JP5527335B2 - Radio wave intensity distribution measuring system and radio wave intensity distribution measuring method - Google Patents

Description

  The present invention relates to a radio wave sensor and a radio wave intensity distribution measurement system for measuring a radio wave intensity distribution in short-range radio, particularly, an RFID system.

  In recent years, short-range wireless systems such as a wireless LAN are often installed in offices, warehouses, factories, and the like. Introduction and maintenance are low cost, and installation and relocation are easy to promote.

  The installation of the wireless LAN system can be performed by the user himself / herself in a small place where the radio wave environment is stable. However, when installed in offices, warehouses, factories, etc. for business use, introduction support services such as measurement of radio wave environment and placement design are also used.

  As a radio wave environment measurement tool used for such a service, a system is commercially available in which a card-type receiving device is inserted into a portable PC and the radio wave intensity distribution is measured using dedicated software. This measurement system can record the radio field intensity in contrast to the layout, and does not require specialized knowledge as compared to a large measuring device.

  Some systems that measure the radio wave environment use the communication system itself. For example, the base station sends radio environment monitoring command signals to multiple terminal stations, the terminal station transmits the monitored radio environment data to the base station, and analyzes all radio environment monitor data received by the base station. A method of diagnosing the radio wave environment is described in Patent Document 1 below.

On the other hand, the spread of RFID systems has been started for the purpose of article management, logistics efficiency, and the like. In particular, in a system using a passive tag, the range in which communication can be performed is limited.

  The reading situation of a system using passive tags depends on the movement of people, articles, etc. near the reading range. Further, if the output of the reader is increased unnecessarily, it interferes with another reader or reads a tag to be read by another reader. As described above, when introducing an RFID system using a passive tag, it is important to grasp temporal and local fluctuations in radio wave environment within a relatively small range.

  At present, it is common to determine the antenna arrangement of the reader by trial and error while actually checking the reading by attaching the tag to the article.

  When installing an RFID system using a passive tag, there is a demand for grasping temporal and local fluctuations in radio field intensity within a range where reading is desired.

  In addition, there is a demand for grasping the intensity of interference radio waves from other readers that arrive at the reader.

  Moreover, it is necessary to avoid the influence of a measuring instrument and a measurer as much as possible on the radio wave to be measured in the measurement of the radio wave intensity.

  On the other hand, as a measurement method of the radio wave environment, there is a method of using the measurement target wireless communication system as described above. If this is applied to an RFID system using a passive tag, the tag itself must receive an environment monitoring command from the reader, measure the radio wave environment, and send it back to the reader.

  In this case, there exists a subject that the intensity | strength of the electromagnetic wave of the range which a passive tag cannot communicate cannot be measured. In addition, since it is impossible to measure the radio field intensity at the same time as transmitting the radio wave, there is a problem in that it is impossible to grasp the radio field intensity distribution that changes every moment in a situation where an article or a person moves.

  As described above, there is a system in which a receiver and software are mounted on a portable PC. In this case, since it is necessary for the measurer to be always near the PC and operate the software, there is a problem that the presence of the measurer always affects the measurement result. In addition, there is a problem that it is difficult to measure the radio field intensity on an article conveyed by a belt conveyor or a carriage. In addition, there is a problem in that it is costly and troublesome to simultaneously measure the radio field intensity at a plurality of points.

  The present invention has been made in view of the above-described points, can perform measurement without the influence of the measurer, and can perform measurement at a point where the terminal station (or tag) of the target communication system cannot communicate. There is a radio wave sensor and radio wave intensity measurement system that can perform real-time measurement in a situation where the target communication system is in operation, can measure at multiple points simultaneously, and can be measured on a moving article. The purpose is to propose.

  Further, by using this radio wave intensity distribution measurement system, it is possible to optimize the reading efficiency, suppress the interference between reader / writers, and minimize the influence on the human body and medical equipment.

