JP2011007560A - Receiving device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a receiving device and method being new and improved, capable of obtaining a directivity electronically in reception, while suppressing the circuit scale.SOLUTION: The receiving device includes: a first number (integer of ≥3) of antennas for receiving a signal emitted from a radiator; a second number(integer of ≥2, the second number<the first number) of analog processing units for performing analog processing with respect to the signal received by antennas being connected; a connection changeover unit for, while one analog processing unit is connected to one antenna, changing antennas to be connected to the other analog processing units in succession; a transfer function acquisition unit for acquiring the differences of transfer functions between a signal acquired by the one analog processing unit through the one antenna, and signals acquired by the other analog processing units through the other antennas in the same time zone; and a multiplication unit for multiplying each of the differences between the transfer functions acquired by the transfer function acquisition unit based on signals acquired in a different time zone, by weights for directing corresponding to the other antennas connected to the other analog processing units.

Description

  The present invention relates to a receiving apparatus and a receiving method.

  An aircraft, a ship, and the like are provided with a radar for detecting surrounding targets (target objects). Specifically, an aircraft or a ship can detect a surrounding target by transmitting a signal and receiving a reflected wave. In recent years, research on millimeter wave radars for use in automobile collision prevention devices has been actively conducted.

  The above-described radar is roughly classified into an active radar and a passive radar. The active radar is a radar that detects a target by transmitting a signal and receiving a reflected wave, like a radar provided in an aircraft or a ship. On the other hand, a passive radar is a radar that detects the presence of a target by capturing a signal emitted from the target without transmitting a signal.

  For example, a passive radar used for millimeter wave detection includes a single signal, an RF (Radio Frequency) unit, and a digital signal processing unit via an AD conversion unit. This passive radar can detect in which direction the target is present by mechanically scanning the direction of one antenna and changing the direction of the beam. For this antenna, a parabolic antenna is used in order to obtain strong directivity.

  On the other hand, electronic scanning can be performed by using an array antenna. Specifically, a radar that uses an array antenna includes a plurality of branches each consisting of one antenna and one RF unit, and adjusts the amplitude and phase of the output from each branch with respect to the output from each branch. Directivity can be obtained electronically by digitally multiplying a weighting factor that determines directivity. However, since a plurality of branches are required to configure this radar, there is a problem that the cost increases.

  In order to solve this problem, an active radar including a plurality of antennas, one RF unit, and a switch that selectively connects the plurality of antennas to the RF unit has been proposed (see, for example, Non-Patent Document 1). . More specifically, this active radar transmits a periodic signal and sequentially switches antennas connected to one RF unit using a switch. Moreover, since this active radar transmits a periodic signal, it is possible to grasp and adjust a phase shift of periodic signals received via different antennas in different time zones.

S. Tokyo, A .; Kawakubo, K. et al. Fujita, H, Fujinami, “Electronically Scanned Millimeter-wave Radar for Pre-Crush Safety and Adaptive Cruise Control System”

  However, as described above, the passive radar is a radar that does not transmit a signal and detects the presence of the target by capturing a signal emitted from the target. In addition, a signal generated by a target such as a person existing in nature has no periodicity. Therefore, it has been difficult to obtain directivity by integrating signals received by a plurality of antennas in different time zones in a passive radar.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is a novel and improved technique capable of electronically obtaining directivity in reception while suppressing the circuit scale. And a receiving method.

  In order to solve the above-described problem, according to an aspect of the present invention, signals are received by a first number (an integer of 3 or more) of antennas that receive a signal emitted from a radiator and a connected antenna. While the second number (integer of 2 or more, second number <first number) of analog processing units for performing analog processing on the signal, one analog processing unit, and one antenna are connected, the other A connection switching unit for sequentially switching antennas connected to the analog processing unit, a signal obtained by the one analog processing unit via the first antenna, and the other signal via another antenna in the same time zone Each transfer function difference obtained by the transfer function obtaining unit based on signals obtained in different time zones, and a transfer function obtaining unit for obtaining a transfer function difference from the signal obtained by the analog processing unit And the other Receiving apparatus comprising: a multiplication unit for multiplying the directivity for weights corresponding to the other antenna is connected to the analog processing unit, it is provided.

  In order to solve the above problem, according to another aspect of the present invention, a first number (an integer of 3 or more) of antennas that receive a signal emitted from a radiator and a connected antenna A second number (two or more integers, a second number <first number) of analog processing units for performing analog processing on the received signal; the second number of analog processing units; and the first number A connection switching unit that switches the connection relationship of a number of antennas, and a signal for directivity corresponding to the antenna that is connected to each analog processing unit in each of the signals obtained by the second number of analog processing units in the same time zone A multiplier for multiplying weights, a correlation detector for detecting each correlation value of values obtained by the multiplier, and a correlation value detected by the correlation detector based on signals obtained in different time zones A correlation summation unit for summing Receiving apparatus is provided.

