JP6548189B2 - Wireless communication system - Google Patents

Description

  The present invention relates to a wireless communication system for transmitting wireless signals from a plurality of transmitters to a receiver.

  2. Description of the Related Art In recent years, wireless communication systems that transmit status monitoring of various devices installed at remote points and measurement data and the like from measuring devices to a receiver as a wireless signal from a transmitter have become widespread. In this type of radio communication system, one receiver is often configured to receive radio signals from a plurality of transmitters, and the received radio signal is a radio signal from any transmitter of its own system. The information for detecting whether it is is transmitted / received (for example, patent document 1).

  FIG. 5 is a block diagram showing the configuration of the wireless communication system 100 described in Patent Document 1. As shown in FIG. FIG. 6 is a schematic diagram showing the format of a wireless signal of the conventional wireless communication system 100. As shown in FIG. The wireless communication system 100 includes a plurality of transmitters 120 for alternatively selecting a plurality of wireless channels and transmitting a wireless signal, and a receiver 110 for receiving a wireless signal.

  Each of the transmitters 120 includes, for example, a transmission unit 121 formed of a specific low power radio station, and transmits to the receiver 110 a radio signal including information according to the type of each transmitter 120 and the type of the system to which it belongs. doing. The receiver 110 includes, for example, a control unit 111 including a microcomputer, a receiving unit 112 including a specific low power radio station, a storage unit 113 including a non-volatile semiconductor memory, and an operation input unit including a liquid crystal panel and switches. And 114 are provided. The receiving unit 112 operates according to the control of the control unit 111, and when the measured signal strength is higher than a predetermined threshold, receives the radio signal flowing in the wireless channel and outputs the signal to the control unit 111.

  The radio signal transmitted by the transmitter 120 to the receiver 110 has a format as shown in FIG. 6 and is composed of a preamble PA, a unique word UW, data DA, and an error detection code CR. The preamble PA is, for example, a bit string consisting of bit synchronization patterns that alternately repeat "0" and "1". The first bit is set to "0" and the last bit is set to "1". The bit sequence can be regarded as a preamble PA only in the case. The unique word UW consists of bits different from the preamble PA and is set to a length of 32 bits. Data DA is a bit string including the identification address of the transmitter 120 that has transmitted and transmission information that the transmitter 120 performs transmission, and the bit length can be made variable according to the contents of the transmission information to be transmitted. . The error detection code CR is a bit string composed of a CRC, and is set to be able to detect an abnormality such as bit inversion in at least a bit string constituting the data DA at the time of transmission and reception. The receiver 110 scans each wireless channel by time division every predetermined scan period, and receives the following data when it detects a preamble PA including a bit synchronization pattern.

JP 2011-066530 A

  However, in the conventional wireless communication system, there is a problem that the transmission time of the preamble or the like becomes longer than the identification address of the transmitter and the transmission time of the transmission information to be transmitted. For example, in the case where a transmitter of an apparatus installed at a remote point uses a small-capacity battery or an environmental power generator as a power source, it is required that the power consumption be as low as possible. Since the wireless transmission power occupies most of the power consumption in the transmitter, the wireless communication system having a long transmission time has a problem that the power consumption of the transmitter is increased.

  The present invention solves the above-mentioned problems, and an object of the present invention is to provide a wireless communication system capable of reducing the power consumption of the transmitter.

A wireless communication system according to the present invention is a wireless communication system including a plurality of transmitters for transmitting a wireless signal and a receiver for receiving the wireless signal transmitted from the transmitter, wherein the wireless signal is transmitted during a transmission period. Information data to be transmitted in a predetermined pattern repeating a period and a non-transmission period, and a data start signal transmitted by a carrier wave of a frequency set in advance for each of the transmitters by providing an immediately preceding non-transmission period immediately before the information data. And a data end signal transmitted immediately after the information data by providing a non-transmission period immediately after the information data, and the receiver is synchronized with the predetermined pattern stored in advance after the data start signal of the frequency is received. and received, the information data received before receiving the data end signal, output by the received information, the radio signal transmitted from the transmitter Said information data, characterized in that it is hopping for each of said transmission period by the carrier having a frequency different from said frequency of the data start signal transmitted from the transmitter.

