JPH0611516Y2 - Direction finder - Google Patents

Description

[Detailed Description of the Device] “Industrial Application Field” This device switches the reception output of the azimuth measuring antenna in a time-divisional manner and captures it, and the level of the reception output captured in each switching section is the arrival of the radio wave. A signal corresponding to the azimuth is obtained, the signal is detected by the receiver and supplied to the azimuth indicator to indicate the azimuth of the incoming radio wave, and the output of the receiver is supplied to the sound receiver to detect the audible frequency of the incoming radio wave. The present invention relates to a direction finder that receives a modulated signal.

“Prior Art” FIG. 3 shows a conventional direction finder. The azimuth measuring antennas 11 having orthogonal 8-shaped directional characteristics, for example, the loop antennas 11a and 11b orthogonal to each other are connected to the switch unit 12, and each antenna output is time-divided by a switch signal from the switch signal generator 13. It is switched and captured. For example, as shown in FIG. 4A, the signal 14 _NS is taken in from the loop antenna 11a facing in the north-south direction, then the polarity of the output of the loop antenna 11a is inverted, and the signal 14 _NS
The signal 14 _EW is taken in as _SN , then the signal 14 _EW is taken in from the loop antenna 11b facing in the east-west direction, and then the polarity of the output of the loop antenna 11b is inverted and taken in as the signal 14 _WE . This is repeated thereafter. In this way, a signal having a level corresponding to the arrival direction of the received radio wave is obtained in each time-divisional acquisition section.

In this example, the adder 15 adds the received signal of the sense antenna 16 to the received signal thus time-divisionally captured. This addition output is as shown in FIG. 4B, for example. This added output is amplified and detected by the receiver 17, and a signal corresponding to the envelope is obtained, and this detected output is input to the direction instructing unit 18 to instruct the arrival direction of the received radio wave.

The detection output of the receiver 17 is also branched and supplied to the sound receiving unit 19,
The audio frequency modulated signal in the received radio wave is received by a speaker or a headphone.

By the time-divisional acquisition of the reception output of the azimuth measuring antenna 11, an output in which the phase of the detection output of the receiver 17 changes with respect to the antenna reception output time-divisional acquisition phase according to the radio wave arrival direction is obtained. That is, with respect to the time-divisional acquisition of the reception output of the antenna 11, a modulation output in which the phase of the envelope changes according to the direction of arrival of the radio wave is obtained, which enables azimuth measurement.

Conventionally, a signal in which the envelope changes according to the azimuth is obtained by rotating the loop antenna or the goniometer, and the angular position where the output is minimized is detected by the sound receiving unit 19 as a sound deadening point. It has also been performed to detect the arrival direction of a radio wave from the angular position of an antenna or a goniometer.

However, when the sound receiving unit 19 tries to receive the modulated signal that originally exists in the incoming radio wave, the output level of the receiver changes due to the envelope, and the sound output of the sound receiving unit 18 is also this envelope. And the modulated signal becomes difficult to hear.

[Means for Solving Problems] According to the present invention, a variable level adjuster is inserted in series between the receiver and the sound receiving unit, and the output level of the receiver is the level detector to detect the antenna reception output. The detection is performed in synchronization with the time-divisional acquisition, and the detection level is retained. Each of the held detection levels is supplied to the variable level adjuster as a control signal in synchronization with the time-divisional acquisition, so that the output level of the variable level adjuster becomes substantially constant. Therefore, the modulated signal sound can be heard at a substantially constant level from the sound receiving unit regardless of the envelope change due to the time-divisional acquisition of the antenna reception signal.

"Embodiment" FIG. 1 shows an embodiment of the present invention. The parts corresponding to those in FIG. 3 are designated by the same reference numerals. In this invention, a variable level adjuster 21 is inserted in series between the output side of the receiver 17 and the sound receiving section 19. In this example, the input side of the variable level adjuster 21 is connected to the output side of the receiver 17, and the output side of the variable level adjuster 21 is connected to the amplifier 22-resistor 23-switch 24.
-A case where the sound receiving unit 19 is connected through the buffer circuit 25.

The output level of the receiver 17 is detected in synchronism with the time-divisional acquisition of the antenna reception signal, and the detection level is held individually. In this example, the output side of the variable level adjuster 21 passes through the resistor 26-diode 27, and further through the switches 28 _N , 28 _S , 28 _E , and 28 _W separately, and capacitors 29 _N , 29 _S , 29 _E , and 29 _{W respectively.} Of the capacitors and the other ends of these capacitors are grounded.

As will be clearly shown below, these capacitors 29 _N , 2
9 _S , 29 _E and 29 _W respectively hold the output levels of the receiver 17 in synchronization with the time-divisional acquisition of the antenna reception output, and these are sent to the variable level adjuster 21 at the same time as the time-divisional acquisition. It is supplied as a control signal. That is, the capacitors 29 _N , 29 _S , 29 _E , and 29 _W are connected to the common amplifier 3 through the switches 31 _N , 31 _S , 31 _E , and 31 _W , respectively.
The output side of the amplifier 32 is connected to the control terminal 34 of the variable level adjuster 21 through the level setter 33.