  In order to solve the above-described problem, according to another aspect of the present invention, a first number (an integer of 3 or more) of antennas that receive a signal emitted from a radiator, and connected antennas A second number (an integer greater than or equal to two, a second number <first number) of analog processing units that perform analog processing on the signal received by the receiving method, While connecting one analog processing unit and one antenna, a step of sequentially switching antennas connected to other analog processing units, and a signal obtained by the one analog processing unit via the one antenna A step of obtaining a transfer function difference from a signal obtained by the other analog processing unit via another antenna in the same time zone, and a signal obtained based on the signal obtained in a different time zone. And each of the difference of the transfer function, the reception method comprising the steps of multiplying the directivity for weights corresponding to the other antenna is connected to the other analog processing unit is provided.

  In order to solve the above-described problem, according to another aspect of the present invention, a first number (an integer of 3 or more) of antennas that receive a signal emitted from a radiator, and connected antennas A second number (an integer greater than or equal to two, a second number <first number) of analog processing units that perform analog processing on the signal received by the receiving method, A step of switching the connection relationship between the second number of analog processing units and the first number of antennas, and each analog processing for each of the signals obtained by the second number of analog processing units in the same time zone A step of multiplying a weight for directivity corresponding to the antenna connected to the unit, a step of detecting a correlation value of each of the values obtained by the multiplication, and a signal obtained in a different time zone. Correlation Receiving method comprising a step of summing.

  As described above, according to the receiving apparatus and the receiving method of the present invention, it is possible to obtain directivity in reception electronically while suppressing the circuit scale.

It is explanatory drawing which showed an example of the use of a passive radar. It is explanatory drawing which showed the structure of the radar using an array antenna. It is explanatory drawing which showed the arrival signal to each antenna of an active radar. It is explanatory drawing which showed the received signal of each antenna of the active radar in a different time slot | zone. It is explanatory drawing which showed the arrival signal to each antenna of a passive radar. It is explanatory drawing which showed the received signal of each antenna of the passive radar in a different time slot | zone. It is explanatory drawing which showed the structure of the passive radar concerning 1st Embodiment. It is explanatory drawing which showed the detailed structure of the transfer function acquisition part. It is explanatory drawing which showed the signal received in each antenna in a different time slot | zone. It is the flowchart which showed the flow of operation | movement of the passive radar concerning 1st Embodiment. It is explanatory drawing which showed the structure of the passive radar concerning 2nd Embodiment. It is the flowchart which showed the flow of operation | movement of the passive radar concerning 2nd Embodiment.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

Further, the “DETAILED DESCRIPTION OF THE INVENTION” will be described according to the following item order.
1. 1. Overview of passive radar and examples of applications Background First embodiment 3-1. Configuration of Passive Radar according to First Embodiment 3-2. 3. Operation of passive radar according to first embodiment Second embodiment 4-1. Configuration of Passive Radar according to Second Embodiment 4-2. 4. Operation of passive radar according to second embodiment Summary

<1. Overview of passive radar and examples of applications>
First, with reference to FIG. 1, the outline | summary of the passive radar 20 which is one Embodiment of this invention, and an example of an application are demonstrated.

  Radar is roughly classified into active radar and passive radar. The active radar is a radar that detects a target by transmitting a signal and receiving a reflected wave, like a radar provided in an aircraft or a ship. On the other hand, a passive radar is a radar that detects the presence of a target by capturing a signal emitted from the target without transmitting a signal.

  Here, it is known that an object having a certain temperature emits a wide-range (broadband) radio wave (signal) based on Planck's law. A human is an example of a radiator that emits such a signal. For this reason, as shown in FIG. 1, the passive radar 20 which is one embodiment of the present invention can detect a human as a target based on a signal emitted from the human.

  FIG. 1 is an explanatory diagram showing an example of use of the passive radar 20. As shown in FIG. 1, the passive radar 20 includes a plurality of antennas A1 to A10, and can receive signals emitted by humans with the plurality of antennas A1 to A10. Note that the radiation level of a signal emitted by a human depends on body temperature and frequency.

  Moreover, although mentioned later for details, the passive radar 20 can control the directivity in reception electronically. For example, the passive radar 20 can receive signals emitted from human parts by controlling directivity. Here, when a human conceals metal or liquid, the metal or liquid becomes an obstacle, and it is assumed that the signal that can be received is different between the part where the metal or liquid is concealed and the other part. For this reason, the passive radar 20 can be used for detection of dangerous materials such as metal as an example.

<2. Background>
Subsequently, as a background to the creation of the passive radar according to the embodiment of the present invention, problems of the radar related to the present invention will be described with reference to FIGS.

  FIG. 2 is an explanatory diagram showing the configuration of the radar 50 using the array antenna. As shown in FIG. 2, the radar 50 includes a plurality of antennas A1 to A10, a plurality of switches S1 to S10, a plurality of transmission processing units Tx1 to Tx10, a plurality of reception processing units Rx1 to Rx10, and a plurality of reception processing units Rx1 to Rx10. Digital / analog converters DA1 to DA10, a plurality of analog / digital converters AD1 to AD10, multipliers m1 to m10, a memory 52, and an adder 54 are provided.