  According to this configuration, the data start signal transmitted by the carrier wave of the frequency set in advance for each transmitter is received, and the data start signal follows the data start signal with the predetermined pattern and frequency stored in advance by the transmitter and the receiver. Since the receiver synchronously receives the information data transmitted in the predetermined pattern, the transmitter transmits the shortest data start signal and the information data, so that the receiver can receive the data without malfunction and the consumption of the transmitter. Power can be reduced.

  Further, in the wireless communication system of the present invention, the data start signal is set to a 1-bit signal whose frequency is different for each of the transmitters.

  According to this configuration, since the frequency of the data start signal is different in each transmitter, it is possible to prepare for communication to receive information data transmitted from the transmitter in a predetermined pattern only by the receiver receiving the data start signal.

  In the wireless communication system according to the present invention, the wireless signal includes the data start signal transmitted by the carrier wave of the frequency, the information data transmitted in the predetermined pattern by providing the immediately preceding non-transmission period, and The present invention is characterized in that the data end signal is transmitted by providing the immediately subsequent non-transmission period immediately after the information data and transmitted a plurality of times.

  According to this configuration, since the wireless signal is repeated and transmitted a plurality of times, the probability that the receiver can receive can be improved. In particular, since short radio signals can be transmitted, the number of repetitions can be increased even if the power of the transmitter is low.

  In the wireless communication system of the present invention, the wireless signal is a 1-bit communication signal by turning on and off a carrier wave.

  According to this configuration, it is possible to perform transmission with less power by setting it as 1-bit communication in which the carrier wave is 1 during the predetermined transmission period and 0 when the carrier is off.

  In the wireless communication system of the present invention, the power supply of the transmitter is an induced electromotive force by electromagnetic induction.

  According to this configuration, since the power of the transmitter is supplied by the induced electromotive force, it is not necessary to connect a battery or a wire for receiving power to the transmitter. Therefore, it is compact and lightweight, and can be installed freely.

  According to the present invention, the data start signal transmitted by the carrier wave of the frequency set in advance for each transmitter is received, and the data start signal is continued with the predetermined pattern and frequency stored in advance by the transmitter and the receiver. The receiver synchronously receives information data transmitted in a predetermined pattern. Therefore, the transmitter can transmit the shortest data start signal and the information data, and the receiver can receive the data without malfunction, thereby reducing the power consumption of the transmitter. Therefore, it is possible to provide a wireless communication system capable of reducing the power consumption of the transmitter.

FIG. 1 is a block diagram showing a wireless communication system according to an embodiment of the present invention. It is a block diagram which shows the structure of a transmitter. FIG. 3 (a) is a time chart of transmission power, and FIG. 3 (b) is a time chart of the frequency of a carrier wave. It is a time chart explaining received signal strength of a receiver. It is a block diagram which shows the structure of the conventional radio | wireless communications system. FIG. 1 is a schematic view showing the format of a wireless signal of a conventional wireless communication system.

First Embodiment
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the dimensions are appropriately changed for the sake of easy understanding.

  FIG. 1 is a block diagram showing a wireless communication system 1 according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the transmitter 20. As shown in FIG. FIG. 3 is a time chart explaining a radio signal transmitted from the transmitter 20, FIG. 3 (a) is a time chart of transmission power, and FIG. 3 (b) is a time chart of carrier frequency. FIG. 4 is a time chart explaining the received signal strength of the receiver.

  As shown in FIG. 1, the wireless communication system 1 according to the present embodiment includes a plurality of transmitters 20 that transmit a wireless signal, and a receiver 10 that receives a wireless signal transmitted from the transmitter 20. . The receiver 10 includes a receiving unit 10a capable of receiving the wireless signal transmitted from the transmitter 20, obtains information data from the wireless signal received by the receiving unit 10a, and outputs the information data as received information. The receiving system 50 includes a plurality of receivers 10 and an information processing unit 40, and processes received information according to the purpose of the wireless communication system 1.

