JP2006148446A - Data communication equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide data communication equipment capable of minimizing the influence of radio waves generated by external equipment and improving communication efficiency even under the environment that radio communication equipment and equipment generating strong noise exist on the periphery in the data communication equipment for performing communication between terminals within a system. <P>SOLUTION: A radio wave intensity detection circuit 116 outputs signals based on the intensity of reception radio waves. A level storage/setting circuit 140 outputs an upper limit value and a lower limit value for distinguishing the radio waves generated by communicating partner equipment and noise generated by a radio wave transmission source different from that to a comparator circuit 141. The comparator circuit 141 compares the amplitude value of reception signals indicated by signals inputted from an AD circuit 139 with the upper limit value and the lower limit value inputted from the level storage/setting circuit 140 and outputs signals indicating a compared result. On the basis of the compared result, the communication with the communicating partner equipment is controlled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a data communication apparatus that performs data communication with other communication apparatuses using radio waves, and particularly to image data and the like in an environment where communication failure due to radio waves generated by devices outside the system occurs. The present invention relates to a data communication apparatus that improves the efficiency of data communication.

Conventionally, the following technologies related to wireless communication have been disclosed. For example, Patent Literature 1 describes a wireless device that starts reception after determining whether a radio wave is to be received by detecting the reception level of the radio wave. Patent Document 2 describes a method for confirming a received radio wave when the radio wave to be received is FM modulated. This method utilizes the fact that the radio wave intensity varies when noise is received, but the amplitude is substantially constant in the case of an FM modulated radio wave. This Patent Document 2 also shows a method for determining whether or not a radio wave is to be received by monitoring a rate at which the radio wave intensity exceeds a predetermined threshold level within a predetermined time. Patent Document 2 also shows a method of starting transmission after receiving radio waves before starting transmission and confirming that radio waves to be received are not transmitted.
JP-A-7-321687 Japanese Patent Laid-Open No. 10-224242

  In the techniques described in each of the above patent documents, when determining whether or not the radio wave is to be received, a determination is made by comparing a predetermined determination level or determination pattern with the radio wave intensity being received. Yes. Therefore, when there are multiple devices that perform wireless communication in the vicinity, the difference between the strength of the radio wave generated by them and the strength of the radio wave to be received becomes small, and the radio wave strength keeps a constant level. There arises a problem that it becomes impossible to distinguish between a desired radio wave and a radio wave of communication by another device.

  Furthermore, the above-mentioned patent document does not describe a response when noise occurs during reception of the desired radio wave, and if noise occurs during reception of the desired radio wave, an error in the data being received is not described. The detection is performed by inspection using an error detection code or an error correction code added to the data. However, if noise from a peripheral device occurs during reception, the amount of error that occurs increases, and the probability that erroneous detection or correction will occur increases. In order to cope with this problem, it is necessary to add a large amount of inspection data for error detection code or error correction code to transmission data. In this case, the amount of communication data increases, and communication data is increased. The problem of reduced efficiency occurs.

  The present invention has been made in view of the above-described problems, and is an environment in which a device that performs wireless communication or a device that generates strong noise exists in the periphery in a data communication device that performs communication between terminals in its own system. It is an object of the present invention to provide a data communication apparatus that can improve the communication efficiency while minimizing the influence of radio waves generated by an external device.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the invention according to claim 1 is based on the strength of received radio waves in a data communication apparatus that performs data communication with a communication counterpart apparatus using radio waves. A radio field intensity range that is set in order to distinguish a radio field intensity detection unit that generates a radio field intensity signal, a radio wave generated by the communication partner apparatus, and a noise generated by a radio wave source different from the communication partner apparatus And noise detection means for detecting whether or not the noise is included in the received radio wave, and a detection result of the noise by the noise detection means And a communication control means for controlling communication with the communication partner apparatus based on the data communication apparatus.

  According to a second aspect of the present invention, in the data communication apparatus according to the first aspect, the communication control unit sets the radio field intensity range based on the radio field intensity signal at the time of past communication with the communication partner apparatus. It is characterized by doing.