  Each of the plurality of antennas A1 to A10 corresponds to one of the plurality of transmission processing units Tx1 to Tx10 and one of the plurality of reception processing units Rx1 to Rx10. Each of the plurality of antennas A1 to A10 is connected to a corresponding transmission processing unit Tx or reception processing unit Rx via a switch S1.

  For example, the transmission processing unit Tx1 and the reception processing unit Rx1 correspond to the antenna A1, and the antenna A1 is connected to the transmission processing unit Tx1 or the reception processing unit Rx1 via the switch S1. Such a pair of each antenna A and the corresponding transmission processing unit Tx and reception processing unit Rx is referred to as a branch.

  In each branch, the antenna A receives a signal coming from the target, and the reception processing unit Rx performs analog processing (RF processing) on the signal received by the antenna A. The analog / digital conversion unit AD converts the signal analog-processed by the reception processing unit Rx into a digital format, and the memory 52 holds the signal converted into the digital format.

  After that, the multipliers m1 to m10 multiply the signals obtained through the branches by the directional weights W (1) to W (K) that determine the directivity of the reception (antennas A1 to A10). . Thereby, the amplitude and phase of the signal obtained through each branch are adjusted. And the addition part 54 adds the multiplication value obtained by the multiplication parts m1-m10, and can obtain the array output corresponding to the signal transmitted from the specific direction.

  Here, the directional weight will be briefly described. In the example shown in FIG. 1, the signal comes from the direction of θ. In this case, the signals received by each of the antennas A1 to A10 arranged at the interval D are different in phase by “2π / λ × D × sin (θ)”. The directing weight for directing the receiving direction (beam) in the θ direction is created so as to cancel this phase difference.

  The directional weight can be created by various methods. For example, when scanning in the direction of 360 degrees in increments of 10 degrees, 36 types of directing weights are prepared for each of the antennas A1 to A10. A signal from the direction corresponding to the directional weight can be obtained as an array output by multiplying the signals obtained via the antennas A1 to A10 by one directional weight and totaling the signals.

  Furthermore, the radar 50 can obtain each of signals from 36 directions as an array output by performing the above multiplication and total using 36 kinds of directional weights. As a result, for example, it is possible to estimate that the direction corresponding to the largest array output is the signal arrival direction.

  However, the radar 50 using this array antenna requires the same number of RF units (transmission processing units Tx1 to Tx10 and reception processing units Rx1 to Rx10) as the antennas A1 to A10, which increases the cost. There's a problem. In order to solve this problem, there has been proposed an active radar that includes a plurality of antennas and one RF unit and sequentially switches antennas connected to the one RF unit. The active radar will be described below with reference to FIGS. 3 and 4.

  FIG. 3 is an explanatory view showing signals reaching the antennas of the active radar. Since the active radar transmits a predetermined repetitive signal, the repetitive signal reflected at the target reaches each of the antennas A1 to A10 arranged in order as shown in FIG. Note that FIG. 3 shows an example in which the phase delay increases as the antenna number increases because the target is closest to the antenna A1 and farthest from the antenna A10.

  Further, this active radar switches the antenna connected to the RF unit at the cycle of the repetitive signal. For example, as shown in FIG. 3, the active radar switches the connection destination with the RF unit in the order of antenna A1, antenna A2, and antenna A3. The signals received at each antenna by this switching are shown in FIG.

  FIG. 4 is an explanatory diagram showing received signals of the respective antennas in different time zones. As shown in FIG. 4, by performing switching of the reception antennas in a repeated signal cycle, the reception signals of the respective antennas in different time zones have the same waveform as the signals reaching the respective antennas in the same time zone.

  Specifically, the waveform of the reception signal of the antenna A2 in the time zones t13 to t14 matches the waveform of the signal reaching the antenna A2 in the time zones t11 to t12. Similarly, the waveform of the reception signal of the antenna A3 in the time zones t15 to t16 matches the waveform of the signal reaching the antenna A3 in the time zones t11 to t12.

  In other words, this active radar can obtain a signal equivalent to a case where signals are received by all the antennas in the same time period by switching the reception antenna at the cycle of the repeated signal. Therefore, this active radar can obtain the directivity similar to that of the radar 50 described with reference to FIG. 2 by multiplying each of the signals obtained in different time zones by the weight for directivity.

  However, as described above, the passive radar is a radar that does not transmit a signal and detects the presence of the target by capturing a signal emitted from the target. In addition, a signal generated by a target such as a person existing in nature has no periodicity. Therefore, as described with reference to FIGS. 5 and 6, it is difficult to obtain directivity by integrating signals received by a plurality of antennas in different time zones in a passive radar.

