JP5585337B2 - Wireless communication terminal and wireless communication method - Google Patents

Description

  The present invention relates to a wireless communication terminal and a wireless communication method for performing wireless communication using the same.

  In recent years, wireless communication terminals such as non-contact RF (Radio Frequency) tags and RFID (RF IDentification) that perform near field communication (NFC) of several centimeters to several meters through a magnetic field or electromagnetic field have become widespread. doing. Wireless communication terminals are used in various fields such as ETC (Electronic Toll Collections), keyless entry, boarding cards, electronic money, and authentication cards.

  As an example of using such a wireless communication terminal, the wireless communication terminal receives position information specifying the position of the HF transmitter from the HF transmitter, and transmits it to the UHF receiver together with information specifying the own wireless communication terminal. Thus, a technique for identifying the position of a wireless communication terminal on the UHF receiver side while avoiding interference due to communication between the wireless communication terminal and the UHF receiver is known (for example, Patent Document 1).

JP-A-10-136435

  Conventionally, wireless communication terminals have been configured with relatively small size and low cost in consideration of portability. In recent years, further downsizing and cost reduction of wireless communication terminals are desired. Therefore, conventionally, the external shape of the wireless communication terminal can be enlarged to some extent, and the distance between the antenna that receives electromagnetic waves and the control circuit (MCU: Micro Controller Unit) that operates with a high-frequency rectangular wave can be separated. However, due to the miniaturization of the wireless communication terminal itself and the space limitation of the location where the wireless communication terminal is installed, there is no flexibility in the arrangement of the antenna and the control circuit, and the distance between the antenna and the control circuit must be shortened. It is gone.

  As a result, high-frequency noise accompanying the operation of the control circuit inside the wireless communication terminal wraps around the antenna and the demodulation circuit, leading to deterioration of the S / N ratio (Signal to Noise ratio) and reception sensitivity. Even if the above-mentioned Patent Document 1 is applied to the deterioration of the S / N ratio and the like, it does not lead to a solution.

  Therefore, in view of such a problem, an object of the present invention is to provide a wireless communication terminal and a wireless communication method capable of improving the S / N ratio without causing an increase in the size of the wireless communication terminal.

In order to solve the above problem, a wireless communication terminal of the present invention includes a first antenna that receives a first signal including modulated first information from a transmission source device, and a first antenna that is received by the first antenna. A demodulating circuit for demodulating the signal; an on / off control unit for turning on / off the demodulating circuit; an information extracting unit for extracting first information from the demodulated first signal; A control circuit that operates in synchronization with the control circuit clock, and a modulation circuit that modulates the first information and the second information and transmits the first information and the second information through the second antenna. with the door, the control circuit clock operates in response to an interrupt signal generated by said wireless communication terminal, after the information extraction unit has extracted the first information from the first signal to start, control circuit With the feature that the clock stops That.

  The time after the first information is extracted from the first signal may be an arbitrary time from when the first information is extracted until the demodulation circuit starts the next demodulation of the first signal.

  The on / off control unit may be intermittently activated to turn on the demodulation circuit, and the control circuit clock may be stopped.

  The control circuit may intermittently perform at least one of the on / off control unit and the transmission control unit according to the interrupt signal.

  The interrupt signal may be an overflow signal generated when a timer for counting the timer clock reaches a predetermined value, or a signal based on an edge in the demodulated first signal.

  The edge-based signal in the demodulated first signal may include an edge-based signal that indicates a start signal of valid data in the demodulated first signal.

  The timer may count the sub clock used for the peripheral operation of the control circuit as the timer clock while the information extraction unit performs the process of extracting the first information.

  An external oscillator that generates a clock having a higher frequency than the analog clock supplied to the control circuit is further provided, and the timer uses the external oscillator as a timer clock while the information extraction unit performs the process of extracting the first information. The clocks generated by may be counted.

  A clock forming circuit for forming a clock based on the carrier wave of the first signal or the second signal is further provided, and the timer is used as a timer clock while the information extraction unit performs the process of extracting the first information. The clocks formed by the forming circuit may be counted.

  As the modulation method of the first signal, an OOK modulation method or a PPM modulation method may be used.

In order to solve the above-described problem, another wireless communication terminal of the present invention receives a first signal including a first signal including modulated first information from a transmission source device, and the first antenna receives the first signal. First
A demodulating circuit for demodulating the signal, an on / off control unit for turning on and off the demodulating circuit, and the demodulated first
It has an information extracting unit that extracts the first information from the signal, and a control circuit which operates in synchronization with the control circuit clock control circuit in response to an interrupt signal generated by the wireless communications terminal The control circuit clock is stopped after the operation clock is activated and the information extraction unit is activated to extract the first information from the first signal.

In order to solve the above-described problem, a demodulation circuit that demodulates a first signal including modulated first information received by a first antenna, and a control that operates in synchronization with a control circuit clock and controls the demodulation circuit in the radio communication method for performing radio communication by the wireless communication terminal and a circuit, control circuit, clock control circuit operates in response to an interrupt signal generated by the wireless communications terminal,
The control circuit is activated to turn on the demodulation circuit, stop the control circuit clock, and turn the demodulation circuit to the first
The control circuit clock is activated in response to the interrupt signal, and the control circuit is activated to extract a part or all of the first information from the demodulated first signal, and control is performed. When the circuit clock is stopped and the first information is extracted, the demodulation circuit is turned off.

  The components based on the technical idea of the wireless communication terminal and the description thereof can be applied to the wireless communication method.

  As described above, according to the wireless communication terminal and the wireless communication method of the present invention, the S / N ratio can be improved without increasing the size of the wireless communication terminal.

It is explanatory drawing which showed the schematic relationship of each apparatus which comprises a radio | wireless communications system. It is the functional block diagram which showed the schematic function of the radio | wireless communication terminal. It is the external view which illustrated the external appearance of the radio | wireless communication terminal. It is explanatory drawing for demonstrating the influence of the noise on the demodulated 1st signal. 4 is a timing chart for explaining an intermittent operation of a demodulation circuit, a control circuit, and a modulation circuit. 4 is a timing chart for explaining an intermittent operation of a demodulation circuit, a control circuit, and a modulation circuit. 4 is a timing chart for explaining an intermittent operation of a demodulation circuit, a control circuit, and a modulation circuit. It is the flowchart which showed the whole flow of the radio | wireless communication method.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  Wireless communication terminals such as RF tags and RFID perform short-range wireless communication such as several centimeters to several meters in a non-contact manner. Here, not only a passive type wireless communication terminal that operates by receiving power supply from an RF reader, but also an active type wireless communication terminal in which a power source is provided in the wireless communication terminal itself, the reception distance is deliberately It is possible to limit the communication area of the wireless communication terminal by setting a short distance, and to identify in which communication area (region, place) the wireless communication terminal is included. For example, a wireless communication terminal mounted on a cargo, a pallet, a container, etc. in the field of logistics communicates with a predetermined HF transmitter whose plane position is fixed. It is possible to track the location of the target package and track where the target package is.

