JP2016223779A - Radio wave arrival direction orientation device and radio wave arrival direction orientation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To orientate the arrival direction of a radio wave signal having an arbitrary frequency without changing a specific frequency band of a band pass filter.SOLUTION: A radio wave arrival direction orientation device includes: an antenna unit having a plurality of reception antennas for receiving a radio wave signal, and for outputting a first analog signal corresponding to the radio wave signal; an oscillator configured to output a signal having a reference frequency, and to be capable of changing the reference frequency; a mixer for mixing the first analog signal output by each reception antenna with the signal having the reference frequency to generate a mixed signal; a band pass filter for allowing a second analog signal in a specific frequency band in each mixed signal generated by the mixer to pass; and an orientation part for calculating a phase difference between the respective second analog signals which have passed the band pass filter, and for orientating the arrival direction of the radio wave signal received by the antenna unit from the phase difference.SELECTED DRAWING: Figure 6

Description

  The technology disclosed in the present specification relates to a radio wave arrival direction locating device.

  Conventionally, the direction of arrival of radio waves that determines the direction of arrival of pulse wave signals, which are radio signals radiated with partial discharges and spark discharges that occur at insulation degradation points in power equipment such as transmission and distribution lines, substation equipment, and power receiving equipment. There is an orientation device (see Patent Documents 1 and 2). This radio wave arrival direction locating device includes a plurality of receiving antennas that receive a pulse wave signal and output an analog signal corresponding to the pulse wave signal, and an analog signal output from each receiving antenna is within a specified frequency band. A band-pass filter that passes the analog signal, a calculation unit that calculates a phase difference between each analog signal that has passed through the band-pass filter, and an arrival direction of the pulse wave signal received by the receiving antenna from the calculated phase difference. And an orientation part for orientation.

JP 2006-250870 A JP 2011-242244 A

  The radio wave arrival direction locating apparatus can determine the arrival direction of a radio signal including a frequency component within a specified frequency band of a bandpass filter, but the arrival of a radio signal that does not include a frequency component within a specified frequency band. The direction cannot be determined. Here, the radio wave signal includes, in addition to the pulse wave signal, for example, a continuous wave signal transmitted from a mobile phone, a broadcasting station, an eavesdropper, or the like, or a burst wave signal transmitted from a transmitter for biotelemetry, for example. . Since the pulse wave signal includes various frequency components in a relatively wide band from a low frequency component to a high frequency component, the arrival direction of the pulse wave signal can be determined by the radio wave arrival direction locator.

However, continuous wave signals and burst wave signals contain only frequency components within a relatively narrow frequency band, and the frequency band differs depending on the application. For this reason, the radio wave direction-of-arrival locating device can determine the direction of arrival for continuous wave signals and burst wave signals that include frequency components within the specified frequency band of the bandpass filter. The direction of arrival cannot be determined for those not including frequency components in the frequency band. On the other hand, every time the frequency of the target continuous wave signal or burst wave signal is different, it is possible to replace the band pass filter with one having a specified frequency band including the frequency as a pass band. This causes problems such as a complicated configuration of the radio wave arrival direction locator.
The present specification discloses a technique capable of solving at least a part of the problems described above.

The technology disclosed in this specification can be implemented as the following forms.
(1) A radio wave arrival direction locating device disclosed in the present specification is a radio wave arrival direction locating device, which receives a radio signal and outputs a first analog signal corresponding to the radio signal. And an antenna unit configured to output a reference frequency signal and change the reference frequency, and to mix the first analog signal output from each of the reception antennas and the reference frequency signal. A mixer that generates a mixed signal, a band-pass filter that passes a second analog signal within a specified frequency band among each of the mixed signals generated by the mixer, and the band-pass filter A phase difference unit that calculates a phase difference between each of the second analog signals and determines an arrival direction of the radio signal received by the antenna unit from the phase difference. . The radio wave arrival direction locating apparatus outputs a reference frequency signal, an oscillator configured to change the reference frequency, a first analog signal output from each receiving antenna, and a reference frequency signal output from the oscillator. And a mixer for generating a mixed signal. For this reason, by changing the reference frequency of the signal output from the transmitter, the analog signal of an arbitrary frequency output from each receiving antenna can be maintained in the phase difference between the analog signals, and the frequency can be bandpassed. It can be converted to a signal that is within the specified frequency band of the filter. The bypass filter extracts a second analog signal within a specified frequency band from each mixed signal generated by the conversion, and the orientation unit calculates a phase difference between the extracted second analog signals, The arrival direction of the radio signal received by the receiving antenna is determined from the phase difference. As described above, according to the radio wave arrival direction locating apparatus, it is possible to determine the arrival direction of a radio signal having an arbitrary frequency without changing the prescribed frequency band (center angular frequency) of the bandpass filter.

(2) In the radio wave arrival direction locating device, an A / D converter that A / D converts each second analog signal to generate a digital signal, and at least one of the plurality of second analog signals An envelope detector for generating an envelope signal, and an analog signal of one component of a high frequency component and a low frequency component of the envelope signal generated by the envelope detector. And a filter circuit that outputs the analog signal of the one component to the A / D converter as a trigger signal for the A / D conversion, and the orientation unit is generated by the A / D converter. The phase difference between the second analog signals may be calculated based on the digital signals. When the antenna unit is placed in an environment in which continuous wave signals, pulse wave signals, and burst wave signals are mixed, each receiving antenna has a mixture of continuous wave signals, pulse wave signals, and burst wave signals. The signal is received and a first antenna signal corresponding to the mixed signal is output, and the envelope detector generates an envelope signal corresponding to the mixed signal. Here, the high-frequency component signal in the envelope signal is a signal derived from a pulse wave signal or a burst wave signal, and the low-frequency component signal is a signal derived from a continuous wave signal. According to this radio wave arrival direction locating device, when the filter circuit passes a high-frequency component signal, an A / D converted signal based on a trigger signal synchronized with a high-frequency pulse wave signal or burst wave signal is output to the locating unit. Is done. For this reason, the arrival direction of a pulse wave signal or a burst wave signal can be determined while suppressing the influence of a low-frequency continuous wave signal. In addition, when the filter circuit passes a low-frequency component signal, a signal that has been A / D converted based on a trigger signal synchronized with the low-frequency continuous wave signal is output to the orientation unit. For this reason, the arrival direction of the continuous wave signal can be determined while suppressing the influence of the high-frequency pulse wave signal or burst wave signal.

(3) In the radio wave arrival direction locating device, the filter circuit allows a high-frequency component analog signal to pass through the envelope signal, and uses the high-frequency component analog signal as the A / D conversion trigger signal. A high-pass mode to be output to the A / D converter, and an analog signal having a low frequency component in the envelope signal is passed, and the A / D conversion is performed using the analog signal having the low frequency component as a trigger signal for the A / D conversion. It may be configured to be switchable to a low-pass mode that outputs to a device. According to this radio wave arrival direction locating device, the direction of the arrival of a pulse wave signal or a burst wave signal is determined while suppressing the influence of a continuous wave signal of a low frequency component by switching the mode of the filter circuit, and a high frequency component. It is possible to both determine the arrival direction of the continuous wave signal while suppressing the influence of the pulse wave signal and the burst wave signal.

(4) In the radio wave arrival direction locating device, further, a quadrature detector that generates a quadrature detection signal by quadrature detection of at least one of the plurality of second analog signals, and the quadrature detector generated by the quadrature detector When the length of the quadrature detection signal is equal to or greater than the threshold, the radio signal is identified as a burst wave signal. When the length of the quadrature detection signal is less than the threshold, the radio signal is a pulse wave signal. It is good also as a structure provided with the 1st identification part identified. According to this radio wave arrival direction locating device, it is possible to distinguish whether the radio wave signal received by the receiving antenna is a burst wave signal or a pulse wave signal.

(5) In the radio wave arrival direction locator, further, a quadrature detector for quadrature detection of at least one of the plurality of second analog signals, and a length of a signal quadrature detected by the quadrature detector are measured. Memory storing identification information for identifying each of a plurality of transmitters that periodically transmit burst wave signals having different lengths, and correspondence information indicating a correspondence relationship between the lengths of the burst wave signals And, based on the length of the orthogonally detected signal measured by the measurement unit and the correspondence information, which of the plurality of transmitters is the source of the radio signal received by the receiving antenna It is good also as a structure provided with the 2nd identification part to identify. According to the radio wave arrival direction locating device, the receiving antenna receives signals from a plurality of transmitters even if the burst wave signals to be transmitted are relatively short but the burst wave signals have different lengths. It is possible to identify which of the plurality of transmitters is the source of the radio signal.

(6) In the radio wave arrival direction locating device, the plurality of receiving antennas are disposed behind the first to third antenna elements and the first to third antenna elements, and the first to third antennas are arranged. A ground plate for blocking radio signals coming from behind the antenna element, and the orientation unit outputs the first analog signal output from the first antenna element and the second antenna element. A first phase difference that is a phase difference from the first analog signal, and the first analog signal output from the first antenna signal and the third antenna element output from the first antenna element. And a second phase difference that is a phase difference between the first phase difference and the second phase difference, and received by the first to third antenna elements from the first phase difference and the second phase difference. It may be configured to locating the direction of arrival of the radio signal by calculating the horizontal angle and the elevation angle of the direction of arrival of the radio signal. According to this radio wave arrival direction locating device, the elevation angle and horizontal angle of the radio wave signal arrival direction are calculated using the first to third antenna elements, compared to a configuration using only two antennas. Therefore, the direction of arrival of radio waves can be limited to a narrower range. In addition, since non-target signals arriving at the first to third antenna elements from the direction opposite to the source of the radio signal are blocked by the ground plate, the radio signal is affected by the influence of the non-target signals. It can suppress that the precision of the orientation of an arrival direction falls.

(7) In the radio wave arrival direction locator, an imaging unit that captures an image in the front direction of the reception antenna, a display unit that displays the image captured by the imaging unit, and a display processing unit, The display processing unit may be configured to display an instruction image indicating an arrival direction of the radio wave signal determined by the orientation unit on the image displayed on the display unit. According to the radio wave arrival direction locating device, the arrival direction of the radio signal can be grasped from the display content of the display unit.