  The transmitter 20 is provided with the transmission part 20a, the control part 20b, and the power supply part 20c, as shown in FIG. The transmitting unit 20a includes an electronic circuit having a function of transmitting a wireless signal and an antenna. The control unit 20 b is an electronic circuit having a function of preparing a wireless signal including information data, and includes an arithmetic processing unit and a storage unit (not shown). The power supply unit 20c has a function of supplying necessary power to the transmission unit 20a and the control unit 20b. In the present embodiment, the power supply unit 20c includes a power generation unit 20d and a power supply circuit unit 20e. The power generation unit 20 d is an environmental power generation device that generates an induced electromotive force by electromagnetic induction. The power supply circuit unit 20 e is an electronic circuit that adjusts the power generated by the power generation unit 20 d to a desired state.

  In the power generation unit 20 d used in the wireless communication system 1 of the present embodiment, the permanent magnet moves relative to the coil due to the movement of the drive shaft to generate a current in the coil. The power generation unit 20 d is not limited to the electromagnetic induction type environmental power generation device, and may be, for example, a piezoelectric type. In these cases, the generated power is not constant and is supplied after being rectified to a desired DC voltage by the power supply circuit unit 20e. In addition, in the case of using an environmental power generation apparatus in which the generated power is relatively constant, the power supply circuit unit 20e becomes simpler, and for example, it may be called a constant voltage circuit. Although the power supply unit 20c having the power generation unit 20d is provided in the present embodiment, the wireless signals described below are the same even when the power supply unit including the battery is provided.

  In the wireless communication system 1 of the present embodiment, the wireless signal shown in FIG. 3 is transmitted from the transmitter 20 a of the transmitter 20. The radio signal includes a data start signal ST, information data Da, Db, Dc, and a data end signal SO.

  As shown in FIG. 3A, the wireless signal is transmitted in a predetermined pattern Ta repeating a transmission period Ton and a non-transmission period Toff. In the case shown in FIG. 3A, the data start signal ST is transmitted in the first transmission period Ton. After the immediately preceding non-transmission period Tof1, the information data Da, Db, and Dc are transmitted in a predetermined pattern Ta repeating the transmission period Ton and the non-transmission period Toff, respectively. The data end signal SO is transmitted in the transmission period Ton that follows the non-transmission period Tof2. At this time, as shown in FIG. 3B, in the first transmission period Ton, the carrier frequency is the preset frequency F1, and in the subsequent transmission period Ton, the frequencies of F1a, F1b, F1c, and F1d are in order. Make it hop. In the information data Db of FIG. 3A, the transmission power is zero, and the carrier wave of the frequency F1b of FIG. 3B is a virtual one not being transmitted.

  The wireless signal is a 1-bit communication signal by turning on and off the carrier wave. That is, it is 1 when the carrier wave is on in the predetermined transmission period Ton and 0 when it is off. The information data Da, Db, Dc mean 3-bit digital information. In the case of FIG. 3A, (101) is represented. The amount of information can be increased by the number of repetitions of the predetermined pattern Ta, and in the case of eight times, for example, 8-bit digital information can be transmitted. However, even in the case of transmitting digital information in which the amount of information of such 3 bits to 8 bits is relatively small, the conventional wireless signal has a problem that the transmission time of a preamble or the like becomes long.

  In the wireless communication system 1 of the present embodiment, the immediately preceding non-transmission period Tof1 is provided immediately before the information data Da, and the data start signal ST is transmitted. The data start signal ST is transmitted on the carrier wave of frequency F1. In the example of FIG. 3A, the data start signal ST is set to a 1-bit signal. However, the transmittable data start signal ST is a 1-bit signal whose digital value is "1" and not a 1-bit signal whose digital value is "0".

