JP2014137347A - Radio communication apparatus and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a radio communication apparatus capable of performing a radar operation.SOLUTION: A radio communication apparatus 1 includes: a transmitter 3; a receiver 4 separately arranged from the transmitter 3; and a phase difference detector 2 adjacently arranged to the transmitter 3. The phase difference detector 2 includes two separated reception antennas 20A, B, and detects a phase difference between an electric signal received by the reception antenna 20A and an electric signal received by the reception antenna 20B. A phase difference is detected by receiving a reflection wave reflected against an object after irradiation from the transmitter 3 by the reception antennas 20A, B of the phase difference detector 2, to thereby detect the object.

Description

  The present invention relates to a wireless communication apparatus and a wireless communication method capable of detecting an object by receiving a reflected wave reflected by the object.

  Low-power radio stations are institutionalized as radio stations that can be used and operated by anyone without requiring a license or qualification. A low-power radio station is a radio station that conforms to certain technical standards and has an antenna power of 0.01 W or less. The low power radio station includes a specific low power radio station, a radio station of a low power security system, a radio station of a low power data communication system, a radio station of a digital cordless telephone, and the like.

  The specific low-power radio station is limited in use to several applications, and the frequency, modulation method, and antenna power are specified for each application. Then, two standards are defined for radar use in specific power-saving radio stations (that is, for detecting a target object by radiating a radio wave to the target object and receiving a reflected wave from the target object). One is for a moving body detection sensor, and the frequencies are defined as 10.5 to 10.55 GHz and 24.05 to 24.25 GHz. The other one is for millimeter wave radar, and is defined as 60.0 to 61.0 GHz and 76.0 to 77.0 GHz. A low power radio station cannot be used for radar at frequencies other than these frequency bands.

  Although it is not a radar operation | movement, there exists a thing of patent documents 1-3 as a radio | wireless apparatus which can detect a target object.

  Patent Document 1 discloses an apparatus for detecting an intruder who has entered a room. In this method, a transmitting device and a receiving device are installed in a room, radio waves from the transmitting device are received by the receiving device, and an intruder is detected from fluctuations in the reception level.

  Patent Document 2 describes that an intruder intrusion into a monitoring area is detected from fluctuations in radio field intensity of a radio signal transmitted by a wireless LAN access point.

  In Patent Document 3, a receiving unit is disposed indoors, and a radio wave that enters the indoor through a window or the like is received by the receiving unit, and an intruder entering the indoor is detected based on fluctuations in the reception level of the radio wave. It is described.

  All of the devices described in Patent Documents 1 to 3 detect an intruder by detecting that the multipath environment from the transmitter to the receiver changes due to the presence of the intruder as a change in the reception level. Is.

JP 7-141577 A JP2010-218071 Japanese Patent No. 4528946

  However, in the methods described in Patent Documents 1 to 3, unlike the operation of a radar that can detect an object on the transmitter side, the object is detected on the receiver side away from the transmitter. . Therefore, in Patent Documents 1 to 3, in order to know the detection of an object on the transmitter side, it is necessary to feed back the object information obtained on the receiver side to the transmitter side by some method, which is compared with the radar operation. Then it takes time.

  Further, as described above, the frequency band in which radar can be used in the low-power radio station is very limited. Furthermore, the frequency that can be used by radar in a low-power radio station is high, and there is a great demand for easy detection using a lower frequency when detecting an object such as a person or a foreign object several meters away. For these reasons, the use of radar in low-power radio stations has not progressed much.

  Therefore, wireless communication of low-power wireless communication that can use frequencies other than those frequency bands (for example, frequencies defined by standards such as wireless LAN, ZigBee (registered trademark), telemeter / telecontrol, Bluetooth (registered trademark)). In the apparatus, it has been desired to perform a radar operation. However, in a radar apparatus, a transmitter and a receiver are integrally configured, and a carrier wave is not modulated with data and transmitted. On the other hand, in the wireless communication apparatus, a receiver arranged apart from the transmitter is arranged, and a carrier wave is modulated with data and transmitted from the transmitter to the receiver. For this reason, it is impossible to directly perform a radar operation in a wireless communication apparatus, neither in the configuration of the apparatus nor in the communication standard.

  In order to realize the radar operation in the wireless communication apparatus, it is conceivable to use the methods described in Patent Documents 1 to 3. That is, in a wireless communication apparatus composed of a transmitter and a receiver, another receiver is provided in the vicinity of the transmitter, and a reflected wave from the object is received by a receiver in the vicinity of the transmitter. It is to realize a wireless communication apparatus that detects an object from fluctuations in the range. However, this method cannot be realized due to the following problems. The reception level is usually detected by using a logarithmic amplifier called RSSI (Received Signal Strength Indication). The logarithmic amplifier does not change much in output even when weak radio waves are applied when strong radio waves are detected. For this reason, when the receiver is arranged in the vicinity of the transmitter, the RSSI output is saturated by the sneaking from the transmitter to the receiver, and a minute change due to reflection from the object cannot be detected.