  According to a third aspect of the present invention, in the data communication device according to the first aspect, the communication control unit is configured such that when the intensity of the received radio wave is within the radio field intensity range as a result of the comparison by the noise detection unit. Starts communication with the communication partner apparatus.

  According to a fourth aspect of the present invention, the data communication device according to the first aspect further comprises storage means for storing an error period in which the intensity of the received radio wave is out of the radio wave intensity range during a predetermined period. The communication control means executes a retransfer process for retransferring data corresponding to the error period from the communication partner apparatus.

  According to a fifth aspect of the present invention, in the data communication device according to the fourth aspect, the communication control means, as the re-transfer process, includes the number of times the received radio wave intensity is out of the radio wave intensity range, and the error. The information specifying the head position and the length of the data corresponding to the period is transmitted to the communication partner apparatus, so that necessary data is retransferred from the communication partner apparatus.

  According to a sixth aspect of the present invention, in the data communication device according to the fourth aspect, the communication control means transmits, as the re-transfer process, information specifying the entire data of the reception unit to the communication partner device. Thus, necessary data is retransferred from the communication partner apparatus.

  According to a seventh aspect of the present invention, in the data communication device according to the fourth aspect, the communication control means, as the re-transfer process, includes the number of times the received radio wave intensity is out of the radio wave intensity range, and the error. By transmitting information specifying the start position and length of the data corresponding to the period to the communication partner device, retransmitting necessary data from the communication partner device, and the entire data in the reception unit. By transmitting the designated information to the communication partner apparatus, and performing a whole retransfer process for retransmitting necessary data from the communication partner apparatus, and the type of the data and the strength of the received radio wave are The partial re-transmission process and the whole re-transfer process are performed according to the number of times that the radio field intensity range is exceeded or the amount of data received from the communication partner apparatus during the error period. Wherein the selecting and executing either one of.

  According to the present invention, by comparing the intensity of the received radio wave with the radio wave intensity range, it is detected whether or not the received radio wave includes a noise component, and communication with the communication partner apparatus is performed based on the detection result. Because it is controlled, it is possible to improve the communication efficiency by minimizing the influence of radio waves generated by external devices even in the environment where devices that perform wireless communication or devices that generate strong noise exist in the vicinity. The effect is obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In the present embodiment, a wireless communication system including an imaging device (imaging device 1 in FIG. 1) and a display device (display device 2 in FIG. 2) that perform wireless communication with each other will be described as an example. The imaging device has an imaging function, and after an imaging condition is set by the display device, starts an imaging operation and has a function of wirelessly transmitting captured image data to the display device. The display device has a function of receiving and displaying image data from the imaging device and transmitting control data for controlling the imaging conditions to the imaging device.

  The image data communication in this embodiment uses an “image packet” for image data communication. In the description, the amount of data transmitted in one image packet is 256 bytes. For example, when transmitting an image of VGA (640 × 480) size, the compressed image data is about 60 KB, and thus about 250 image packets are used for transmission for one screen. After the image packet is transferred, it is necessary to transfer a result notification packet for notifying the communication result in order to check whether the transfer is successful. That is, if no transfer error occurs in the transfer of one screen, the image packet and the result notification packet are transferred approximately 250 times each. In addition, when an error occurs, data retransfer is performed in addition to the above transfer.

  FIG. 1 is a block diagram illustrating a configuration of an imaging apparatus 1 according to an embodiment of the present invention. Hereinafter, each component in the figure will be described. The imaging unit 101 is composed of a combination of a solid-state imaging device and its peripheral members and circuits, and generates image data by imaging. The captured image data is converted into JPEG data, transmitted to the display device 2 by wireless communication via the wireless communication unit 111, and an image is displayed on the display device 2. The work memory 102 stores image data generated by the imaging unit 101 and the like. The image compression circuit 103 converts the image data into JPEG data (compressed image data).