  Among such tracking systems, the detection range of a wireless communication terminal is relatively wide. For example, in an asset management system, a wireless communication terminal is attached to a personal computer, furniture, measuring instrument, etc. as an asset, and the wireless communication terminal periodically The target asset is taken out and managed by sending a signal to. In the child monitoring system, a wireless communication terminal is attached to a bag of children such as elementary school students to confirm attendance at school and to manage fixed point passing. Furthermore, when entering or leaving a construction site or the like, there is a demand for managing entry and exit of passengers such as automobiles and workers while riding on automobiles from the viewpoint of alleviating traffic congestion on the nearby roads. In the following embodiments, a wireless communication system that can be used in such various environments will be described.

(Wireless communication system 100)
FIG. 1 is an explanatory diagram showing a schematic relationship between devices constituting the wireless communication system 100. The wireless communication system 100 includes an HF transmitter 110, a wireless communication terminal 120, a UHF receiver 130, and an information collection server 140.

  The HF transmitter 110 includes an HF (High Frequency) wireless transmission circuit, and periodically transmits a first signal including predetermined information, for example, device information that can identify the HF transmitter 110 itself. Send (call) to. The HF wireless transmission circuit transmits an electromagnetic wave of 13.56 MHz, for example, as a carrier wave in consideration of the reception distance and power consumption of the wireless communication terminal 120. Here, 13.56 MHz in HF 3 MHz to 30 MHz is used as a carrier wave. However, it is not limited to such a band, and a band of LF (Low Frequency) 30 kHz to 300 kHz and MF (Middle Frequency) 300 kHz to 3 MHz may be used. it can. In addition to the electromagnetic wave, the HF transmitter 110 may transmit the first signal through light, ultrasonic waves, or infrared rays. As an example of the 1st information contained in the 1st signal, what specifies the position information where HF transmitter 110 is installed is mentioned. Another example of the first information included in the first signal includes a combination of operation information indicating whether the HF transmitter 110 is operating normally and an ID of the HF transmitter 110. Hereinafter, the case where the first information is device information that can identify the HF transmitter 110 itself will be described as an example.

  The device information included in the first signal includes an identifier that can identify the own HF transmitter 110 and the other HF transmitter 110. When the HF transmitter 110 is fixedly arranged, the fact that the HF transmitter 110 itself can be specified means that the position of the HF transmitter 110 can also be specified. For example, in the information collection server 140, when the position of the HF transmitter 110 is associated with the HF transmitter 110 specified by the device information, the position of the HF transmitter 110 is uniquely specified by the device information. Can do. Furthermore, the device information includes numerical values indicating latitude and longitude at which the HF transmitter 110 is arranged, identifiers commonly assigned to a plurality of HF transmitters 110 arranged in units of regions such as country, prefecture, city, etc. It may be information directly indicating. Here, the “position” includes not only an absolute position but also a relative position or a virtual position in a computer or the like.

  Also, periodically transmitting the first signal means that only valid data including device information is intermittently transmitted as a first signal at a predetermined cycle, or the wireless communication terminal 120 is made aware of the presence of the HF transmitter 110. Therefore, it includes a case where only the carrier wave is continuously transmitted as the first signal, and valid data including device information is intermittently superimposed in the meantime.

  The wireless communication terminal 120 is formed of an RF tag or RFID, is incorporated in various movable objects (for example, luggage, pallets, containers, cards, mobile phones, etc.) and transmitted by the HF transmitter 110. One signal is received, and a second signal having a carrier frequency different from that of the first signal is transmitted (transmitted) to the UHF receiver 130. Also, the wireless communication terminal 120 has second information that is predetermined information, for example, terminal information that can uniquely identify the own wireless communication terminal 120 or a group including the own wireless communication terminal 120. The wireless communication terminal 120 transmits the combination of the device information included in the first signal transmitted by the HF transmitter 110 and the terminal information to the UHF receiver 130, thereby specifying the HF transmission specified by the device information. The information collection server 140 can recognize that the own wireless communication terminal 120 is located within the communication area of the device 110.

  Further, as a modulation method of the first signal, for example, 10% ASK (Amplitude Shift Keying) modulation method (% indicates a modulation degree) or OOK (On Off Keying) modulation in which the 30% ASK modulation method is expressed in binary. A method or a PPM (Pulse Position Modulation) modulation method can be used. Since the above-described passive type wireless communication terminal 120 is configured to operate upon receiving power supply from the HF transmitter 110, the first signal has both functions of power supply and signal transmission. Therefore, the wireless communication terminal 120 must be operated with limited power. Here, it is possible to reduce power consumption by using an OOK modulation method or a PPM modulation method that can realize modulation / demodulation with a relatively simple configuration.

  Such modulation schemes and data formats are defined by ISO (International Organization for Standardization), and standardization is progressing worldwide. Since these passive type wireless communication terminals 120 have no power supply other than the power based on the first signal, the reception distance after securing the power for operating the wireless communication terminal 120 is several centimeters to several tens of centimeters. It will be about. On the other hand, in the active type wireless communication terminal 120 as in the present embodiment, an amplifier is added and the received first signal is amplified. Therefore, from the HF transmitter 110 to the wireless communication terminal 120 (downward) The receiving distance is extended from several meters to several tens of meters.

  The UHF receiver 130 has a UHF (Ultra HF) radio reception circuit, and receives the second signal transmitted from the radio communication terminal 120. The UHF wireless reception circuit receives radio waves such as 315 MHz, 433 MHz, and 950 MHz through an electromagnetic field. The UHF receiver 130 may have a function of transmitting a signal in addition to a function of receiving the second signal. When the wireless communication terminal 120 supports both transmission and reception, the wireless communication terminal 120 Can also provide information.

  Further, while the HF transmitter 110 assumes a communication distance (down) of about 10 m, the UHF receiver 130 uses UHF, and therefore has a communication distance (up) of about 100 m longer than that. realizable. Therefore, the arrangement density of the UHF receivers 130 can be made lower than that of the HF transmitters 110.

  The information collection server 140 is connected to a plurality of UHF receivers 130 through a communication network 142 such as the Internet or a dedicated line, and from the UHF receiver 130, a combination of device information related to the UHF transmitter 110 and terminal information related to the wireless communication terminal 120. The communication area of the HF transmitter 110 where the wireless communication terminal 120 exists, that is, the position of the wireless communication terminal 120 is specified.