  The present invention solves the above problems, and an object thereof is to realize a wireless communication apparatus and a wireless communication method capable of detecting an object by a radar operation.

  The invention according to claim 1 includes a transmitter and a receiver disposed apart from the transmitter, and is disposed in the vicinity of the transmitter in a wireless communication apparatus that wirelessly transmits a signal from the transmitter to the receiver. A phase difference detector, the phase difference detector having two receiving antennas spaced apart from each other and a detector for detecting a phase difference between two signals respectively received by the two receiving antennas; A radio communication apparatus characterized in that a reflected wave from an object of a signal transmitted from a transmitter is received by each of two receiving antennas, and the object is detected from a phase difference between the two received signals. .

  According to a sixth aspect of the present invention, there is provided a wireless communication apparatus that includes a transmitter and a receiver that is disposed apart from the transmitter, and that wirelessly transmits a signal from the transmitter to the receiver. And a transmitter having at least two transmitting antennas spaced apart from each other, the phase difference detector having a phase difference between a receiving antenna for receiving a signal from the transmitting antenna and a phase difference detector. A detector for detecting, and reflecting a phase difference between a reflected wave from an object of a signal transmitted from one of the transmitting antennas and a reflected wave from an object of a signal transmitted from the other one The wireless communication apparatus is characterized in that a signal is received by a receiving antenna and an object is detected from a phase difference detected by a detector.

  The transmitter and the receiver can be of any configuration conventionally used as a wireless communication device. In particular, a low-power radio station is desirable. In low-power radio stations, the radar-usable frequencies are limited, but if the radio communication device of the present invention is used, the frequencies other than the radar-usable frequencies are frequencies defined by the low-power radio communication standard. The radar operation can be made possible together with the low power wireless communication. Low-power wireless communication is a standard such as a wireless LAN, ZigBee, telemeter / telecontrol, or Bluetooth. The modulation method of wireless communication in the wireless communication apparatus of the present invention may be analog modulation or digital modulation, and may be any method that modulates any of frequency, phase, and amplitude. Further, it may be a spread spectrum system or OFDM wireless communication. Furthermore, the present invention is also applicable to MISO, SIMO, and MIMO in which at least one of the antennas of the transmitter or the receiver is plural.

  However, since the present invention detects an object based on a phase difference between signals having the same frequency, narrowband wireless communication is preferable to broadband wireless communication (spread spectrum communication, OFDM, or the like). Narrowband communication is superior to broadband communication in sensitivity and accuracy.

  The data transmitted by the transmitter may be arbitrary, for example, environmental data such as the ambient temperature of the transmitter. In particular, it is preferable to transmit information on the phase difference detected by the phase difference detector. Since the detection result of the object can be obtained also on the receiver side, the detection accuracy of the object can be improved and the detection range can be expanded.

  A plurality of phase difference detectors may be provided near the transmitter or the receiver. By detecting the phase difference using a plurality of phase difference detectors, the sensitivity and accuracy of object detection can be improved.

  In the inventions according to claims 1 and 6, a phase difference detector is also provided in the vicinity of the receiver, and the phase difference detector receives the transmitted wave from the object and detects the phase difference, thereby the receiver side In this case, the object may be detected. Thereby, the detection accuracy of a target object can be improved and the detection range can be expanded.

  In the invention according to claim 1, the detector of the phase difference detector can employ any configuration capable of detecting the phase difference. For example, the following configuration can be adopted.

  The first is a configuration having a multiplier that multiplies and outputs two received signals, and a first low-pass filter that cuts and outputs a high-frequency component of the output of the multiplier.

  The second is a first phase shifter to which a signal from one of the reception antennas is input, and a second phase shifter to which a signal from the other of the reception antennas is input and the phase shift amount is equal to the first phase shifter. A first multiplier that multiplies a signal received by one of the receiving antennas and a signal received by the other of the receiving antennas and phase-shifted by the second phase shifter, and received by one of the receiving antennas. And a second multiplier that multiplies and outputs the signal phase-shifted by the first phase shifter and a signal received by the other of the receiving antennas, an output of the first multiplier, and an output of the second multiplier And a first low-pass filter that cuts out and outputs a high-frequency component of the output of the first subtracter.

  According to the second configuration, the offset is stable, and the position measurement accuracy can be improved. In the second configuration, the output of the detector depends on the phase shift amounts of the first phase shifter and the second phase shifter, and the phase shift amount of the first phase shifter and the second phase shifter is 90. The output is maximum at °. Therefore, if the phase shift amount is 90 °, the object can be detected with high sensitivity. The first configuration is inferior to the second configuration in detection accuracy, but the configuration is simpler than the second configuration, which is advantageous for reducing the cost of the apparatus.

  In the invention according to claim 6, for example, the following configuration can be used as the configuration of the detector. The configuration includes a non-linear element that squares and outputs a signal from the receiving antenna, and a first low-pass filter that outputs a high-frequency component out of the output of the non-linear element.

