JP2009031865A - Radio sensor system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio sensor system for accurately performing data communication between a sensor station and an external station while suppressing the increase of power consumption. <P>SOLUTION: This radio sensor system is configured of a sensor station which carries out the sampling of a sensor signal, and transmits the sampled sensor data by radio; and an external station which receives the sensor data transmitted from the sensor station. A gain adjustment packet for adjusting receiving sensitivity is attached to the front part of the main body section of data to be transmitted so that radio data transmission between a sensor station and an external station can be performed, and when an NACK signal showing the generation of a communication error is received, the number of gain adjustment packets is increased according to a communication error frequency err, and the radio data transmission is retried. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention comprises a sensor station that samples a sensor signal and wirelessly transmits the sampled sensor data, and an external station that receives sensor data transmitted from the sensor station. It relates to a sensor system.

  In recent years, wireless sensor technology has attracted attention as an important technology that supports a ubiquitous society. The wireless sensor system includes a sensor station in which a sensor and a wireless communication module are integrated, and an external station that receives sensor data transmitted from the sensor station.

  A sensor station of such a wireless sensor system is generally small, and a small capacity power source such as a button-type battery is often used as an operating power source. Therefore, reduction of power consumption is required, and data communication from the sensor station is performed with low output and low duty. In such low-power / low-duty data communication, the influence of noise becomes extremely large, and accurate data communication becomes difficult.

Conventionally, as a technique for enabling data communication with low output and low duty in such a wireless sensor system, a technique described in Patent Document 1 has been proposed. In the wireless sensor system described in this document, noise is detected by transmitting sensor data following a preamplifier code used for specifying a sampling start position and a synchronization code used for cueing sensor data. The data is easily identified.
JP 2006-270462 A

  By the way, in such a wireless sensor system, in general, when a receiving station fails to receive data, a notification to that effect is sent to the transmitting station and data communication is retried. However, if there is no change in the situation such as noise, there is a high probability that data reception will fail again even after retrying, and data reception may not be successful no matter how many times wireless data communication is retried. Of course, if the output and duty of data transmission are increased, such a situation can be avoided, but this leads to an increase in power consumption.

  The present invention has been made in view of such a situation, and a problem to be solved is a wireless communication that can accurately perform data communication between a sensor station and an external station while suppressing an increase in power consumption. It is to provide a sensor system.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
The invention according to claim 1 includes a sensor station that performs sampling of sensor signals and transmits the sampled sensor data wirelessly, and an external station that receives sensor data transmitted from the sensor station. Wireless data transmission between the sensor station and the external station by attaching a gain adjustment signal for reception sensitivity adjustment in front of the main body portion of the data to be transmitted. At the time, when a communication error occurs, the gist is that the gain adjustment signal is lengthened in accordance with the number of communication errors and the wireless data transmission is retried.

  In the above configuration, a gain adjustment signal for adjusting the reception sensitivity is attached in front of the main part of the data to be transmitted so that wireless data transmission is performed between the sensor station and the external station. In such a case, the station that has received the transmission data receives the main part of the transmitted data after adjusting the reception sensitivity based on the gain adjustment signal. The longer the gain adjustment signal at this time, the better the reception sensitivity can be adjusted. Therefore, accurate data reception is possible even when the influence of noise is large. However, assuming that the reception condition is bad, if the gain adjustment signal is lengthened from the beginning, the communication time required for one wireless data communication is increased, leading to an increase in power consumption. On the other hand, if the gain adjustment signal is shortened, a communication error occurs when reception conditions are bad.

  On the other hand, in the above configuration, when a communication error occurs during wireless data transmission, the gain adjustment signal is lengthened in accordance with the number of such communication errors to retry wireless data transmission. For this reason, when the reception condition is good, wireless data communication can be performed with a short gain adjustment signal, and only when the reception condition is bad, the gain adjustment signal can be lengthened to receive data. Therefore, according to the above configuration, it is possible to accurately perform wireless data communication between the sensor station and the external station while suppressing an increase in power consumption.