  In the wireless communication system 100 described above, the wireless communication terminal 120 incorporated in the movable loadable object receives the first signal from the HF transmitters 110 that have a relatively short communication distance but are relatively installed (FIG. 1). Middle, indicated by a solid arrow), and the terminal information of the self-radio communication terminal 120 is added to the UHF receiver 130 having a long communication distance (indicated by a broken arrow in FIG. 1).

  In this way, the wireless communication system 100 can distribute the load of the UHF receiver 130 to the HF transmitter 110 by making the upstream and downstream communication paths different based on the wireless communication terminal 120. A communication error caused by radio wave interference when wireless communication terminals in the vicinity respond to the call from the UHF receiver all at once in response to a call from the UHF receiver as in a configuration in which only a conventional UHF receiver is arranged is eliminated. The As a result, the transmission / reception timings are dispersed, collisions between radio signals are avoided, and the throughput of the radio communication system 100 is improved.

  Furthermore, in the configuration of only the conventional UHF receiver, the movement of the wireless communication terminal within a wide communication area by the UHF receiver could not be grasped, but in this embodiment, between the narrow communication areas by the HF transmitter 110. It is possible to grasp the movement of the wireless communication terminal 120 over a shorter distance because it is recognized by the difference in device information. Further, once the UHF receiver 130 is installed on the network of the wireless communication system 100, the communication area of the entire wireless communication system 100 can be freely set by adding or removing relatively inexpensive HF transmitters 110. Can be scaled.

(Wireless communication terminal 120)
FIG. 2 is a functional block diagram illustrating a schematic function of the wireless communication terminal 120, and FIG. 3 is an external view illustrating the external appearance of the wireless communication terminal 120. As shown in FIG. 2, the wireless communication terminal 120 is formed in an active type, and includes a first antenna 150, a demodulation circuit 152, a modulation circuit 154, a second antenna 156, a power supply unit 158, a memory 160, and the like. The timer 162 and the control circuit 164 are included.

  As shown in FIG. 3, the first antenna 150 includes a coil wound around the printed circuit board 180 for several turns, and receives a first signal including the modulated first information. If the frequency is as low as 40 kHz, the shape of the antenna becomes relatively large and it is easy to pick up ambient noise. However, in this embodiment, 13.56 MHz HF is used, so only a few turns of the coil are used. Thus, an antenna can be realized.

  The demodulation circuit 152 includes a reception amplifier 182, a coupling capacitor 184, a BPF (Band Pass Filter) 186, a rectifier 188, a first LPF (Low Pass Filter) 190, a comparator 192, and a second LPF 194, and the wireless signal received by the first antenna 150. A first signal in the signal is demodulated.

  The reception amplifier 182 amplifies the input radio signal with a relatively low gain. Thereby, even if the output power of the HF transmitter 110 is about 200 mW, the reception distance can be extended to about 10 m. Generally, the radio wave intensity of the HF transmitter 110 is 47 mV / m or less at a position separated by 10 m, and such a reception distance of 10 m can be realized by slightly amplifying with the reception amplifier 182. In addition, the reception distance can be set to an appropriate value by increasing or decreasing the output power of the HF transmitter 110, the antenna gain of the first antenna 150, and the amplifier gain of the reception amplifier 182 according to the application. . For example, the reception distance is set to more than a dozen meters for container unit position management that requires long-distance communication, and is set to about several meters for pallet unit position management used in logistics.

  The coupling capacitor 184 cuts the DC component of the input radio signal. If the frequency used for communication of the wireless communication terminal 120 is as low as 40 kHz, the capacity of the coupling capacitor increases. In this case, in order to perform the intermittent operation of the demodulation circuit 152, when the power supply by the power supply unit 158 is turned on / off, the inrush current at the time of turning on increases and the settling time until the reception amplifier 182 operates normally. As a result, the time during which the supply of power is stopped cannot be secured for a long time. In the present embodiment, since 13.56 MHz HF is used, the capacity of the coupling capacitor 184 can be reduced, and the settling time of the reception amplifier 182 is shortened. Can be secured for a long time.

  The BPF 186 passes a predetermined band centered on 13.56 MHz from the radio signal and extracts the first signal. The rectifier 188 rectifies the extracted first signal, and generates an envelope of the first signal in combination with the first LPF 190 and the second LPF 194. The first LPF 190 smoothes the rectified first signal. The comparator 192 compares the smoothed first signal with a predetermined threshold and binarizes the first signal. In this embodiment, since the OOK modulation method or the PPM modulation method is employed, the comparator 192 only needs to be able to determine the difference between the two amplitudes of the first signal. However, the signal output from the first LPF 190 or the second LPF 194 has a small amplitude when the reception sensitivity of the wireless communication terminal 120 is low or power consumption is large, and it is difficult for the comparator 192 to determine. In the present embodiment, the amplitude of the first signal is maintained through the maintenance of the reception sensitivity by the reception amplifier 182 and the reduction of the power consumption due to the intermittent operation of the demodulation circuit 152 and the control circuit 164, which will be described later. It is avoiding.

  Similar to the first LPF 190, the second LPF 194 smoothes the rectified first signal. However, the first LPF 190 is intended to cause the control circuit 164 to accurately read the demodulated first signal, whereas the second LPF 194 is intended to cause the control circuit 164 to accurately acquire the signal change timing. It is said. For this reason, the second LPF 194 is set to have a higher cutoff frequency than the first LPF 190 in order to avoid delay due to settling time.

  The modulation circuit 154 transmits information processed by the control circuit 164, for example, device information and terminal information, to the UHF receiver 130 through the second antenna 156, for example, using 950 MHz UHF. The second antenna 156 is configured by a helical antenna and transmits radio waves by an electromagnetic field. In the present embodiment, the first antenna 150 and the second antenna 156 are configured as separate bodies, but may be configured as the same body. That is, the information received and extracted from the first antenna 150 may be modulated and transmitted from the first antenna 150. It is obvious to those skilled in the art that the first antenna 150 and the second antenna 156 are configured as one body.

  The power supply unit 158 includes a primary battery or a secondary battery, and supplements the power based on the first signal transmitted from the HF transmitter 110 with the power of the battery, while demodulating circuit 152, modulation circuit 154, memory 160, the timer 162, the control circuit 164, and the like. Therefore, demodulation processing and modulation processing can be performed even in a situation where there is no power supply based on the first signal. However, the demodulation circuit 152 and the modulation circuit 154 are connected via switches 196a and 196b, and the switches 196a and 196b are ON / OFF controlled by the control circuit 164.

  The memory 160 includes a ROM, a RAM, an EEPROM, a flash memory, and the like, and holds a control program and terminal information for performing this embodiment. The memory 160 temporarily holds device information read from the first signal.

