JPH09236647A - Direction finder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direction finder wherein incoming direction of two interfering waves in the same reception frequency band is simultaneously and automatically measured, and the communication content of the two interfering waves is separated and obtained according to in-coming angle. SOLUTION: The direction finder comprises three units of receiver 2 wherein the non-directional output obtained by synthesizing the output of an antenna system 1 of 8-like directivity assigned orthogonally with the output of the antenna elements constituting the antenna system 1 is independently amplified and frequency-converted, three units of 90-degree hybrid circuit 3 which output I, Q signal of obtained intermediate frequency signal, three units of AD converter 4 which AD converts intermediate frequency I, Q signal, and a digital calculation device 5 which processes the obtained digital I, Q data, and based on the calculated average value and difference of in-coming direction of two interfering waves in the same reception frequency band, each in-coming direction is decided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direction finder capable of separately measuring the directions of arrival of two waves interfering in the same reception frequency band and simultaneously separating and listening to the contents of communication.

[0002]

2. Description of the Related Art Conventionally, a direction finder for measuring the arrival direction of a radio wave automatically uses a directional antenna such as a quadrature loop antenna and an omnidirectional antenna for determining a sense to automatically guide a pointer. A wide variety of systems are in practical use, such as those that are displayed or those that draw a propeller figure on a CRT. However, the arrival directions of two radio waves interfering in the same reception frequency band can be separately measured, or
A direction finder that can separately acquire the communication contents of two radio waves has not been announced yet.

In recent years, as digital technology has advanced, the outputs of the respective antenna elements forming the antenna array are individually amplified to a level at which they can be digitally processed, and then A / D converted to obtain the obtained respective antenna outputs. Music data (MUSIC; Multiple Sig)
A method has been developed in which the arrival directions of a plurality of interference waves are individually detected by performing processing such as nal classification). However, even in this digital processing method, it takes a long time to perform complicated calculations and processes, and it is difficult to separately extract communication contents that change in a short time.

As described above, according to the current method, the directions of arrival of two waves that interfere with the same reception frequency band are individually detected, and at the same time, the communication contents of radio waves are separately acquired and recognized in association with the detected directions. Can not.

[0005]

In the direction finding work, it is necessary to recognize the communication content and the arrival direction in correspondence with each other even when there is interference wave. Therefore, the arrival direction of the interference wave is measured separately. It is an issue to realize a device that can separate and acquire the communication contents in real time.

[0006]

In the direction finder according to the present invention, the direction of arrival of two radio waves interfering with the same reception frequency band can be calculated in real time by processing the digitized reception signal. Yes, the means is described below.

When an antenna having an 8-shaped directivity arranged orthogonally, for example, a quadrature adcock antenna, its output is amplified and frequency-converted, the I.V. of the intermediate frequency signal is obtained. Q data is Ins, Qns, Ie respectively
When the sum of the outputs of the respective antenna elements of the w, Qew and Adcock antennas is defined as an omnidirectional antenna output, the I.V. of the intermediate frequency signal obtained by amplifying and frequency converting the output. Q
By using the following data as Iv and Qv, the following algebraic calculation is performed to calculate an average value of arrival angles θ1 and θ2 of two radio waves interfering in the same reception band; θ ₀ and a difference of arrival angles 1/2; δ. .

[Equation 1]

[Equation 2] Here, J ₀ (β) and J1 (β) are the Bessel functions of the first kind, β is the phase constant of the received radio wave = 2π / λ, and is 1/2 the antenna spacing of the adcock antenna used. Average value of the angle of arrival obtained by the above calculation; θ
₀ and 1/2 of the difference in the angle of arrival; from δ to θ1 = θ ₀ + δ,
And θ2 = θ ₀ −δ are calculated.

When the arrival angles θ1 and θ2 of the two waves are determined, the following arithmetic processing is performed in order to separate the two interfering waves using this data.

(Equation 3) and,

(Equation 4) The signal component from the arrival angle θ1 is not included in Ir1 or Qr1 which is the above calculation result after being deleted,
It is data of only signal components from the arrival angle θ2.
Similarly, the signal component from the arrival angle θ2 is not deleted and included in Ir2 or Qr2, and is data of only the signal component from the arrival angle θ1.

