JPS6047971A - Azimuth correcting type azimuth detector - Google Patents

Abstract

PURPOSE:To make it possible to indicate an accurate azimuth angle to an azimuth indicating part by performing accurate error correction always automatically, by providing a memory apparatus for storing the amplitude of a principle spectrum component and the numerical value group of a phase angle as a data base and a corrected data processing part for outputting said data base to the azimuth indicating part. CONSTITUTION:A corrected data processing part 5 and a memory apparatus 6 are provided other than an antenna 1, a receiver 2, an azimuth detecting part 3 and an azimuth indicating part 4. The corrected data processing part 5 receives frequency information (f) and azimuth information theta during measurement from the receiver 2 and the azimuth detecting part 3 and performs the correction processing of an azimuth angle upon the reference of an error correcting value group stored in the memory apparatus 6 to output the corrected azimuth information theta' to the azimuth indicating part 4. The frequency information (f) is outputted as a digital numerical value signal corresponding to frequency during measurement while the azimuth information theta is outputted as a digital numerical value signal corresponding to a measured azimuth angle during measurement. When the azimuth angle signal of the azimuth detecting part 3 is an analogue value, the analogue signal is subjected to digital conversion before outputting.

Description

[Detailed description of the invention] The present invention relates to improvements in direction finder error correction.

No matter how accurate the device itself is, direction finders can cause errors in the measured azimuth due to radio wave disturbance caused by surrounding objects due to installation conditions and other factors. For example, when installed on a ship or the like, since the ship body is a rectangular conductor, errors such as biquadrant, quadrant, and sextant usually occur due to the influence of the rectangular conductor. This error is frequency dependent, but the measurable frequency band of direction finders is, for example, 200 KH2 to 1
0 MHz, so the error must be corrected by taking the frequency into consideration. Conventional error correction methods include, for example, in the case of a quadrant error, multiple Prepare a resistance element of , and divide the element into a certain section (
For example, 200 KH2 to H2. I MH2~5
MHz.

Previously, a hardware method was used in which the correction was performed by switching for every 5 MH, l, ~10 MH2), or a correction curve was created for each measurement frequency band section and the azimuth angle was corrected from now on. It was done through a soft method. The former has the advantage that the measured azimuth angle can be immediately read as a corrected value with sufficiently high accuracy by dividing the frequency band into even smaller divisions (for example, the division from 200 KH2 to 11 kHz is divided into 200 KH2 pitches). However, such fine division is almost impossible due to the equipment configuration. In the latter method, errors are corrected by referring to a correction curve after reading the measured azimuth angle using a direction finder, but if you try to improve accuracy, the number of sets of correction curves is large, making it an extremely troublesome task.

In the field where direction finders are used, there is usually no room for such personnel.

An object of the present invention is to provide a direction finder which eliminates the above-mentioned drawbacks, automatically performs accurate error correction at any frequency in the measurement frequency band, and indicates the correct azimuth angle to the azimuth indicator. Our goal is to provide the following.

The structure of the present invention is illustrated by an embodiment shown in FIG. Direction finders generally have antennas 1. Receiver 2. Direction detection unit 3. The present invention further includes a correction data processing section 5 and a storage device 6. The correction data processing unit 5 includes the receiver 2. Receiving the frequency information j being measured and the azimuth information θ from the azimuth detection unit 3, the azimuth is corrected by referring to the error correction value group stored in the storage device B, and the corrected azimuth is determined. The information θ' is output to the direction indicating section 4. The frequency information f is output via the output means of the receiver 2 as a digital numerical signal corresponding to the frequency under measurement. Further, the azimuth information θ is outputted via the output means of the azimuth detection section 3 as a digital numerical signal corresponding to the measured azimuth angle during measurement. If the azimuth signal of the azimuth detection unit B is an analog value, it is output after being converted into a digital value. As described above, the technology for outputting frequency information and direction information as digital numerical signals is already known for direction finders, and it is sufficient to use that technology.

The storage device 6 stores the measurable frequency range of the direction finder into a plurality of divided frequency bands, for example 200 KH2 to 2.
100 KH2 width for MH2, 2 MH2 to 10 M
H2 is divided into 200 KH2 widths, and for each divided frequency band, the numerical values of the amplitude and phase angle of the main spectrum components of the error correction value curve against the azimuth measurement angle are collected.
Store it in advance as a base.