  The timer 162 selects one timer clock from the plurality of timer clocks (analog clock, main clock, sub clock) output from the control circuit 164, and counts the timer clock. Here, the analog clock is a clock whose source is a crystal oscillator externally attached to the control circuit 164. The main clock is a clock that is generated in the control circuit 164 and operates the on / off control unit 170, the information extraction unit 172, and the transmission control unit 174, which are core parts of the control circuit 164. When used in the description, it may be referred to as a control circuit clock. The control circuit operates in synchronization with such a control circuit clock (main clock). The sub clock is a clock that is generated in the control circuit 164 and controls peripherals built in the control circuit 164, such as serial communication and timer control. In this embodiment, the analog clock operates at 32 kHz, and the main clock and sub clock operate at 8 MHz.

  The control circuit 164 whose power consumption is assumed to be driven by a battery is normally prepared in a plurality of low power consumption modes, and an analog clock, a main clock, The sub clock can be stopped. In the intermittent operation of the present embodiment, for example, the supply of the main clock and the sub clock to the control circuit 164 is stopped and only the analog clock is operated. The timer 162 counts the analog clock, and the counted value is determined in advance. When the specified value is reached, an overflow signal for interrupt is generated.

  However, in addition to the overflow signal of the timer 162, the demodulated first signal is also input to the interrupt terminal a of the control circuit 164. The control circuit 164 is a signal based on the overflow signal or the edge of the first signal. Triggers interrupt processing when triggered by

  In addition to the above-described analog clock, main clock, and sub clock, a clock formed by an external oscillator or a clock forming circuit can also be used as a timer clock. The application of this embodiment of the external oscillator and clock generation circuit will be described in detail later.

  The control circuit 164 is composed of a semiconductor integrated circuit including an MCU, reads a control program for operating the own control circuit 164 and parameters from the ROM, and cooperates with a RAM as a work area and other electronic circuits. The wireless communication terminal 120 is managed and controlled as a whole. In addition, the control circuit 164 functions as an on / off control unit 170, an information extraction unit 172, and a transmission control unit 174 that start operation by an interrupt signal. Below, the necessity (premise part) of this embodiment is described first, and after that, each function part in the control circuit 164 is explained in full detail.

  The premise of the present embodiment is that when the on / off control unit 170 is intermittently activated at a predetermined cycle and the demodulation circuit 152 is turned on, the control circuit clock is stopped and the on / off control unit 170 is stopped. Captures the modulated signal from the first antenna 150. Then, after the control circuit clock (main clock) operates according to the interrupt signal generated in the wireless communication terminal 120 and the information extraction unit 172 is activated to extract the first information from the first signal Control circuit clock at any time from when the first information is extracted until the demodulation circuit 152 starts the next capture (demodulation) of the modulation signal (first signal) from the first antenna 150 Is at a point to stop. As a result, when the demodulating circuit 152 extracts the first information from the demodulated signal obtained by demodulating the modulated signal, noise associated with the operation of the control circuit clock (main clock) is not superimposed. There is an effect that the S / N ratio can be improved without incurring.

  By the way, as described above, in order to reduce the outer shape of the battery and to operate the wireless communication terminal 120 for a long time in order to reduce the size and cost of the wireless communication terminal 120, the wireless communication terminal 120 is wireless. There is a demand for lower power consumption of the communication terminal 120. In order to realize such low power consumption, it is desirable that intermittent operation of the demodulation circuit 152 and the modulation circuit 154 with relatively high power consumption be performed.

  However, if the intermittent period is lengthened, the average current consumption is reduced, but the speed at which the wireless communication terminal 120 passes through the range where the HF transmitter 110 can be received is limited. That is, in the intermittent operation in which the wireless communication terminal 120 passes through the vicinity of the HF transmitter 110 while the demodulation circuit 152 is stopped, the original role of the wireless communication terminal 120 communicating with the HF transmitter 110 is achieved. Can no longer be fulfilled. Therefore, an extreme intermittent operation cannot be performed even for the purpose of reducing power consumption.

  On the other hand, conventionally, there are few external restrictions, and it was possible to arrange | position the distance of the 1st antenna which receives electromagnetic waves, and the control circuit which operate | moves with a high frequency rectangular wave. However, the distance between the first antenna and the control circuit is inevitably shortened due to downsizing and space limitations of the installation destination of the wireless communication terminal.

  Then, accompanying the operation of the control circuit inside the wireless communication terminal, specifically, accompanying the operation of the main clock (control circuit clock) that operates the on / off control unit 170, the information extraction unit 172, and the transmission control unit 174 of the control circuit 164. The high frequency noise generated in this way wraps around the first antenna and the demodulation circuit, leading to deterioration of the S / N ratio and reception sensitivity. For example, when the output power of the HF transmitter 110 is 200 mW and the control circuit clock in the control circuit is not operating, the reception distance from the HF transmitter 110 can be secured up to about 10 m. As soon as the clock is operated, the reception distance is reduced to less than 1 m.

  This indicates that a difference of about 10 times occurs in the communication distance with the HF transmitter 110 depending on whether or not the control circuit clock is operated in the control circuit, and the reception sensitivity ratio is simply 10 dB when converted in decibels. Also become. Further, since the waveform of the control circuit clock in the control circuit is rectangular, it includes high-level harmonics, which further degrades the S / N ratio and the reception sensitivity.

  FIG. 4 is an explanatory diagram for explaining the influence of noise on the demodulated first signal. For example, taking the modulation signal of the PPM modulation method of 100% ASK as an example, the waveform of an ideal modulation signal input to the wireless communication terminal 120 is a state in which there is a carrier as shown in FIG. And the state where there is no carrier wave are repeated alternately. In the demodulating circuit 152, a HI (High) level signal is output while the carrier wave is present in the modulated signal, and a LOW level is output while there is no carrier wave, as in the demodulated signal shown in FIG. The control circuit 164 reads the demodulated first signal and converts it into data. However, if the control circuit continues to operate at a position close to the first antenna during this demodulation operation, noise accompanying the operation of the control circuit is generated, and the actual modulation signal is as shown in FIG. Originally, noise is superimposed on the period 200 when the carrier wave should not be detected.

  In this way, the demodulation circuit recognizes the noise in the period 200 that is equal to or greater than the threshold value of the comparator 192 as HI, and is demodulated that should repeat LOW and HI originally as in the demodulated signal shown in FIG. The first signal is fixed to HI. Here, in order to obtain the original demodulated signal as shown in FIG. 4A while continuing the reading operation of the demodulated first signal (operation of the control circuit), the reception distance that can ensure the S / N ratio. For example, the distance must be reduced to a little less than 1 m.