When this Ir1 or Qr1 is DA converted, an intermediate frequency signal of only the radio wave from the arrival angle θ2 is reproduced. By demodulating the reproduced intermediate frequency signal, each communication content can be separately acquired.

[0010]

According to the above means, the arrival angle of two interference waves can be individually detected by a simple algebraic operation, and at the same time, the communication contents of the two interference waves are separated and individually acquired in real time. be able to.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a direction finder according to the present invention. In FIG. 1, 1 is an antenna system.
Each of ns and ew is constituted by an Adcock antenna installed in the north-south direction and the east-west direction, respectively, and has orthogonal 8-character directivity. Further, the outputs of the respective antenna elements constituting the respective Adcock antennas are combined to extract a non-directional output 1v. 2a, 2
b, 2c are receivers, and each antenna 1ns, 1ew, 1
It receives the output of v, amplifies and frequency converts it, and outputs it as an intermediate frequency signal. Reference numerals 3a, 3b, and 3c are 90-degree hybrid circuits, and I (in-phase component) Q (90
Output to the phase component) signal. 4ai, 4aq, 4bi,
Reference numerals 4bq, 4ci, and 4cq denote AD converters, which convert each of the I and Q signals into a digital value to convert Ins, Qns, I
Outputs ew, Qew, Iv, and Qv. Numeral 5 denotes a digital arithmetic processing unit which performs the operations of the above (Equation 1) and (Equation 2) to calculate the angles of arrival θ1 and θ2. Further, using the obtained arrival angles θ1 and θ2, calculations of (Equation 3) and (Equation 4) are performed to calculate Ir1, Ir2, or Qr1, Qr2. 6 is a numerical value of the angles of arrival θ1 and θ2 calculated by the display,
Or display in polar coordinates. Reference numeral 7 is a DA converter, which converts the digital values Ir1 and Ir2 or Qr1 and Qr2 to D.
A-converted and reproduced as an intermediate frequency signal. 8 is a demodulator,
The modulation component of the reproduced intermediate frequency signal is extracted.

Although the above description has been given of the embodiment in which the algebraic arithmetic is executed using the digital arithmetic processor, each I.D. Q
Prepare a data table with data as addresses, and
With the digital data obtained by the D converter, the calculation result stored at each address can be directly read.

As described above, according to the direction finder of the present invention, it is possible to automatically and simultaneously measure the arrival directions of two waves that interfere in the same reception band. In addition, it is possible to separate and extract the communication contents that are interfering and interfere with each other and become meaningless, and obtain them as clear signals at the same time and in association with the direction of arrival. It enables efficient operation of business such as.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a configuration of a direction finder according to an embodiment of the present invention.

[Explanation of symbols]

 1 Antenna system 2 Receiver 3 90 degree hybrid circuit 4 AD converter 5 Digital arithmetic processor 6 Display 7 DA converter 8 Demodulator

Claims (3)

[Claims] 1. An orthogonally arranged two-system antenna having directional characteristics, an omnidirectional antenna, three reception / amplifiers each receiving an output of each of these antennas, and each reception thereof. The I.D. of each intermediate frequency signal that is the output of the amplifier. Three 90-degree hybrid circuits that generate Q signals, six AD converters that convert the output of each of these 90-degree hybrid circuits into digital signals, and data processing that performs algebraic arithmetic processing on the outputs of these AD converters. 2), the digital data output from each AD converter is subjected to algebraic arithmetic processing, and interference is generated from the difference between the average value and the arrival angle of the arrival angles of the two waves that interfere in the same reception frequency band. A direction finder characterized by individually calculating the arrival direction of a radio wave. 2. Each I.D. 2. The direction finder according to claim 1, wherein a data table having Q data as an address is prepared, and the operation result is directly read from the digital data obtained by each AD converter. 3. Two types of I.V. having the above directivity are provided. The sine value of one of the angles of arrival obtained by the above calculation on the Q data,
And the cosine value are crossed and multiplied, and the sum and difference are taken to eliminate the radio wave having the arrival angle used for processing, and the data processor that outputs the residual data and the output residual data DA converter that converts the to an analog value,
The direction finder according to claim 1 or 2, further comprising a demodulator configured by a detector for demodulating a modulated signal from an intermediate frequency signal obtained as an analog value.