(8) In the radio wave arrival direction locating device, the specified frequency band of the bandpass filter includes a frequency of a low frequency component signal of each of the mixed signals generated by the mixer, and a high frequency component It is good also as a structure which does not include the frequency of this signal. According to this radio wave arrival direction locating device, it is possible to determine the arrival direction of a radio signal having a frequency higher than the specified frequency band of the bandpass filter.

  The technology disclosed by this specification can be implemented in various forms. For example, radio wave arrival direction locating method, burst wave signal and pulse signal identification method, burst wave signal transmission source identification method and radio wave arrival direction locating device, computer program for realizing the function of these methods or devices, It can be realized in the form of a recording medium or the like on which the computer program is recorded.

External view schematically showing the overall configuration of the radio wave arrival direction locating device 1 Explanatory drawing which shows the front structure of the antenna unit 10 Explanatory drawing which shows the rear surface structure of the antenna unit 10 The perspective view which shows the external appearance structure of the 1st receiving antenna 11a. Explanatory drawing which shows the YZ cross-sectional structure of the 1st receiving antenna 11a. Block diagram showing the configuration of the control unit 20 The block diagram which shows the structure of the frequency converter 100 and the analog phase processing circuit 200 Explanatory drawing of a flow until the trigger generation part 290 produces | generates a trigger signal from a radio wave signal Time chart illustrating transmission pattern of burst wave signals of telemetry transmitters ID1 and ID2 Flow chart showing the orientation process Conceptual diagram for explaining a method of specifying the arrival direction of a radio signal (part 1) Conceptual diagram for explaining a method of specifying the arrival direction of a radio signal (part 2) Conceptual diagram for explaining a method of specifying the arrival direction of a radio signal (part 3) The image figure which shows the example of the orientation result displayed on the display apparatus 30

A. First embodiment:
A-1. Constitution:
(Configuration of radio wave arrival direction locator 1)
FIG. 1 is an external view schematically showing the overall configuration of the radio wave arrival direction locating apparatus 1. FIG. 1 shows XYZ axes orthogonal to each other for specifying the direction. In this specification, for convenience, the Z-axis positive direction is referred to as the upward direction, the Z-axis negative direction is referred to as the downward direction, the Y-axis positive direction is referred to as the forward direction, and the Y-axis negative direction is referred to as the backward direction. However, the radio wave arrival direction locating device 1 may be installed in a direction different from such a direction. The same applies to FIG.

  The radio wave arrival direction locating device 1 includes an antenna unit 10, a control unit 20, and a display device 30. In FIG. 1, the antenna unit 10 is fixed to a tripod 40 in order to perform fixed point location where a radio signal is received at a predetermined position and the arrival direction of the radio signal is specified (specified). The tripod 40 is preferably formed of a non-metallic material (for example, wood) in order to reduce the influence of disturbance radio noise.

(Configuration of antenna unit 10)
FIG. 2A is an explanatory diagram showing a front configuration of the antenna unit 10, and FIG. 2B is an explanatory diagram showing a rear (back) configuration of the antenna unit 10. The antenna unit 10 includes a first reception antenna 11a, a second reception antenna 11b, a third reception antenna 11c, a camera 18, and a support member 19 that supports them.

  The first to third receiving antennas 11a, 11b, and 11c receive radio wave signals (pulse wave signals, continuous wave signals, burst wave signals) transmitted from radio wave transmission sources, and antenna analog signals corresponding to the radio wave signals. Sa (t), Sb (t), and Sc (t) are output, respectively. The antenna analog signals Sa (t), Sb (t), and Sc (t) correspond to the “first analog signal” in the claims. Since the first to third receiving antennas 11a, 11b, and 11c all have the same configuration, the configuration of the first receiving antenna 11a will be described below, and the second and third receiving antennas 11b and 11c will be described. A description of the configuration is omitted. FIG. 3 is a perspective view showing an external configuration of the first receiving antenna 11a, and FIG. 4 is an explanatory view showing a YZ sectional configuration of the first receiving antenna 11a.

  The first receiving antenna 11a includes an antenna element 12a, a ground plate 13a, and a radio wave absorber 14a. In FIG. 3, the radio wave absorber 14a is not shown. The first receiving antenna 11a is, for example, an inverted L antenna. That is, the antenna element 12a is a linear conductive member such as a copper wire or an aluminum wire having a low electric resistance, and is formed in an L shape bent at an angle of 90 degrees in the middle. The cross-sectional shape of the antenna element 12a is circular. For this reason, the reception sensitivity with respect to the radio signal is uniform over the entire circumference of the antenna element 12a. Hereinafter, of the two linear portions constituting the antenna element 12a, the longer linear portion arranged in parallel in the vertical direction (Z-axis direction) is referred to as a long-side portion 12az and is referred to as the front-rear direction (parallel to the Y-axis direction). The shorter straight line portion arranged at is referred to as a short side portion 12ay.

  The ground plate 13a is, for example, a metal plate-like member, and is arranged on the rear side (Y-axis negative direction) side of the long side portion 12az of the antenna element 12a. Therefore, as shown in FIG. 4, radio signals P1, P2, P3 coming from the front of the first receiving antenna 11a can be received by the antenna element 12a, while from the rear of the first receiving antenna 11a. Incoming radio signals P4, P5 and P6 are shielded by the ground plate 13a and are not received by the antenna element 12a. That is, the first receiving antenna 11a has a directivity characteristic that receives a radio signal arriving from the front and does not receive external radio noise arriving from the rear. The ground plate 13a has an elliptical shape extending in the longitudinal direction of the long side portion 12az, and the long side portion 12az of the antenna element 12a is disposed at the center of the ground plate 13a. For this reason, the bias of the phase characteristic due to the difference in the arrival directions of the radio signals P1, P2, P3 can be reduced.

  A radio wave absorber 14a is provided on the front side of the ground plate 13a. For this reason, it can suppress that the radio signal P1, P2, P3 which arrives from the front of the 1st receiving antenna 11a carries out multiple reflection by the earth board 13a. A gap 15a is provided between the antenna element 12a and the radio wave absorber 14a.

  An opening 16a is formed on the lower end side of the ground plate 13a, and the short side portion 12ay of the antenna element 12a penetrates through the opening 16a to the rear surface side of the ground plate 13a, and the tip portion thereof is a transmission cable. It is connected to one end of C (see FIG. 1). The other end of the transmission cable C is connected to the control unit 20 described later, and the antenna analog signal Sa (t) output from the first reception antenna 11a is transmitted to the control unit 20 via the transmission cable C. . The antenna analog signals Sb (t) and Sc (t) output from the second and third receiving antennas 11b and 11c are also transmitted to the control unit 20 via the transmission cable C. The length of the antenna element 12a is preferably approximately λ / 4. Here, λ is the wavelength of the maximum frequency of a radio wave signal (pulse wave signal, burst wave signal, continuous wave signal) to be standardized.

  The camera 18 is, for example, a CCD (Charge Coupled Device) camera, images a subject in the forward direction ((Y-axis positive direction)) of the antenna unit 10, and outputs data of the captured image. The camera 18 is also connected to the control unit 20 via the transmission cable C, and image data output from the camera 18 is transmitted to the control unit 20 via the transmission cable C. The camera 18 corresponds to an “imaging unit” in the claims.

  As shown in FIGS. 2A and 2B, the support member 19 is a rod-shaped member, and the central portion of the rod-shaped member is formed in a shape bent at an angle of 60 degrees. For this reason, the center position of the support member 19 and the positions of both ends are in a positional relationship corresponding to the apex of an equilateral triangle, and at each position, the first reception antenna 11a, the second reception antenna 11b, and the third The receiving antennas 11c are respectively supported. For this reason, the first to third receiving antennas 11a, 11b, and 11c are arranged at equal intervals on the XZ plane. The camera 18 is supported by the support member 19 at a substantially central position of an equilateral triangle formed by the first to third receiving antennas 11a, 11b, and 11c. The support member 19 is provided with a tripod mounting portion (not shown) for fixing the tripod 40 (see FIG. 1). In addition, the support member 19 may be provided with a grip portion (not shown) for receiving radio wave signals while the user grips and moves the antenna unit 10.

(Configuration of control unit 20)
FIG. 5 is a block diagram showing the configuration of the control unit 20. As shown in FIG. 5, the control unit 20 includes a frequency conversion unit 100, an analog phase processing circuit 200, an AD conversion unit 300, an orientation unit 400, and a display processing unit 500. FIG. 6 is a block diagram showing the configuration of the frequency conversion unit 100 and the analog phase processing circuit 200. In the following description, “a, b, c” added to the end of each component or signal code corresponds to that of the first to third receiving antennas 11a, 11b, 11c.

(Configuration of frequency converter 100)
The frequency conversion unit 100 converts the antenna analog signals Sa (t), Sb (t), and Sc (t) having arbitrary frequency components into the order of the antenna analog signals Sa (t), Sb (t), and Sc (t). It has a configuration for maintaining a phase difference and converting the signal into a signal within a predetermined frequency band. Specifically, as shown in FIG. 6, the frequency conversion unit 100 includes an input unit 111a, 111b, 111c, a local oscillator 114, a splitter 116, a frequency setting unit 117, and a mixer (a mixer and a multiplier). 120a, 120b, 120c, amplifiers 122a, 122b, 122c, low-pass filters (hereinafter referred to as “LPF”) 124a, 124b, 124c, and output units 113a, 113b, 113c. The local oscillator 114 corresponds to the “oscillator” in the claims, and the mixers 120a, 120b, and 120c correspond to the “mixer” in the claims.