  As the gain adjustment signal, any signal can be used as long as it is a signal having a pattern capable of specifying that the receiving side is a gain signal. Most simply, as described in claim 2, It is possible to use a signal (“101010... 10”) composed of a bit string in which a logic level signal “1” and a logic level signal “0” are alternately repeated.

  By the way, there are cases where the cause of reception failure is other than the influence of noise, and cannot be solved only by adjusting reception sensitivity. In such a case, in order to avoid that the retry of wireless data communication is repeated indefinitely, in the invention according to claim 3, in the wireless sensor system according to claim 1 or 2, the length of the gain adjustment signal is Wireless data transmission is canceled on condition that the value is equal to or greater than a predetermined cancellation determination value.

  In addition, the confirmation of the communication error in the wireless sensor system according to any one of claims 1 to 3 may be performed as described in claim 4 with a gain adjustment signal, a data header, a main part of the data, and a data footer. Wireless data communication is performed in this order, and after the reception sensitivity is adjusted using the gain adjustment signal in the station that has received the wireless data communication, the data header, the data body part, and the data footer are received in that order. Otherwise, it can be performed by determining a communication error. In addition, as described in claim 5, when transmitting wireless data, a check code is also transmitted, and at the station receiving the wireless data communication, the main part of the received data is inspected using the check code. As a result, a communication error may also be determined when a data error is detected. As the check code, a checksum code can be easily used. However, if more accurate, a cyclic redundancy check (CRC: Cycical (CRC) is used as the check code as described in claim 6. Cyclic) Redundancy Check) code should be used.

  By the way, in the wireless sensor system according to the first to sixth aspects, as described in the seventh aspect, for example, the external station uses a command for specifying a sampling condition of the sensor signal as a main part of data to be transmitted. It is possible to apply the present invention to a wireless sensor system configured to sample a sensor signal by setting a sampling condition based on the received command.

  Hereinafter, an embodiment of the wireless sensor system of the present invention will be described in detail with reference to FIGS. The wireless sensor system according to the present embodiment includes a sensor station 10 configured as illustrated in FIG. 1A and an external station 20 configured as illustrated in FIG. 1B. Yes. By the way, in the following explanation, “B” is added to the end of a numerical value when it is expressed in binary, and “H” is added to the end of a numerical value when expressed in hexadecimal. To describe.

  First, the configuration of the sensor station 10 of this wireless sensor system will be described with reference to FIG. A plurality of sensors each having a unique sensor ID (in the figure, 16 sensors having sensor IDs “0” to “15”) can be connected to the sensor station 10. Each of these sensors is connected to the analog switch 11. The analog switch 11 is configured to select any one of the connected sensors and connect it to a resistance variable device 12 such as a digital potentiometer. Further, the variable resistance device 12 is connected to a CPU (Central Processing Unit) module 14 via an analog / digital (A / D) converter 13. The CPU module 14 that performs various processes related to sensor data sampling and sensor data transmission includes a DMA (Direct Memory Access) unit 15 and a memory 16 and a wireless module 17 connected to the outside. ing.

  In such a sensor station 10, the CPU module 14 operates the analog switch 11 to select a sensor to be sampled, and operates the resistance variable device 12 to control the gain (Gain) and offset of the sensor output at the time of sampling. (Offset) is set. Further, the CPU module 14 sets a sampling cycle through insertion of a wait clock with respect to the bus clock of the built-in CPU. Sensor data (Data), which is an A / D conversion value of the sensor output captured under the sampling conditions set in this way, is directly written into the memory 16 by the DMA unit 15. The CPU module 14 manages the number of sensor data to be sampled (sampling number) by the number of accesses to the A / D converter 13 of the DMA unit 15.