  In addition, when the demodulation circuit is operated intermittently, the control circuit 164 takes the following procedure as an example. That is, when the intermittent period arrives, the control circuit turns on the demodulation circuit, determines the presence or absence of the carrier of the first signal when the first signal is settled, and demodulates the first signal when it is determined that there is a carrier. Then, the demodulation circuit is stopped. When it is determined that there is no carrier wave, the demodulation circuit is immediately stopped.

  Here, when the S / N ratio deteriorates due to the arrangement of the first antenna 150 and the control circuit 164, and the demodulated signal is not correctly demodulated as shown in FIG. Actually, even when there is no carrier wave of the first signal, it is erroneously recognized that there is a carrier wave, and the demodulation of the first signal is erroneously started, resulting in a waste of power consumption.

  In order to avoid the influence of the operation of the control circuit 164 on the demodulated first signal, the arrangement of the first antenna and the control circuit may be devised, but the outer shape of the wireless communication terminal that has been desired in recent years is arranged. It cannot be freely changed, and it is difficult to avoid the noise accompanying the operation of the control circuit in a layout manner. Further, it is possible to shield the periphery of the control circuit and prevent noise leakage, but it is not possible to obtain a significant effect. In this case, although the reception amplifier is added and the reception distance is extended with respect to the reception sensitivity, the reception distance is shortened through the deterioration of the S / N ratio, and the superiority of the reception amplifier is lost.

  Under such circumstances, the decoding function for reading the demodulated first signal and converting it into data is separated from the control circuit by hardware, and the decoding function and the demodulation circuit are combined into a custom chip. If only the custom chip is operated, the control circuit can be stopped, so that it is considered that the problem of noise accompanying the operation of the control circuit is less likely to occur. However, in that case, enormous costs such as production of custom chips are required.

  Therefore, in the present embodiment, the demodulation circuit 152 and the modulation circuit 154 are intermittently operated. The control circuit 164 includes a minimum processing for operating the demodulation circuit 152 and the modulation circuit 154 (on / off control of the demodulation circuit 152, processing for reading the demodulated first signal and extracting device information, or extraction) Only the device information and the terminal information for identifying the self-radio communication terminal 120 are transmitted), otherwise, the control circuit 164 is stopped to shift to the interrupt signal waiting state. That is, while the demodulation circuit 152 and the modulation circuit 154 are intermittently operated, the control circuit 164 is also intermittently operated for a shorter time.

  5 to 7 are timing charts for explaining the intermittent operation of the demodulation circuit 152, the control circuit 164, and the modulation circuit 154. FIG. In particular, FIGS. 5 and 6 show the intermittent operation in the OOK modulation method and FIG. 7 shows the intermittent operation in the PPM modulation method. Here, it is assumed that the HF transmitter 110 continuously transmits only the carrier wave as the first signal so that the wireless communication terminal 120 can grasp the presence of the HF transmitter 110, and about every predetermined cycle, for example, about 30 msec. Valid data including device information is superimposed for 5 msec (for example, 40 μsec × 128 bits).

  Here, first, an intermittent period for intermittently operating the demodulator circuit 152 (hereinafter simply referred to as an intermittent period, a period for intermittently operating the demodulator circuit 152 (for example, 30 msec)) is determined, and a timer. 162. The intermittent period is determined by the assumed moving speed of the wireless communication terminal 120 and the necessary acquisition frequency of valid data. The on / off control unit 170, the information extraction unit 172, and the transmission control unit 174, which are functional units of the control circuit 164, operate in response to the interrupt signal. As the interrupt signal, an overflow signal generated when the above-described timer 162 reaches a predetermined value or a signal based on an edge in the demodulated first signal is used.

  In the present embodiment, the HI level is output from the comparator 192 in the state where the carrier of the first signal is detected but the valid data that is a part of the carrier is not detected. The signal is determined through a signal based on an edge where the first signal falls from HI to LOW.

  The on / off control unit 170 performs on / off control for turning on and off the demodulation circuit 152. Specifically, when an overflow signal based on the intermittent period is generated in the timer 162 (time t1 in FIG. 5 (a)), the on / off control unit 170 is activated to turn on the demodulation circuit 152 through the switch 196a, and the reception amplifier 182 and the comparator Before the 192 is activated, the control circuit 164 itself is immediately stopped. Such a stop is a stop of the clock for the control circuit in the control circuit 164, and the power supply itself of the control circuit 164 is continuously turned on to accept the interrupt signal. Since the activation time of the reception amplifier 182 and the comparator 192 is approximately 250 μsec, the on / off control unit 170 can stop the control circuit 164 with sufficient margin (more precisely, the control circuit clock is stopped).

  That is, when the on / off control unit 170 is intermittently activated at a predetermined cycle and the demodulation circuit 152 is turned on, the control circuit clock is stopped, the on / off control unit 170 is stopped, and the demodulation circuit 152 is connected to the first antenna 150. The modulation signal is taken in from.

  In the present embodiment, when the control circuit 164 completes necessary processing, not only the self-control circuit 164 is stopped immediately, but also the demodulation circuit 152 and the modulation circuit 154 are operated intermittently to further reduce power consumption. be able to.

  Subsequently, the on / off control unit 170 is activated at the timing when the first signal is settled (time t2 in FIG. 5A), determines the presence or absence of the carrier wave of the first signal, and determines that the carrier wave is present (FIG. 5 ( As shown in a) and (b), after demodulating the first signal, the demodulating circuit 152 is stopped, and if there is no carrier wave, it is assumed that valid data cannot be obtained until the next intermittent period, and the process shown in FIG. As shown, the demodulation circuit 152 is stopped immediately and the next intermittent period is awaited. Thus, power consumption consumed by the demodulation circuit 152, the control circuit 164, and the modulation circuit 154 is reduced.

  The information extraction unit 172 executes a process of reading the demodulated first signal and extracting device information.

  The on / off control unit 170 determines the presence or absence of the carrier wave of the first signal at the timing when the first signal is settled (time t2 in FIG. 5 (a)). It shifts to the standby state waiting for the valid data of the signal. Then, the information extraction unit 172 uses a signal based on an edge indicating the start signal of valid data in the demodulated first signal as an interrupt signal (here, the falling signal of the first signal maintained at HI). Upon receipt (time t3 in FIG. 5B), the valid data reading process is started.

  The information extraction unit 172 first authenticates the valid data before reading the valid data. Valid data is sent, for example, in 1 bit 40 μsec, and a pulse having a different time width, for example, 33.76 μsec, is provided at the head for authentication. The information extraction unit 172 is activated in response to a signal based on the first edge (time t3 in FIG. 5B), reads the count value of the timer 162 and holds it in the memory 160, and immediately stops the control circuit 164 itself. .

