JPS5926910B2 - Interference wave direction detection device for direction finder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The directivity is determined by mechanically rotating the directional antenna itself or a goniometer to which its output is applied, or by purely electrical methods such as balanced modulation of the antenna output with a low frequency signal. The direction of arrival of the radio waves can be directly indicated by substantially rotating the antenna, further combining and detecting the outputs of the omnidirectional antenna, and determining the phase of the detected output with respect to the rotation period.

In such a direction finder, when a radio wave stronger than the radio wave whose direction of arrival is to be detected is simultaneously received, conventional devices only indicate the direction of arrival of the strong radio wave.
It was not possible to determine the direction of arrival of weak interference waves.

Therefore, the present invention provides a device that can determine the arrival direction of weak interference waves in the above-mentioned cases.

FIG. 1 shows an embodiment of the present invention, in which directional loop antennas 1 and 2 are arranged so that their directivities are orthogonal,
The outputs are added to balanced modulators 3 and 4.

In addition, from the low frequency oscillator 5, two waves having a phase difference of 90 degrees are generated.
the outputs of the modulators 3 and 4, respectively.
balanced modulating the output of the antenna by adding
The output of the omnidirectional antenna 6 is added to a combiner 8 along with a signal whose phase is shifted by 90 degrees by a phase shifter 7.

The output of the synthesizer 8 is applied to a receiver 9 where amplification, frequency conversion, etc. are performed, and the output is applied to a detector 10.

Therefore, in the same way as when the antenna 1.2 is directly rotated at the output period of the oscillator 5, a low frequency output having the output frequency of the oscillator and a phase corresponding to the arrival direction of the radio wave can be obtained from the detector 10. .

By applying this output to the band transducer 12 via the changeover switch 11, the low frequency output is extracted and added to the phase comparator 13.

Further, the low frequency output of the reference phase is taken out from the oscillator 5 and applied to the phase adjuster 14, and the output is applied to the phase comparator 13, and the phase adjuster 14 is controlled by the output of this phase comparator. Then, this adjustment amount is displayed on, for example, a digital display 15.

That is, if there is a phase difference between the output of the phase adjuster 14 and the output of the filter 12, the output of the comparator 13
Since the adjustment amount of 4 changes, the output phase of the regulator tracks the output phase of the Oki wave device 12, and therefore the display 1
5 indicates the output phase of the Oki transducer 12, and therefore the arrival direction of the radio wave.

In such a device, a low frequency filter 16 to which the output of the detector 10 is added, a tuned amplifier 17 to which the output is added, and a detector 18 to which the output of the amplifier is added are further provided, and the changeover switch 11 is The output of the detector is applied to the filter 12 through the filter.

In the above-mentioned apparatus, if there is a weak interference wave and only that interference wave is received, the receiving section 9 sends out a signal as shown in FIG. 2a.

If only strong radio waves are received, the signal shown in the figure is sent out.

However, when these two radio waves interfere, beat frequency components of the carrier waves a and b are generated, so that a signal as shown in FIG. 3C is sent out from the receiver 9.

When this signal is detected and the Oki transducer 12 extracts the same frequency component as the output of the oscillator 5, the phase thereof approximately corresponds to the arrival direction of the strong radio wave, so the direction of the radio wave is indicated.

Next, when detecting the arrival direction of weak interference waves, the switch 11 is changed to apply the output of the wave detector 18 to the wave detector 12.

In this case, when the output frequency component of the oscillator 5 is removed by the low frequency remover 16 and the amplifier 17 is adjusted so that its tuning frequency becomes the difference between the two carrier waves, other weak interference waves are removed. Even if it exists, its influence is removed.

Therefore, as shown in FIG. 2d, only the high frequency pulsating component in FIG. 2C is sent out from the amplifier 17.

Since this output is detected by the wave detector 18 and applied to the wave transducer 12, a component of the same frequency as the oscillator 5 as shown by the broken line in FIG. In addition to this, the phase of this signal is indicated on the display 15.

The beat frequency signal shown in FIG. 2 d is at the point p when the amplitudes shown in a and b of the same figure become minimum.

Since the amplitude becomes minimum at q, the phase of the signal e has the average value of the phase angles of the signals obtained by detecting the signals a + b, respectively.

That is, the display 15 indicates the direction exactly in the middle between the direction of arrival of strong radio waves and the direction of arrival of weak radio waves.

Therefore, based on this instruction value and the direction of the strong radio waves, it is possible to know the direction of arrival of the weak radio waves.

In this manner, the device of the present invention can detect the direction of arrival of weak radio waves when there is interference between strong radio waves and weak radio waves.

Furthermore, the direction of arrival of strong radio waves can be directly read.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is a diagram showing the configuration of an embodiment of the present invention.
FIG. 3 is a waveform diagram illustrating the operation of the device shown in the figure. In the figure, 1 and 2 are directional antennas, 3 and 4 are balanced modulators, 5 is a low frequency oscillator, 6 is an omnidirectional antenna, 1 is a 90 degree phase shifter, 8 is a mixer, and 9 is a receiving section. , 10 is a detector, 11 is a changeover switch, 12 is an Oki waver, 13 is a phase comparator, 14 is a phase adjuster, 15 is a display, 16 is a low frequency removal filter, 17 is a tuning amplifier, 18 is a detection It is a vessel.

Claims (1)

[Claims] 1 In a direction finder that determines the direction of arrival of radio waves by detecting the phase with respect to the rotation period of the output obtained by combining the output of an omnidirectional antenna with the balanced modulated output of an antenna whose directivity is mechanically or electrically rotated. A device for detecting the direction of interference waves, comprising: means for amplifying and detecting the beat frequency signals when there are interference waves; and means for detecting the phase of the detected output with respect to the rotation period.