  The antenna analog signal Sa (t) output from the first receiving antenna 11a is input to the input unit 111a, and the antenna analog signal Sb (t) output from the second receiving antenna 11b is input to the input unit 111b. The antenna analog signal Sc (t) output from the third receiving antenna 11c is input to the input unit 111c. The local oscillator 114 generates and outputs an oscillation signal Vm (t) having a reference frequency. The local oscillator 114 is configured to be able to change the reference frequency of the oscillation signal Vm (t). The frequency setting unit 117 changes the reference frequency of the oscillation signal Vm (t) to an arbitrary value based on, for example, a user input operation. The oscillation signal Vm (t) corresponds to a “reference frequency signal” in the claims.

  The splitter 116 distributes the oscillation signal Vm (t) output from the local oscillator 114 into three, and considers three signals of equal power and the same phase (each signal is regarded as the oscillation signal Vm (t)). Output. The mixer 120a mixes (multiplies) the antenna analog signal Sa (t) input from the first receiving antenna 11a via the input unit 111a and the oscillation signal Vm (t) output from the splitter 116, and mixes them. A signal S120a (t) is generated. Here, among the symbols “S120a (t)” attached to the mixed signal S120a (t), the four characters “120a” next to S are attached to the mixer 120a that outputs the mixed signal S120a (t). It is a sign. Hereinafter, similarly, the sign of each signal is obtained by adding “(t)” to S or V, the sign given to each component in the analog phase processing circuit 200 that generates the signal, and “(t)”. And

  The mixed signal S120a (t) includes the sum frequency signal having the sum of the frequency of the antenna analog signal Sa (t) and the frequency of the oscillation signal Vm (t), and the frequency of the antenna analog signal Sa (t). And a difference frequency signal having a frequency component that is a difference from the frequency of the oscillation signal Vm (t). The amplifier 122a amplifies the mixed signal S120a (t), and the LPF 124a passes the difference frequency signal S124a (t) having a lower frequency among the mixed signals S120a (t) amplified by the amplifier 122a, and outputs an output unit. 113a outputs this difference frequency signal S124a (t).

  The mixer 120b mixes the antenna analog signal Sb (t) input from the second receiving antenna 11b via the input unit 111b and the oscillation signal Vm (t) output from the splitter 116, and mixes the mixed signal S120b ( t). The mixed signal S120b (t) includes a sum frequency signal having a frequency component of the sum of the frequency of the antenna analog signal Sb (t) and the frequency of the oscillation signal Vm (t), and the frequency of the antenna analog signal Sb (t). And a difference frequency signal having a frequency component that is a difference from the frequency of the oscillation signal Vm (t). The amplifier 122b amplifies the mixed signal S120b (t), and the LPF 124b passes the difference frequency signal S124b (t) having a lower frequency out of the mixed signal S120b (t) amplified by the amplifier 122b, and outputs it. 113b outputs this difference frequency signal S124b (t). The mixer 120c mixes the antenna analog signal Sc (t) input from the third receiving antenna 11c via the input unit 111c and the oscillation signal Vm (t) output from the splitter 116, and mixes the mixed signal S120c ( t). The mixed signal S120c (t) includes a sum frequency signal having a sum frequency component of the frequency of the antenna analog signal Sc (t) and the frequency of the oscillation signal Vm (t), and the frequency of the antenna analog signal Sc (t). And a difference frequency signal having a frequency component that is a difference from the frequency of the oscillation signal Vm (t). The amplifier 122c amplifies the mixed signal S120c (t), and the LPF 124c passes the difference frequency signal S124c (t) having a lower frequency out of the mixed signal S120c (t) amplified by the amplifier 122c, and outputs it. 113c outputs this difference frequency signal S124c (t). The mixed signals S120a (t), 120b (t), and 120c (t) correspond to “mixed signals” in the claims.

(Configuration of analog phase processing circuit 200)
The analog phase processing circuit 200 performs quadrature detection on the difference frequency signals S124a (t), S124b (t), and S124c (t) output from the output units 113a, 113b, and 113c, and a difference frequency signal V1b (t) described later. , V1c (t), V3b (t), and V3c (t). Specifically, as shown in FIG. 6, the analog phase processing circuit 200 includes a front end unit 210, an amplification unit 220, a first distribution circuit 230, a first mixer unit 240, a first LPF unit 250, A second distribution circuit 260, a second mixer unit 270, a second LPF unit 280, and a trigger generation unit 290 are provided. The front end unit 210, the amplification unit 220, the first distribution circuit 230, the first mixer unit 240, the first LPF unit 250, the second distribution circuit 260, the second mixer unit 270, and the second LPF unit. 280 corresponds to the “orthogonal detector” in the claims.

(Front end part 210)
The front end unit 210 includes input units 211a, 211b, and 211c, SAW filters (Surface Acoustic Wave Filters) 212a, 212b, and 212c, and output units 213a, 213b, and 213c. The SAW filters 212a, 212b, and 212c correspond to “bandpass filters” in the claims.

  The difference frequency signal S124a (t) output from the output unit 113a is input to the input unit 211a, and the difference frequency signal S124b (t) output from the output unit 113b is input to the input unit 211b. The difference frequency signal S124c (t) output from the output unit 113c is input.

  The SAW filter 212a passes the specified frequency signal S212a (t), which is a signal within a specified frequency band, out of the difference frequency signal S124a (t) input to the input unit 211a, and the output unit 213a The signal S212a (t) is output. The SAW filter 212b passes the specified frequency signal S212b (t), which is a signal in the same specified frequency band as the SAW filter 212a, out of the difference frequency signal S124b (t) input via the input unit 211b, and outputs it. The unit 213b outputs the specified frequency signal S212b (t). The SAW filter 212c passes the specified frequency signal S212c (t), which is a signal in the same specified frequency band as the SAW filter 212a, out of the difference frequency signal S124c (t) input via the input unit 211c, and outputs it. The unit 213c outputs the specified frequency signal S212c (t). The difference frequency signals S124a (t), S124b (t), S124c (t) input to the respective input units 211a, 211b, 211c are passed through SAW filters 212a, 212b, 212c having narrow band pass characteristics, By extracting the prescribed frequency signals S212a (t), S212b (t), S212c (t) within the prescribed frequency band, the analog phase processing circuit 200 uses the difference frequency signal S124a (t ), The difference frequency signal S124b (t), and the difference frequency signal S124c (t) can be accurately calculated. The specified frequency signals S212a (t), S212b (t), and S212c (t) correspond to the “second analog signal” in the claims. Note that the prescribed frequency bands of the SAW filters 212a, 212b, and 212c are fixed values, and in the present embodiment, the center angular frequency that defines the prescribed frequency bands of the SAW filters 212a, 212b, and 212c is 400 MHz.

  The front end unit 210 further includes a local oscillator 214, a SAW filter 215, and an output unit 216. The local oscillator 214 generates and outputs an oscillation signal. The SAW filter 215 passes a signal within a specific frequency band among the oscillation signals output from the local oscillator 214, and the output unit 216 outputs a signal that has passed through the SAW filter 215. In the present embodiment, the frequency band of the signal that the SAW filter 215 passes is assumed to be 300 MHz.

(Amplifier 220)
The amplification unit 220 includes input units 221a, 221b, and 221c, preamplifiers 222a, 222b, and 222c, digital attenuators 223a, 223b, and 223c, main amplifiers 224a, 224b, and 224c, an input unit 225, an attenuator 226, a main And an amplifier 227.

  The specified frequency signal S212a (t) output from the output unit 213a of the front end unit 210 is input to the input unit 221a, and the specified frequency signal output from the output unit 213b of the front end unit 210 to the input unit 221b. S212b (t) is input, and the specified frequency signal S212c (t) output from the output unit 213c of the front end unit 210 is input to the input unit 221c. The preamplifiers 222a, 222b, and 222c amplify the weak defined frequency signals S212a (t), S212b (t), and S212c (t) in the 400 MHz band input to the input units 221a, 221b, and 221c by about 40 dB, respectively. The digital attenuators 223a, 223b, and 223c adjust the frequencies of the amplified specified frequency signals S212a (t), S212b (t), and S212c (t) to a predetermined level, and the main amplifiers 224a, 224b, and 224c The regulated frequency signals S212a (t), S212b (t), and S212c (t) after adjustment are amplified. The amplifying unit 220 is provided with a gain adjustment circuit (not shown) that adjusts the digital attenuator 223 in accordance with the intensity of the radio signal received by the first to third receiving antennas 11a, 11b, and 11c. Yes. The gain adjustment circuit adjusts the digital attenuator 223 so that the input is suitable for mixers (241, 243b, 243c, 245) of the first mixer section 240 described later. A signal input from the output unit 216 to the input unit 225 is adjusted to a predetermined level by the attenuator 226 and amplified by the main amplifier 227.

(First distribution circuit 230)
The first distribution circuit 230 includes splitters 231 and 233 and a hybrid coupler 232. The splitter 231 receives two signals that have passed through the frequency conversion unit 100, the front end unit 210, and the amplification unit 220 from the first receiving antenna 11a (that is, two defined frequency signals S212a (t) output from the main amplifier 224a). And outputs two signals of equal power and the same phase (hereinafter, each signal is assumed to be a specified frequency signal S212a (t)).

  The hybrid coupler 232 distributes the signal amplified by the amplifying unit 220 and output from the main amplifier 227 into two, and is an oscillation signal Vn1 (t) having an equal power and a phase angle of 0 ° (0 in FIG. 6). And an oscillation signal Vn2 (t) having a phase angle of 90 ° (shown as π / 2 in FIG. 6) is output. The splitter 233 distributes the oscillation signal Vn1 (t) output from the hybrid coupler 232 having a phase angle of 0 ° into three, and has three signals of equal power and the same phase (hereinafter, each signal is an oscillation signal Vn1 (t ) Is output. The splitters 231 and 233 and the hybrid coupler 232 will be described as having amplifiers (not shown) therein. By adjusting the amplification factor of each amplifier, the signal output from the hybrid coupler 232 and the signals output from the splitters 231 and 233 can be made equal power.