  Then, the information extraction unit 172 is activated in response to a signal based on the second edge (time t4 in FIG. 5B), re-reads the count value of the timer 162, and the count value stored in the memory 160 is Check if the difference matches 33.76 μsec. If it can be determined that the difference from the count value is 33.76 μsec, a predetermined data acquisition cycle and number of times based on the start signal of valid data are set in the timer 162 based on the OOK modulation method. The control circuit 164 itself is immediately stopped.

  Here, if the difference from the count value does not match 33.76 μsec, the signal is the same frequency as that of the carrier wave but is not assumed in the present embodiment, or the first signal It is considered that the demodulating circuit 152 is activated while the valid data is being transmitted, and the information extraction unit 172 has reacted with a signal based on an edge in the middle of the valid data. Therefore, when the difference from the count value does not match 33.76 μsec, the information extraction unit 172 may cancel the process of extracting the device information in the intermittent period.

  Here, the data acquisition cycle and the number of times are set in the timer 162 on the assumption that the valid data has a fixed length. However, in the case of a variable length, only the data acquisition cycle is set in the timer 162, and the information extraction unit 172 detects authentication data indicating the end of valid data corresponding to the authentication data provided at the head of the valid data described above, and stops the timer 162.

  Thereafter, the information extraction unit 172 shifts to the overflow signal waiting state by the timer 162 and receives the overflow signal from the timer 162 every time the data acquisition cycle set in accordance with the bit rate of the modulation signal is reached (FIG. 5 ( b) Time t5 to time t10) Start up, read the demodulated signal from the first signal in 1-bit units through the reading terminal b of the control circuit 164, and immediately stop the control circuit 164 itself each time. By doing so, the first signal that has passed through the second LPF 194 is not affected by the noise associated with the operation of the control circuit 164, so that the original value of the first signal can be read accurately. When all the valid data is read (time t10 in FIG. 5B), the information extraction unit 172 reads the last bit and then turns off the demodulation circuit 152. In this way, the information extraction unit 172 extracts device information from the first signal.

  That is, immediately after the control circuit clock (main clock) operates according to the interrupt signal generated in the wireless communication terminal 120 and the information extraction unit 172 is activated to extract the first information from the first signal. In addition, the control circuit clock is stopped.

  With the configuration of the information extraction unit 172, the wireless communication terminal 120 of this embodiment can extract a demodulated signal including device information using the existing control circuit 164 without adding a new custom chip.

  Further, in the wireless communication terminal 120 according to the present embodiment, when the on / off control unit 170 is intermittently activated at a predetermined cycle and the demodulation circuit 152 is turned on, the control circuit clock is stopped and the on / off control unit 170 is stopped. Thus, the demodulation circuit 152 takes in the modulation signal from the first antenna 150. Then, immediately after the control circuit clock (main clock) operates according to the interrupt signal generated in the wireless communication terminal 120 and the information extraction unit 172 is activated to extract the first information from the first signal. In addition, the control circuit clock is stopped. As described above, the wireless communication terminal 120 according to the present embodiment does not affect the noise of the first signal due to the operation of the control circuit 164. Therefore, the deterioration of the S / N ratio is avoided, and the reception distance is extended or reduced in size. Figured. The wireless communication terminal 120 of the present embodiment stops the control circuit clock (main clock) and operates the control circuit 164 intermittently, so that it can be used for a long time with low power consumption.

  Furthermore, the wireless communication terminal 120 of the present embodiment can not only add a custom chip, but can also shorten the distance between the control circuit 164 and the first antenna 150 while ensuring an S / N ratio. is there. For example, in the control circuit 164 and the first antenna 150, as shown in FIG. 3, each element can be arranged adjacent to a small and three-dimensional printed circuit board 180, and there is a demand for reduction in size and weight. It becomes possible to satisfy.

  The transmission control unit 174 performs transmission control for transmitting the extracted device information and terminal information for specifying the wireless communication terminal 120 itself. As described above, when all of the valid data is read, the information extraction unit 172 turns off the demodulation circuit 152 after reading the last bit. At this time, the transmission control unit 174 turns off the demodulation circuit 152 and turns on the modulation circuit 154 through the switch 196b (at time t11 in FIG. 5B), causing the modulation circuit 154 to transmit the device information and the terminal information. When the transmission is completed (time t12 in FIG. 5B), the modulation circuit 154 is turned off. Then, the transmission control unit 174 immediately stops the control circuit 164 itself.

  Here, during the operation of the modulation circuit 154, the control circuit 164 is not operated intermittently. However, since the demodulated signal has already been extracted, the problem of noise does not occur. When the modulation circuit 154 can output a signal indicating the completion of transmission, or when it has a function that can automatically stop the modulation circuit 154 itself when the transmission is completed, the transmission control unit 174 is similar to the modulation circuit 154. After turning on, the control circuit 164 itself can be quickly stopped. The control circuit 164 intermittently performs at least one of the on / off control unit 170 and the transmission control unit 174 described above according to the interrupt signal.

  Here, the transmission control unit 174 transmits the device information and the terminal information every time the information extraction unit 172 extracts the device information. However, the present invention is not limited to this case. For example, while the device information is equal, As long as the HF transmitters 110 to be received are equal, the information collection server 140 determines that the position (communication area) of the wireless communication terminal 120 has not changed, so the device information and the terminal information are not transmitted every time. It is possible to transmit only when a predetermined number of pieces of equal device information are received, or to freely set the number of transmissions and timing. With this configuration, it is possible to eliminate unnecessary data transmission and further reduce power consumption.

  Next, the intermittent operation in the PPM modulation method will be described with reference to FIG. Regarding the operation substantially equivalent to the OOK modulation method, the redundant description is omitted, and only the portion where the operation is different will be described here.

  The on / off control unit 170 performs on / off control of the demodulation circuit 152 as in the OOK modulation method. The information extraction unit 172 executes a process of reading the demodulated first signal and extracting device information.

  Specifically, the information extraction unit 172 is activated in response to a signal based on the second edge (time t4 in FIG. 7B) and authenticates valid data. If valid data is authenticated, the count value of the timer 162 is read and held in the memory 160 based on the PPM modulation method, and the control circuit 164 itself is immediately stopped.

