JPH0323585Y2 - - Google Patents

Description

[Detailed description of the invention] "Industrial application field" This invention detects the eastward component, westward component, and southward component of the direction of arrival of the received radio waves from the received output obtained by switching multiple antenna elements. The present invention relates to a direction finder which obtains a north direction component and supplies these to four input sides of a direction indicator to indicate the arrival direction of radio waves.

``Prior art'' A direction finder that obtains a signal representing a direction component by extracting a phase change at a switching point in a signal obtained by switching multiple antenna elements works well even when the frequency of incoming radio waves is not high. It has the advantage that the antenna element spacing is not affected by the wavelength of incoming radio waves.

However, conventional direction finders of this type had the disadvantage that if the incoming radio waves were weak, the instructions would be erratic and difficult to read. The purpose of this invention is to eliminate this drawback and provide a direction finder that provides direction guidance only when the incoming radio waves are at a predetermined level or higher, thereby providing stable direction guidance.

"Means for Solving the Problem" According to this invention, the eastward component, westward component, southward component, and northward component of the direction of arrival of received radio waves are respectively supplied to the four input sides of the direction indicator. A gate circuit is inserted in series, and the northward component, the eastward component, and the southward component,
The above westward component is sequentially extracted by a synthesis circuit,
A sine wave output is taken out from the synthesis circuit by a wave generator, the output of the wave generator is compared with a reference value by a comparator, and the output of the comparator when the wave generator output is greater than the reference value is used to control the four gate circuits mentioned above. Each is considered open.

"Operation" According to this configuration, only when the level of the incoming radio wave is equal to or higher than a predetermined value, the gate circuit is opened and a signal is supplied to the direction indicator, so that a stable instruction without fluctuation can be obtained.

"Embodiment" First, the principle of a direction finder used in an embodiment of this invention will be explained.

For example, as shown in FIG. 1, antennas 11N and 11S are arranged on a straight line 10, and antennas 11E and 11W are arranged on a straight line 12 perpendicular to the straight line 10. For example, when a radio wave 13 arrives at such an antenna at a straight line 10 and an angle θ, the signals obtained from the antenna 11N and the antenna 11S are alternately switched and extracted, and the phase difference between these outputs is detected. Then, as the angle θ becomes smaller, these phase differences become larger, and the polarity of the detection output is reversed each time the switching of the antenna is reversed. When θ becomes 90°, the phase difference between the signals of antennas 11N and 11S becomes zero. Conversely, for the antennas 11E and 11W, the smaller θ, the smaller the phase difference, and the larger θ, the larger the phase difference, and the polarity of the phase detection output is also reversed depending on the switching direction.

Therefore, the detection output of these phase differences is transmitted to the antenna 1.
For example, coils 14N and 14 shown in FIG.
When the corresponding detection output currents are supplied to S, 14E, and 14W, a permanent magnet 15 is rotatably provided at the center of the composite magnetic field generated by these coils, and a pointer 16 is provided on its axis, the incoming radio wave The pointer 16 can be directed in a direction corresponding to the direction of arrival of the pointer 13.

FIG. 3 shows an embodiment of this invention. The output of a stable oscillator 17 such as a crystal oscillator is frequency-divided to generate a switching control signal from a receiving output switching signal generator 18, and the receiving output switching signal generator 18
is supplied to the antenna switching signal generator 19 to alternately generate positive and negative switching signals 22N and 22S from the terminal 21 as shown in FIG. 4A, and then,
Similarly, a positive switching signal 22E and a negative switching signal 22W are alternately generated from the terminal 23, and the switching signal 22
It is repeated to alternately generate N and 22S for a certain period of time and to alternately generate switching signals 22E and 22W for a certain period of time. These switching signals are applied to the antenna switching section 24, and when the antenna switching signal 22N is generated, the antenna 11N is connected to the phase detection receiving circuit 25, and thereafter the switching signals 22S, 2
When 2E and 22W are generated, the antennas 11S, 11E and 11W are connected to the phase detection receiving circuit 25, respectively.

In the phase detection receiving circuit 25, the input signal is amplified by an amplifier 26, further phase detected by a phase detection circuit 27, and a component corresponding to the switching frequency of the antenna is extracted by a wave generator 28 from the detection output. That is, by switching the antennas 11N and 11S, for example, as shown in FIG. 4B, the reception signals 29N and 29S of those antennas are received alternately, and further by switching the antennas 11E and 11W, these reception signals are received. Signals 29E and 29W are received alternately. Therefore, in the phase detection circuit 27, as shown in FIG. 4C, a pulse 30N corresponding to the phase difference is generated at the boundary between the signals 29N and 29S, for example in the negative direction in the figure, and at the boundary between the signals 29S and 29N, a pulse 30N is generated in the negative direction in the figure. Phase detection pulse 30 with the same magnitude and opposite direction
S occurs. Similarly, the detection pulse 30E corresponding to the phase difference between the signals 29E and 29W, and the signal 2
Detection pulse 3 corresponding to the phase difference between 9W and 29E
0W is generated as shown in FIG. 4C.

