JPH07229957A - Wireless direction monitor - Google Patents

Abstract

PURPOSE:To achieve correction and control of variations in phase and amplitude between receiving system channels attributed to a deviation from an actually received signal by providing a calibration signal frequency modulator to be controlled with a signal processor to input a modulation signal outputted from the modulator to a calibration signal generator. CONSTITUTION:A modulation signal is inputted into a calibration signal generator 11 from a calibration signal frequency modulator 13 and a calibration signal is modulated in frequency according to a band width of an intermediate frequency band filter centering on the frequency the same as that of a received signal. A calibration signal outputted from the generator 11 is inputted into a calibration signal distributor 12 and distributed to signals in equal phase and equal amplitude to be inputted into calibration signal switches 3a and 3b respectively later. The calibration signals are inputted into receivers 5a and 5b. The calibration signals converted into an intermediate frequency and outputted are distributed separately to be inputted into a signal processor 8 via a phase detection circuit 6 and an amplitude detection circuit 7 to obtain a correction data for phase deviation and amplitude deviation within the band width of the intermediate frequency band filter between two receiving system channels.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless direction finder for detecting the arrival direction of radio waves coming from an arbitrary direction.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram of a conventional radio direction finder, and FIG. 2 is a detailed block diagram of a receiver 5 in FIG. In FIG. 5, 1 is a plurality of antenna elements, 2 is connected to these antenna elements 1, and an antenna switch 3a, 3b for selecting a predetermined antenna element is connected to this antenna switch 2, The first and second calibration signal switches 4a and 4b for switching between the calibration signal and the reception signal are connected to the first and second calibration signal switches 3a and 3b, respectively. A second RF coaxial cable,
5a and 5b are first and second receivers respectively connected to these first and second RF coaxial cables,
Reference numeral 6 is a phase detection circuit for inputting the outputs of the first and second receivers 5a and 5b together to detect the phase relationship between the two, and 7 is also the first and second receivers 5a and 5a. 5
An amplitude detection circuit for inputting the outputs of b together and for detecting the amplitude relationship between the two, a signal processor 8 for processing the outputs of the phase detector 6 and the amplitude detector 7, and for calculating azimuth information, Reference numeral 9 is a local signal generator for outputting a local signal for frequency conversion to the first and second receivers 5a, 5b, and 10 is for inputting an output signal from the local signal generator, dividing the output signal into two, and outputting it. , A local signal distributor 11 of which the output signal of the local signal generator 9 is input as a reference signal, and a calibration signal generator 12 for producing a calibration signal, and 12 is an output signal of the calibration signal generator 11 , The first and second calibration signal switches 3a, 3
calibration signal distributor for inputting into b, 14a, 14
c and 14d are control signal lines, and 15 to 22 are the receiver 5
In the configuration diagram of a and 5b, 15 is the RF coaxial cable 5
Input terminals connected to a and 5b, 16 is an RF amplifier for amplifying the signal connected to the input terminal 15, and 17 is for converting the RF signal connected to the RF amplifier 16 into an intermediate frequency signal. , 18 is an intermediate frequency band filter for limiting the signal band connected to the frequency converter 17, and 19 is an intermediate frequency for amplifying the intermediate frequency signal output from the intermediate frequency band filter 18. Variable gain amplifier, 20 is an output terminal connected to the intermediate frequency variable gain amplifier 19, 21
Is a local signal terminal for inputting a local signal to the frequency converter 17, and 22 is a control signal terminal for inputting a control signal of the intermediate frequency variable gain amplifier 19.