  Thereafter, the information extraction unit 172 shifts to an interrupt wait by a signal based on the falling edge of the first signal and detects a signal based on the falling edge of the first signal (FIG. 7B, time t5 to time At t10), the count value of the timer 162 is read, the difference from the previous value held in the memory 160 is calculated, and the bit value is determined according to the difference (capture mode). 164 stops itself. By doing so, the first signal that has passed through the second LPF 194 is not affected by the noise associated with the operation of the control circuit 164, so that the original value of the first signal can be read accurately. When all the valid data is read (time t10 in FIG. 7B), the information extraction unit 172 reads the last bit and then turns off the demodulation circuit 152. In this way, the information extraction unit 172 extracts device information from the first signal. Similar to the OOK modulation method, the transmission control unit 174 performs transmission control for transmitting the extracted device information and terminal information for specifying the wireless communication terminal 120 itself.

  As described above, even with the PPM modulation method, an effect equivalent to that of the OOK modulation method can be obtained, the deterioration of the S / N ratio can be avoided without adding a new decoding circuit, and the reception distance can be extended. Along with downsizing, low power consumption enables long-time use.

  Here, the timer clock will be specifically described. As shown in FIG. 2, the timer 162 selects one timer clock from a plurality of timer clocks (analog clock, main clock, sub clock) output from the control circuit 164, and uses the timer clock as the timer clock. Count. The core portion of the control circuit 164 operates by the main clock, and the peripheral built in the control circuit 164 operates by the sub clock.

  However, at the normal time when communication is stopped, in order to reduce power consumption, both the main clock and the sub clock that operate the control circuit 164 are stopped, and only the analog clock is enabled. Therefore, the timer 162 counts the intermittent period based on the analog clock, and when the intermittent period is reached, the timer 162 interrupts the control circuit 164 with the overflow signal (FIG. 5A or FIG. 7A point in time t1), The demodulation circuit 152 is turned on.

  The control circuit 164 validates the main clock and the sub clock after the interruption, but deactivates the main clock and the sub clock again and stops the control circuit clock of the control circuit 164 itself every time the above-described processing ends.

  However, since the period of the analog clock is 30 μsec or more, the bit value may not be appropriately acquired depending on the transfer rate of the OOK modulation method or the PPM modulation method. In the above-described example, it is necessary to detect a bit value at an arbitrary time point with a period of 40 μsec in the OOK modulation method, and it is necessary to determine a short pulse such as 8 μsec in the PPM modulation method.

  Therefore, when only the main clock of the main clock and the sub clock in the control circuit 164 is stopped and the sub clock is not stopped, when an intermittent period arrives (time t1 in FIG. 5A or FIG. 7A), control is performed. While the information extraction unit 172 of the circuit 164 performs the process of extracting the device information, the timer 162 counts the sub clock as the timer clock instead of the analog clock. Since the subclock operates at a high speed, for example, at a frequency of 8 MHz, the bit value can be appropriately acquired even when the transfer rate of the OOK modulation method or the PPM modulation method is high.

  The sub clock consumes less power for the target peripheral, and the influence on the demodulation circuit 152 is very small compared to the main clock. Therefore, the problem of noise does not occur even if the subclock is operated continuously. Then, the transmission control unit 174 transmits the device information and the terminal information to the modulation circuit 154, and when the transmission is completed (time t12 in FIG. 5 (b) or FIG. 7 (b)), the timer 162 again serves as the timer clock. Count analog clocks.

  As another example, it is assumed that the wireless communication terminal 120 further includes an external oscillator 210 that generates a clock having a frequency higher than that of the analog clock (indicated by a one-dot chain line in FIG. 2), and the timer 162 includes information on the control circuit 164. While the extraction unit 172 performs the process of extracting the device information, the clock generated by the external oscillator 210 may be counted as the timer clock. In this way, by providing an external clock whose frequency can be freely set apart from the analog clock, main clock, and sub clock that cannot be easily changed because they are used for other circuits in the first place, OOK It is possible to flexibly cope with the setting or change of the communication speed by the modulation method or the PPM modulation method, and it is possible to set an optimum frequency.

  As yet another example, it is assumed that the wireless communication terminal 120 further includes a clock forming circuit 212 that forms a clock based on the carrier wave of the first signal or the second signal (indicated by a broken line in FIG. 2). While the information extraction unit 172 of the control circuit 164 performs the process of extracting the device information, the clock formed by the clock forming circuit 212 can be counted as the timer clock. The carrier wave of the first signal or the second signal has a very high frequency compared to the period in which the bits of the first signal change. Therefore, a sufficiently high clock can be obtained by shaping such a carrier wave with a PLL (Phase Locked Loop) or the like.

(Wireless communication method)
Next, a wireless communication method for performing wireless communication using the above-described wireless communication terminal 120 will be described. FIG. 8 is a flowchart showing the overall flow of the wireless communication method. In the wireless communication terminal 120, an intermittent period for performing the intermittent operation of the demodulation circuit 152 is preset in the timer 162, and the timer 162 counts the intermittent period through an analog clock. In addition, the control circuit 164 detects the overflow signal generated when the timer for counting the clock reaches a predetermined value (intermittent period) or the signal generated based on the edge of the demodulated first signal. The control circuit clock operates every time an embedded signal is activated, and each functional unit functions when the control circuit 164 is activated. After the predetermined processing is completed, the control circuit clock is stopped immediately. Here, in order to understand the overall flow of the wireless communication method, description of the control circuit clock operation and stop in the flowchart is omitted.

  When an overflow signal from timer 162 is received as an interrupt signal (YES in S250), control circuit 164 is activated, on / off control unit 170 of control circuit 164 turns on demodulation circuit 152, and temporarily stops control circuit 164. (S252). In this way, the demodulation circuit 152 is shifted to a state where the first signal can be read. The on / off control unit 170 then activates the control circuit 164 again in response to the interrupt signal from the timer 162 in response to the activation of the reception amplifier 182 and the comparator 192 of the demodulation circuit 152, and the carrier wave of the first signal. Whether or not there is is determined (S254).

  If it is determined that there is a carrier wave (YES in S254), the information extraction unit 172 waits for a signal based on an edge indicating the start signal of valid data in the first signal as an interrupt signal (S256). When the information extraction unit 172 receives a signal based on an edge indicating the start signal of valid data in the first signal as an interrupt signal from the demodulation circuit 152 (YES in S256), the information extraction unit 172 authenticates whether the start signal is correct ( S258). The information extraction unit 172 authenticates at the start signal authentication step S258, and if it is a signal based on the edge of the desired start signal (YES in S258), waits for an interrupt signal (S260), and for each interrupt signal Then (YES in S260), the control circuit 164 is started, the demodulated part or all (here, 1-bit unit) of the first signal is read, and the control circuit 164 is stopped (S262).

  The information extraction unit 172 determines whether or not all the valid data in the first signal has been read (S264). If the information extraction unit 172 determines that reading has not been completed (NO in S264), the information extraction unit 172 immediately stops the control circuit 164 itself and interrupts. The processing from the signal waiting state S260 is repeated. If it is determined that all have been read (YES in S264), the device information is extracted after reading the last bit (S266), the demodulation circuit 152 is turned off (S268), and the modulation circuit 154 is turned on (S270). ), The extracted device information and terminal information are transmitted through the modulation circuit 154 (S272), and the modulation circuit is turned off (S274).