  When providing a phase difference detector on both the transmitter side and the receiver side, the configuration of the detector may be the same on the transmitter side and the receiver side, or may be different. Good.

  According to a twelfth aspect of the present invention, in the wireless communication method for wirelessly transmitting a signal from a transmitter to a receiver, reflected waves from an object of the signal transmitted from the transmitter are separated in the vicinity of the transmitter. It is a wireless communication method characterized by receiving at two places, detecting a phase difference between two received signals, and detecting an object from the phase difference.

  The invention according to claim 14 is a wireless communication method in which a signal is transmitted wirelessly from a transmitter to a receiver, wherein signals are transmitted from two spaced apart locations of the transmitter, and the target of the signal transmitted from one location A signal reflecting the phase difference between the reflected wave from the object and the reflected wave from the object of the signal transmitted from the other location is received near the transmitter, and the phase difference reflected in the received signal is detected. A wireless communication method characterized in that an object is detected from a phase difference.

  According to the present invention, a simple configuration in which a phase difference detector is added to a conventional wireless communication device including a transmitter and a receiver (for example, a wireless communication device used for low-power wireless communication such as wireless LAN and ZigBee). In the wireless communication apparatus, the object can be detected by the radar operation. Naturally, it is possible to detect an object while performing wireless communication.

  The present invention is particularly effective in a wireless communication apparatus that performs low-power wireless communication. In low-power radio stations, the radar-usable frequencies are limited, but the present invention is not a radar device, but a radio communication device that performs low-power radio communication. If so, radar operation is possible at various frequencies. Therefore, for example, in low power wireless communication such as wireless LAN, ZigBee, telemeter / telecontrol, Bluetooth, etc., it is possible to easily detect an object by radar operation.

  In addition, since the radar operation by the wireless communication apparatus of the present invention detects an object based on a phase difference, even if a signal having the same frequency wraps around from the transmitter to the phase difference detector, it is affected. The object can be detected without any problem.

1 is a diagram illustrating a configuration of a wireless communication device 1 according to a first embodiment. The figure which showed the structure of the phase difference detector 2. FIG. The figure which showed the other structure of the phase difference detector 2. FIG. The graph which showed the output of the phase difference detector 2 in Experimental example 1. FIG. The graph which showed the output of the phase difference detector 2 in Experimental example 1. FIG. The graph which showed the output of the phase difference detector 2 in Experimental example 2. FIG. The graph which showed the output of the phase difference detector 2 in Experimental example 2. FIG. The graph which showed the output of the phase difference detector 2 in Experimental example 3. FIG. The graph which showed the output of the phase difference detector 2 in Experimental example 3. FIG. FIG. 6 is a diagram illustrating a configuration of a wireless communication apparatus 200 according to a second embodiment. FIG. 6 is a diagram illustrating a configuration of a wireless communication apparatus 300 according to a third embodiment. The figure which showed the structure of the phase difference detector 302. FIG.

  Hereinafter, specific examples of the present invention will be described with reference to the drawings. However, the present invention is not limited to the examples.

  FIG. 1 is a diagram illustrating a configuration of the wireless communication device 1 according to the first embodiment. As illustrated in FIG. 1, the wireless communication device 1 includes a transmitter 3, a receiver 4 that is disposed apart from the transmitter 3, and a phase difference detector 2 that is provided adjacent to the transmitter 3. doing. By radiating a carrier wave modulated with data as a radio wave from a transmission antenna 30 provided in the transmitter 3 and receiving the radio wave by a reception antenna 40 provided in the receiver 4, the transmitter 3, the receiver 4, Are conducting low-power wireless communications.

  The transmitter 3 and the receiver 4 can be of any configuration conventionally used as a wireless communication device for a low power wireless station. For example, a transmitter and a receiver used for wireless LAN, ZigBee, FRID, Bluetooth, telemeter / telecontrol, and the like can be used as the transmitter 3 and the receiver 4 of the wireless communication apparatus 1 of the first embodiment. As a modulation method of the radio wave to be transmitted, any modulation method may be adopted according to the communication standard. Either analog modulation or digital modulation may be used, and any of frequency, phase, and amplitude may be modulated. Further, a spread spectrum method or OFDM may be used. However, as described later, the wireless communication device 1 according to the first embodiment detects a phase difference between signals having the same frequency and detects an object based on a change in the phase difference. When the frequency of the signal fluctuates greatly, or when the frequency band is wide such as OFDM, the detection accuracy and sensitivity of the object may be reduced. Therefore, it is desirable that the communication system has a narrow band.