The radio wave intensity distribution measurement system of the present invention includes a first antenna that receives radio waves in a first frequency band, a second antenna that communicates in a second frequency band different from the first frequency band, and a communication device Receiving the first frequency band radio wave transmitted from the first antenna, detecting a radio field intensity of the received radio wave, and information indicating the radio field intensity detected by the detection unit Communication that transmits to the communication apparatus via the second antenna via the second frequency band, and receives signals transmitted from the communication apparatus via the second frequency band via the second antenna and having a part, a radio wave sensor comprising a, a, a processor for obtaining an electric field intensity distribution on the basis of the prior SL information indicating the electric wave strength received by the communication device.

  According to the present invention, when an RFID system using a passive tag is installed, it is possible to grasp temporal and local fluctuations in radio field intensity within a range to be read.

  According to the present invention, it is possible to grasp the intensity of interference radio waves from other readers that arrive at the reader.

  According to the present invention, measurement can be performed while minimizing the influence of a measuring instrument and a measurer on a radio wave to be measured.

  According to the present invention, it is possible to measure the intensity of radio waves in a range where the passive tag cannot communicate.

  According to the present invention, it is possible to measure the radio field intensity at the same time as transmitting the radio wave, and it is possible to grasp the radio field intensity distribution that changes from time to time in a situation where an article or a person moves.

  According to the present invention, it is possible to measure the radio field intensity on an article conveyed by a belt conveyor, a carriage, or the like.

  According to the present invention, it is possible to easily measure radio field intensity at a plurality of points simultaneously at low cost.

It is a conceptual diagram which shows the electromagnetic wave intensity distribution measuring system of this invention. It is a detailed block diagram which shows the electromagnetic wave intensity distribution measurement system of this invention. It is a figure which shows the detailed block diagram of the electromagnetic wave sensor of this invention. It is a figure which shows the structural example of the interference measurement system of this invention. It is a figure which shows the example of a measurement of the electromagnetic wave intensity in the movement tag of this invention.

    FIG. 1 is a conceptual diagram showing a state in which the radio wave intensity distribution measuring system of the present invention is applied to a passive tag type RFID system. As shown in the figure, the radio wave intensity distribution measuring system of the present invention comprises a radio wave intensity data processing device 11, a radio wave intensity collecting device 12, a reader / writer (read / write device) 13, and radio wave sensors (21 to 23). .

  The radio wave sensors (21 to 23) include two types of antennas, for example, a short-range wireless antenna (21b to 23b) and a detection antenna (21a to 23a). The short-range wireless antenna is used for short-range wireless communication. As the short-range wireless, a wireless I / F having a wider communication range than a passive RFID system, such as specific low power, wireless LAN, Bluetooth, Zigbee, infrared communication, or the like is used. The detection antenna is used to receive the radio wave transmitted from the reader / writer and measure the intensity of the radio wave. This detection antenna has the same directivity, polarization characteristics, impedance characteristics, and the like as the tag antenna. In addition, for example, a non-directional antenna may be used as a detection antenna in the case of interference investigation, pre-installation investigation, and the like.

  The frequency channel and identification information (ID) of short-range wireless communication used by each radio wave sensor are set in advance in the radio wave intensity data processing device 11 and each radio wave sensor. In advance, the radio wave intensity data processing device 11 measures the position of the radio wave sensor using an image recognition device or the like, and creates map information in which the positions of a plurality of radio wave sensors are associated with IDs. The radio wave intensity data processing device 11 is composed of a personal computer and software on the personal computer, and in conjunction with the reader / writer 13, a plurality of radio wave sensors ( 21 to 23), the ID and the radio wave intensity data are acquired by controlling the radio wave intensity collecting device 12 by using short-range radio, and associated with the position where the radio wave sensors (21 to 23) set in advance are placed. Record or display. The reader / writer (or master station) 13 transmits, for example, a radio wave in the UHF band, and measures the strength of the radio wave by a plurality of radio wave sensors (21 to 23) having detection antennas. The radio wave intensity data processing device 11 is connected to the radio wave intensity collecting device 12 and the reader / writer 13 with a cable or the like, and sends a collection control command to the reader / writer 13 so as to send UHF band radio waves. Radio wave intensity data to which IDs are added is acquired from a plurality of radio wave sensors. Each radio wave sensor (21-23) detects the intensity of the radio wave transmitted by the reader / writer 13 received by the detection antenna (21a-23a), adds the ID from the short-range radio antenna 21b to the radio wave intensity data, and wirelessly To send.