  If it is determined in the carrier wave determination step S254 that there is no carrier wave (NO in S254), it is assumed that valid data cannot be obtained until the next intermittent period, the demodulation circuit 152 is turned off, and the control circuit is promptly turned on. 164 itself is stopped (S276).

  Similarly, in the start signal authentication step S258, if the authenticated signal is not a signal based on the edge of the desired start signal (NO in S258), it is assumed that valid data cannot be obtained, and the demodulation circuit 152 is turned off. The control circuit 164 itself is immediately stopped (S276).

  Even when such a wireless communication method is used, deterioration of the S / N ratio is avoided without adding a new decoding circuit, and the reception distance is extended and downsized, and the power consumption is reduced for a long time. Is possible.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  In the above-described embodiment, an example in which device information is extracted from the first signal, terminal information is added to the device information, and the second signal is transmitted is given. However, the effect of this embodiment is achieved in the process of extracting information from the first signal, and does not require transmission of the second signal.

  Therefore, as a modification of the present embodiment, for example, a first antenna 150 that receives a first signal including modulated first information from a transmission source device, and a first signal that is received by the first antenna 150 are received. Operates in synchronization with a control circuit clock having a demodulation circuit 152 that demodulates, an on / off control unit 170 that turns on and off the demodulation circuit 152, and an information extraction unit 172 that extracts first information from the demodulated first signal And a control circuit clock operates in response to an interrupt signal generated in the wireless communication terminal 120, and the information extraction unit 172 is activated to extract first information from the first signal. Immediately after this, a wireless communication terminal 120 in which the control circuit clock stops is also provided. The wireless communication terminal 120 acquires device information from the first signal and determines it according to a predetermined condition. For example, the wireless communication terminal 120 approaches the predetermined HF transmitter 110 so that the wireless communication terminal 120 It is possible to light the provided LED in green or red, or to sound a buzzer.

  In the above-described embodiment, the active type wireless communication terminal 120 has been mainly described. However, the embodiment can also be applied to a passive type.

  Note that each step of the wireless communication method of the present specification does not necessarily have to be processed in time series in the order described in the flowchart, and may include processing in parallel or by a subroutine.

  The present invention can be used for a wireless communication terminal and a wireless communication method.

DESCRIPTION OF SYMBOLS 110 ... HF transmitter 120 ... Wireless communication terminal 130 ... UHF receiver 150 ... First antenna 152 ... Demodulation circuit 154 ... Modulation circuit 156 ... Second antenna 158 ... Power supply unit 162 ... Timer 164 ... Control circuit 170 ... On / off control unit 172 ... Information extraction unit 174 ... Transmission control unit 210 ... External oscillator 212 ... Clock formation circuit

Claims (12)

In a wireless communication terminal,
A first antenna that receives a first signal including modulated first information from a transmission source device; a demodulation circuit that demodulates the first signal received by the first antenna;
An on / off control unit for turning on and off the demodulation circuit, and the first signal from the demodulated first signal.
And a transmission control unit for transmitting the extracted first information and second information related to the own wireless communication terminal, and a control that operates in synchronization with the control circuit clock. Circuit,
A modulation circuit that modulates the first information and the second information and transmits the modulated information through a second antenna;
With
The control circuit clock operates according to an interrupt signal generated in the wireless communication terminal,
The control circuit clock is stopped after the information extraction unit is activated and extracts the first information from the first signal.
A wireless communication terminal characterized by the above. After extracting the first information from the first signal, after extracting the first information,
The wireless communication terminal according to claim 1, wherein the wireless communication terminal is an arbitrary time until the demodulation circuit starts the next demodulation of the first signal. The on-off control unit is intermittently activated to turn on the demodulation circuit, and the control circuit clock is stopped.
The wireless communication terminal according to claim 1, wherein the wireless communication terminal is a wireless communication terminal. The control circuit according to any one of claims 1 to 3, wherein the control circuit intermittently performs at least any one of an on / off control unit and a transmission control unit in accordance with the interrupt signal. Wireless terminal. The interrupt signal is an overflow signal generated when a timer for counting a timer clock reaches a predetermined value, or a signal based on an edge in the demodulated first signal. Item 5. A wireless communication terminal according to any one of Items 1 to 4. The radio communication terminal according to claim 5, wherein the signal based on the edge in the demodulated first signal includes a signal based on an edge indicating a start signal of valid data in the demodulated first signal. The timer counts a sub clock used for a peripheral operation of the control circuit as the timer clock while the information extraction unit performs the process of extracting the first information. The wireless communication terminal according to 5 or 6. An external oscillator that generates a clock having a higher frequency than the analog clock supplied to the control circuit;
The timer counts a clock generated by the external oscillator as the timer clock while the information extraction unit performs the process of extracting the first information. 7. A wireless communication terminal according to 6. A clock forming circuit for forming a clock based on the carrier wave of the first signal or the second signal;
6. The timer counts a clock formed by the clock forming circuit as the timer clock while the information extraction unit performs a process of extracting the first information. Or the radio | wireless communication terminal of 6. The radio communication terminal according to claim 1, wherein an OOK modulation scheme or a PPM modulation scheme is used as the modulation scheme of the first signal. In a wireless communication terminal,
A first antenna that receives a first signal including modulated first information from a transmission source device; a demodulation circuit that demodulates the first signal received by the first antenna;
An on / off control unit for turning on and off the demodulation circuit, and the first signal from the demodulated first signal.
A control circuit that operates in synchronization with a control circuit clock, and an information extraction unit that extracts the information of
With
The control circuit clock operates in response to an interrupt signal generated in the wireless communication terminal, and the information extraction unit is activated to extract the first information from the first signal. The clock stops,
A wireless communication terminal characterized by the above. A radio communication terminal having a demodulation circuit that demodulates a first signal including modulated first information received by a first antenna, and a control circuit that operates in synchronization with a control circuit clock and controls the demodulation circuit A wireless communication method for performing wireless communication by:
The control circuit includes:
The control circuit clock operates according to an interrupt signal generated in the wireless communication terminal,
The control circuit is activated to turn on the demodulation circuit, stop the control circuit clock, and shift the demodulation circuit to a state where the first signal can be extracted;
The control circuit clock operates in response to the interrupt signal, and the control circuit is activated to extract part or all of the first information from the demodulated first signal, and the control circuit clock Stop
A radio communication method, wherein the demodulation circuit is turned off when the first information is extracted.

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