  The phase difference detector 2 may be configured as an apparatus integrated with the transmitter 3 or may be a separate apparatus. In short, the phase difference detector 2 may be provided adjacent to the transmitter 3. As shown in FIG. 2, the phase difference detector 2 includes two receiving antennas 20 </ b> A and 20 </ b> B that are provided apart from each other. The two receiving antennas 20A and 20B receive the electric signal from the transmitting antenna 30. The receiving antennas 20A and 20B are connected to the input sides of the multipliers 23A and 23B through band pass filters 21A and 21B and amplifiers 22A and 22B, respectively. The band-pass filters 21A and B transmit only the frequency band of the radio wave transmitted by the transmitter 3, and the amplifiers 22A and B amplify the electrical signals from the band-pass filters 21A and B, respectively.

  A PLL (Phase-locked loop) circuit 24 is commonly connected to the other input side of the multipliers 23A and 23B. The PLL circuit 24 generates a signal close to the frequency of the received radio wave. In the multipliers 23A and 23B, the phase of the electrical signal received by the receiving antenna 20A and the phase of the electrical signal received by the receiving antenna 20B is obtained by multiplying the electrical signal from the receiving antennas 20A and 20B by the signal from the PLL circuit 24. Down-converted to an intermediate frequency electrical signal for easy comparison.

  Note that down-conversion using the multipliers 23A and 23B and the PLL circuit 24 is not always necessary. When the frequency of the radio wave radiated from the transmitter 3 is low, the multipliers 23A, B and the PLL circuit 24 are omitted, and down-conversion is not necessary.

  The output sides of the multipliers 23A and B are connected to the two input sides of the multiplier 28 via bandpass filters 25A and 25 and amplifiers 27A and 27B, respectively. The bandpass filters 25A and 25B transmit only signals in the intermediate frequency band. The amplifiers 27A and B amplify electric signals from the bandpass filters 25A and 25B. The multiplier 28 multiplies the electric signals from the amplifiers 27A and 27B and outputs the result. Then, after being amplified by the amplifier 26, the difference signal is extracted by the low-pass filter 29 out of the sum signal and the difference signal generated by the multiplication by the multiplier 28, and is extracted as the output of the phase difference detector 2. The electrical signal output from the phase difference detector 2 is a DC value corresponding to the phase difference between the electrical signal received by the receiving antenna 20A and the electrical signal received by the receiving antenna 20B. The output of the phase difference detector 2 is input to the transmitter 3.

  Next, the operation of the wireless communication apparatus 1 according to the first embodiment will be described.

  The transmitter 3 radiates a radio wave that is a signal from the transmission antenna 30 toward the receiver 4, and performs low power wireless communication when the receiver 4 receives the radio wave. Here, when an object exists, a part of the radio wave is reflected by the object and returns to the transmitter 3 side. The phase difference detector 2 receives the reflected wave by the receiving antennas 20A and 20B.

  Here, the multipath from the transmitting antenna 30 of the transmitter 3 to the receiving antennas 20A and 20B of the phase difference detector 2 through reflection by the object varies depending on the presence / absence, position, orientation, etc. of the object. Therefore, there is a difference in phase between the electrical signal received by the receiving antenna 20A and the electrical signal received by the receiving antenna 20B. Thus, there is a correspondence between detection of the object and the phase difference, and the object can be detected by detecting the phase difference by the phase difference detector 2.

  The transmitter 3 modulates the carrier wave with the voltage value from the phase difference detector 2 (or detection information such as the position and movement of the measurement object calculated from the voltage value) and transmits the modulated carrier wave to the receiver 4. Thereby, the detection of the object can be known not only on the transmitter 3 side but also on the receiver 4 side. As a result, the detection range and accuracy of the object can be improved.

  As described above, according to the wireless communication device 1 of the first embodiment, the object can be detected on the transmitter 3 side by the radar operation. Further, in the low-power radio station, the radar-usable frequency is limited. However, when the radio communication apparatus 1 according to the first embodiment is used, the frequency is determined by the low-power radio communication standard that is a frequency other than the radar-usable frequency. It is possible to enable radar operation together with low-power wireless communication at a specified frequency.

  The wireless communication device 1 according to the first embodiment is realized by a simple configuration in which the phase difference detector 2 is provided in the vicinity of the transmitter 3 of the conventional wireless communication device. That is, the transmitter 3 and the receiver 4 of the conventional wireless communication apparatus can be diverted, and the object can be detected by the radar operation easily and at low cost.

  In addition, since the wireless communication device 1 according to the first embodiment detects an object with a phase difference of the same frequency, even if there is a so-called sneak received directly from the transmission antenna to the reception antenna 20, the target is not affected. An object can be detected.

[Modification of phase difference detector]
The phase difference detector 2 can use another configuration as long as it can detect the phase difference of the electrical signals received by the receiving antennas 20A and 20B. For example, the configuration shown in FIG. 3 can be adopted. The phase difference detector of the modification shown in FIG. 3 is obtained by replacing the configuration of the section from the bandpass filters 25A and 25B to the amplifier 26 in the phase difference detector 2 of the first embodiment as follows. The output of the band pass filter 25A is divided into two, one being connected to the multiplier 129A via the amplifier 127, and the other being connected to the multiplier 129B via the phase shifter 128B and the amplifier 127. The output of the bandpass filter 25B is also divided into two parts, one being connected to the multiplier 129B via the amplifier 127, and the other being connected to the phase shifter 128A having the same phase shift amount as the phase shifter 128B, and the amplifier 127. It is connected to the multiplier 129A. The output sides of the multipliers 129 </ b> A and B are connected to the subtractor 120, and the output side of the subtractor is connected to the amplifier 26.