  FIG. 5 is an explanatory diagram showing signals reaching each antenna of the passive radar. As shown in FIG. 5 as an example, a signal emitted from a target such as a human body has no periodicity. For this reason, as shown in FIG. 6, even if the antenna is periodically switched and received, the waveform of the received signal obtained by reception of each antenna is greatly different. That is, as shown in FIG. 6, the waveform of the reception signal of antenna A1 in time zones t21 to t22, the waveform of the reception signal of antenna A2 in time zones t23 to t24, and the reception signal of antenna A3 in time zones t25 to t26 There is no correlation between the waveforms.

  Under the background described above, the passive radar 20 according to the first embodiment of the present invention and the passive radar 20 'according to the second embodiment have been created. According to the passive radar 20 according to the first embodiment and the passive radar 20 ′ according to the second embodiment, directivity can be obtained electronically based on signals received by different antennas in different time zones. It is. Hereinafter, the passive radar 20 according to the first embodiment and the passive radar 20 'according to the second embodiment will be described in detail.

<3. First Embodiment>
(3-1. Configuration of Passive Radar According to First Embodiment)
FIG. 7 is an explanatory diagram showing the configuration of the passive radar 20 according to the first embodiment. As shown in FIG. 7, the passive radar 20 according to the first embodiment includes ten antennas A1 to A10, two reception processing units Rx1 and Rx2, two analog / digital conversion units AD1 and AD2, A plurality of multiplication units m1 to m10, a switch 21, a memory 22, a transfer function acquisition unit 24, a switch 26, and an addition unit 28 are provided.

  The plurality of multiplication units m1 to m10, the transfer function acquisition unit 24, the switch 26, and the addition unit 28 can be configured by a DSP (Digital Signal Processor).

  The antennas A1 to A10 are arranged on the passive radar 20 at regular intervals (D), for example. Each of the antennas A1 to A10 can receive a signal emitted from a radiator such as a human being as a target. In addition, each of the antennas A1 to A10 is connected to one side of the switch 21.

  The switch 21 has the antennas A1 to A10 connected to one side and the reception processing units Rx1 and Rx2 connected to the other side. The switch 21 functions as a connection switching unit that switches the connection relationship between the antennas A1 to A10 and the reception processing units Rx1 and Rx2.

  More specifically, the switch 21 sequentially connects the antennas A2 to A10 to the reception processing unit Rx2 while the antenna A1 and the reception processing unit Rx1 are connected. A set of the antenna A1 and the reception processing unit Rx1 is referred to as a basic branch, and a set of the antenna A and the reception processing unit Rx2 connected to the reception processing unit Rx2 is referred to as a target branch.

  Each of the reception processing units Rx1 and Rx2 functioning as the RF unit performs analog processing on a signal received by the antenna A connected via the switch 21. Specifically, each of the reception processing units Rx1 and Rx2 includes a frequency conversion unit, a filter, and the like, and down-converts a signal received by the antenna to a predetermined frequency band.

  FIG. 7 illustrates an example in which the number of antennas A is 10 and the number of reception processing units Rx is 2. However, the present embodiment is not limited to this example. For example, the number of antennas A is not particularly limited as long as it is a first number that is an integer of 3 or more. Further, the number of reception processing units Rx is not particularly limited as long as it is an integer equal to or larger than 2 and is a second number smaller than the first number.

  The analog / digital conversion units AD1 and AD2 convert the signals analog-processed by the reception processing units Rx1 and Rx2 into a digital format. Specifically, the analog / digital conversion unit AD1 obtains the reception data of the basic branch by converting the signal analog-processed by the reception processing unit Rx1 into a digital format. The analog / digital conversion unit AD2 obtains reception data of the target branch by converting the signal analog-processed by the reception processing unit Rx2 into a digital format.

  The memory 22 holds a pair of reception data of the basic branch and reception data of the target branch obtained by the analog / digital conversion units AD1 and AD2 in the same time zone. As described above, the switch 21 sequentially connects the antennas A2 to A10 to the reception processing unit Rx2 while the antenna A1 and the reception processing unit Rx1 are connected. Is retained.

  The transfer function obtaining unit 24 obtains one pair of received data from the memory 22 one by one, and obtains a difference between transfer functions of each received data constituting the received data pair based on correlation detection. For example, the transfer function acquisition unit 24 acquires a pair of the reception data of the basic branch obtained via the antenna A1 and the reception data of the target branch obtained via the antenna A2, and performs a process on the reception data of the basic branch. Get the transfer function difference of the received data of the target branch. The transfer function difference means a phase or amplitude difference caused by an optical path difference or the like. Here, with reference to FIG. 8, the detailed structure of such a transfer function acquisition part 24 is demonstrated.

  FIG. 8 is an explanatory diagram showing a detailed configuration of the transfer function acquisition unit 24. As shown in FIG. 8, the transfer function acquisition unit 24 includes a plurality of shift registers 32A and 32B, a variable delay unit 34, a multiplication unit 36, an addition unit 37, a phase difference / amplitude difference detection unit 38, Is provided.

