JPS5813867B2 - direction finding device - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a direction finding device, and in particular, it is designed to correct a pointing error that occurs when the passband width and time constant of a detection circuit are changed depending on the format of received radio waves. It relates to a direction finding device.

FIG. 1 is a block diagram showing a general direction finding device.

In FIG. 1, an incoming radio wave induced by an orthogonal loop antenna 1 passes through a goniometer 2, is applied to a receiving section 3, is amplified and detected, and is then applied to a modulator 4.

The modulator 4 modulates the modulated wave of about 30 KHz from the oscillator 5 using the detection output of the receiver 3 and applies it to the resolver 6 .

The rotating shaft of the resolver 6 is connected to the rotating shaft of the goniometer 2, and is rotated by an electric motor 7.

Therefore, the rotation angle of the electric motor 7 and the arrival direction of the received signal have a maximum point and a minimum point in a fixed relationship.

In this way, the signal that has been amplified and detected by the receiver 3, modulated by the modulator 4, and passed through the resolver 6 has a certain relationship with the rotation angle of the electric motor 7, and is transmitted to the deflection coil 9 of the display cathode ray tube 8 ( (shown in FIG. 3).

Therefore, the deflection direction of the display cathode ray tube 8 is driven in a constant relationship with the rotation angle of the electric motor 7, and the display cathode ray tube 8 displays a figure as shown in FIG.

FIG. 2 shows a display graphic of the display cathode ray tube 8, and in FIG. 2, the direction pointed by the graphic has a fixed relationship with the arrival direction of radio waves.

Therefore, the arrival direction of radio waves can be detected from the display graphic shown in FIG.

However, in the general direction finding device shown in FIG. It is necessary to change the time constant of the detection circuit or change the time constant of the detection circuit.

Therefore, a difference occurs in the signal delay time from when a radio wave is received by the orthogonal loop antenna 1 to when a detection output is generated at the receiving section 3.

As a result, the directions indicated by the display figures on the display cathode ray tube 8 are no longer the same direction, resulting in an azimuth error.

In other words, for signals with a carrier wave such as A3 radio waves, the level of the carrier wave is stable and does not change, so if the signal is received by the receiving section 3 with a narrow passband width, stable reception with high sensitivity can be achieved. .

On the other hand, when receiving radio waves such as SSB, the received signal does not have a carrier wave but only sideband waves, so the receiver has a passband width that is large enough to pass the necessary sideband waves, and the detection circuit The time constant of the smoothing circuit becomes commensurate with that.

Therefore, it is necessary to change the passband width of the receiving section 3 and the time constant of the detection circuit depending on the format of the received radio wave, and as a result, an azimuth error appears in the display figure of the display cathode ray tube 8.

According to experiments, the azimuth error is about 10 degrees when the received radio waves are A3 radio waves and when they are SSB radio waves.

This invention was made to eliminate these conventional drawbacks, and when the format of received radio waves changes,
A direction finding device is provided in which the display of the display cathode ray tube 8 is corrected by passing a current through an angle correction coil provided on the display cathode ray tube 8.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a side view showing an embodiment of the display cathode ray tube 8 used in the direction finding device according to the present invention.

In FIG. 3, the deflection coil 9 is to which the output of the resolver 6 shown in FIG. 1 is applied.

The angle correction coil 10 is wound at an appropriate position from near the deflection coil of the cathode ray tube 8 to near the screen, and generates magnetic flux parallel to the axis of the cathode ray tube 8.
1 to a DC power source 12.

The variable resistor 11 determines the azimuth error that occurs depending on the format of the received radio waves, and causes a current proportional to the azimuth correction curve created in advance based on this azimuth error to flow through the angle correction coil 10.

It should be noted that each component circuit other than the cathode ray tube 8 is the same as the general direction finding device shown in FIG.

Now, electrons emitted from an electron gun (not shown) of the cathode ray tube 8 are deflected by a deflection coil 9 in proportion to the output of the resolver 6 shown in FIG.

In the angle correction coil 10, the deflected electrons are
corrected and deflected by a magnetic flux density proportional to the orientation correction curve,
The corrected normal display figure is displayed on the display cathode ray tube 8.

As described above, according to the present invention, the angle correction coil is wound around the display cathode ray tube, and the angle correction current is passed through the angle correction coil depending on the format of the received radio waves. Even if the format of the radio wave changes, no azimuth error will appear in the displayed figures of the display cathode ray tube, allowing accurate display.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a general direction finding device. FIG. 2 shows a display figure of a display cathode ray tube. FIG. 3 is a side view showing an embodiment of a display cathode ray tube used in the direction finding device according to the present invention. In the figure, 1 is an orthogonal loop antenna, 2 is a goniometer, 3 is a receiver, 4 is a modulator, 5 is an oscillator, 6 is a resolver, 8 is a display cathode ray tube, 9 is a deflection coil, and 10 is an angle correction coil. be.

Claims (1)

[Claims] 1. A goniometer to which a signal induced in the antenna is applied, a receiving part that amplifies and detects the output of the goniometer, a modulator that modulates a modulated wave from an oscillator by the output of the receiving part, and a goniometer to which the output of the modulator is applied. a resolver having a rotating shaft connected to the rotating shaft of the goniometer; a display cathode ray tube in which the output of the resolver is applied to a deflection coil; and a magnetic flux wound around the cathode ray tube and substantially parallel to the axis of the cathode ray tube. What is claimed is: 1. A direction finding device comprising: an angle correction coil that generates an angle correction coil, and an angle correction current that is caused to flow through the angle correction coil depending on the format of received radio waves.