  The radio wave intensity data processing device 11 associates the collected ID and radio wave intensity data from a plurality of radio wave sensors with the set map information, and displays the radio wave distribution (31 to 33) shown in FIG. To display. As an example different from the above, an example in which the radio wave intensity data processing device 11 collects radio wave intensity from each radio wave sensor at different times will be described.

  The radio wave intensity data processing device 11 sequentially sends out radio wave intensity collection commands assigned with individual IDs at different times via the radio wave intensity collection device 12. In each radio wave sensor (21 to 23), the radio wave intensity detected when receiving the same radio wave intensity collection command as its own ID and its own ID are given to the radio wave intensity collecting apparatus 12 by short-range wireless communication. Send. Other processes are the same as described above.

  Further, the collection timing of the collection control command sent from the radio wave intensity collecting device 12 is set so that the measurement and collection of the radio wave intensity is started in accordance with the transmission timing of a desired modulated wave or non-modulated wave sent from the reader / writer 13. You may control to.

  FIG. 2 is a detailed configuration diagram showing the radio wave intensity distribution measuring system of the present invention.

  The radio wave intensity data processing device 11 includes a display unit 11a, an input unit 11b, a communication unit 11c, a control unit 11d, a data processing unit 11f, and a data recording unit 11e. The radio wave intensity collecting device 12 includes an antenna and a short-range wireless transmission / reception unit. The radio wave sensor 21 includes a UHF band RFID antenna 12, a short-range wireless antenna 21b, a short-range wireless transmission / reception unit 21c, and a detection processing unit 21d. The position data of the radio wave sensor is input from the input unit and recorded in the data recording unit 11e. The control unit 11d receives the ID and the radio wave intensity data from the radio wave sensor via the antenna of the radio wave intensity collecting device 12 and the short-range wireless transmission / reception unit, and stores the plurality of IDs and the radio wave intensity data in the data recording unit 11e. The data processing unit 11f estimates the radio wave intensity distribution from the position information, ID, and radio wave intensity information of the radio wave sensor recorded in the data recording unit 11e, and the result is displayed on the display unit 11a or the data recording unit 11e. To be recorded. Further, the radio wave intensity data processing device 11 selects the antenna of the reader / writer 13, antenna beam direction, transmission power control, transmission timing via the communication unit 11c and the cable 60 based on the data recorded in the data recording unit 11e. Control etc. may be controlled. The reader / writer 13 transmits radio waves to the tag 4 and starts communication. The radio wave sensor 21 receives the radio wave transmitted from the reader / writer 13 with the antenna 21a, and detects the radio wave intensity with the detection processing unit 21d. The short-range wireless transmission / reception unit 21c adds an ID to the radio wave intensity detected by the detection processing unit 21d, and transmits the radio wave intensity to the radio wave intensity collection device 12 via the antenna 21b. The radio wave sensor 21 may transmit the detected radio wave intensity and ID to the radio wave intensity collecting apparatus 12 after receiving a command from the radio wave intensity collecting apparatus 12.

  FIG. 3 shows a detailed configuration diagram of the radio wave sensor.