  The shift register 32A receives the received data of the basic branch, and sequentially shifts the input received data of the basic branch to the subsequent register.

  The variable delay unit 34 delays the reception data of the target branch. Note that the variable delay unit 34 can change the delay time of the reception data of the target branch. The shift register 32B receives the reception data of the target branch delayed by the variable delay unit 34, and sequentially shifts the input reception data of the target branch to the rear register.

  The multiplication unit 36 multiplies the reception data of the basic branch held in the shift register 32A and the reception data of the target branch held in the shift register 32B. Then, the adding unit 37 adds up the multiplication values obtained by the multiplication in the multiplication unit 36.

  The phase difference / amplitude difference detection unit 38 detects the phase difference and amplitude difference between the reception data of the target branch and the reception data of the basic branch based on the total value obtained by the addition unit 37. More specifically, when the delay time in the variable delay unit 34 corresponds to the phase difference, the peak value is obtained by the adding unit 37. Therefore, the phase difference / amplitude difference detection unit 38 detects the delay time in the variable delay unit 34 when the peak value is obtained by the addition unit 37 as the phase difference between the reception data of the basic branch and the reception data of the target branch. May be. Further, the phase difference / amplitude difference detection unit 38 may detect the amplitude difference by comparing the same waveform portion of the reception data of the basic branch and the reception data of the target branch after detecting the phase difference.

  Here, the phase difference / amplitude difference detection will be described more specifically with reference to FIG. FIG. 9 is an explanatory diagram showing signals received at the respective antennas A in different time zones. As shown in FIG. 9, the signals received from the antennas A1 and A2 in the time zones t1 to t2 have a phase difference, but the waveforms partially match. Therefore, since the peak value is obtained when the delay time in the variable delay unit 34 corresponds to the phase difference, the phase difference / amplitude difference detection unit 38 can detect the delay time at this time as the phase difference.

  Similarly, the signals received from the antennas A1 and A3 in the time zones t3 to t4 have a phase difference but partially match in waveform. Therefore, since the peak value is obtained when the delay time in the variable delay unit 34 corresponds to the phase difference, the phase difference / amplitude difference detection unit 38 can detect the delay time at this time as the phase difference. The same applies to the antennas A4 to A10.

The transfer function acquisition unit 24 acquires the transfer function indicating the phase difference and the amplitude difference in this way, and holds the acquired transfer function in association with the branch. An example of the transfer function held by the transfer function acquisition unit 24 is shown below. A _{2 to} A ₁₀ correspond to amplitude differences, and θ ₂ to θ ₁₀ correspond to phase differences.

  The switch 26 supplies the transfer function of each branch held by the transfer function acquisition unit 24 to the multiplication unit m that performs multiplication of the directional weight corresponding to the branch among the multiplication units m1 to m10.

For example, the transfer function “1” of the branch including the antenna 1 is supplied to the multiplication unit m1 via the switch 26, and the multiplication unit m1 is directed to the branch weight including the antenna 1 and the transfer function “1”. ". Similarly, the transfer function “A ₂ e ^jθ2 ” of the branch including the antenna 2 is supplied to the multiplication unit m2 via the switch 26, and the multiplication unit m2 and the directional weight W (2) corresponding to the branch including the antenna 2 Multiply the transfer function “A ₂ e ^jθ2 ”. Multipliers m3 to m10 perform similar processing. The multiplication of the directional weight is a process corresponding to the parallel movement of the waveform on the time axis.

  The adder 28 adds up the multiplication values obtained by the multiplications in the multipliers m1 to m10. The total value obtained as an array output by the adder 28 indicates a signal transmitted from the direction corresponding to the directional weights W (1) to (K) multiplied by the multipliers m1 to m10. Therefore, the passive radar 20 can obtain signals transmitted from other directions by changing the directional weights W (1) to (K) to values corresponding to the other directions.

(3-2. Operation of Passive Radar According to First Embodiment)
Next, the operation flow of the passive radar 20 according to the first embodiment will be described.

The operation of the passive radar 20 according to the first embodiment mainly includes the following five steps.

(Step 1)
In advance, the number of directivity weights corresponding to the reception direction is created for each reception direction.

(Step 2)
In nine different time zones, a received data pair consisting of the received data of the basic branch and the received data of the target branch is acquired, and the received data pair is stored in the memory 22.
For (i = 2; i <10; i ++) {
The antenna A1 and the reception processing unit Rx1 are connected.
The antenna A (i) and the reception processing unit Rx2 are connected.
}

(Step 3)
The phase of the reception data of the basic branch obtained by the combination of the antenna A1 and the reception processing unit Rx1 and the reception data of the target branch obtained by the combination of the antenna A (i) and the reception processing unit Rx2 And the amplitude are compared to obtain the difference of the transfer function for the basic branch. The pair of received data to be compared at this time is composed of received data acquired in the same time zone.