  The data bus 104 transmits control data and image data for controlling each unit in the imaging apparatus 1. The error detection circuit 105 adds an error detection code to the transmission data and detects an error in the reception data based on the error detection code added to the reception data. The transmission buffer 106 is a buffer in which transmission data is temporarily accumulated. The reception buffer 107 is a buffer in which received data is temporarily accumulated. The error table 108 includes a memory that stores a detection result of an error in received data, a register that stores an error occurrence start position and an error duration in the received data when an error occurs, and an error that writes data to the register. And a sorting circuit.

  The clock circuit 109 generates a synchronization clock (CK signal) and supplies it to each unit in the imaging apparatus 1. The CPU 110 controls the operation of each unit in the imaging device 1. In particular, the CPU 110 controls communication with the display device 2 in cooperation with the wireless communication unit 111. The wireless communication unit 111 performs wireless communication with the display device 2. In the wireless communication unit 111, the encoding circuit 112 performs transmission data encoding processing. The modulation circuit 113 performs transmission data modulation processing. The antenna 114 transmits and receives radio waves. The demodulation circuit 115 performs a demodulation process on the received data. The radio wave intensity detection circuit 116 detects the intensity of the received radio wave. The decryption circuit 117 performs decryption processing on the received data.

  Next, the operation of the imaging apparatus 1 will be described. At the time of imaging, the imaging unit 101 images a subject, generates digital image data based on the subject image, and outputs the digital image data. Image data output from the imaging unit 101 is written into the work memory 102 via the data bus 104. The image data on the work memory 102 is converted into JPEG data (compressed image data) by the image compression circuit 103 and is written into the work memory 102 again. JPEG data on the work memory 102 is communicated in a unique packet format defined as an image packet. On the work memory 102, 16-byte header data created by the CPU 110 for an image packet is also stored.

  At the time of transmission, the header and JPEG data are sequentially read from the work memory 102 as data constituting an image packet, and input to the error detection circuit 105 through the data bus 104. In the error detection circuit 105, a CRC code, which is a typical error detection code, is added to the end of the data string and is written in the transmission buffer 106 as transmission data. The transmission data written in the transmission buffer 106 is radiated into the air by the wireless communication unit 111 and transmitted to the display device 2.

  In the wireless communication unit 111 during transmission, transmission data is input from the transmission buffer 106 to the encoding circuit 112. The encoding circuit 112 converts the input 8-bit data into 1-bit data, adds a 1-bit start bit for wireless communication every 8 bits, and then synchronizes with the timing of the wireless communication. Output to. The modulation circuit 113 converts the input digital signal into an analog signal, modulates the digital signal with the wireless carrier frequency being used, and outputs the modulated signal to the antenna 114. The antenna 114 radiates the analog signal output from the modulation circuit 113 into the air as a radio wave. Note that the operation timing of circuits other than the wireless unit 111 is synchronized with the CK signal output from the clock circuit 109.

  The operation at the time of receiving the control packet including the control data transmitted from the display device 2 for setting the imaging condition and the like is as follows. The wireless communication unit 111 demodulates the signal received by the antenna 114 by the demodulation circuit 115 and outputs it as digital data for each bit. This digital data is converted into 8-bit digital data by the decoding circuit 117 and output to the reception buffer 107. Data read from the reception buffer 107 is input to the error detection circuit 105. Error detection is performed on the data by the error detection circuit 105, and the data is written to the work memory 102 via the data bus 104.

  The analog data being processed by the demodulation circuit 115 is also output to the radio wave intensity detection circuit 116. The radio wave intensity detection circuit 116 measures the intensity of the radio wave being received based on the signal output from the demodulation circuit 115, and determines whether the received radio wave is a radio wave from the display device 2 based on the measurement result. And the determination result is output to the error table 108. The error table 108 records the detection result in an internal memory, and when the radio wave intensity detection circuit 116 determines that an error has occurred, obtains the number of errors, the occurrence start position, and the duration period and writes them in a register. . The CPU 110 reads the data written in the register of the error table 108, and executes error processing according to the result. The operation when receiving the result notification packet transmitted from the display device 2 is the same as described above.