(First mixer section 240)
The first mixer unit 240 includes mixers 241, 243b, 243c, 245 and amplifiers 242, 244b, 244c, 246. The mixer 241 mixes the specified frequency signal S212a (t) corresponding to the first receiving antenna 11a output from the splitter 231 and the oscillation signal Vn1 (t) output from the splitter 233 and having a phase angle of 0 °. A mixed signal S241 (t) with a small distortion is generated. This mixed signal S241 (t) includes a sum frequency signal having a frequency component (= 700 MHz) of the sum of the frequency (400 MHz) of the specified frequency signal S212a (t) and the frequency (300 MHz) of the oscillation signal Vn1 (t); A difference frequency signal having a frequency component (= 100 MHz) of a difference between the frequency of the prescribed frequency signal S212a (t) and the frequency of the oscillation signal Vn1 (t). The amplifier 242 amplifies the mixed signal S241 (t) generated by the mixer 241.

  The mixer 243b mixes the specified frequency signal S212b (t) corresponding to the second receiving antenna 11b output from the main amplifier 224b and the oscillation signal Vn1 (t) output from the splitter 233 and having a phase angle of 0 °. Then, a mixed signal S243b (t) with a small distortion is generated. The mixed signal S243b (t) includes a sum frequency signal having a sum frequency component (= 700 MHz) of the frequency (400 MHz) of the specified frequency signal S212b (t) and the frequency of the oscillation signal Vn1 (t), and a specified frequency signal. A difference frequency signal having a frequency component (= 100 MHz) of a difference between the frequency of S212b (t) and the frequency of the oscillation signal Vn1 (t). The amplifier 244b amplifies the mixed signal S243b (t) generated by the mixer 243b.

  The mixer 243c mixes the specified frequency signal S212c (t) corresponding to the third receiving antenna 11c output from the main amplifier 224c and the oscillation signal Vn1 (t) output from the splitter 233 and having a phase angle of 0 °. Then, a mixed signal S243c (t) with a small distortion is generated. The mixed signal S243c (t) includes a sum frequency signal having a sum frequency component (= 700 MHz) of the frequency (400 MHz) of the specified frequency signal S212c (t) and the frequency of the oscillation signal Vn1 (t), and a specified frequency signal. A difference frequency signal having a frequency component (= 100 MHz) of a difference between the frequency of S212c (t) and the frequency of the oscillation signal Vn1 (t). The amplifier 244c amplifies the mixed signal S243c (t) generated by the mixer 243c.

  The mixer 245 mixes the specified frequency signal S212a (t) corresponding to the first receiving antenna 11a output from the splitter 231 and the oscillation signal Vn2 (t) output from the hybrid coupler 232 and having a phase angle of 90 °. A mixed signal S245 (t) with a small distortion is generated. The mixed signal S245 (t) includes a sum frequency signal having a sum frequency component (= 700 MHz) of the frequency of the specified frequency signal S212a (t) and the frequency of the oscillation signal Vn2 (t), and the specified frequency signal S212a (t ) And a difference frequency signal having a frequency component (= 100 MHz) of a difference between the frequency of the oscillation signal Vn2 (t). The amplifier 246 amplifies the mixed signal S245 (t) generated by the mixer 245.

(First LPF unit 250)
The first LPF unit 250 includes four LPFs 251, 252 b, 252 c, and 253. The LPF 251 passes the lower frequency difference signal S251 (t) of the mixed signal S241 (t) amplified by the amplifier 242, and the LPF 252b passes the mixed signal S243b (t) amplified by the amplifier 244b. The difference frequency signal S252b (t) having the lower frequency is passed. The LPF 252c passes the difference frequency signal S252c (t) having a lower frequency out of the mixed signal S243c (t) amplified by the amplifier 244c, and the LPF 253 passes the mixed signal S245 (t) amplified by the amplifier 246. The difference frequency signal S253 (t) having the lower frequency is passed.

(Second distribution circuit 260)
The second distribution circuit 260 includes four splitters 261, 262 b, 262 c, and 263. The splitter 261 distributes the difference frequency signal S251 (t) that has passed through the LPF 251 of the first LPF unit 250 into two, and has two signals of equal power and the same phase (each signal is a difference frequency signal S251 (t)) Output). The splitter 262b distributes the difference frequency signal S252b (t) that has passed through the LPF 252b of the first LPF unit 250 into two signals, and each of the two signals has the same power and the same phase (each signal is the difference frequency signal S252b (t)) Output). The splitter 262c distributes the difference frequency signal S252c (t) that has passed through the LPF 252c of the first LPF unit 250 into two signals, each of which has two signals of equal power and the same phase (each signal is a difference frequency signal S252c (t)). Output). The splitter 263 distributes the difference frequency signal S253 (t) that has passed through the LPF 253 of the first LPF unit 250 into two, and has two signals of equal power and the same phase (each signal is a difference frequency signal S253 (t)) Output).

(Second mixer unit 270)
The second mixer unit 270 includes four mixers 271b, 271c, 273b, and 273c. The mixer 271b mixes the difference frequency signal S251 (t) output from the splitter 261 and the difference frequency signal S252b (t) output from the splitter 262b to generate a mixed signal S271b (t). This mixed signal S271b (t) is a sum frequency signal having a sum frequency component (= 200 MHz) of the frequency (100 MHz) of the difference frequency signal S251 (t) and the frequency (100 MHz) of the difference frequency signal S252b (t). And a difference frequency signal having a frequency component (= 0 MHz) of a difference between the frequency of the difference frequency signal S251 (t) and the frequency of the difference frequency signal S252b (t). The mixer 271c mixes the difference frequency signal S251 (t) output from the splitter 261 and the difference frequency signal S252c (t) output from the splitter 262c to generate a mixed signal S271c (t). This mixed signal S271c (t) includes a sum frequency signal having a frequency component (= 200 MHz) of the sum of the frequency of the difference frequency signal S251 (t) and the frequency (100 MHz) of the difference frequency signal S252c (t), and the difference frequency A difference frequency signal having a frequency component (= 0 MHz) of a difference between the frequency of the signal S251 (t) and the frequency of the difference frequency signal S252c (t). The mixer 273b mixes the difference frequency signal S253 (t) output from the splitter 263 and the difference frequency signal S252b (t) output from the splitter 262b to generate a mixed signal S273b (t). The mixed signal S273b (t) includes a sum frequency signal having a sum frequency component (= 200 MHz) of the frequency (100 MHz) of the difference frequency signal S253 (t) and the frequency of the difference frequency signal S252b (t), and the difference frequency. A difference frequency signal having a frequency component (= 0 MHz) of a difference between the frequency of the signal S253 (t) and the frequency of the difference frequency signal S252b (t). The mixer 273c mixes the difference frequency signal S253 (t) output from the splitter 263 and the difference frequency signal S252c (t) output from the splitter 262c to generate a mixed signal S273c (t). This mixed signal S273c (t) includes a sum frequency signal having a frequency component (= 200 MHz) of the sum of the frequency (100 MHz) of the difference frequency signal S253 (t) and the frequency of the difference frequency signal S252c (t), and the difference frequency A difference frequency signal having a frequency component (= 0 MHz) of a difference between the frequency of the signal S253 (t) and the frequency of the difference frequency signal S252c (t).

(Second LPF unit 280)
The second LPF unit 280 includes four LPFs 281b, 281c, 283b, and 283c. The LPF 281b passes the difference frequency signal V1b (t) having a lower frequency among the mixed signals S271b (t) generated by the mixer 271b, and the LPF 281c includes the S271c (t) generated by the mixer 271c, The difference frequency signal V1c (t) having the lower frequency is passed. The LPF 283b passes the difference frequency signal V3b (t) having a lower frequency among the mixed signals S273b (t) generated by the mixer 273b, and the LPF 283c transmits the mixed signal S273c (t) generated by the mixer 273c. The difference frequency signal V3c (t) having the lower frequency is passed. The difference frequency signals V1b (t), V1c (t), V3b (t), V3c (t) are antenna analog signals Sa (t), Sb (t), Sc (t) (difference frequency signals S124a (t), S124b (t), S124c (t)) is a signal obtained by quadrature detection, and corresponds to a “quadrature detection signal” in the claims.

(Trigger generation unit 290)
The trigger generation unit 290 includes an envelope detector 291, a splitter 292, an LPF 293, a high-pass filter (hereinafter referred to as “HPF”) 294, and a changeover switch 295. The envelope detector 291 receives the specified frequency signal S212a (t) output from the output unit 213a of the front end unit 210, detects the envelope of the specified frequency signal S212a (t), and responds to the envelope Generating an envelope signal. The splitter 292 distributes the envelope signal generated by the envelope detector 291 into two, and outputs two post-distributed signals having the same power and the same phase. The LPF 293 blocks a signal in a frequency band of, for example, 16 Hz or more among the post-distribution signals output from the splitter 292 and passes a signal in a frequency band of less than 16 Hz. On the other hand, the HPF 294 blocks a signal in a frequency band of, for example, less than 16 kHz among the post-distribution signals output from the splitter 292 and passes a signal in a frequency band of 16 kHz or more. The changeover switch 295 is connected to the LPF 293 and outputs a signal in a frequency band of less than 16 Hz output from the LPF 293 as a trigger signal Tri, and is connected to the HPF 294 and outputs a frequency band of 16 kHz or more output from the HPF 294. The signal can be switched to a high-pass mode that outputs the trigger signal Tri.

(Configuration of AD conversion unit 300)
The AD conversion unit 300 shown in FIG. 5 has a power detector (not shown), and the trigger signal Tri output from the trigger generation unit 290 of the analog phase processing circuit 200 (see FIG. 6) is supplied to the power detector. A digital pulse wave signal is output when the signal level of the trigger signal Tri is greater than or equal to the reference level. The output of the digital pulse wave signal from the power detector means that the first receiving antenna 11a has received the radio wave signal. The AD conversion unit 300 outputs the difference frequency signals V1b (t), V1c (t), V3b (t), and V3c (t) of the analog phase processing circuit 200 in synchronization with the digital pulse wave signal output from the power detector. Sampling and holding. Then, the AD conversion unit 300 converts the sampled and held difference frequency signals V1b (t), V1c (t), V3b (t), and V3c (t) into digital signals and outputs them to the orientation unit 400. That is, the difference frequency signals V1b (t), V1c (t), V3b (t), and V3c (t) are converted into the AD conversion unit in synchronism when the first receiving antenna 11a receives a radio signal of a predetermined level or higher. 300 is output to the orientation unit 400.