Next, the operation will be described. The radio waves of the signal coming from the external space are input to the plurality of antenna elements 1 with a phase difference corresponding to the angle of arrival, and then the antenna switching unit 2 selects two predetermined elements, and the outputs of these two elements are respectively output. It is input to the calibration signal switches 3a and 3b. The signals output from the calibration signal switches 3a and 3b are input to the input terminals 15 of the receivers 5a and 5b via the RF coaxial cables 4a and 4b, respectively. The signal input from the input terminal 15 is amplified by the RF amplifier 16, and then the frequency converter 17
Is mixed with the local signal input from the local signal terminal 21, converted into a signal of an intermediate frequency by the frequency converter 17, and output. The intermediate frequency signal is band-limited by the intermediate frequency band filter 18, amplified by the intermediate frequency gain variable amplifier 19, and output from the output terminal 20. The intermediate frequency signals output from the output terminals 20 of the receivers 5a and 5b are divided into two,
It is input to the phase detection circuit 6 and the amplitude detection circuit 7, respectively. The detection signals output from the phase detection circuit 6 and the amplitude detection circuit 7 are input to the signal processor, and the arrival direction of the received signal is calculated. The variable intermediate frequency gain amplifier 19 in each of the receivers 5a and 5b has a function of changing the gain in accordance with the received signal level by the control signal from the signal processor 8 so as to suppress the fluctuation of the output signal level. The local signal input to the local signal terminal 21 of each of the receivers 5a and 5b is output from the local signal generator 9 set to a predetermined frequency by the control signal from the signal processing unit 8 and supplied to the local signal distributor 10. It is input, distributed, and reaches the receivers 5a and 5b. Prior to the calculation of the arrival direction of the received signal described above, the calibration for correcting the phase / amplitude variation of each receiving system is performed. The local signal divided by the local signal generator 9 is input to the calibration signal generator 11 and frequency-converted to output a CW wave calibration signal having the same frequency as the received signal. The calibration signal output from the calibration signal generator 11 is input to the calibration signal distributor 12, is divided into signals of equal phase and equal amplitude, and is then input to the calibration signal switches 3a and 3b, respectively. The calibration signal input to the calibration signal switches 3a and 3b is output to the RF coaxial cables 4a and 4b side at the time of calibration and is input to the receivers 5a and 5b in the same manner as the external incoming signal. The calibration signals converted to the intermediate frequency and output from the receivers 5a and 5b are distributed and input to the phase detection circuit 6 and the amplitude detection circuit 7. The detection signals output from the phase detection circuit 6 and the amplitude detection circuit 7 are input to the signal processor 8 and the correction data of the phase shift and the amplitude shift between the two receiving channels are obtained.

[0004]

Since the conventional radio direction finder is constructed as described above, there is a large difference in frequency deviation and amplitude level between the calibration signal at the time of calibration and the actual received signal. In this case, the phase-amplitude relationship changes from that at the time of calibration due to variations in the in-band group delay deviation of the intermediate frequency band filters in the two receivers, phase changes due to gain changes of the intermediate frequency variable gain amplifier, temperature characteristics, etc. There is a problem that the amplitude variation becomes large, and the accuracy of the direction calculation of the incoming signal deteriorates.

The present invention has been made in order to solve the above problems, in which the calibration signal is frequency-modulated within the band of the intermediate frequency band filter, and the phase variations of the two receiving systems within the band are measured during calibration. However, it is an object of the present invention to provide a wireless direction finder that corrects a phase shift due to a frequency shift in an actual received signal.

[0006]

A radio direction finder according to the present invention is provided with a calibration signal frequency modulator controlled by a signal processor in order to frequency modulate a calibration signal. The output modulation signal is input to the calibration signal generator.

[0007]

Since the radio direction finder according to the present invention measures the phase variation between the channels of the receiving system in the intermediate frequency band in advance during the calibration, the influence of the phase shift on the shift of the received signal from the center frequency is suppressed. be able to.

[0008]

【Example】

Example 1. 1 is a block diagram of an embodiment of a wireless direction finder according to the present invention, and FIG. 2 is a block diagram of the receiver in FIG. 1, which has already been described. 1 to 1 in FIG.
2 and 14 are the same as those in FIG. 4, 13 is connected to the control signal line 14b to which the control signal from the signal processor 8 is sent,
A calibration signal frequency modulator for generating a modulation signal to be input to the calibration signal generator 11.

Next, the operation will be described. The radio waves of the signal coming from the external space are input to the plurality of antenna elements 1 with a phase difference corresponding to the angle of arrival, and then the antenna switching unit 2 selects two predetermined elements, and the outputs of these two elements are respectively output. It is input to the calibration signal switches 3a and 3b. The signals output from the calibration signal switches 3a and 3b are input to the input terminals 15 of the receivers 5a and 5b via the RF coaxial cables 4a and 4b, respectively. The signal input from the input terminal 15 is amplified by the RF amplifier 16, and then the frequency converter 17
The signal is mixed with the local signal input from the local signal terminal 21 input to, and converted into a signal of an intermediate frequency by the frequency converter 17, and output. The intermediate frequency signal is band-limited by the intermediate frequency band filter 18, amplified by the intermediate frequency gain variable amplifier 19, and output from the output terminal 20. The intermediate frequency signals output from the output terminals 20 of the receivers 5a and 5b are divided into two,
It is input to the phase detection circuit 6 and the amplitude detection circuit 7, respectively. The detection signals output from the phase detection circuit 6 and the amplitude detection circuit 7 are input to the signal processor, and the arrival direction of the received signal is calculated. The variable intermediate frequency gain amplifier 19 in each of the receivers 5a and 5b has a function of changing the gain in accordance with the received signal level by the control signal from the signal processor 8 so as to suppress the fluctuation of the output signal level. The local signal input to the local signal terminal 21 of each of the receivers 5a and 5b is output from the local signal generator 9 set to a predetermined frequency by the control signal from the signal processing unit 8 and supplied to the local signal distributor 10. It is input, distributed, and reaches the receivers 5a and 5b. Prior to the calculation of the arrival direction of the received signal described above, the calibration for correcting the phase / amplitude variation of each receiving system is performed. The local signal divided by the local signal generator 9 is input to the calibration signal generator 11 and frequency-converted to output a calibration signal having the same center frequency as the received signal. The modulation signal is input to the calibration signal generator 11 from the calibration signal frequency modulator 13, and the calibration signal is frequency-modulated with the bandwidth of the intermediate frequency band filter 18 centered on the same frequency as the received signal. The calibration signal output from the calibration signal generator 11 is input to the calibration signal distributor 12,
After being distributed to signals of equal phase and equal amplitude, they are input to the calibration signal switching devices 3a and 3b, respectively. The calibration signal input to the calibration signal switching devices 3a and 3b is the R signal at the time of calibration.
The signals are output to the F coaxial cables 4a and 4b side and input to the receivers 5a and 5b in the same manner as the external incoming signals. The receiver 5
The calibration signals converted to the intermediate frequencies from a and 5b and output are respectively distributed, input to the phase detection circuit 6 and the amplitude detection circuit 7, and the detection signals output from the phase detection circuit 6 and the amplitude detection circuit 7 are Correction data of the phase shift and the amplitude shift within the band of the intermediate frequency band filter 18 between the two receiving channels are input to the signal processor 8.