  In the phase difference detector of this modification, as with the phase difference detector 2 of the first embodiment, a DC value reflecting the phase difference between the electric signal received by the receiving antenna 20A and the electric signal received by the receiving antenna 20B. Is obtained as output. Since the output is larger than that of the phase difference detector 2 of the first embodiment, it is possible to detect an object with higher sensitivity. In particular, if 90 ° is selected as the phase amount of the phase shifters 128A and B in the phase difference detector of the modified example, the output is twice as large as that of the phase difference detector 2 of the first embodiment, and the sensitivity is higher. The object can be detected. In addition, since the output is a sine wave and the output is 0 when the phase difference is 0, it is easier to detect the variation in the phase difference and the detection accuracy of the object is improved.

  The operation of the modified phase difference detector will be specifically described in detail. The electrical signal received by the receiving antenna 20A of the phase difference detector and down-converted by the multiplier 23A and the PLL circuit 24 is cos (ωt + θA), and is received by the receiving antenna 20B. Similarly, the down-converted electrical signal is cos (ωt + θB). ), Where ω is 2πf, f is the oscillation frequency of the oscillator 40, θA and θB are the phases, the phase of the multiplier 129A is delayed by φ by the electric signal cos (ωt + θA) and the phase shifter 128A. An electric signal cos (ωt + θB−φ) is input. The multiplier 129B receives the electric signal cos (ωt + θB) and the electric signal cos (ωt + θA−φ) whose phase shift is delayed by φ by the phase shifter 129B. Therefore, the output of the multiplier 129A is cos (ωt + θA) · cos (ωt + θB−φ), and is (½) · cos (ψ + φ) except for the high-frequency component cut by the low-pass filter 29 in the subsequent stage. . Here, θA−θB, that is, the phase difference is set as ψ. Similarly, the output of the multiplier 129B is (1/2) · cos (ψ−φ).

  The electrical signals (1/2) · cos (ψ + φ) and (1/2) · cos (ψ−φ) output from the multipliers 129A and 129B are input to the subtractor 120. The output from the subtractor 120 is (1/2) · cos (ψ−φ) − (1/2) · cos (ψ + φ) = sinψ · sinφ. Thereafter, after the signal is amplified by the amplifier 26, the high-frequency component which has already been omitted in the calculation is cut by the low-pass filter 29, and sinφ · sinφ is output.

  The voltage value of sin ψ · sin φ is a value corresponding to the phase difference ψ (= θA−θB) of the electrical signal received by the receiving antennas 20A and 20B, and the phase difference ψ corresponds to the movement of the object. It is the value. Therefore, the object can be detected from the voltage value of the electric signal sinψ · sinφ. As shown by this result, when φ is 90 °, the output becomes maximum from sin φ = 1, so that the phase shift amount φ of the phase shifters 128A and B is desirably set to 90 °. This is because the sensitivity of object detection can be improved.

[Various experimental examples]
When the wireless communication apparatus 1 of Example 1 was used for communication according to various communication standards, an experiment was performed to determine whether or not an object can actually be detected. In this experiment, the object was a person, and the movement and the stop were repeated near the position between the transmitter 3 and the receiver 4 and 1.5 m away from the transmitter 3. The experimental results are shown below.

[Experimental Example 1]
4 and 5 show the case where the wireless communication apparatus 1 performs low-power wireless communication in which the frequency is 5.8 GHz, the modulation method is ASK, the modulation speed is 200 kHz, and the data to be transmitted is a repetition of 0 and 1. 4 is a graph showing an output (voltage value corresponding to a phase difference) of the phase difference detector 2; 4 shows the output of the phase difference detector 2 when there is no object (person), and FIG. 5 shows the output of the phase difference detector 2 when the object repeats moving and stopping.

  As shown in FIG. 4, when there is no target (when the target is far away from the wireless communication device 1), the output hardly varies with time and has a constant predetermined value. On the other hand, as shown in FIG. 5, when the object moves / stops between the transmitter 3 and the receiver 4, the output repeatedly fluctuates in time up and down, and the output is almost constant in time. It can be seen that the regions appear alternately. Looking at the correspondence between this output and the movement stop of the object, the area where the output fluctuates corresponds to the time when the object moves, and the area where the output is constant corresponds to the time when the object stops. I understand that it corresponds.

  Thus, it has been found that in the low-power wireless communication using the communication method as in Experimental Example 1, the wireless communication device 1 can detect the object.