(Configuration of orientation unit 400, display processing unit 500, and display device 30)
The orientation unit 400 includes a CPU 410 and a memory 420, and receives the digital signals of the output values V1b, V1c, V3b, and V3c sampled and held by the AD conversion unit 300, and the elevation angle of the arrival direction of the radio signal from the radio source θz and horizontal angle φx are calculated and output to the display processing unit 500. The display processing unit 500 controls the display operation of the display device 30. The control unit 20 and the display device 30 are integrated in FIG. 1, but may be separated from each other. In addition, the antenna unit 10 and the control unit 20 are not limited to a configuration that performs wired communication via the transmission cable C, and may be configured to perform wireless communication.

A-2. Operation:
The antenna analog signals Sa (t), Sb (t), and Sc (t) output from the first to third receiving antennas 11a, 11b, and 11c are expressed by the following equations.

Sa (t) = S1 × sin ωt (1)
Sb (t) = S2 × sin {ω (t−Δt2)} (2)
Sc (t) = S3 × sin {ω (t−Δt3)} (3)
S1 to S3 are the amplitudes of the antenna analog signals Sa (t), Sb (t), Sc (t), and ω (= 2πf) is the antenna analog signals Sa (t), Sb (t). , Sc (t). In the present embodiment, the first receiving antenna 11a is the reference antenna, Δt2 is the arrival time difference of the radio signal of the second receiving antenna 11b with respect to the first receiving antenna 11a, and ωΔt2 is the first receiving antenna 11a. This is the arrival phase difference of the radio signal of the second receiving antenna 11b with respect to the receiving antenna 11a. Δt3 is the arrival time difference of the radio signal of the third reception antenna 11c relative to the first reception antenna 11a, and ωΔt3 is the arrival phase difference of the radio signal of the third reception antenna 11c relative to the first reception antenna 11a. .

The oscillation signal Vm (t) output from the local oscillator 114 is represented by the following equation.
Vm (t) = Vm × cos (ωat + θ) (4)
Vm is the amplitude of the oscillation signal Vm (t), and ωa (= 2πfa) is the angular frequency of the oscillation signal Vm (t) output from the local oscillator 114 (fa is the reference frequency of the oscillation signal Vm (t)). And θ is the phase angle of the local oscillator 114.

(Operation of Analog Phase Processing Circuit 200)
The operation of the analog phase processing circuit 200 will be described. A description of the amplification in the amplifiers 242, 244b, 244c, and 246 is omitted. In the analog phase processing circuit 200, the difference frequency signals S124a (t), S124b (t), and S124c (t) output from the frequency converter 100 are converted into the prescribed frequency bands (400 MHz) of the SAW filters 212a, 212b, and 212c. Only when the difference frequency signals S124a (t), S124b (t), and S124c (t) are orthogonally detected, the difference frequency signal V1b (t) remarkably indicating the arrival time differences Δt2 and Δt3. , V1c (t), V3b (t), and V3c (t) are generated.

  Specifically, among the difference frequency signals S124a (t), S124b (t), and S124c (t) output from the frequency converter 100, the specified frequency signal S212a (t) that has passed through the SAW filters 212a, 212b, and 212c. , S212b (t), S212c (t) can be expressed by the following equations.

S212a (t) = Ea (t) × sin {(ω−ωa) t−θ} (5)
S212b (t) = Eb (t) × sin {(ω−ωa) t−ωΔt2−θ} (6)
S212c (t) = Ec (t) × sin {(ω−ωa) t−ωΔt3−θ} (7)
Ea (t), Eb (t), and Ec (t) are envelope functions representing changes (envelopes) of the amplitudes of the specified frequency signals S212a (t), S212b (t), and S212c (t). . In general, when each receiving antenna 11a, 11b, 11c receives only a continuous wave signal, the values of Ea (t), Eb (t), and Ec (t) are constant, and each receiving antenna 11a, 11b, 11c When only a burst wave signal is received, the values of Ea (t), Eb (t), and Ec (t) change to a triangular wave shape or a rectangular wave shape.

  An oscillation signal Vn1 (t) output from the local oscillator 214 of the front end unit 210, passing through the amplification unit 220, and output from the splitter 233 of the first distribution circuit 230 and having a phase angle of 0 °, and output from the hybrid coupler 232 The oscillation signal Vn2 (t) having a phase angle of 90 ° is expressed by the following equation.

Vn1 (t) = Vn × sin (ωbt + φ) (8)
Vn2 (t) = Vn × sin (ωbt + φ + (π / 2)) = Vn × cos (ωbt + φ) (9)
Vn is the amplitude of the oscillation signal, fb (= ωb / (2π)) is the local oscillation frequency of the oscillation signal output from the local oscillator 214, and φ is the phase angle of the local oscillator 214. In this embodiment, it is assumed that the local transmission frequency is 300 MHz.

  From the above equations (8), (9), etc., the mixed signals S241 (t), S243b (t), S243c (t), S245 (t) output from the mixers 241, 243b, 243c, 245 are as follows: It can be expressed by the following formula.

S241 (t) = S212a (t) × Vn1 (t) = (1/2) × Vn × Ea (t) × [cos {(ω−ωa−ωb) t−θ−φ} −cos {(ω− ωa + ωb) t−θ + φ}] (10)
S243b (t) = S212b (t) * Vn1 (t) = (1/2) * Vn * Eb (t) * [cos {([omega]-[omega] a- [omega] b) t- [omega] [Delta] t2- [theta]-[phi]}-cos {( ω−ωa + ωb) t−ωΔt 2 −θ + φ}] (11)
S243c (t) = S212c (t) × Vn1 (t) = (1/2) × Vn × Ec (t) × [cos {(ω−ωa−ωb) t−ωΔt3−θ−φ} −cos {( ω−ωa + ωb) t−ωΔt 3 −θ + φ}] (12)
S245 (t) = S212a (t) × Vn2 (t) = (1/2) × Vn × Ea (t) × [sin {(ω−ωa−ωb) t−θ−φ} + sin {(ω−ωa + ωb ) T−θ + φ}] (13)

  Among the mixed signals S241 (t), S243b (t), S243c (t), and S245 (t), the difference frequency signals S251 (t), S252b (t), and S252c (passed through the LPFs 251, 252b, 252c, and 253) t) and S253 (t) can be expressed by the following equations.

S251 (t) = (1/2) * Vn * Ea (t) * cos {([omega]-[omega] a- [omega] b) t- [theta]-[phi]} (14)
S252b (t) = (1/2) * Vn * Eb (t) * cos {([omega]-[omega] a- [omega] b) t- [omega] [Delta] t2- [theta]-[phi]} (15)
S252c (t) = (1/2) * Vn * Ec (t) * cos {([omega]-[omega] a- [omega] b) t- [omega] [Delta] t3- [theta]-[phi]} (16)
S253 (t) = (1/2) * Vn * Ea (t) * sin {([omega]-[omega] a- [omega] b) t- [theta]-[phi]} (17)
In this way, the LPFs 251, 252 b, 252 c, and 253 block the 700 MHz band component signal among the mixed signals S 241 (t), S 243 b (t), S 243 c (t), S 245 (t), The difference frequency signals S251 (t), S252b (t), S252c (t), and S253 (t) in the 100 MHz band that clearly show the time differences Δt2 and Δt3 are passed through and output to the second mixer section 270 at the subsequent stage.

  From the above equations (14) to (17), etc., the mixed signals S271b (t), S271c (t), S273b (t), and S273c (t) output from the mixers 271b, 271c, 273b, and 273c are It can be expressed by the following formula.

S271b (t) = S251 (t) × S252b (t) = (1/8) × Vn ² × Ea (t) × Eb (t) × [cos {2 (ω−ωa−ωb) t−ωΔt2−2θ -2φ} + cosωΔt 2] (18)
S271c (t) = S251 (t) × S252c (t) = (1/8) × Vn ² × Ea (t) × Ec (t) × [cos {2 (ω−ωa−ωb) t−ωΔt3−2θ -2φ} + cos ωΔt 3] (19)
S273b (t) = S253 (t) × S252b (t) = (1/8) × Vn ² × Ea (t) × Eb (t) × [sin {2 (ω−ωa−ωb) t−ωΔt2−2θ -2φ} + sin ωΔt 2] (20)
S273c (t) = S253 (t) × S252c (t) = (1/8) × Vn ² × Ea (t) × Ec (t) × [sin {2 (ω−ωa−ωb) t−ωΔt3−2θ -2φ} + sin ωΔt 3] (21)
As is apparent from these equations, the mixed signals S271b (t), S271c (t), S273b (t), and S273c (t) are detection outputs that depend on the arrival phase differences ωΔt2 and ωΔt3.

  Of the mixed signals S271b (t), S271c (t), S273b (t), S273c (t), the difference frequency signals V1b (t), V1c (t), V3b (passed through the LPFs 281b, 281c, 283b, 283c, respectively. t) and V3c (t) can be expressed by the following equations.

V1b (t) = (1/8) × Vn 2 × Ea (t) × Eb (t) × cosωΔt2 ··· (22)
V1c (t) = (1/8) × Vn 2 × Ea (t) × Ec (t) × cosωΔt3 ··· (23)
V3b (t) = (1/8) × Vn 2 × Ea (t) × Eb (t) × sinωΔt2 ··· (24)
V3c (t) = (1/8) × Vn 2 × Ea (t) × Ec (t) × sinωΔt3 ··· (25)
In this way, each LPF 281b, 281c, 283b, 283c blocks the signal of the 200 MHz band component among the mixed signals S271b (t), S271c (t), S273b (t), S273c (t), and the above arrival time difference. Difference frequency signals V1b (t), V1c (t), V3b (t), and V3c (t) of direct current components that significantly indicate Δt2 and Δt3 are passed.