  Also, immediately after the information data Dc, a non-transmission period Tof2 is provided immediately after and the data end signal SO is transmitted. In the example of FIG. 3A, the data end signal SO is set to a 1-bit signal. However, the data end signal SO that can be transmitted is a 1-bit signal whose digital value is "1" and not a 1-bit signal whose digital value is "0".

  The immediately preceding non-transmission period Tof1 and the immediately subsequent non-transmission period Tof2 are equal to the non-transmission period Toff. The above wireless signal has the shortest transmission time for recognizing the start of transmission of data and the end of transmission, which greatly reduces the transmission time required when transmitting digital information with a small amount of information.

  Further, as shown in FIG. 3B, the carrier wave of the information data Da, Db, Dc changes to the frequency F1a, F1b, F1c hopping from the frequency F1 of the carrier wave of the data start signal ST. Further, the data end signal SO is hopped to a frequency F1d different from the frequency F1.

  In the wireless communication system 1 of the present embodiment, the wireless signal is transmitted in a predetermined pattern Ta repeating the transmission period Ton and the non-transmission period Toff shown in FIG. 3A, and subsequently, an interval is made from the non-transmission period Toff. After that, it is repeatedly transmitted with the repetition pattern Tb shown in FIG. 3A again. This wireless signal can be repeated as long as necessary power is supplied to the transmission unit 20a by the power generated by the power generation unit 20d, but it is preferable to set the number of repetitions in advance.

  In the wireless communication system 1 of the present embodiment, the frequency F1 of the carrier wave of the data start signal ST shown in FIG. 3 is preset so as to be different for each of the transmitters 20 shown in FIG. The receivers 10 for the number of transmitters 20 are prepared corresponding to different transmitters 20 having different first frequencies F1 of carrier waves.

  Each receiver 10 is preset to be able to receive different frequencies F1, and is waiting for a data start signal ST from the corresponding transmitter 20.

  The receiver 10 synchronizes so that it can receive a radio signal with a predetermined pattern Ta when the received signal strength (RSSI) at the frequency F1 exceeds the detection threshold. FIG. 4 is a time chart showing the received signal strength indicator (RSSI) of the receiver 10 when the radio signal shown in FIG. 3 (a) is received.

  Since the radio signal from the transmitter 20 is repeated in a predetermined pattern Ta shown in FIG. 3, the received signal strength indicator (RSSI) of the receiver 10 is also detected in a period corresponding to the transmission period Ton. Furthermore, since it changes from the frequency F1 of the carrier wave of the data start signal ST to the hopping frequencies F1a, F1b and F1c, the received signal strength (RSSI) is detected by changing the reception frequency of the receiver 10 correspondingly. . If the reception signal of the frequency F1 is an interference wave which is not a radio signal from the transmitter 20, then it is impossible to receive repetition and frequency hopping with a predetermined pattern Ta stored in advance. Therefore, as shown in FIG. 4, when the received signal strength indicator (RSSI) is received in synchronization with the predetermined pattern Ta stored in advance, it is clear that it is a wireless signal from the transmitter 20. Therefore, the information data Da, Db, Dc transmitted following the data start signal ST are output as reception information of 3-bit digital information.

  In the wireless communication system 1 of the present embodiment, the wireless signal is repeatedly transmitted in the repetition pattern Tb after an interval from the non-transmission period Toff. Since the radio signal is repeated and transmitted a plurality of times, the probability that the receiver 10 can receive can be improved. In particular, since short radio signals can be transmitted, the number of repetitions can be increased even if the power of the transmitter 20 is low. Then, after receiving the repetitive pattern Tb, the receiver 10 repeatedly outputs the repetitive wireless signal as reception information. The information processing unit 40 shown in FIG. 1 can temporarily store and compare repeated wireless signals and select correct information.

  In addition to the information data Da, Db, and Dc to be transmitted, a parity signal may be added so as to be transmitted thereafter, in order to be able to select a more correct signal.