  Next, the configuration of the external station 20 of the wireless sensor system of this embodiment will be described with reference to FIG. The external station 20 is mainly configured by a CPU module 21 that performs processing related to command of sensor data sampling conditions and reception of the sensor data. The CPU module 21 of the external station 20 is connected to a wireless module 22 for performing wireless data communication with the sensor station 10 and a memory 23 for storing various data. Further, a user interface (UI) 24 having an input device such as a keyboard and an output device such as a display is connected to the CPU module 21.

Acquisition of sensor data in the wireless sensor system of the present embodiment configured as described above is performed through the following procedures 1) to 10).
1) First, the user inputs sensor data sampling conditions (sensor ID, sensor output gain and offset, sampling period, sampling number, etc.) through the UI 24.

2) The CPU module 21 of the external station 20 generates a command based on the input condition and transmits it to the sensor station 10 in response to the input of the sampling condition in the procedure 1).
3) In response to the reception of the command, the CPU module 14 of the sensor station 10 sets a sampling condition according to the command received from the external station 20.

4) The user performs an operation to start sampling of sensor data through the UI 24.
5) In response to the sampling start operation in the above step 4), the CPU module 21 of the external station 20 transmits a command “sendStartSignal” requesting the start of sampling of sensor data to the sensor station 10.

  6) In response to the reception of the command “sendStartSignal”, the CPU module 14 of the sensor station 10 samples the sensor data under the conditions set in the procedure 3) and stores the result in the memory 16. .

7) The user performs an operation to start downloading sensor data through the UI 24.
8) In response to the download start operation in step 7), the CPU module 21 of the external station 20 transmits a command (“sendRequestData”) requesting the start of sampling of sensor data to the sensor station 10.

  9) In response to receiving the command “sendRequestData”, the CPU module 14 of the sensor station 10 reads the sampled sensor data from the memory 16 and transmits it to the external station 20.

10) The CPU module 21 of the external station 20 stores the sensor data received from the sensor station 10 in its own memory 23.
Next, details of wireless data communication between the sensor station 10 and the external station 20 performed in the above procedures 2), 5), 8) and 9) will be described. In the wireless sensor system of the present embodiment, in such wireless data communication, a gain adjustment signal for adjusting the reception sensitivity by the receiving station before the main part of the data to be transmitted, that is, the data string or command of the sensor data is provided. I am trying to attach it. The gain adjustment signal is a signal (“101010... 10B”) in which a logic level signal “1” and a logic level signal “0” are alternately repeated. In this embodiment, such a gain adjustment signal has a variable length. In the present embodiment, the length of the gain adjustment signal is increased or decreased in packet units of unit bit length. Here, the length of one gain adjustment signal packet, that is, the length of the gain adjustment packet is set to “1 word” (here, “16 bits”).

  FIG. 2A shows the structure of transmission data used for command transmission from the external station 20 to the sensor station 10. As shown in the figure, command transmission is performed in the order of a command header, a command packet constituting the main part of the command, and a command footer following a plurality of gain adjustment packets. Here, the command header for indicating the start position of the command is set to “FFH”, and the command footer for indicating the end position of the command is set to “00H”.

  Further, as shown in FIG. 2B, the command packet is composed of, for example, a “6 bit” command bit, a “2 bit” reserve bit, and a “8 bit” set value bit. A code indicating the type of command is stored in the command bit. For example, in the case of a command “sendActiveChannel” for designating a sensor ID to be sampled, the value of the command bit is set to “80H”. The set value bit stores a value set by the command.

  FIG. 3A shows the structure of transmission data used for sensor data transmission from the sensor station 10 to the external station 20. As shown in the figure, the sensor data transmission follows a plurality of gain adjustment packets, followed by a data string header, a data string of sensor data (main part of data to be transmitted), a check code header, a check code, and a data string footer. Done. Here, the data string header for indicating the start position of the data string composed of one or more data packets is set to “FF00H”, and the data string footer for indicating the end position of the data string is set to “00FFH”. ing. The check code header for indicating the start position of the check code attached to the end of the data string is set to “00H”.