  Next, the configuration of the display device 2 will be described. FIG. 2 is a block diagram illustrating the configuration of the display device 2 according to the present embodiment. The display device 2 has a function of controlling the imaging device 1 (setting imaging conditions, etc.) and a function of receiving and displaying compressed image data transmitted from the imaging device 1. In the display device 2, the function of the configuration given the same name as the configuration of the imaging device 1 is the same as the configuration of the imaging device 1 described above, and thus the description thereof will be omitted. Hereinafter, the configuration different from the imaging device 1 will be described. To do. The LCD 218 displays an image. The display circuit 219 includes a drive circuit for driving the LCD 219 and the like. The image decompression circuit 220 performs decompression processing on the compressed image data in JPEG format received from the imaging apparatus 1.

  Next, the operation of the display device 2 will be described. The operation of receiving and displaying image data from the imaging device 1 is as follows. The antenna 214 in the wireless communication unit 211 having the same configuration as that of the wireless communication unit 111 of the imaging device 1 receives a radio wave from the imaging device 1 and outputs an analog signal based on this radio wave to the demodulation circuit 215. The analog signal is demodulated by the demodulation circuit 215 to become 1-bit digital data. Subsequently, the start bit added by the encoding circuit 112 of the imaging device 1 for wireless communication is removed by the decoding circuit 217, and an 8-bit unit is obtained. It is converted into digital data and output to the reception buffer 207.

  The compressed image data written in the reception buffer 207 is written in the work memory 202 through the error detection circuit 205 and the data bus 204. At this time, the CRC code is checked by the error detection circuit 205 to detect a transmission error accompanying communication. The detection result is stored in a register in the error detection circuit 205. The detection result is appropriately read out and processed by the CPU 210.

  The compressed image data written in the work memory 202 is read into the image expansion circuit 220 via the data bus 204 and subjected to JPEG expansion processing, and then converted into display data represented by known Y, Cb, and Cr. It is converted and written to the work memory 202 again. The written display data is read to the display circuit 219 at a predetermined display cycle, and an image based on the display data is displayed on the LCD 218.

  The analog data being processed by the demodulation circuit 215 is also output to the radio wave intensity detection circuit 216. The radio wave intensity detection circuit 216 measures the intensity of the radio wave being received, determines whether the received radio wave is a radio wave from the imaging device 1 based on the measurement result, and outputs the determination result to the error table 208. To do. The error table 208 records the detection result in an internal memory, and when the radio wave intensity detection circuit 216 determines that an error has occurred, obtains the number of errors, the occurrence start position, and the duration period and writes them in a register. . The CPU 210 reads the data written in the register of the error table 208 and executes error processing according to the result.

  The operation for transmitting the result notification packet to the imaging apparatus 1 is as follows. After receiving the image packet, the CPU 210 performs a reception confirmation process, which will be described later, and generates a result notification packet. The CPU 210 outputs the generated result notification packet to the error detection circuit 205 via the data bus 204. In the error detection circuit 205, a CRC code is added to the end of the data string, and is written in the transmission buffer 206 as transmission data. The transmission data written in the transmission buffer 206 is radiated into the air by the wireless communication unit 211 and transmitted to the imaging apparatus 1.

  Next, a procedure for converting compressed image data into communication data in the imaging apparatus 1 and a start bit adding method performed by the encoding circuit 112 will be described. The compressed image data is encoded in units of 256 bytes and transferred as image data packets. As shown in FIG. 3, the image data packet has a structure in which 256 bytes of image data follow the 16 bytes header created by the CPU 110. The error detection circuit 105 performs an error detection code addition process after converting the input byte unit data into bit units.

  Specifically, as shown in FIG. 3, 2192-bit (274 bytes) data in which a CRC code for error detection of 16 bits (2 bytes) is added to the input header and 2176 bits (272 bytes) of image data. It is output from the error detection circuit 105 and stored in the transmission buffer 106. Data is read from the transmission buffer 106 in accordance with the timing of wireless transmission, and the read data is output to the modulation circuit 113 after the start bit is added by the encoding circuit 112. As a start bit, 1 bit is added to the head of byte data (1 bit is added to 8 bits), so that the entire data size is 2466 bits as shown in FIG.