The output of the receiving circuit 25 is switched by a switching circuit 31 to provide each detection output 30N, 30S, 30E,
For 30W, terminals 32N, 32S, 32E,
The power is switched to 32W and supplied. The polarities are then all supplied as the same polarity, for example positive polarity. This switching circuit 31 is performed in synchronization with switching of the antenna by a switching signal from the reception output switching signal generator 18, and is constituted by a so-called analog demultiplexer. These terminals 32N, 32S, 32
The detected outputs separated into E and 32W are integrated by integrating circuits 33N, 33S, 33E and 33W, respectively, and converted into DC. Integrating circuit 33
Integrating capacitors of N, 33S are commonly used,
Signals at each terminal 32N, 32S are integrated with opposite polarity. Similarly, the integration circuits 33E and 33W have a common integration capacitor and perform integration with opposite polarities.

These integration circuits 33N, 33S, 33E, 33
For example, as shown in Fig. 4 D, E, F, and G, the output of W is an output whose polarity differs in proportion to cosθ in Fig. 1, that is, a northward component and a southward component of the radio wave arrival direction, and sinθ. Outputs with proportionally different polarities, that is, eastward and westward components of the radio wave arrival direction, are obtained. The outputs of these integrating circuits are sent to drive circuits 36N, 36 for direction indicator 35 through gate circuits 34N, 34S, 34E, 34W, respectively.
The indicator 35 is, for example, similar to that described with reference to FIG. 2, and the outputs of these drive circuits are supplied to the corresponding coils 14N, 14S, 14E, 14W.

In this invention, the direction is given only when the incoming radio waves are at a predetermined level or higher. Therefore, the outputs of the integrating circuits 33N, 33S, 33E, and 33W are supplied to the combining circuit 37, and the combining circuit 37 sequentially takes out the outputs of the integrating circuit 33N, the integrating circuit 33E, and the integrating circuits 33S, 33W in this order. The level of the output changes sinusoidally, and the sine wave is the frequency component, that is, the integration circuit 33
The outputs of N, 33E, 33S, and 33W are taken out by a wave generator 38 that passes through a repetition frequency, and are compared with a reference value at a terminal 41 by a comparator 39.
If it is larger than the reference value, the gate circuit 3
Open 4N, 34S, 34E, and 34W.

The antenna switching section 24 in FIG. 3 is configured as shown in FIG. 5, for example. That is, when the switching signal 22N is generated from the terminal 21, the high frequency blocking coil 42
The diode 43 is made conductive through the high frequency blocking coil 45, and current flows to the ground terminal 46 through the high frequency blocking coil 45. Therefore, the terminal 47N connected to the antenna 11N is connected to the receiving circuit 25 through the capacitors 48 and 49, through the conductive diode 43, and then through the capacitor 51. Further, a diode 53 is conducted from the terminal 21 through a high frequency blocking coil 52, and a terminal 47E connected to the antenna 11E is connected through a capacitor 54.
Furthermore, it is connected to a termination resistor 55 through a diode 53. Similarly, the diode 57 is made conductive through the high frequency blocking coil 56 by the switching signal at the terminal 21, and therefore the terminal 4 connected to the antenna 11W is turned on.
7W is passed through the capacitor 58 and further through the diode 5.
7 to the termination resistor 59. In this way, the antennas 11E and 11W are connected to the terminating resistor 5.
5, 59, these are the antenna 11N.
This is done so as not to adversely affect the reception operation of the receiver.

When the switching signal 22S is applied to the terminal 21, the diode 62 is made conductive from the ground terminal 46 through the high frequency blocking coil 61.
A current flows through the terminal 21 through the terminal 21. Therefore, the terminal 47S connected to the antenna 11S is connected to the capacitor 6.
3 and 64 in turn, and further through the conductive diode 62, and from there through the capacitor 51 to the receiving circuit 25. Also, at that time, terminal 21
The negative switching signal 22S causes the diodes 65 and 66 to conduct through the coils 52 and 56, respectively, and therefore the terminals 47E and 47W are connected to the terminating resistors 55 and 66 through the diodes 65 and 66, respectively.
59, so that the antennas 11E and 11W do not adversely affect the signal from the antenna 11S when receiving the signal.