  Note that the low-pass filter 29 of the phase difference detector 2 has a cut-off frequency of about 20 Hz for detecting the motion of the object, and when the ASK modulation speed approaches the cut-off frequency such as 200 bps (100 Hz) or less, the ASK The modulated data appears as the output of the phase difference detector 2. However, since data is not generally sent at such a low speed, detection of an object is not affected.

[Experiment 2]
FIGS. 6 and 7 are phase difference detectors in the case of low-power wireless communication with a frequency of 2450 MHz (wireless LAN frequency), a modulation method of π / 4 QPSK, a carrier wave modulated with a PN code (PN15), and a communication speed of 128 kbps. 2 is a graph showing the output of 2. 6 shows the output of the phase difference detector 2 when there is no object, and FIG. 7 shows the output of the phase difference detector 2 when the object repeats moving and stopping.

  As shown in FIG. 6, when there is no object, there is almost no temporal variation in output as in FIG. On the other hand, when the object has repeatedly stopped moving as shown in FIG. 7, similarly to FIG. 5, a region where the output repeatedly fluctuates in time up and down, and a region where the output is almost constant over time. And appear alternately. Therefore, it was found that the object can be detected by the wireless communication device 1 even in the low-power wireless communication as in Experimental Example 2.

[Experiment 3]
8 and 9 show phase differences in the case of low-power wireless communication of IEEE 802.15.4 (ARIB STD-T66) standard with a frequency of 2.41 GHz, a modulation scheme of O-QPSK, spread spectrum, and a communication speed of 38400 bps. 5 is a graph showing the output of the detector 2. FIG. 8 shows the output of the phase difference detector 2 when there is no object, and FIG. 9 shows the output of the phase difference detector 2 when the object repeats moving and stopping.

  As shown in FIG. 8, when there is no object, the output is almost constant over time. When the object repeats moving stop as shown in FIG. 9, the output fluctuates greatly in time up and down. An area where the output was repeated and an area where the output was almost constant in time appeared alternately. Therefore, it was found that the target can be detected by the wireless communication device 1 even in the low-power wireless communication as in Experimental Example 3.

  From the above experimental examples 1 to 3, it was found that the wireless communication apparatus 1 of the first embodiment can operate as a radar regardless of the modulation method and frequency of wireless communication. Further, as in Experiment 3, the radar operation was possible even when the spectrum was spread.

  In FIGS. 4, 6, and 8 of Experimental Examples 1 to 3, the output is slightly disturbed at the initial stage, but this is because the experimenter approaches the apparatus for the operation of the logger, and is not essential.

  FIG. 10 illustrates a wireless communication apparatus 200 according to the second embodiment. The wireless communication apparatus 200 according to the second embodiment has a configuration in which the phase difference detector 202 having the same configuration as that of the phase difference detector 2 is provided adjacent to the receiver 4 in the wireless communication apparatus 1 according to the first embodiment. Hereinafter, in the phase difference detector 202, the same components as those of the phase difference detector 2 are denoted by the same reference numerals. In the wireless communication apparatus 200 according to the second embodiment, not only the object can be detected on the transmitter 3 side by the radar operation as in the first embodiment, but also the object can be detected on the receiver 4 side. Can do. That is, the multipath from the transmitting antenna 30 of the transmitter 3 through the object to the receiving antennas 20A and 20B of the phase difference detector 202 changes depending on the presence / absence, position, orientation, etc. of the object. For this reason, there is a difference in phase between the signal received by the receiving antenna 20A and the signal received by the receiving antenna 20B, and the phase difference is detected by the phase difference detector 202 to detect the object. be able to.

  As described above, according to the wireless communication apparatus 202 of the second embodiment, the object can be detected on both the transmitter 3 side and the receiver 4 side, so that the detection accuracy of the object and the effect of expanding the detection range are achieved. There is.

  In the second embodiment, the phase difference detector installed adjacent to the receiver 4 has the same configuration as the phase difference detector 2 installed adjacent to the transmitter 3, but has a different configuration. May be used. For example, the configuration shown in FIG. 3 may be used as the phase difference detector on the transmitter 3 side, and the configuration shown in FIG. 2 may be used as the phase difference detector on the receiver 4 side. The reverse is also possible.

  FIG. 11 illustrates a wireless communication apparatus 300 according to the third embodiment. The wireless communication apparatus 300 according to the third embodiment uses the transmitter 303 instead of the transmitter 3 and the phase difference detector 302 instead of the phase difference detector 2 in the wireless communication apparatus 1 according to the first embodiment. is there. Other configurations are the same as those of the wireless communication apparatus 1 of the first embodiment.

  The transmitter 303 includes two transmission antennas 333A and 333B that are separated from each other. For example, a transmitter used for a wireless communication device such as MIMO or MISO can be used as the transmitter 303 of the wireless communication device 300 of the third embodiment.