  The check code is an error detection code for verifying received data. Here, a cyclic redundancy check code, so-called CRC (Cyclical (Cyclic) Redundancy Check) code is used as such a check code. This CRC code is generated by applying a cyclic algorithm (generator polynomial) to the data.

  Each data packet constituting the data string transmits one sensor data. As shown in FIG. 3B, the data packet includes an ID bit of “4 bits” and a data bit of “12 bits”. It is configured. The value of sensor data is stored in the data bit, and the ID of the sensor storing the sensor data is stored in the data bit.

  As described above, in the wireless sensor system of the present embodiment, a gain adjustment signal for adjusting reception sensitivity is attached in front of a command or sensor data data string which is a main part of data to be transmitted, and the sensor station 10 and the external Wireless data transmission with the station 20 is performed. In such a case, the receiving station adjusts the reception sensitivity based on the gain adjustment signal and then receives the main part of the transmitted data. The longer the gain adjustment signal at this time, that is, the greater the number of gain adjustment packets, the better the reception sensitivity can be adjusted, so accurate data reception is possible even when the influence of noise is large become. However, assuming that the reception condition is bad, if the gain adjustment signal is made longer from the beginning, the communication time per data transmission becomes longer, leading to an increase in power consumption. On the other hand, if the gain adjustment signal is shortened, data cannot be transmitted when reception conditions are poor.

  Therefore, in this embodiment, when a communication error occurs during wireless data communication, the gain adjustment signal is lengthened (increase the number of gain adjustment packets) in accordance with the number of such communication errors, and wireless data transmission is retried. Like to do. Therefore, when the reception condition is good, the gain adjustment signal can be lengthened only when the reception condition is bad while performing the wireless data communication with the gain adjustment signal being short. Therefore, in the wireless sensor system of this embodiment, it is possible to accurately perform data communication between the sensor station and the external station while suppressing an increase in power consumption.

  Specifically, in the first data communication, the transmitting station adds three gain adjustment packets to the head of data to be transmitted (command or sensor data data string), that is, “48 (= 16 × 3) A bit gain adjustment signal is added to transmit data. In the wireless sensor system of this embodiment, when data transmission fails here, that is, when there is a communication error, data transmission is performed again. When the number of communication errors becomes 3 or more, the number of gain adjustment packets added to the transmission data is increased by one. That is, at the time of the fourth data transmission, four gain adjustment packets are attached to perform data transmission. Thereafter, every time the number of communication errors increases by “3”, the number of gain adjustment packets is increased by “1”, that is, the length of the gain adjustment signal is increased by “16 bits”.

  On the other hand, there are cases where the cause of reception failure is other than the influence of noise, and it cannot be solved only by adjusting reception sensitivity. In the wireless sensor system of the present embodiment, the length of the gain adjustment signal (the number of gain adjustment packets) is greater than or equal to the predetermined stop determination value in order to avoid repeated indefinite repetition of wireless data communication in such a case. The wireless data transmission is canceled on the condition that it has become. More specifically, in the wireless sensor system of the present embodiment, when the number of gain adjustment packets exceeds “10”, that is, when the length of the gain adjustment signal exceeds “160 bits”, wireless data communication To stop.

  Incidentally, in this wireless sensor system, the receiving station confirms whether or not a communication error has occurred through the following determinations a) and b). When it is determined that there is no communication error, the receiving-side station outputs a signal indicating that communication was successful (ACK signal), and if a communication error is confirmed, it indicates a signal indicating that communication has failed (NACK signal). A reply is made to each transmitting station.

  a) If the order of reception is in the order of the command transmission or the order of the sensor data transmission, it is determined that the communication is successful, and if not, a communication error is determined. That is, when a command is received, if a command header, a command packet (a main part of data to be transmitted), and a command footer are not received in order following the gain adjustment packet, it is determined as a communication error. When sensor data is received, if it is not received in the order of the data string header, the data string (the main part of the data to be transmitted), the check code header, the check code, and the data string footer following the gain adjustment packet, it is determined as a communication error. .

  b) When the external station 20 receives the sensor data, the data string is inspected using the check code received together with the data string. As a result, if an error in the data is detected, it is determined as a communication error. As described above, a CRC code is used here as a check code.