Since the error of a direction finder is a periodic function of the azimuth angle θ, the experimentally determined curve is decomposed into a Fourier series to the required precision, for example, E(θ) = A[l + AI Sin (θ→−α+
) +A2 Sin (2θ + α2) + A35in (
6θ+α3). Here, AQ-A3 is the amplitude, α1
~α3 is a phase component, and its (direction) differs depending on the frequency.

The first term in the above equation is a fixed error that is not related to direction, the second term is called a biquadrant error, the third term is a quadrant error, and the fourth term is a sextile error. It is enough to consider the ingredients. When correcting an error, an error is included in the measured azimuth, so an error correction curve for the measured azimuth is created from the above equation. In this case as well, it is displayed in the same way as in the above equation, but the amplitude and 9-phase acid content are different. The corresponding constant, B
q −B5 +β1 to β3, and these values are stored in the storage device B for each frequency band.

Storage device O is usually a read-only memo! I (ROM)
is used, but in some cases it can be changed, so
Random access memory (RAM) may also be used.

The correction data processing section 5 includes a central processing unit (CPU), R
The data processing is shown in the flowchart of FIG.

Step P1 is a step of searching to which frequency band the frequency information f belongs. The number of the frequency band division in the storage device 6 is indicated by l in the range from the lowest frequency belonging to the frequency band to the next frequency band fl+j, and from the lowest frequency band to the next frequency band fl+j, and from the lowest frequency band to the highest frequency Increase the number to the band. Therefore, after finding the frequency band I□ to which f belongs in the procedure shown in the subroutine (search for f), in the next step P2, the spectrum component B of the error correction value curve of the frequency band f□ is determined. -B3. β, ~β, are read from the L storage device 6. The next step P3 is to calculate the error correction value for each component B. .

B, 5in (θ+β, ), B2 Sin (2θ
+β2) I B5 Sin (sθ+β3) can be calculated and summed to obtain E(θ).

In step P4, E(θ) is added to the measured azimuth angle θ and corrected azimuth information θ' is output. However, since it is an angle display, 08
Correct the values so that they fall within ~560°.

By the way, the direction information θ is continuously
Therefore, if a new θ is input at step P5, the process goes to step P5 and thereafter, and it is examined whether the frequency information f belongs to the same frequency band. If the frequency band is the same, error correction is performed for the new azimuth. If they are out of the same frequency band, go back to researching the first f.

Although error correction (direction) depends on frequency, in the present invention, the measurement frequency range is divided into frequency band groups, and the error correction value is constant within each frequency band.

This is because the experimentally determined error correction value will not cause a large error even if the above assumption is made if the frequency band is appropriately determined.

Corrected orientation information θ is sent from the correction data processing unit 5 to the orientation detection unit 3.
When ' is sent, it is displayed numerically on a digital display or as a prober type image on a cathode ray tube.

As explained above, since the direction finder according to the present invention performs automatic error correction, there is no need for any troublesome correction operations in the field, which were conventional. This automatic correction is still based on pneumatic means and does not add anything to the mechanical structure of the direction finder.

Further, in the present invention, since only the amplitude and phase of the main spectrum of the error correction curve are stored in the storage section as data pace, there is an advantage that the memory capacity does not need to be so large.

Ru. Also, depending on the frequency band, please refer to 1. It also becomes possible to reduce the number of spectral components to be processed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a flow chart showing the operation of the correction data processing section. DESCRIPTION OF SYMBOLS 1... Antenna, 2... Receiver, 3... Azimuth detection section, 4... Azimuth instruction section, 5... Correction data processing section,
6...Storage device, f...Frequency information, 0.0'...
・Direction information. Patent applicant: Koden Seisakusho Co., Ltd. Patent attorney: Akihiko Sato

Claims (1)

[Claims] An antenna, a receiver, a direction detecting section, a direction indicating section, etc.
In a direction finder that outputs frequency information from the receiver and direction information from the direction detection section as digital signals, each frequency band in the measurement frequency range is
a storage device for storing, as a data base, a numerical group of amplitudes and phase angles of main spectral components obtained by Fourier series decomposition of angles of error correction straight curves for azimuth measurement angles; Select the frequency band to which the frequency belongs, read the numerical value of the main spectrum component of the error correction value curve of the frequency band from the storage device, and calculate the azimuth error correction value corresponding to the azimuth information signal from the numerical value. , and a correction data processing section that adds up the azimuth measurement angle and outputs it to the azimuth indicating section.