(Operation of frequency converter 100)
The operation of the frequency conversion unit 100 will be described. As described above, the frequency converter 100 converts the antenna analog signals Sa (t), Sb (t), and Sc (t) having arbitrary frequency components into the antenna analog signals Sa (t), Sb (t), and Sc. The phase difference of (t) is held, and the SAW filters 212a, 212b, and 212c are converted into signals within the specified frequency band (400 MHz).

  Specifically, from the above equations (1) to (4), the mixed signals S120a (t), S120b (t), and S120c (t) output from each of the mixers 120a, 120b, and 120c are expressed by the following equations. Can be expressed as

S120a (t) = Sa (t) × Vm (t) = (1/2) × S1 × Vm × [sin {(ω + ωa) t + θ} + sin {(ω−ωa) t−θ}] (26 )
S120b (t) = Sb (t) × Vm (t) = (1/2) × S2 × Vm × [sin {(ω + ωa) t−ωΔt2 + θ} + sin {(ω−ωa) t−ωΔt2−θ}] (27)
S120c (t) = Sc (t) × Vm (t) = (1/2) × S3 × Vm × [sin {(ω + ωa) t−ωΔt3 + θ} + sin {(ω−ωa) t−ωΔt3−θ}] (28)

  Among the mixed signals S120a (t), S120b (t), and S120c (t), the difference frequency signals S124a (t), S124b (t), and S124c (t) that have passed through the LPFs 124a, 124b, and 124c are expressed by the following equations. Can be expressed as

S124a (t) = (1/2) × S1 × Vm × sin {(ω−ωa) t−θ} (29)
S124b (t) = (1/2) × S2 × Vm × sin {(ω−ωa) t−ωΔt2−θ} (30)
S124c (t) = (1/2) * S3 * Vm * sin {([omega]-[omega] a) t- [omega] [Delta] t3- [theta]} (31)

  As shown in the above equations (29) to (31), the frequency fout (= (ω−ωa) / (2π)) of the difference frequency signals S124a (t), S124b (t), and S124c (t) is The frequency f (= ω / (2π)) of the antenna analog signals Sa (t), Sb (t), Sc (t) and the reference frequency fa (= ωa) of the oscillation signal Vm (t) output from the local oscillator 114 / (2π)). Therefore, by changing the reference frequency fa of the oscillation signal Vm (t) by the frequency setting unit 117, the antenna analog signals Sa (t), Sb (t), Sc (t) having arbitrary frequency components are converted into the antennas. The phase difference between the analog signals Sa (t), Sb (t), and Sc (t) can be maintained and converted into a signal within a predetermined frequency band.

  Here, radio wave signals received by the first to third receiving antennas 11a, 11b, and 11c include not only pulse wave signals but also continuous wave signals and burst wave signals. The pulse wave signal is a signal including various frequency components in a relatively wide frequency band from several hundred KHz to several GHz, and the frequency component in the specified frequency band of the SAW filters 212a, 212b, and 212c of the front end unit 210. (400 MHz). Therefore, it is assumed that the antenna analog signals Sa (t), Sb (t), and Sc (t) output from the first to third receiving antennas 11a, 11b, and 11c are not passed through the frequency conversion unit 100. In addition, even if the configuration is applied to the front end unit 210, the SAW filters 212a, 212b, and 212c are caused to input a pulse wave signal that is caused by the pulse wave signal and within the specified frequency band. The direction of arrival can be determined.

  On the other hand, continuous wave signals and burst wave signals contain only frequency components within a relatively narrow frequency band, and the frequency band differs depending on the application. Therefore, if the antenna analog signals Sa (t), Sb (t), and Sc (t) are provided to the front end unit 210 without passing through the frequency conversion unit 100, a continuous wave signal or a burst wave signal is assumed. Among them, the direction of arrival can be determined for those including the frequency components in the specified frequency band, but the direction of arrival cannot be determined for those not including the frequency components in the specified frequency band.

  On the other hand, in this embodiment, the antenna analog signals Sa (t), Sb (t), and Sc (t) are provided to the front end unit 210 via the frequency conversion unit 100. In the frequency conversion unit 100, the frequency setting unit 117 changes the reference frequency fa of the oscillation signal Vm (t), so that the antenna analog signals Sa (t), Sb (t), Sc (including only specific frequency components are changed. t) is the difference frequency that holds the phase difference between the antenna analog signals Sa (t), Sb (t), and Sc (t) and whose frequency components are within the specified frequency bands of the SAW filters 212a, 212b, and 212c. Signals S124a (t), S124b (t), and S124c (t) can be converted. For example, when the frequency f of the continuous wave signal received by the first to third receiving antennas 11a, 11b, and 11c is 800 MHz, the reference frequency fa of the oscillation signal Vm (t) is set to 400 MHz by the frequency setting unit 117. Then, the frequency fout (= f−fa) of the difference frequency signals S124a (t), S124b (t), and S124c (t) is set to 400 MHz, that is, a frequency within the specified frequency band of the SAW filters 212a, 212b, and 212c. can do. When the frequency f of the continuous wave signal received by the first to third receiving antennas 11a, 11b, and 11c is 1200 MHz, the frequency setting unit 117 sets the reference frequency fa of the oscillation signal Vm (t) to 800 MHz. Then, the frequency fout (= f−fa) of the difference frequency signals S124a (t), S124b (t), and S124c (t) is set to 400 MHz, that is, a frequency within the specified frequency band of the SAW filters 212a, 212b, and 212c. can do.

(Operation of trigger generation unit 290)
FIG. 7 is an explanatory diagram of a flow until the trigger generation unit 290 generates the trigger signal Tri from the radio signal. As described above, radio wave signals include continuous wave signals and burst wave signals in addition to pulse wave signals. In many environments, these plural types of radio wave signals are mixed. When the antenna unit 10 is arranged in such an environment, the first to third receiving antennas 11a, 11b, and 11c receive a mixed signal in which a continuous wave signal, a pulse wave signal, and a burst wave signal are mixed. , Antenna analog signals Sa (t), Sb (t), Sc (t) corresponding to the mixed signals are output, respectively, and the front-end unit 210 defines specified frequency signals S212a (t), S212b ( t) and S212c (t) are output.

  Here, when the specified frequency signal S212a (t) corresponding to such a mixed signal is input to the envelope detector 291, the waveform of the envelope signal generated by the envelope detector 291 is shown in FIG. Thus, the waveform is such that a DC signal is superimposed on the half-wave signal. The half wave signal is a signal caused by a pulse wave signal or a burst wave signal, and the direct current signal is a signal caused by a continuous wave signal. Therefore, if the envelope signal generated by the envelope detector 291 is used as the trigger signal Tri when receiving a pulse wave signal or a burst wave signal, the reception intensity of the DC signal, that is, the continuous wave signal changes. The trigger level (reference voltage for comparison) must be adjusted each time, and a stable trigger signal Tri may not be generated.

  On the other hand, in this embodiment, the trigger generation unit 290 can be switched between a low-pass mode and a high-pass mode. For this reason, when the target of orientation is a pulse wave signal or a burst wave signal, the DC signal is removed from the envelope signal when the trigger generator 290 is set to the high-pass mode by the changeover switch 295 (see the upper part of FIG. 7). A half-wave component signal is output as the trigger signal Tri. That is, even if the reception intensity of the continuous wave signal changes, it is not necessary to adjust the trigger level, and a stable trigger signal Tri caused by the pulse wave signal or the burst wave signal can be generated. On the other hand, when the orientation target is a continuous wave signal, when the trigger generation unit 290 is set to the low-pass mode by the changeover switch 295 (see the lower part of FIG. 7), the signal of the DC component in which the half-wave signal is removed from the envelope signal Is output as the trigger signal Tri. That is, the trigger signal Tri that enters the trigger operation simultaneously with the start of the orientation can be generated due to the continuous wave signal without being affected by the pulse wave signal or the burst wave signal.

(Operation of the orientation unit 400)
The operation of the orientation unit 400 will be described by taking as an example the case where the trigger generation unit 290 is set to the high-pass mode. In this case, when the first receiving antenna 11a receives at least one of a pulse wave signal and a burst wave signal (a packet communication signal PS and a beacon signal BS, which will be described later), the AD conversion unit 300 transfers to the orientation unit 400. Difference frequency signals V1b (t), V1c (t), V3b (t), and V3c (t) are input. Assume that a burst wave signal is transmitted from a plurality of telemetry transmitters. This telemetry transmitter is attached to an animal and transmits a burst wave signal including information on the behavior and state of the animal by wireless communication.

  FIG. 8 is a time chart illustrating a transmission pattern of burst wave signals of the first and second telemetry transmitters ID1 and ID2. As shown in FIG. 8, the burst wave signal includes a packet communication signal PS and a beacon signal BS. Each of the telemetry transmitters ID1 and ID2 repeatedly transmits the packet communication signal PS at the packet period TM1 and repeatedly transmits the beacon signal BS at the beacon period TM2. The beacon period TM2 is a period shorter than the packet period TM1, for example, the packet period TM1 is 10 s, and the beacon period TM2 is 2 s. In this way, the beacon signal BS having a shorter signal length than the packet communication signal PS is transmitted from the packet communication signal PS while transmitting the packet communication signal PS, which is obliged to be transmitted by the Radio Law, as long as possible. By transmitting with a short transmission cycle, it is possible to suppress the power consumption of the telemetry transmitter as compared with the case where only the packet communication signal PS is transmitted. Moreover, since the transmission cycle of the beacon signal BS can be shorter than the transmission cycle of the packet communication signal PS, the movement of the target animal can be appropriately tracked.