  FIG. 4 shows a flowchart of a “data transmission routine” executed by the station on the data transmission side in wireless data communication in the wireless sensor system of this embodiment. The processing of this routine is performed by the CPU modules 14 and 21 of the station in response to a data transmission request.

  When the processing of this routine is started, the CPU modules 14 and 21 first execute transmission of commands or sensor data in the above-described manner in step S10. After that, it waits until an ACK signal or NACK signal is received from the receiving station (S20, S30). Here, if the communication succeeds and the ACK signal is received (S20: YES), the CPU modules 14 and 21 terminate the processing of this routine as it is. On the other hand, if the communication fails and the NACK signal is received (S30: YES), the CPU modules 14 and 21 perform the processing after step S40.

  When the process proceeds to step S40, the CPU modules 14 and 21 add “1” to the value of the communication error count err in step S40. The communication error count err is a counter indicating the number of communication errors that have occurred during the current wireless data communication, and its value is reset to “0” at the start of this routine.

  Subsequently, in step S50, the CPU modules 14 and 21 confirm whether or not the communication error count err is a multiple of the packet addition count n. If the communication error number err is not a multiple of the packet addition number n (S50: NO), the CPU modules 14 and 21 return to step S10 and retry the data communication while maintaining the current number of gain adjustment packets. To do.

  On the other hand, if the communication error count err is a multiple of the packet addition count n (S50: YES), the CPU modules 14 and 21 add “1” to the number of gain adjustment packets added to the head of the transmission data in step S60. . In the present embodiment, the value of the number n of packet additions is set to “3”, and the number of gain adjustment packets is increased every time a communication error occurs three times as described above. .

  After incrementing the number of gain adjustment packets in this way, the CPU modules 14 and 21 confirm in step S70 whether or not the number of gain adjustment packets after the increment is equal to or greater than a predetermined stop determination value TRMERR. As described above, in this embodiment, wireless data communication is stopped when the number of gain adjustment packets exceeds “10”, and the value of the stop determination value TRMERR is set to “10”.

  If the number of gain adjustment packets is less than the stop determination value TRMERR (S70: NO), the CPU modules 14 and 21 return to step S10 and attach gain adjustment packets increased by “1” from the previous time. Then, retry the data communication. On the other hand, if the number of gain adjustment packets is equal to or greater than the cancellation determination value TRMERR (S70: YES), the CPU modules 14 and 21 cancel the current wireless data communication after notifying the transmission failure in step S80. To do.

  On the other hand, FIG. 5 shows a flowchart of a “data transmission routine” executed by a data receiving station in wireless data communication in the wireless sensor system of the present embodiment. The processing of this routine is repeatedly performed by the CPU modules 14 and 21 while waiting for data reception.

  When this routine is started, the CPU modules 14 and 21 first check in step S100 whether or not a gain adjustment packet has been received. If reception of the gain adjustment packet is not confirmed here (S100: NO), the CPU modules 14 and 21 terminate the processing of this routine as it is. On the other hand, if the gain adjustment packet has been received (S100: YES), the CPU modules 14 and 21 continue to adjust the reception sensitivity using the received gain adjustment packet as long as the gain adjustment packet continues to be received. (S110, S120).

  When the transmission of the gain adjustment packet is finished and the main part of the data (data string or command of sensor data) is received, the CPU modules 14 and 21 determine in step S130 a communication error based on the reception order of the a). Perform the determination. When the external station 20 receives sensor data from the sensor station 10, the CPU module 21 subsequently checks the data string based on the check code in b) to determine whether there is a communication error. Confirm (S140, S150). If no communication error is confirmed, an ACK signal is transmitted to the transmitting station in step S160. If a communication error is confirmed, a NACK signal is transmitted to the transmitting station in step S170. Terminate the process.