(Step 4)
Multipliers m1 to m10 multiply the transfer function of each branch obtained in step 3 by the directional weight corresponding to each branch. The array output obtained by the sum of the multiplication values in the adder 28 corresponds to a received signal having a directivity in a specific direction.

(Step 5)
In order to change the reception directivity, the directivity weight used in step 4 is changed to a weight corresponding to another direction, and step 4 is repeated.

  The operation flow of the passive radar 20 according to the first embodiment as described above is shown in FIG. 10 as a flowchart.

  As shown in FIG. 10, first, the passive radar 20 sets the directional weight corresponding to each reception direction to each branch (S304). Then, the switch 21 connects the antenna A1 and the reception processing unit Rx1 (S308). Further, “i” is set to “2”, the switch 21 connects the antenna Ai and the reception processing unit Rx2 (S316), and a pair of reception data obtained in the basic branch and reception data obtained in the target branch is obtained. The memory 22 holds (S320). If “i = 10” is not satisfied (S324), the passive radar 20 adds “1” to “i” (S326), and repeats the processing from S316.

  Thereafter, the transfer function acquisition unit 24 acquires the difference of the transfer function of the reception data of the target branch with respect to the reception data of the basic branch based on each reception data constituting the pair of reception data held in the memory 22 ( S328).

  Subsequently, the multipliers m1 to m10 multiply the difference between the transfer functions of the respective branch branches by the directing weight corresponding to each branch (S332). Furthermore, by adding the multiplication values obtained in S332 (S336), the adding unit 28 can realize directional reception from the direction corresponding to the directional weight multiplied in S332.

  In addition, when changing the reception directivity (S340), the passive radar 20 changes the directivity weight corresponding to each branch (S344), and repeats the processing from S332.

  As described above, the passive radar 20 according to the first embodiment multiplies the difference in the transfer function with respect to the basic branch by the directing weight, not the reception data itself obtained by different branches in different time zones. . For this reason, according to the passive radar 20 according to the first embodiment, it is possible to realize directional reception of a signal having no periodicity emitted from a radiation pair such as a human while suppressing the number of reception processing units Rx. Is possible.

<4. Second Embodiment>
Next, a passive radar 20 ′ according to a second embodiment of the present invention will be described with reference to FIG. 11 and FIG. In the passive radar 20 ′ according to the second embodiment, the transfer function acquisition unit 24 that detects the phase difference and the amplitude difference described with reference to FIG. Can be planned.

(4-1. Configuration of Passive Radar According to Second Embodiment)
FIG. 11 is an explanatory diagram showing a configuration of a passive radar 20 ′ according to the second embodiment. As shown in FIG. 11, the passive radar 20 ′ according to the second embodiment includes ten antennas A1 to A10, two reception processing units Rx1 and Rx2, and two analog / digital conversion units AD1 and AD2. , A plurality of multiplication units m1 to m10, a switch 41, a memory 42, a switch 43, a correlation detection unit 44, and a correlation summation unit 46.

  The plurality of multiplication units m1 to m10, the correlation detection unit 44, and the correlation summation unit 46 can be configured by a DSP (Digital Signal Processor).

  The antennas A1 to A10 are arranged on the passive radar 20 'at a constant interval (D), for example. Each of the antennas A1 to A10 can receive a signal emitted from a radiator such as a human being as a target. In addition, each of the antennas A1 to A10 is connected to one side of the switch 41.

  In the switch 41, the antennas A1 to A10 are connected to one side, and the reception processing units Rx1 and 2 are connected to the other side. The switch 21 functions as a connection switching unit that switches the connection relationship between the antennas A1 to A10 and the reception processing units Rx1 and Rx2.

  More specifically, the switch 41 sequentially connects the antennas A1 to A10 with the reception processing unit Rx1, and while the same antenna A is connected to the reception processing unit Rx1, the other antenna A is subjected to reception processing. Connected sequentially to the part Rx2.

  For example, the switch 41 sequentially connects the antennas A2 to A10 to the reception processing unit Rx2 while the antenna A1 and the reception processing unit Rx1 are connected. Thereafter, the switch 41 connects the antenna A2 and the reception processing unit Rx1, and while the antenna A2 and the reception processing unit Rx1 are connected, the antenna A1 and the antennas A3 to A10 are sequentially connected to the reception processing unit Rx2.

  Each of the reception processing units Rx1 and Rx2 functioning as the RF unit performs analog processing on a signal received by the antenna A connected via the switch 41. Specifically, each of the reception processing units Rx1 and Rx2 includes a frequency conversion unit, a filter, and the like, and down-converts a signal received by the antenna to a predetermined frequency band.

  Although FIG. 11 illustrates an example in which the number of antennas A is 10 and the number of reception processing units Rx is 2, the present embodiment is not limited to such an example. For example, the number of antennas A is not particularly limited as long as it is a first number that is an integer of 3 or more. Further, the number of reception processing units Rx is not particularly limited as long as it is an integer equal to or larger than 2 and is a second number smaller than the first number.