  The radio wave sensor includes a UHF band RFID antenna 21a, a detection processing unit 21d, a short-range wireless transmission / reception unit 21c, a short-range wireless antenna 21b, and a battery 21e. The detection processing unit 21d includes a BPF 211d and a detection IC 212d. The detection IC 212d includes a detection diode and a log amplifier. The short-range wireless transmission / reception unit 21c includes a microcomputer 211c and a transmission / reception unit 212c. The microcomputer 211c includes an AD converter, a program memory, a RAM, and the like, and collects detected radio wave intensity data, controls the transmission / reception unit, transmits data to the transmission / reception unit, and the like. The radio wave sensor receives the radio wave from the reader / writer via the antenna 21a, passes a signal of a predetermined band by the BPF 211d of the detection processing unit 21d, and detects the radio wave intensity by the detection IC 212d. The microcomputer 211c converts the radio wave intensity signal from the detection IC 212d into a digital value, adds its own ID, and sends it to the transmission / reception unit 212c. The transmission / reception unit 212c wirelessly transmits the radio wave intensity data with the ID added thereto to the radio wave intensity collecting apparatus (not shown) via the short-range radio antenna 21b. In addition, the microcomputer 211c receives the radio field intensity collection command with ID from the radio field intensity collection device received by the short-range wireless transmission / reception unit 21c, and adds its own ID to the radio field intensity information if the command is addressed to itself. Send. The battery 21e supplies power to the detection IC 212d, the microcomputer 211c, and the transmission / reception unit 212c. When the radio wave sensor is driven by a battery, the degree of freedom of the observation point is increased, and the radio wave intensity on a moving body such as a cart or a belt conveyor can be measured.

  FIG. 4 shows a configuration example of the interference measurement system.

  Components having the same functions as those in FIG. Although not shown, the radio wave intensity data processing device 11 and the three reader / writers (13, 14, 15) may be connected by a LAN network or connected by a wired cable. Alternatively, each reader / writer may be connected to a separate control PC, and the radio wave intensity data collection device and the control PC may be connected by LAN. The radio wave intensity data processing device 11 controls each reader / writer (13, 14, 15, 16) to sequentially transmit radio waves. Each radio wave sensor (21 to 24) measures the radio wave intensity of the radio wave transmitted from each reader / writer, adds its own ID, and transmits the radio wave intensity to the radio wave intensity collecting device 12 wirelessly. The radio wave intensity data processing device 11 calculates the transmission time rate of each reader / writer (13, 14, 15, 16) from the radio wave intensity data from each radio wave sensor (21-24), and the degree of interference between the reader / writers. Predict.

  FIG. 5 shows a measurement example of the electric field strength of the moving tag.

  Components having the same functions as those in FIG. Reference numeral 41 denotes a carriage on which a plurality of containers with RFID tags 50 are mounted. Reference numeral 41 denotes a situation in which one carriage is moving. The point C on the near side of the drawing indicates the latest situation in time in the order of point A, point B, and point C. Reference numeral 38 denotes a reading area of the reader / writer 13. By specifying the point in time when the radio wave intensity from the reader / writer 13 to the tag 50 is maximized, the command transmission timing from the reader / writer 13 to the tag is optimized. The radio wave sensor 21 is attached to the carriage 41 in order to specify the time when the radio wave intensity becomes maximum. The radio wave intensity data processing device 11 instructs the reader / writer 12 to send radio waves intermittently. Before the carriage 41 enters the reading area, the radio wave transmission time rate may be small. When the carriage 41 is at point A, the radio wave sensor 21 is located at a position outside the reading area of the reader / writer 13, so that the received radio wave intensity is low. When the carriage 41 is at the point B, the radio wave sensor 21 is located within the reading area of the reader / writer 13, so that the received radio wave intensity is high. When the carriage 41 is at the point C, the radio wave sensor 21 is located outside the reading area from the reader / writer 13 and the received radio wave intensity is reduced again. Since the information indicating the radio field intensity is sequentially transmitted from the radio wave sensor to the radio field intensity data processing apparatus 11, the radio field intensity data processing apparatus can grasp the position of the carriage 41 in real time, and sends a command at the optimum position. be able to. As a result, the reading performance is improved and the time required for the reader / writer to transmit radio waves can be minimized, so that interference with other reader / writers and power consumption can be reduced.