According to the wireless sensor system of the present embodiment described above, the following effects can be obtained.
(1) In the wireless sensor system of the present embodiment, a sensor station 10 is provided with a gain adjustment signal (gain adjustment packet) for adjusting reception sensitivity before a main body portion (data string or command of sensor data) of data to be transmitted. The wireless data transmission between the external stations 20 is performed. When a communication error occurs during wireless data transmission, the number of gain adjustment packets is increased according to the number of communication errors, the gain adjustment signal is lengthened, and wireless data transmission is retried. Therefore, when reception conditions are good, wireless data communication is performed with a short gain adjustment signal (the number of gain adjustment packets is small), but only when the reception conditions are bad, the gain adjustment signal is lengthened (gain adjustment packet). Data reception) can be performed. Accordingly, it is possible to accurately perform data communication between the sensor station 10 and the external station 20 while suppressing an increase in power consumption.

  (2) In the wireless sensor system of the present embodiment, wireless data transmission is stopped on condition that the number of gain adjustment packets (the length of the gain adjustment signal) is equal to or greater than a predetermined stop determination value TRMERR. Yes. Therefore, when the cause of reception failure is other than the influence of noise and cannot be solved only by adjusting the reception sensitivity, it is possible to avoid the retry of wireless data communication being repeated indefinitely.

  (3) In the wireless sensor system of the present embodiment, wireless data communication is performed using a gain adjustment signal, a data header (data string header, command header), a main part of data to be transmitted (sensor data data string, command packet), and data. The footer (data sequence footer, command footer) is performed in this order. On the other hand, after the reception sensitivity adjustment is performed using the received gain adjustment signal, the receiving station determines that there is a communication error except when the data header, the main body of the data, and the data footer are received in that order. I am doing so. Therefore, the presence or absence of a communication error can be easily and accurately confirmed.

  (4) In the wireless sensor system of the present embodiment, when transmitting sensor data, a check code is also transmitted, and at the station that has received the wireless data communication, the main part of the received data (data string of sensor data) Is checked using the check code, and as a result, when a data error is detected, a communication error is determined. In addition, a CRC code is used as such a check code. Therefore, the presence or absence of a communication error can be confirmed more accurately.

In addition, the said embodiment can also be changed and implemented as follows.
In the above embodiment, a CRC code is used as a check code for detecting an error in a data string of received sensor data, but other data error detection codes such as an MD code and a checksum code are used. You may make it do. Further, it may be possible to omit the addition of the check code to the transmission data and the verification of the reception data using the check code.

  In the above embodiment, the presence or absence of a communication error is confirmed through the reception order or the verification of received data using a check code. However, the presence or absence of a communication error may be confirmed in other modes. . Even in such a case, as long as the gain adjustment signal is lengthened according to the number of communication errors and the wireless data transmission is retried, the effect described in the above (1) can be obtained.

  In the above-described embodiment, a signal (“101010... 10”) composed of a bit string in which a logic level signal “1” and a logic level signal “0” are alternately repeated is used as the gain adjustment signal. However, any signal can be used as the gain adjustment signal as long as the signal has a pattern that can be specified by the receiving side.

  In the above embodiment, every time a communication error occurs three times, the number of gain adjustment packets is increased by “1”, that is, the length of the gain adjustment signal is increased by “16 bits”. The addition mode of the adjustment signal can be changed as appropriate. For example, the gain adjustment signal may be lengthened every time a communication error occurs, or the length of the gain adjustment signal to be increased may be changed.

  In the above embodiment, when the number of gain adjustment packets exceeds “10”, that is, when the length of the gain adjustment signal exceeds “160 bits”, the wireless data communication is stopped. The length of the gain adjustment signal when the wireless data communication is stopped is not limited to this, and can be arbitrarily changed.