  The packet communication signal PS includes the type of animal to which each telemetry transmitter ID1, ID2 is attached and the identification information (ID1, ID2) of each telemetry transmitter ID1, ID2. Further, the signal length (transmission width) ΔTM1 of the packet communication signal PS transmitted from the first and second telemetry transmitters ID1 and ID2 is the same length, for example, about 80 ms. On the other hand, the signal length ΔTM2 of the beacon signal BS transmitted from the first telemetry transmitter ID1 and the signal length ΔTM3 of the beacon signal BS transmitted from the second telemetry transmitter ID2 are different from each other. The length ΔTM2 is 12 ms, and the signal length ΔTM3 is 24 ms. The signal lengths ΔTM2 and ΔTM3 of each beacon signal BS are both shorter than the signal length (transmission width) ΔTM1 of the packet communication signal PS.

  When the difference frequency signals V1b (t), V1c (t), V3b (t), and V3c (t) are input, the CPU 410 of the orientation unit 400 executes the orientation process shown in FIG. The CPU 410 determines whether the received radio wave signal is a pulse wave signal or a burst wave signal based on the input difference frequency signals V1b (t), V1c (t), V3b (t), V3c (t). Identify. Here, in general, the signal length (pulse width) of a pulse wave signal is several ns, whereas the signal length (burst width) of a burst wave signal is several ms, so both signal lengths are large. Different. Further, the detection time length (signal length, duration length) of any one of the difference frequency signals V1b (t), V1c (t), V3b (t), and V3c (t) is the signal length of the radio signal. It has been confirmed by experiments that it is proportional to. Therefore, based on the difference in the detection time length, it is possible to identify whether the received radio wave signal is a pulse wave signal or a burst wave signal.

  Specifically, the CPU 410 measures the detection time length of any one of the difference frequency signals V1b (t), V1c (t), V3b (t), and V3c (t) (S110). At this time, the CPU 410 functions as a “measurement unit” in the claims. The CPU 410 determines that the received radio wave signal is a burst based on whether or not the measured detection time length is equal to or greater than a first threshold value (a value between a signal length of a general burst wave signal and a signal length of a pulse wave signal). Whether it is a wave signal or a pulse wave signal is identified. At this time, the CPU 410 functions as a “first identification unit” in the claims. In S120, when CPU 410 identifies that the received radio wave signal is a burst wave signal (YES), CPU 410 identifies whether the burst wave signal is packet communication signal PS or beacon signal BS (S130). As described above, since the signal lengths ΔTM2 and ΔTM3 of the beacon signals BS are both shorter than the signal length (transmission width) ΔTM1 of the packet communication signal PS, the detection time length is the second threshold (for example, the signal length). Whether or not the burst wave signal is the packet communication signal PS or the beacon signal BS based on whether or not the value is greater than or equal to the value ΔTM1 and the signal length ΔTM2 or the signal length ΔTM3). it can.

  In S130, when the CPU 410 identifies that the burst wave signal is the packet communication signal PS (YES), the CPU 410 acquires the identification information included in the packet communication signal PS, and from the acquired identification information, Whether the transmission source is the first or second telemetry transmitter ID1, ID2 is identified (S140). In S130, when the CPU 410 identifies that the burst wave signal is not the packet communication signal PS, that is, the beacon signal BS (NO), the transmission source of the beacon signal BS is the first based on the detection time length measured in S110. The first telemetry transmitter ID 1 or the second telemetry transmitter ID 2 is identified (S150). Here, in the memory 420, identification information (ID1, ID2) of each telemetry transmitter ID1, ID2, and the signal length (ΔTM2, ΔTM3) of the beacon signal BS transmitted from each telemetry transmitter ID1, ID2 are stored. Correspondence information indicating the correspondence relationship is stored. Therefore, the CPU 410 identifies whether the source of the beacon signal BS is the first or second telemetry transmitter ID1, ID2 based on the detection time length measured in S110 and the correspondence information. be able to. At this time, the CPU 410 functions as a “second identification unit” in the claims. In S120, if the detection time length measured in S110 is less than the first threshold (NO), the CPU 410 identifies that the received radio wave signal is a pulse wave signal (S160).

After executing any of the processes of S140, S150, and S160, the CPU 410 calculates the arrival time differences Δt2 and Δt3 based on the difference frequency signals V1b (t), V1c (t), V3b (t), and V3c (t). (S170). Specifically, equation (32) is established from equation (22) and equation (24) described above, and equation (33) is established from equation (23) and equation (25).
tan (ωΔt2) = V3b (t) / V1b (t) (32)
tan (ωΔt3) = V3c (t) / V1c (t) (33)
Thereby, the arrival time differences Δt 2 and Δt 3 are
Δt2 = ω ⁻¹ × arctan (V3b (t) / V1b (t)) (34)
Δt3 = ω ⁻¹ × arctan (V3c (t) / V1c (t)) (35)
As can be obtained.

  Thus, the CPU 410 can calculate the arrival time difference Δt2 of the radio signal of the second receiving antenna 11b with respect to the first receiving antenna 11a which is the reference antenna, using the output values V1b, V3b and (34). . Similarly, the arrival time difference Δt3 of the electromagnetic pulse wave signal of the third receiving antenna 11c with respect to the first receiving antenna 11a which is the reference antenna can be calculated using the output values V1c, V3c and (35). Since the arrival time difference Δt and the phase difference Θ have a relationship of Θ = 2πfΔt, the calculation of the arrival time difference Δt by the orientation unit 400 is synonymous with the calculation of the phase difference Θ.

After executing the processing of S170, the CPU 410 calculates the horizontal angle θx and the elevation angle θz of the arrival direction of the radio signal based on the arrival time differences Δt2, Δt3, etc. calculated in S170 (S180). FIG. 10 is a conceptual diagram for explaining a method of specifying the arrival direction of a radio signal transmitted from a transmission source. Since the transmission source of the radio signal is sufficiently far from the first to third reception antennas 11a, 11b, and 11c, the radio signal arriving at each reception antenna 11a, 11b, and 11c can be assumed to be a plane wave. The distance between the receiving antennas 11a, 11b, and 11c is D, the wavelength of the prescribed frequency (400 MHz) of the SAW filters 212a, 212b, and 212c of the analog phase processing circuit 200 (see FIG. 6) is λ, and the short side of the antenna element 12a When the angle between the portion 12ay (front direction of the antenna) and the arrival direction of the radio signal is θ, the phase difference Θ (= 2πfΔt) can be expressed as follows.
Θ = (D / λ) × sin (θ) (36)

FIGS. 11 and 12 are conceptual diagrams for explaining a method of specifying the arrival direction of the radio signal transmitted from the transmission source when the receiving antennas 11a, 11b, and 11c are arranged at the vertices of the equilateral triangle. . The three receiving antennas 11a, 11b, and 11c are arranged at the vertices of an equilateral triangle on the YZ plane, and the antenna interval (length of one side of the equilateral triangle) D is λ / 4. . The position vectors r1, r2, r3 of the first to third receiving antennas 11a, 11b, 11c can be expressed as follows.
r1 = (0,0,0) (37)
r2 = (0, + (λ / 4) × sin (π / 6), − (λ / 4) × cos (π / 6)) (38)
r3 = (0, − (λ / 4) × sin (π / 6), − (λ / 4) × cos (π / 6)) (39)

An arrival direction vector (unit vector) of the radio signal from the transmission source is represented by v. The angle formed by the position vector r2 of the second receiving antenna 11b with respect to the first receiving antenna 11a and the arrival direction vector v is δ21, and the position vector r3 of the third receiving antenna 11c with respect to the first receiving antenna 11a and the direction of arrival. If the angle formed with the vector v is δ31, it can be expressed as follows.
cos (δ21) = <v, r2> / | r2 | = 4 <v, r2> / λ (40)
cos (δ31) = <v, r3> / | r3 | = 4 <v, r3> / λ (41)
Here, <v, r> is an inner product of the arrival direction vector v and the position vector r.

Here, the sum r2 + r3 of the position vectors is a vector on the Z-axis, and the difference r2-r3 of the position vectors is a vector on the Y-axis. The angle formed by the sum r2 + r3 of the position vectors that are vectors on the Z axis and the arrival direction vector v is θz, and the angle formed by the difference r2−r3 of the position vectors that are vectors on the Y axis and the arrival direction vector v is θy. Then, it can be expressed as follows.
cos (θz) = <v, r2 + r3> / | r2 + r3 |
= 4 · 3 ^-0.5 (<v, r2> + <v, r3>) / λ (42)
cos (θy) = <v, r2-r3> / | r2-r3 |
= 4 (<v, r2>-<v, r3>) / λ (43)
Further, the horizontal angle φx of the arrival direction vector v can be expressed as follows.
sin (φx) = cos (θy) / sin (θz) (44)

From the above, the horizontal angle φx and the elevation angle θz of the arrival direction vector v can be expressed as follows.
θz = arccos (4 · 3 ^−0.5 (<v, r2> + <v, r3>) / λ)
= Arccos (3 ^-0.5 (cos (δ21) + cos (δ31))) (45)
φx = arcsin (cos (θy) / sin (θz))
= Arcsin ((cos (δ21) −cos (δ31)) / (1-cos ² (θz)) ^0.5 ) (46)

Here, returning to FIG. 10, when the angle formed by the position vector r and the arrival direction vector v is transformed using Equation (36), it can be expressed as follows.
Θ = (D / λ) × sin (θ) = (D / λ) × sin (δ−π / 2) = − (D / λ) × cos (δ) (47)
That is, the elevation angle θz can be calculated from the sum of the phase differences, and the horizontal angle φx can be calculated from the phase difference difference and the elevation angle θz. As described above, the CPU 410 can calculate the horizontal angle φx and the elevation angle θz in the arrival direction of the radio signal based on the difference frequency signals V1b (t), V1c (t), V3b (t), and V3c (t). .

  After executing the process of S180, the CPU 410 associates the horizontal angle φx and the elevation angle θz calculated in S180 with the identification results in the processes of S140, S150, and S160 and outputs them to the display processing unit 500 (S190). The process ends.