  In addition to the above, the radio wave intensity distribution measuring system of the present invention can also be used for prior survey of usage environment, installation design, usage status monitoring, reader / writer and antenna control according to the environment, and the like.

  A plurality of the configurations and operations described above may be combined and applied.

  The present invention is not limited to the above configuration.

4 tags (slave stations)
DESCRIPTION OF SYMBOLS 11 Radio wave intensity data processing apparatus 11a Display part 11b Input part 11c Communication part 11d Control part 11e Data recording part 11f Data processing part 12 Radio wave intensity collection device 13, 14, 15, 16 Reader / writer (master station)
21, 22, 23, 24 Radio wave sensor 21a, 22a, 23a Detection antenna 21b, 22b, 23b Short-range wireless antenna 21c Short-range wireless transmission / reception unit 21d Detection processing unit 21e Battery 31-37 Radio wave distribution 38 Reading area 41 Dolly 50 RFID tag 60 Wired cable 211c Microcomputer 211d BPF
212c Transmission / reception unit 212d Detection IC

Claims (8)

A radio wave intensity distribution measuring system,
A first antenna that receives radio waves in a first frequency band, a second antenna that communicates in a second frequency band different from the first frequency band, and the first frequency band transmitted from a communication device Of the received radio wave by the first antenna and detecting the radio field intensity of the received radio wave, and information indicating the radio field intensity detected by the detection unit via the second antenna. A radio wave sensor comprising: a communication unit that transmits to the communication device wirelessly in the frequency band of the second frequency band and receives a signal transmitted from the communication device wirelessly in the second frequency band by the second antenna ;
Radio wave intensity distribution measuring system characterized by having a processing device for acquiring the electric field strength distribution on the basis of the information indicating the electric wave strength received in the previous SL communication device. Pre Symbol processor, the radio wave of the first frequency band is available range received by the second communication device, and measure from the electric field strength distribution,
The first antenna has reception characteristics equivalent to the reception characteristics of the second communication device, or reception characteristics that simulate the reception characteristics of the second communication device.
The radio wave intensity distribution measuring system according to claim 1. The reception characteristics include at least one of antenna directivity, polarization characteristics, frequency characteristics, and impedance characteristics.
The radio wave intensity distribution measuring system according to claim 2. The radio wave intensity distribution measuring system according to claim 2 or 3, wherein the second device is a radio tag. The radio wave intensity distribution measurement system according to claim 4, wherein radio waves in the first frequency band are transmitted from the communication device to the radio tag. The radio wave sensor is movably provided,
A position acquisition unit that acquires information indicating the position of the radio wave sensor;
The processing device acquires the electric field intensity distribution based on information indicating the radio wave intensity detected by the radio wave sensor at a plurality of positions and information indicating a position of the radio wave sensor.
The radio wave intensity distribution measuring system according to any one of claims 1 to 5.   The radio wave intensity distribution measurement system according to claim 1, wherein the communication unit transmits information indicating the radio wave intensity with identification information of the radio wave sensor added thereto. A method for measuring radio wave intensity distribution,
The radio wave sensor receives radio waves in the first frequency band transmitted from the communication device via the first antenna,
Detecting the radio wave intensity of the radio wave in the first frequency band received by the first antenna;
Transmitting the information indicating the detected radio wave intensity from the radio wave sensor to the communication device via a second antenna wirelessly in a second frequency band different from the first frequency band;
A signal transmitted from the communication device by radio in the second frequency band is received by the radio wave sensor via the second antenna;
2. A radio field intensity distribution measuring method, comprising: obtaining an electric field intensity distribution based on information indicating the radio field intensity received by the communication device.