  The analog / digital conversion units AD1 and AD2 convert the signals analog-processed by the reception processing units Rx1 and Rx2 into a digital format. Specifically, the analog / digital conversion unit AD1 converts the signal analog-processed by the reception processing unit Rx1 into a digital format. The analog / digital converter AD2 converts the signal analog-processed by the reception processor Rx2 into a digital format.

  The memory 42 holds a pair of reception data obtained by the analog / digital conversion units AD1 and AD2 in the same time zone. As described above, the switch 41 sequentially connects the antennas A1 to A10 with the reception processing unit Rx1, and while the same antenna A is connected to the reception processing unit Rx1, the other antenna A is subjected to reception processing. In order to connect sequentially to the unit Rx2, 90 pairs of received data (180 received data) are held in the memory.

  The switch 43 is a multiplier that multiplies each of the 90 received data pairs held in the memory 42 by a directional weight corresponding to the branch from which the received data is obtained, among the multipliers m1 to m10. m. For example, regarding a pair of reception data obtained via the antenna A1 and reception data obtained via the antenna A8, the switch 43 supplies the reception data obtained via the antenna A1 to the multiplication unit m1, The reception data obtained via the antenna A8 is supplied to the multiplication unit m8.

  Multipliers m <b> 1 to m <b> 10 multiply the reception data supplied via switch 43 by the directional weight. For example, reception data obtained via the antenna A1 is supplied to the multiplication unit m1, and this reception data is multiplied by a directional weight W (1) corresponding to the antenna A1.

  The correlation detection unit 44 detects the correlation value of the received data pair multiplied by the directing weight by the multiplication units m1 to m10. This correlation value increases when the direction corresponding to the directional weight applied to the multiplication units m1 to m10 matches the actual arrival direction of the signal.

  The correlation summation unit 46 sums the correlations of all the received data pairs detected by the correlation detection unit 44, and outputs the total value as an array output. As described above, the correlation value of each pair of received data increases when the corresponding direction of the directional weight matches the actual arrival direction of the signal, and thus the total value obtained by the correlation summation unit 46 is also directional. It becomes larger when the corresponding direction of the use weight matches the actual arrival direction of the signal.

  That is, the total value obtained as the array output by the correlation summation unit 46 indicates the strength of the signal transmitted from the direction corresponding to the directional weights W (1) to (K) multiplied by the multiplication units m1 to m10. Show. Therefore, the passive radar 20 'can obtain the strength of signals transmitted from other directions by changing the directional weights W (1) to (K) to values corresponding to the other directions.

(4-2. Operation of Passive Radar according to Second Embodiment)
Next, the operation flow of the passive radar 20 ′ according to the second embodiment will be described.

The operation of the passive radar 20 ′ according to the first embodiment mainly includes the following four steps.

(Step 1)
In advance, the number of directivity weights corresponding to the reception direction is created for each reception direction.

(Step 2)
The connection relationship between the antenna A and the reception processing unit Rx is switched every 90 time zones, and pairs of reception data obtained via the reception processing units Rx1 and Rx2 are accumulated in the memory 22 in each time zone.
For (i = 1; i <10; i ++) {
For (j = 1; j <10; j ++) {
If (i! = J) {
The antenna A (i) and the reception processing unit Rx (1) are connected.
The antenna A (j) and the reception processing unit Rx (2) are connected.
}
}
}

(Step 3)
Multiply the directional weights as follows.
Array output = 0.0;
Buffer 1 = 0.0;
Buffer 2 = 0.0;
Buffer 3 = 0.0;
For (i = 1; i <10; i ++) {
For (j = 1; j <10; j ++) {
If (i! = J) {
Buffer 1 = received data obtained via antenna A (i) ×
Directional weight corresponding to antenna A (i)
Buffer 2 = received data obtained via antenna A (j) ×
Directional weight corresponding to antenna A (j)
// Process 1
Calculate the correlation value between buffer 1 and buffer 2,
Input correlation value into buffer 3.
Array output = Array output + Buffer 3
}
}
}

(Step 4)
In order to change the directivity of reception, the directivity weight used in step 3 is changed to a weight corresponding to another direction, and step 3 is repeated.

  The flow of the operation of the passive radar 20 'according to the second embodiment as described above is shown as a flowchart in FIG.

  As shown in FIG. 12, first, the passive radar 20 'sets the directional weight corresponding to each reception direction to each branch (S404). The switch 41 sequentially connects the antennas A1 to A10 with the reception processing unit Rx1 and connects the other antenna A to the reception processing unit Rx2 while the same antenna A is connected to the reception processing unit Rx1. Connections are made sequentially (S408). Here, the memory 42 holds a pair of received data obtained by each combination in the same time zone.

  Thereafter, the switch 43 corresponds to the unprocessed received data pair among the 90 received data pairs held in the memory 42, among the multipliers m1 to m10, to the branch from which the received data is obtained. To the multiplication unit m that performs multiplication of the directional weights. Then, the multiplication unit m to which the received data is supplied multiplies the supplied received data by the directional weight corresponding to the branch from which the received data is obtained (S416).