Embodiment 2. In the first embodiment described above, the correction of the phase / amplitude variation with respect to the frequency shift of the received signal has been described, but as shown in FIG.
A variable attenuator 23 is provided after the, to generate a calibration signal corresponding to the received signal level, and the gain setting value of the intermediate frequency gain variable amplifier 19 in the receivers 5a and 5b at the time of calibration and when the actual received signal is received. By eliminating the difference between the two, it is possible to suppress the phase / amplitude variation due to the difference in the gain setting values.

Embodiment 3. As shown in FIG. 4, a calibration system temperature monitor 24 is provided in the vicinity of the calibration signal distributor 12, and the temperature change is monitored as the phase relationship in which the calibration signal is input to the calibration signal switches 3a and 3b changes with temperature. By doing so, the data acquired in advance can be corrected by the signal processing unit to suppress the phase variation.

[0012]

As described above, according to the present invention, the frequency and output level of the calibration signal are changed to correct / suppress the phase / amplitude variation between the receiving channels due to the deviation from the actual received signal. And so on.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a wireless direction finder according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a receiver in the wireless direction finding device according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram showing a wireless direction finder according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram showing a wireless direction finder according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram showing a conventional wireless direction finder.

[Explanation of symbols]

 1 Antenna element 2 Antenna switch 3 Calibration signal switch 4 RF coaxial cable 5 Receiver 6 Phase detection circuit 7 Amplitude detection circuit 8 Signal processor 9 Local signal generator 10 Local signal distributor 11 Calibration signal generator 12 Calibration signal distribution Device 13 Calibration signal Frequency modulator 14 Control signal line 15 Input terminal 16 RF amplifier 17 Frequency converter 18 Intermediate frequency band filter 19 Intermediate frequency variable gain amplifier 20 Output terminal 21 Local signal terminal 22 Control signal terminal 23 Variable attenuator 24 Calibration system Temperature monitor

Claims (3)

[Claims] 1. A plurality of antenna elements, an antenna switching device connected to these antennas, first and second calibration signal switching devices respectively connected to the antenna switching device, and the first and second antennas. First and second RF coaxial cables connected respectively to the calibration signal switching devices, and RF amplifiers connected to the first and second RF coaxial cables respectively, and the RF amplifiers. First and second receivers each including a frequency converter connected to the intermediate frequency band, an intermediate frequency band filter connected to the frequency converter, and an intermediate frequency variable gain amplifier connected to the intermediate frequency band filter. And a phase detection circuit in which the outputs branched from the first and second receivers are connected together, and the other outputs branched from the first and second receivers are connected together. And an amplitude detection circuit, a signal processor connected to the outputs of the phase detection circuit and the amplitude detection circuit together, a local signal generator to which a control signal line is connected from the signal processor, and a local signal generator of the local signal generator. A local signal distributor having two outputs connected to the first and second receivers respectively, and a calibration signal generator connected to the other output of the local signal generator; A radio direction finder comprising a calibration signal distributor, which is connected to an output of a calibration signal generator, and two outputs of which are respectively connected to the first and second calibration signal switching devices. A radio direction finder, wherein a calibration signal frequency modulator is provided between the calibration signal generator and the calibration signal generator, and a modulation signal generated from the modulator is input to the calibration signal generator. 2. A variable attenuator is provided between the calibration signal generator and the calibration signal distributor.
Wireless direction finder as described. 3. The wireless direction finder according to claim 1, further comprising a calibration system temperature monitor near the calibration signal distributor, the monitor signal being provided to the signal processor.