  In the above embodiment, the wireless data communication suspension determination is performed based on the length of the gain adjustment signal (the number of gain adjustment packets). However, such suspension determination is performed based on the number of communication errors and the communication time. You can also

  -The structure of transmission data at the time of wireless data communication is not limited to that illustrated in the above embodiment, and may be changed as appropriate. Even in such a case, a gain adjustment signal is added in front of the main part of the data to be transmitted, and when a communication error occurs, the gain adjustment signal is lengthened according to the number of communication errors, and wireless data transmission is retried. As long as this is done, the effect described in the above (1) can be obtained.

  In the wireless sensor system of the above embodiment, the external station 20 transmits a command for specifying the sampling condition of the sensor signal to the sensor station 10 as the main part of the data to be transmitted. Although the sensor signal is sampled by setting the sampling condition based on the command, the present invention can be applied to a wireless sensor system other than the above configuration. In short, a wireless sensor configured to have a sensor station that performs sensor signal sampling and transmits the sampled sensor data wirelessly and an external station that receives sensor data transmitted from the sensor station. The present invention can be applied to any system.

The block diagram which shows typically the structure of the sensor station about the wireless sensor system which concerns on one Embodiment of this invention. The block diagram which shows typically the structure of the external station about the wireless sensor system of the embodiment. (A) is a schematic diagram schematically showing a structure of transmission data for command transmission employed in the wireless sensor system of the embodiment, and (b) is a schematic diagram showing a structure of a command packet constituting the transmission data. (A) is a schematic diagram schematically showing a structure of transmission data for sensor data transmission employed in the wireless sensor system of the embodiment, and (b) is a schematic diagram showing a structure of a data packet constituting the transmission data. The flowchart which shows the process sequence of the data transmission routine performed with the wireless sensor system of the embodiment. The flowchart which shows the process sequence of the data reception routine performed with the wireless sensor system of the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Sensor station, 11 ... Analog switch, 12 ... Variable resistance device, 13 ... A / D converter, 14 ... CPU module, 15 ... DMA unit, 16 ... Memory, 17 ... Wireless module, 20 ... External station, 21 ... CPU module, 22 ... wireless module, 23 ... memory, 24 ... user interface (UI).

Claims (7)

In a wireless sensor system configured to have a sensor station that performs sensor signal sampling and transmits the sampled sensor data wirelessly and an external station that receives sensor data transmitted from the sensor station,
Along with performing a wireless data transmission between the sensor station and the external station with a gain adjustment signal for adjusting the reception sensitivity in front of the main body portion of the data to be transmitted,
When a communication error occurs during the wireless data transmission, the gain adjustment signal is lengthened according to the number of communication errors, and the wireless data transmission is retried. The wireless sensor system according to claim 1, wherein the gain adjustment signal includes a bit string in which a logic level signal “1” and a logic level signal “0” are alternately repeated. The wireless sensor system according to claim 1, wherein the wireless data transmission is stopped on condition that a length of the gain adjustment signal is equal to or greater than a predetermined stop determination value. The wireless data transmission is performed in the order of the gain adjustment signal, the data header, the main body portion of the data, and the data footer.
The station that has received the wireless data transmission performs reception sensitivity adjustment using the gain adjustment signal, and the data header, the main body of the data, and the data footer are subsequently received in that order, The wireless sensor system according to claim 1, wherein the wireless sensor system is determined to be a communication error. In addition to transmitting a check code when transmitting the wireless data,
The department which received the wireless communication checks the main part of the received data using the check code, and as a result, even when a data error is detected, the communication error is determined. The wireless sensor system described. The wireless sensor system according to claim 5, wherein a cyclic redundancy check code is used as the check code. The external station transmits a command for designating a sampling condition of the sensor signal to the sensor station as a main part of the data,
The wireless sensor system according to claim 1, wherein the sensor station sets a sampling condition based on the received command and samples the sensor signal.

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