In the variable level adjuster 21, for example, the output side of the receiver 17 is connected to the non-inverting input side of the operational amplifier 36 through the resistor 35, the non-inverting input side is grounded through the FET 37, and the gate of the FET 37 is connected to the control terminal 34. , The resistance value between the source and drain of the FET 37 is controlled according to the control signal of the control terminal 34, and the gain of the variable level adjuster 21 is controlled.

Switch 28 _N , 28 _S , 28 _E , 28 _W , capacitor 29
_N , 29 _S , 29 _E , and 29 _{W form} a level detector.

The switch signals for obtaining the signals 14 _NS , 14 _SN , 14 _EW , and 14 _WE shown in FIG. 4 are A, B, C, and FIG.
In the case of D, in this example, the switch signals shown in E, F, G, and H of FIG. 28 _N 31 _N , 28 _S
31 _S , 28 _E 31 _E , 28 _W 31 _W are controlled. Therefore, for the signals 14 _NS , 14 _SN , 14 _EW , and 14 _WE , the adder 1
The output of 5 is 41 _NS , 41 _SN , 41 as shown in FIG. 4B.
_EW , 41 _WE , these signals 41 _NS , 41 _SN , 4
The DC voltage corresponding to each amplitude (level) of 1 _EW and 41 _WE is detected and held in the capacitors 29 _N , 29 _S , 29 _E and 29 _W , respectively. Switches 31 _N , 3 in these detection levels
The AC component due to the switch control of 1 _S , 31 _E , 31 _W is removed by the capacitor 38 in the amplifier 32, and the gain set by the level setter 33 is given to the control terminal 34. For example, when the signal 41 _NS has a large level, the resistance between the source and drain of the FET 37 decreases, and the output level of the variable level adjuster 21 decreases. By such an operation, the output level of the variable level adjuster 21 becomes almost constant.

The detection output which is thus made substantially constant is supplied to the sound receiving section 19 through the amplifier 22 and the buffer circuit 25, and the modulated signal sound can be heard at a substantially constant level. The frequency of this modulated signal is higher than the repetition frequency of the switch signal.

In this example, in order to remove the noise generated immediately after the leading edge of the antenna switch signal, the silent pulse shown in FIG. 2I is applied from the switch signal generator 13 to the switch 24, and the switch 24 is turned off by this silent pulse. . In this switch-off state, the connection point between the switch 24 and the buffer circuit 25 is grounded through the capacitor 39 so that the output immediately before that is supplied to the sound receiving unit 19. Switch 2 again
As for the signals for controlling 8 _N , 31 _N, etc., if the leading edge portion of the antenna switch signal is removed as described above, the corresponding level can be detected without being affected by the disturbance at the time of switching the antenna reception signal.

[Advantage of Device] As described above, according to this device, the detection output of the receiver 17 becomes a substantially constant level by passing through the variable level adjuster 21, and the sound receiving unit 19 is affected by the switching of the switch unit 12. Without receiving the modulated signal, the modulated signal in the received signal can be received.

Although the loop antenna is used in the above description, the present invention can be applied to the case where a plurality of vertical antennas are switched and received to obtain an envelope having a phase according to the direction of arrival, and accordingly, the number of switching switches is four. Not limited to Switch 2 again
4, the capacitor 39 may be omitted.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a direction finder according to the present invention, FIG. 2 is a waveform diagram for explaining the operation thereof, FIG. 3 is a block diagram showing a conventional direction finder, and FIG. FIG. 6 is a waveform diagram for explanation.

Claims (1)

[Scope of utility model registration request] Claims: 1. Two antennas having 8-shaped directional characteristics are provided orthogonally to each other, and the reception output of one antenna is switched by capturing the polarity, and then the reception output of the other antenna is captured by switching the polarity. Repeatedly, the received output of the received radio wave is captured in a time division manner, and the received signal captured in a time division manner is detected by the receiver,
A direction finder that supplies the detected output to the azimuth indicating section to indicate the direction of the incoming radio wave, and also supplies the detected output to a sound receiving section such as a speaker or headphones to receive the modulated signal in the incoming radio wave. In the above, the variable level adjuster is inserted in series between the receiver and the sound receiving unit, and is controlled by a control signal such that the output level of the variable level adjuster decreases as the control signal increases. And a level detector that detects the detection output for each switching section in synchronization with the time-divisional acquisition of the reception output and holds the detection output, and each of the level detectors that are held by the level detector. A direction finder comprising: control means for supplying a detection output of a switching section to the variable level adjuster as the control signal in synchronization with the time divisional acquisition.