advantages such as unlimited line characteristics, making the direction finding device inexpensive and
And it has a simple effect.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are block diagrams showing a radio wave arrival direction detection method according to an embodiment of the present invention, an explanatory diagram of the principle, and waveform diagrams showing arriving waves, and FIGS. Figure 6, 7th
The figures are a block diagram and an explanatory diagram of the principle of a radio wave arrival direction detection method according to another embodiment of the present invention, FIGS. 8 and 9,
FIG. 1O is a block diagram of a phase comparison method, which is a type of conventional detection method, an explanatory diagram of the principle, and a waveform diagram showing arriving waves. In the figure, (1) is a processor, (2) is a comparator, and (3a) ~
(3a) shows an antenna. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] Equipped with a comparator that records and compares (verifies) pulse waveforms, a processor that controls the system, and multiple antennas, it calculates the difference in arrival time by comparing pulse waveforms and detects the direction of arrival from this. A method for detecting the direction of arrival of radio waves.