  The phase difference detector 302 has one receiving antenna 320 as shown in FIG. By this receiving antenna 320, the reflected wave radiated from the transmitting antennas 333A and 333B of the transmitter 303 and reflected by the object is received. The reception antenna 320 is connected to the input side of the multiplier 323 via a bandpass filter 321 and an amplifier 322. A PLL circuit 324 is connected to the other input side of the multiplier 323. The output side of the multiplier 323 is connected to the input side of the nonlinear element 330 via a bandpass filter 325 and an amplifier 327. Here, each component from the receiving antenna 320 to the amplifier 327 and the PLL circuit 324 are the same as those from the receiving antenna 20A to the amplifier 27A and the PLL circuit 24 of the first embodiment.

  The nonlinear element 330 is used to generate a square component of an input signal. Of the output from the non-linear element 330, only the DC component is extracted by the low-pass filter 340 and is extracted as the output of the phase difference detector 302. The signal output from the phase difference extractor 302 is reflected from the transmission antenna 333A through the reflection of the object to the reception antenna 320, and reflected from the transmission antenna 330B through the reflection of the object to the reception antenna 320. DC value corresponding to the phase difference from the wave.

  Next, the operation of the phase difference detector 302 will be described. When there is an object, the reflected wave is radiated from the transmitting antenna 330A and reflected by the object to reach the receiving antenna 320, and the reflected wave radiated from the transmitting antenna 330B and reflected by the object to reach the receiving antenna 320. A phase difference occurs. Since the signal reflecting this phase difference is received by the receiving antenna 320, and the DC value reflecting the phase difference can be extracted by the phase difference detector 302, the object can be detected.

The extraction of the phase difference by the phase difference detector 302 will be described in more detail. The electrical signal output from the transmission antennas 330A and B is cos (ωt), the phase changes by θA in the path from the transmission antenna 330A to the reception antenna 320 through reflection by the object, and is received from the transmission antenna 330B through reflection by the object. Assuming that the phase changes by θB in the path to the antenna 320, the electric signal received by the receiving antenna 320 is cos (ωt + θA) + cos (ωt + θB). This electric signal is input to the nonlinear element 330, and a square component is generated. That is, a component of {cos (ωt + θA) + cos (ωt + θB)} ² is generated. Of this square component, the DC component is 1 + cos (ψ). Of the output of the non-linear element 330, other than this DC component is cut by the low-pass filter 340. After all, the output of the phase difference detector 302 becomes 1 + cos (ψ), and the phase difference ψ can be extracted from this DC value.

  As described above, in the wireless communication device 300 according to the third embodiment, the phase difference is detected by the phase difference detector 302 so that the object can be detected in the radar operation. And there exists an advantage similar to the radio | wireless communication apparatus 1 of Example 1. FIG. That is, with a simple configuration, it is possible to easily detect an object by radar operation at low cost.

  Note that the wireless communication apparatus of the present invention is not necessarily limited to use for low-power wireless communication, and can also be applied to wireless communication other than low-power wireless communication.

  In the first to third embodiments, one or more phase difference detectors may be further provided on the transmitter side or the receiver side to improve the detection accuracy of the target object or to expand the detection range.

  In the wireless communication apparatuses according to the first to third embodiments, the output of the phase difference detector 2 is transmitted as data from the transmitter 3 to the receiver 4, but this is not always necessary, and arbitrary data is transmitted. It may be. For example, environmental data (temperature, humidity, atmospheric pressure, etc.) where the transmitter 3 is placed may be transmitted.

  As is clear from the first to third embodiments, the wireless communication apparatus of the present invention may be MIMO, SIMO, MISO, or the like in which at least one of the transmitter and the receiver has a plurality of antennas.

  Also, in the third embodiment, it is possible to employ a configuration in which a phase difference detector is provided on the receiver 4 side as in the second embodiment, and an object is detected on both the transmitter 3 side and the receiver 4 side. it can.

  The wireless communication apparatus of the present invention can be used for detecting an object by a radar operation at a frequency other than a frequency that can be used by a radar. For example, it can be used for detecting foreign matter between coils in non-contact charging of a vehicle or the like.

1, 200, 300: Wireless communication device 2, 202, 302: Phase difference detector 3, 303: Transmitter 4: Receiver 20A, B, 320: Receiving antenna 21A, B, 25A, B, 321, 325: Band Pass filter 22A, B, 26, 27A, B, 127, 322, 327: Amplifier 23A, B, 28, 129A, B, 323: Multiplier 24, 324: PLL circuit 29, 340: Low pass filter 30, 333A, B : Transmitting antenna 120: Subtractor 128A, B: Phase shifter 330: Non-linear element

Claims (18)