  In addition, although the receiving system 50 includes the plurality of receivers 10 and the information processing unit 40, the plurality of receivers 10 may each include the information processing unit. Further, although the reception system 50 including a plurality of receivers 10 has been described with reference to FIG. 1, the present invention is not limited thereto. For example, a plurality of reception units are provided, and a plurality of outputs corresponding to a plurality of reception units A wireless communication system may be configured with a receiver that can obtain

  In the wireless communication system 1 of the present embodiment, as shown in FIG. 3A, since the transmission power is a time within the total time of the transmission period Ton, compared with the time of the repetition pattern Tb including the non-transmission period Toff. The power of the transmitter 20 can be reduced. Furthermore, since the data start signal ST and the data end signal SO are set to 1-bit signals, the transmission power required for them can be minimized. Further, since the carrier frequency F1 of the data start signal ST is changed for each transmitter 20, only when the receiver 10 receives the data start signal ST, the information data Da transmitted from the transmitter 20 in a predetermined pattern Ta , Db, Dc are ready for communication.

  Hereinafter, the effects of the present embodiment will be described.

  The wireless communication system 1 of the present embodiment includes a plurality of transmitters 20 for transmitting a wireless signal, and a receiver 10 for receiving the wireless signal transmitted from the transmitter 20. The radio signal is provided with information data Da, Db, Dc transmitted in a predetermined pattern Ta repeating a transmission period Ton and a non-transmission period Toff, and a non-transmission period Tof1 immediately before the information data Da. It includes a data start signal ST transmitted by a carrier wave of a preset frequency F1, and a data end signal SO transmitted immediately after the information data Dc by providing a non-transmission period Tof2. The receiver 10 receives the data start signal ST of the frequency F1 in synchronization with the predetermined pattern Ta stored in advance after receiving the data start signal ST, and receives the information data Da, Db, Dc received until the data end signal SO is received, Output as received information.

  According to this configuration, the data start signal ST transmitted by the carrier wave of the frequency F1 preset for each transmitter 20 is received. Then, the receiver 10 synchronizes the information data Da, Db, Dc transmitted in the predetermined pattern Ta following the data start signal ST with the predetermined pattern Ta and frequency stored in advance by the transmitter 20 and the receiver 10. To receive. Therefore, the transmitter 20 can transmit only the shortest data start signal ST and the information data Da, Db, Dc without malfunction and can be received by the receiver 10, and the power consumption of the transmitter 20 can be reduced.

  Further, in the wireless communication system 1 of the present embodiment, the data start signal ST is set to a 1-bit signal in which the frequency F1 is different for each transmitter 20.

  According to this configuration, since the frequency F1 of the data start signal ST is different for each transmitter 20, the transmitter 10 transmits in a predetermined pattern Ta only by receiving the data start signal ST which is a 1-bit signal. It is possible to prepare for communication to receive the information data Da, Db, Dc.

  Further, in the wireless communication system 1 of the present embodiment, the information data Da, Db, Dc of the radio signal transmitted from the transmitter 20 has a frequency different from the frequency F1 of the data start signal ST transmitted from the transmitter 20 The carrier wave is hopped for each transmission period Ton.

  According to this configuration, since the frequency is hopped and transmitted / received, it is possible to be resistant to jamming waves.

  Further, in the wireless communication system 1 of the present embodiment, the wireless signal includes the data start signal ST transmitted by the carrier wave of the frequency F1 and the immediately preceding non-transmission period Tof1, and the information data Da and Db transmitted in the predetermined pattern Ta. , Dc and a data end signal SO transmitted immediately after the information data Da, Db, Dc by providing a non-transmission period Tof 2 immediately after the information data Da, Dc, and Dc.

  According to this configuration, since the wireless signal is repeatedly transmitted a plurality of times, the probability that the receiver 10 can receive can be improved. In particular, since short radio signals can be transmitted, the number of repetitions can be increased even if the power of the transmitter 20 is low.

  Further, in the wireless communication system 1 of the present embodiment, the wireless signal is a 1-bit communication signal by turning on and off the carrier wave.