(Operation of display processing unit 500)
The display processing unit 500 inputs the horizontal angle φx in the arrival direction of the electromagnetic pulse signal calculated by the orientation unit 400, the elevation angle θz, and the image data of the subject imaged by the camera 18 of the antenna unit 10, and performs image display processing. And output to the display device 30. FIG. 13 is an image diagram illustrating an example of the orientation result displayed on the display device 30. On the display screen 31 of the display device 30 (see FIG. 1), a scale 33 composed of horizontal / vertical straight lines and a plurality of concentric circles is superimposed on the image 32 captured by the camera 18. . Further, on the display screen 31, a mark 34 indicating the orientation position of the transmission source is displayed superimposed on the position specified by the horizontal angle φx and the elevation angle θz in the arrival direction of the electromagnetic pulse signal. As a result, the direction of arrival of the radio signal, and further, the source of the radio signal can be easily specified. Further, the mark 34 differs according to the identification result in the processing of S140, S150, and S160 described above. For example, if the radio wave signal is a pulse wave signal, the mark 34 is a mark indicating the pulse wave signal. If the radio wave signal transmission source is a telemetry transmitter, the mark 34 indicates identification information of the telemetry transmitter. Mark. Thereby, not only the arrival direction of the radio wave signal but also the type of the radio wave signal (pulse wave signal, continuous wave signal, burst wave signal) and the type of transmission source (ID1, DI2) are specified from the display screen 31. Can do.

B. Modifications The technology disclosed in the present specification is not limited to the above-described embodiment, and can be modified into various forms without departing from the gist thereof. For example, the following modifications are also possible. .

  In the above embodiment, the radio wave arrival direction locating apparatus 1 having the first to third receiving antennas 11a, 11b, and 11c is exemplified as the radio wave arrival direction locating apparatus. However, the radio wave arrival direction locating apparatus is not limited to this. A configuration that includes two receiving antennas, calculates only one of the elevation angle θz and the horizontal angle φx of the arrival direction of the radio signal based on the signals output from these receiving antennas, and determines the arrival direction of the radio signal But you can. Further, the radio wave arrival direction locating device may be configured to include four or more receiving antennas.

  In the above embodiment, the LPFs 124a, 124b, and 124c are exemplified as the bypass filters. According to this, the LPFs 124a, 124b, and 124c function as down converters, and can calculate the arrival phase difference (time difference) of radio signals having a frequency higher than the central angular frequency of the LPFs 124a, 124b, and 124c. However, the bypass filter is not limited to this and may be a high-pass filter. In the above embodiment, if the LPFs 124a, 124b, and 124c are changed to high-pass filters, the high-pass filter functions as an up-converter, and the arrival phase difference (time difference) of the radio signal having a frequency lower than the central angular frequency of the high-pass filter is increased. Can be calculated.

  In the above-described embodiment, the signal may be distributed from the splitter 231 into three with equal power and the same phase, and one post-distributed signal may be used as an AD conversion synchronization signal (trigger signal) of the AD conversion unit 300. Further, the signal may be distributed from the splitter 263 into three signals with the same power and the same phase, and one post-distributed signal may be used as an AD conversion synchronization signal (trigger signal) of the AD conversion unit 300.

  In the above-described embodiment, the configuration including both the LPF 293 and the HPF 294 is illustrated as the filter circuit. However, the filter circuit is not limited thereto, and may be configured to include only one of the LPF 293 and the HPF 294. Further, the filter circuit may include a bandpass filter that can change the center angular frequency, and may be configured to switch between the high-pass mode and the low-pass mode by changing the center angular frequency.

  10: Antenna unit 11a, 11b, 11c: Receiving antenna 12a: Antenna element 12ay: Short side portion 12az: Long side portion 13a: Earth plate 14a: Radio wave absorber 15a: Air gap 16a: Opening portion 18: Camera 19: Support member 20 : Control unit 30: Display device 31: Display screen 32: Image 33: Scale 34: Mark 40: Tripod 100: Frequency conversion unit 111a, 111b, 111c: Input unit 113a, 113b, 113c: Output unit 114: Local oscillator 116: Splitter 117: Frequency setting unit 120a, 120b, 120c: Mixer 122a, 122b, 122c: Amplifier 124a, 124b, 124c: LPF 200: Analog phase processing circuit 210: Front end unit 211a, 211b, 21 1c: Input unit 212a, 212b, 212c: SAW filter 213a, 213b, 213c: Output unit 214: Local oscillator 215: SAW filter 216: Output unit 220: Amplification unit 221a, 221b, 221c: Input unit 222a, 222b, 222c: Preamplifier 223: Digital attenuator 223a, 223b, 223c: Digital attenuator 224a, 224b, 224c: Main amplifier 225: Input section 226: Attenuator 227: Main amplifier 230: First distribution circuit 231, 233: Splitter 232: Hybrid coupler 240: First 1 mixer section 241, 243b, 243c, 245: mixer 242, 244b, 244c, 246: amplifier 250: first LPF section 251, 252b, 252c, 2 3: LPF 260: Second distribution circuit 261, 262b, 262c, 263: Splitter 270: Second mixer unit 271b, 271c, 273b, 273c: Mixer 280: Second LPF unit 281b, 281c, 283b, 283c: LPF 290: Trigger Generator 291: Envelope detector 292: Splitter 293: LPF 294: HPF 295: Changeover switch 300: AD converter 400: Orientation unit 410: CPU 420: Memory 500: Display processing unit

Claims (9)

Radio wave arrival direction locating device,
An antenna unit having a plurality of receiving antennas for receiving a radio signal and outputting a first analog signal corresponding to the radio signal;
An oscillator configured to output a reference frequency signal and change the reference frequency;
A mixer for generating a mixed signal by mixing the first analog signal output from each of the receiving antennas and the signal of the reference frequency;
A band-pass filter that passes a second analog signal within a specified frequency band of each of the mixed signals generated by the mixer;
Calculating a phase difference between each of the second analog signals that has passed through the band-pass filter, and determining from the phase difference the direction of arrival of the radio signal received by the antenna unit;
A radio wave arrival direction locating apparatus. The radio wave arrival direction locating device according to claim 1, further comprising:
An A / D converter for A / D converting each of the second analog signals to generate a digital signal;
An envelope detector that envelope-detects at least one of the plurality of second analog signals and generates an envelope signal;
Among the envelope signals generated by the envelope detector, an analog signal of one component of a high frequency component and a low frequency component is passed, and the analog signal of the one component is a trigger signal for the A / D conversion A filter circuit that outputs to the A / D converter as
The said orientation part is a radio wave arrival direction orientation apparatus which calculates the phase difference between each said 2nd analog signal based on each said digital signal produced | generated by the said A / D converter. The radio wave arrival direction locating device according to claim 2,
The filter circuit is
A high-pass mode that passes an analog signal of a high-frequency component in the envelope signal and outputs the analog signal of the high-frequency component to the A / D converter as a trigger signal for the A / D conversion, and the envelope signal Among them, the low-frequency component analog signal is allowed to pass, and the low-frequency component analog signal is configured to be switchable to a low-pass mode that outputs the A / D conversion trigger signal to the A / D converter. Radio wave direction locator. The radio wave arrival direction locating device according to any one of claims 1 to 3, further comprising:
A quadrature detector that quadrature-detects at least one of the second analog signals and generates a quadrature detection signal;
When the length of the quadrature detection signal generated by the quadrature detector is greater than or equal to a threshold, the radio signal is identified as a burst wave signal, and the length of the quadrature detection signal is less than the threshold, A radio wave arrival direction locating apparatus comprising: a first identification unit that identifies that the radio wave signal is a pulse wave signal. The radio wave arrival direction locating device according to any one of claims 1 to 4, further comprising:
A quadrature detector for quadrature detection of at least one of the plurality of second analog signals;
A measuring unit for measuring the length of a signal quadrature detected by the quadrature detector;
Identification information that identifies each of a plurality of transmitters that periodically transmit burst wave signals having different lengths, and a memory that stores correspondence information indicating a correspondence relationship between the lengths of the burst wave signals;
Based on the length of the quadrature-detected signal measured by the measurement unit and the correspondence information, it identifies which of the plurality of transmitters is the source of the radio signal received by the receiving antenna. A radio wave arrival direction locating device, comprising: a second identification unit. The radio wave arrival direction locating device according to any one of claims 1 to 5,
The plurality of receiving antennas are disposed behind the first to third antenna elements and the first to third antenna elements, and are radio signals arriving from the rear with respect to the first to third antenna elements. And a grounding plate to block
The orientation unit includes a first phase difference that is a phase difference between the first analog signal output from the first antenna element and the first analog signal output from the second antenna element; Calculating a second phase difference which is a phase difference between the first analog signal output from the first antenna element and the first analog signal output from the third antenna element; From the phase difference and the second phase difference, calculate the horizontal angle and the elevation angle of the arrival direction of the radio signal received by the first to third antenna elements, and determine the arrival direction of the radio signal. Radio wave direction locator. The radio wave arrival direction locating device according to any one of claims 1 to 6, further comprising:
An imaging unit that captures an image in a front direction of the receiving antenna;
A display unit for displaying the image captured by the imaging unit;
A display processing unit,
The radio wave arrival direction locating device, wherein the display processing unit displays an instruction image indicating an arrival direction of the radio wave signal located by the orientation unit on the image displayed on the display unit. The radio wave arrival direction locating device according to any one of claims 1 to 7,
The prescribed frequency band of the bandpass filter includes a frequency of a low frequency component signal among each of the mixed signals generated by the mixer, and does not include a frequency of a high frequency component signal. Orientation device. A method for determining the direction of arrival of radio waves,
A step of generating a mixed signal by mixing a first analog signal corresponding to the radio wave signal and a signal of a reference frequency output from each of a plurality of receiving antennas that have received the radio wave signal;
Passing each of the mixed signals generated by the mixer through a second analog signal in a specified frequency band by a band-pass filter;
Changing the reference frequency to a value at which the second analog signal becomes a signal within the specified frequency band;
Calculating a phase difference between each second analog signal that has passed through the bandpass filter after the reference frequency has been changed;
A radio wave arrival direction locating method comprising: locating the arrival direction of the radio wave signal from the calculated phase difference.

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