In a wireless communication device comprising a transmitter and a receiver disposed away from the transmitter, and wirelessly transmitting a signal from the transmitter to the receiver,
A phase difference detector disposed in the vicinity of the transmitter;
The phase difference detector is
Two receiving antennas spaced apart from each other;
A detector for detecting a phase difference between the two signals respectively received by the two receiving antennas;
Have
The reflected waves from the object of the signal transmitted from the transmitter are respectively received by the two receiving antennas, and the object is detected from the phase difference between the two received signals.
A wireless communication apparatus. Further comprising the phase difference detector in the vicinity of the receiver;
The phase difference detector in the vicinity of the receiver is
The transmitted waves from the object transmitted from the transmitter are respectively received by the two receiving antennas, and the object is detected from the phase difference between the two received signals.
The wireless communication apparatus according to claim 1. The detector is
A multiplier that multiplies and outputs the two received signals;
A first low-pass filter that outputs a high frequency component out of the output of the multiplier;
The wireless communication apparatus according to claim 1, further comprising: The detector is
A first phase shifter to which a signal from one of the receiving antennas is input;
A second phase shifter that receives a signal from the other of the receiving antennas and has a phase shift amount equal to that of the first phase shifter;
A first multiplier that multiplies and outputs a signal received by one of the receiving antennas and a signal received by the other of the receiving antennas and phase-shifted by the second phase shifter;
A second multiplier that multiplies and outputs a signal received by one of the receiving antennas and phase-shifted by the first phase shifter and a signal received by the other of the receiving antenna;
A first subtractor that takes a difference between an output of the first multiplier and an output of the second multiplier;
A first low-pass filter that cuts out and outputs a high-frequency component of the output of the first subtractor;
The wireless communication apparatus according to claim 1, further comprising:   The wireless communication apparatus according to claim 4, wherein a phase shift amount of the first phase shifter and the second phase shifter is 90 °. In a wireless communication device comprising a transmitter and a receiver disposed away from the transmitter, and wirelessly transmitting a signal from the transmitter to the receiver,
A phase difference detector disposed in the vicinity of the transmitter;
The transmitter has at least two transmitting antennas spaced apart from each other;
The phase difference detector is
A receiving antenna for receiving a signal from the transmitting antenna;
A detector for detecting the phase difference;
Have
A signal reflecting a phase difference between a reflected wave of an object transmitted from one of the transmitting antennas and a reflected wave of an object transmitted from the other one is received by the receiving antenna. The object is detected from the phase difference detected by the detector.
A wireless communication apparatus. Further comprising the phase difference detector in the vicinity of the receiver;
The phase difference detector in the vicinity of the receiver is
A signal reflecting a phase difference between a transmitted wave from the object of a signal transmitted from one of the transmitting antennas and a transmitted wave from the object of a signal transmitted from the other one And detecting the object from the phase difference detected by the detector,
The wireless communication apparatus according to claim 6. The detector includes a nonlinear element that squares and outputs a signal from the receiving antenna;
A first low-pass filter that cuts and outputs a high-frequency component of the output of the nonlinear element;
The wireless communication apparatus according to claim 6, wherein the wireless communication apparatus includes: Information on the phase difference detected by the phase difference detector in the vicinity of the transmitter is input to the transmitter,
The transmitter transmits the phase difference information to the receiver;
The wireless communication device according to claim 1, wherein the wireless communication device is a wireless communication device.   The wireless communication device according to claim 1, wherein the wireless communication device is a low-power wireless station.   The wireless communication apparatus according to claim 10, wherein the wireless communication by the wireless communication apparatus is based on a wireless LAN, ZigBee, telemeter / telecontrol, or Bluetooth standard. In a wireless communication method for wirelessly transmitting a signal from a transmitter to a receiver,
The reflected wave by the object of the signal transmitted from the transmitter is received at two locations near the transmitter and separated from each other,
Detecting a phase difference between the two received signals, and detecting the object from the phase difference;
A wireless communication method. The transmitted wave from the object of the signal transmitted from the transmitter is received at two locations in the vicinity of the receiver and apart from each other,
Detecting a phase difference between the two received signals, and detecting the object from the phase difference;
The wireless communication method according to claim 12. In a wireless communication method for wirelessly transmitting a signal from the transmitter to the receiver,
The signal is transmitted from two spaced apart locations of the transmitter,
A signal reflecting the phase difference between the reflected wave from the object of the signal transmitted from one location and the reflected wave from the object of the signal transmitted from the other location is received in the vicinity of the transmitter. ,
Detecting the phase difference reflected in the received signal, and detecting the object from the phase difference;
A wireless communication method. In the vicinity of the receiver, a signal reflecting a phase difference between a transmitted wave from the object of the signal transmitted from one location and a transmitted wave from the object of the signal transmitted from the other location. Received at
Detecting the phase difference reflected in the received signal, and detecting the object from the phase difference;
The wireless communication method according to claim 14.   The wireless communication method according to any one of claims 12 to 15, wherein information on the phase difference detected in the vicinity of the transmitter is transmitted to the receiver.   The wireless communication method according to any one of claims 12 to 16, wherein the wireless communication method is low-power wireless communication.   The wireless communication method according to claim 17, wherein the low-power wireless communication is a standard of wireless LAN, ZigBee, telemeter / telecontrol, or Bluetooth.

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