  According to this configuration, it is possible to perform transmission with less power by setting it as 1-bit communication in which the carrier wave is 1 when it is on in the predetermined transmission period Ton and 0 when it is off.

  Further, in the wireless communication system 1 of the present embodiment, the power supply of the transmitter 20 is an induced electromotive force due to electromagnetic induction.

  According to this configuration, since the power of the transmitter 20 is supplied by the induced electromotive force, it is not necessary to connect the transmitter 20 with a battery or a wire for receiving power. Therefore, it is compact and lightweight, and can be installed freely.

  As described above, the wireless communication system 1 according to the embodiment of the present invention has been specifically described. However, the present invention is not limited to the above embodiment, and various modifications may be made without departing from the scope of the invention. It is possible. For example, modifications can be made as follows, which also fall within the technical scope of the present invention.

  (1) In the present embodiment, although the data start signal ST is set to a 1-bit signal whose frequency F1 is different for each transmitter 20, times to be transmitted from a plurality of transmitters 20 are determined in advance. In this case, the frequency F1 may be the same. Also, it may be configured not by a 1-bit signal but by a 2-bit or 3-bit signal, and frequency hopping may be performed in the transmission of the data start signal ST so that the detection thereof becomes reliable.

  (2) In the present embodiment, the information data Da, Db, Dc are hopped for each transmission period Ton by the carrier wave having a frequency different from the frequency F1, but under an environment where the influence of jamming is small , And may not be frequency hopping. In this case, although it becomes difficult to detect at the timing when there is a jamming signal, the probability can be reduced by repeatedly transmitting.

  (3) In the present embodiment, the radio signal is a 1-bit communication signal by turning on and off the carrier, but if frequency hopping is not performed as described above, the carrier continues continuously for the time of the repetitive pattern Tb. It may be sent. In this case, the data start signal ST, the information data Da, Db, Dc, and the data end signal SO are transmitted as modulation signals.

Reference Signs List 1 wireless communication system 10 receiver 10a receiver 20 transmitter 20a transmitter 20b control unit 20c power supply unit 20d power generation unit 20e power supply circuit unit 40 information processing unit 50 reception system Da information data Db information data Dc information data F1 frequency SO data end Signal ST data start signal Ta predetermined pattern Tb repetitive pattern Toff non-transmission period Tof1 immediately before non-transmission period Tof2 immediately after non-transmission period Ton transmission period

Claims (5)

A plurality of transmitters transmitting radio signals;
A receiver for receiving the radio signal transmitted from the transmitter.
The wireless signal includes information data transmitted in a predetermined pattern repeating a transmission period and a non-transmission period, and a carrier wave of a frequency set in advance for each of the transmitters by providing an immediately previous non-transmission period immediately before the information data. A data start signal to be transmitted, and a data end signal to be transmitted immediately after the information data by providing a non-transmission period immediately,
The receiver receives in synchronization with the predetermined pattern stored in advance after receiving the data start signal of the frequency, and outputs the received information data as reception information until the data end signal is received. Force
The information data of the radio signal transmitted from the transmitter is hopped for each transmission period by a carrier wave of a frequency different from the frequency of the data start signal transmitted from the transmitter. Wireless communication system.   The wireless communication system according to claim 1, wherein the data start signal is set to a 1-bit signal in which the frequency is different for each transmitter. The wireless signal includes the data start signal transmitted by the carrier wave of the frequency, the information data transmitted in the predetermined pattern with the immediately preceding non-transmission period, and the immediately subsequent non-transmission period immediately after the information data. The radio communication system according to any one of claims 1 to 2 , wherein the data end signal is transmitted by providing the data end signal and the data end signal is repeatedly transmitted a plurality of times. The wireless communication system according to any one of claims 1 to 3 , wherein the wireless signal is a 1-bit communication signal by turning on and off a carrier wave. The wireless communication system according to any one of claims 1 to 4 , wherein the power supply of the transmitter is an induced electromotive force by electromagnetic induction.