  Subsequently, the correlation detection unit 44 detects the correlation value of the multiplied received data pair (S420), and the correlation summation unit 46 accumulates the correlation value obtained in S420 (S424). The passive radar 20 'repeats the processing of S416 to S424 described above until there is no unprocessed received data pair (S428).

  Further, when changing the reception direction (S432), the passive radar 20 'changes the direction weight corresponding to each branch (S436) and repeats the processing from S416.

<5. Summary>
As described above, the passive radar 20 according to the first embodiment multiplies the difference in the transfer function with respect to the basic branch by the directing weight, not the reception data itself obtained by different branches in different time zones. . For this reason, according to the passive radar 20 according to the first embodiment, it is possible to realize directional reception of a signal having no periodicity emitted from a radiation pair such as a human while suppressing the number of reception processing units Rx. Is possible.

  Further, since the passive radar 20 ′ according to the second embodiment does not have to implement the transfer function acquisition unit 24 that detects the phase difference and the amplitude difference, the passive radar 20 ′ according to the second embodiment is compared with the passive radar 20 according to the first embodiment. This simplifies the configuration.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

  For example, each step in the processing of the passive radar 20 in the present specification does not necessarily have to be processed in time series in the order described as a sequence diagram or a flowchart. For example, each step in the processing of the passive radar 20 may be processed in an order different from the order described in the flowchart, or may be processed in parallel.

  Further, in the second embodiment, while the switch 41 connects the antennas A1 to A10 sequentially with the reception processing unit Rx1 and connects the same antenna A to the reception processing unit Rx1, Although the example in which the antenna A is sequentially connected to the reception processing unit Rx2 has been described, the present invention is not limited to such an example. For example, as in the first embodiment, the switch 41 may simply connect the antennas A2 to A10 and the reception processing unit Rx2 between the antenna A1 and the reception processing unit Rx1. In this case, the passive radar 20 'according to the second embodiment obtains an array output based on nine pairs of received data.

20, 20 'passive radar 21, 26, 41, 43 switch 22, 42 memory 24 transfer function acquisition unit 28, 37 addition unit 44 correlation detection unit 46 correlation summation unit

Claims (4)

A first number (an integer greater than or equal to 3) of antennas for receiving signals emitted from radiators;
A second number (two or more integers, second number <first number) of analog processing units that perform analog processing on the signal received by the connected antenna;
A connection switching unit that sequentially switches antennas connected to other analog processing units while one analog processing unit and one antenna are connected;
A transfer function difference between the signal obtained by the one analog processing unit via the one antenna and the signal obtained by the other analog processing unit via another antenna in the same time zone is acquired. A transfer function acquisition unit;
Directional weights corresponding to the other antennas connected to the other analog processing unit in each of the transfer function differences obtained by the transfer function obtaining unit based on signals obtained in different time zones A multiplication unit for multiplying;
A receiving device. A first number (an integer greater than or equal to 3) of antennas for receiving signals emitted from radiators;
A second number (two or more integers, second number <first number) of analog processing units that perform analog processing on the signal received by the connected antenna;
A connection switching unit that switches a connection relationship between the second number of analog processing units and the first number of antennas;
A multiplier that multiplies each of the signals obtained by the second number of analog processing units in the same time zone by a directional weight corresponding to an antenna connected to each analog processing unit;
A correlation detection unit for detecting a correlation value of each of the values obtained by the multiplication unit;
A correlation summation unit that sums the correlation values detected by the correlation detection unit based on signals obtained in different time zones;
A receiving device. A first number (an integer greater than or equal to 3) of antennas that receive signals emitted from the radiator, and a second number that performs analog processing on the signals received by the connected antennas (an integer greater than or equal to 2) , A second number <the first number) analog processing units, wherein the receiving method is executed in a receiving device:
Sequentially switching antennas connected to other analog processing units while one analog processing unit is connected to one antenna;
A transfer function difference between the signal obtained by the one analog processing unit via the one antenna and the signal obtained by the other analog processing unit via another antenna in the same time zone is acquired. Steps and;
Multiplying each difference of the transfer function acquired based on signals obtained in different time zones by a directional weight corresponding to the other antenna connected to the other analog processing unit;
Including a receiving method. A first number (an integer greater than or equal to 3) of antennas that receive signals emitted from a radiator, and a second number that performs analog processing on the signals received by the connected antennas (an integer greater than or equal to 2) , A second number <a first number) analog processing units, wherein the reception method is executed in a receiving device:
Switching the connection relationship between the second number of analog processing units and the first number of antennas;
Multiplying each of the signals obtained by the second number of analog processing units in the same time zone by a directional weight corresponding to the antenna connected to each analog processing unit;
Detecting a correlation value of each of the values obtained by the multiplication;
Summing correlation values detected based on signals obtained at different time periods;
Including a receiving method.

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