Similarly, when the signal 22E is applied to the terminal 23, the diode 68 is made conductive through the coil 67, and the terminal 47E is connected to the receiving circuit 25 through the capacitors 54, 69, the diode 68, and the capacitor 71. At this time, the switching signal 22E of the terminal 23 passes through the coils 72 and 73, respectively, the diodes 74 and 75 are made conductive, and the antenna terminal 47
N and 47S are connected to termination resistors 76 and 77 through diodes 74 and 75, respectively.

Similarly, when the switching signal 22W is applied to the terminal 23, the diode 78 becomes conductive, and the terminal 47W is connected to the receiving circuit 25 through the diode 74, and the antenna terminals 47N and 47S are connected to the terminating resistor through diodes 81 and 82, respectively. 76,
77.

In this way, in Figure 5, when one antenna is connected to the receiving circuit, the other antennas are connected to the terminating resistor so that these antennas do not have a negative effect on the antennas connected to the receiving circuit. However, this configuration is not necessarily required, and the antenna that is not connected to the receiving circuit may simply be left open.

As mentioned above, the direction finder according to this invention uses four antennas and can detect directions by switching between them.
Moreover, each antenna receives radio waves one by one, and does not utilize figure-eight characteristics like conventional adkotoku antennas, but instead receives radio waves as an omnidirectional antenna. There is no fear that the figure-of-eight characteristic will be disturbed by the spacing, making it impossible to measure, and it is possible to measure up to high frequencies.

In addition, in the explanation of FIG.
The outputs of the integrator circuits 33E and 33S differ in polarity and have the same magnitude.
The outputs of W are also the same in magnitude and only have different polarities. Therefore, instead of obtaining each signal separately, it is possible to obtain the output of each one of the integrating circuits and produce signals of the same magnitude and opposite polarity from the other. In addition, as shown in FIG. 6, for example, one element of the antenna is common to the two sets of antennas, and the common antenna 11 is arranged at the intersection of the straight lines 10 and 12, and the antenna 11N and the antenna 11 are switched. Then, the antenna 11W and the antenna 11 may be switched.

"Effects of the invention" As described above, according to this invention, the gate circuit is opened only when the level of the incoming radio wave is higher than a predetermined value, and Since the north direction component is supplied to the direction indicator, the indication is stable and easy to see without wavering. It does not directly detect the level of the received radio wave, but extracts a sine wave from the output of the synthesis circuit 37, so when non-directional noise arrives, for example, the integration circuits 33N, 33S, 33
The respective outputs of E and 33W are at approximately the same level, and a sine wave is not obtained from the output of the synthesis circuit 37 or is extremely small, so there is no possibility that the direction indicator 35 will operate due to such noise.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of antenna arrangement in a direction finder according to this invention, FIG. 2 is a diagram showing an example of an indicator, FIG. 3 is a block diagram showing an example of a direction finder according to this invention, and FIG. 4 is a time chart for explaining this, FIG. 5 is a connection diagram showing a specific example of the antenna switching section 24 in FIG. 3, and FIG. 6 is a diagram showing another example of antenna arrangement. 11N, 11S, 11E, 11W...Antenna, 18, 19...Switching signal generator, 24...Switching section, 25...Phase detection receiving circuit, 31...Switching circuit, 33N, 33S, 33E, 33W... Integral circuit, 34N, 34S, 34E, 34W... Gate circuit, 35... Indicator, 36N, 36S, 36
E, 36W...Drive circuit, 37...Composition circuit, 3
8... Wave unit, 39... Comparator, 41... Terminal to which a reference value is given.

Claims (1)

[Claim for Utility Model Registration] A DC signal corresponding to the eastward component of the arrival direction of received radio waves, a DC signal corresponding to the westward component, and a southward component from the reception output obtained by switching a plurality of antenna elements. In a direction finder which obtains a DC signal corresponding to a north direction component and a DC signal corresponding to a north direction component and supplies these to four input sides of a direction indicator to indicate the direction of arrival of radio waves, four gate circuits each inserted in series on the four input sides; a DC signal corresponding to the northward component; a DC signal corresponding to the eastward component; and a DC signal corresponding to the southward component; a synthesis circuit that repeatedly extracts the westward component and the corresponding DC signal; a wave generator that extracts the sine wave output of the frequency of the repetition from the output of the synthesis circuit; A direction finder comprising: a comparator that opens the four gate circuits according to a comparison output when the output of the wave detector is larger than a reference value.