  The start bit addition performed by the encoding circuit 112 and the data output timing to the modulation circuit 113 are as follows. As shown, the start bit (S) 1 bit is followed by 8 bits of data bits (D7 to D0). Since the start bit is always “1” (HI), at the time of decoding, the start bit is detected, and the synchronization for reproduction is taken using the rising timing.

  In this embodiment, the data transfer period for 1 bit is set to 1 μs, and when the data is “1” (HI), 0.6 μs in the 1 μs period is set to HI. When the data is “0” (LO), it is all LO for 1 μs. That is, the data value can be detected by examining the HI / LO of the data at a cycle of 1 μs with reference to the rising edge of the start bit. Then, the rising edge of the next start bit that comes 9 μs after the rising edge of the first start bit is detected, and the timing for data detection is readjusted (reset), whereby the CK signal (clock circuit with the transmitting side) is readied. Output) deviation is adjusted. In addition, the insertion of the start bit guarantees the existence of a “HI” period of 1 bit or more every 9 bits when receiving radio waves of amplitude modulation method, and the radio wave intensity is detected by an amplitude detection circuit with a simple configuration. It is possible to do.

  Next, a detailed configuration of the wireless communication unit 111 will be described. FIG. 4 is a block diagram showing a detailed configuration of the wireless communication unit 111 according to the present embodiment. Since the wireless communication unit 111 and the wireless communication unit 211 of the display device 2 have the same internal configuration and function, only the configuration of the wireless communication unit 111 will be described here. In the present embodiment, the radio modulation method to be used is amplitude modulation.

  In the modulation circuit 113, the analog circuit 129 converts the digital signal input from the encoding circuit 112 into an analog signal. The BPF (band pass filter) 130 passes a component in a predetermined frequency band in the signal input from the analog circuit 129. The oscillation circuit 131 generates a carrier wave having a predetermined frequency. The mixer 132 multiplies the signal input from the BPF 130 by the carrier wave generated by the oscillation circuit 131. The buffer 133 amplifies the signal input from the mixer 132.

  In the demodulation circuit 115, the buffer amplifier 134 amplifies an analog signal based on the received radio wave received by the antenna 114. The rectifier circuit 135 rectifies the signal input from the buffer amplifier 134. An LPF (low pass filter) 136 removes low frequency components from the signal input from the rectifier circuit 135. The binarization circuit 137 converts the analog signal input from the LPF 136 into a digital signal.

  In the radio wave intensity detection circuit 116, the amplitude detection circuit 138 performs a peak detection process on the signal input from the LPF 136. The AD circuit 139 converts the analog signal input from the amplitude detection circuit 138 into a digital signal. The level storage / setting circuit 140 stores the signal input from the AD circuit 139 in accordance with an instruction from the CPU 110, and compares the upper limit value, the lower limit value, and the no-signal value used for comparison by the comparison circuit 141 with the comparison circuit 141. Output to. CPU 110 sets an upper limit value and a lower limit value based on the signal value stored by level storage / setting circuit 140. The comparison circuit 141 compares the amplitude value of the received signal indicated by the signal input from the AD circuit 139 with the upper limit value, lower limit value, and no signal value input from the level storage / setting circuit 140.

  Next, the operation of the wireless communication unit 111 will be described. At the time of transmission, the image data from the transmission buffer 106 is input to the encoding circuit 112 and converted into 1-bit digital data as described with reference to FIG. The output from the encoding circuit 112 is converted into an analog signal by the analog circuit 129 and output to the BPF 130. The signal that has passed through the BPF 130 is multiplied by the carrier wave (2.4 GHz) from the oscillation circuit 131 by the mixer 132, passes through the buffer 133 and the antenna 114, and is radiated into the air.

  At the time of reception, a process reverse to the transmission operation is followed, and the signal received by the antenna 114 is stored in the reception buffer 107 through the demodulation circuit 115 and the decoding circuit 117. In the demodulation circuit 115, detection processing is performed by the buffer amplifier 134, the rectifier circuit 135, and the LPF 136, a carrier wave component in the received radio wave is removed, and a signal is output from the LPF 136. The signal output from the LPF 136 is converted into a digital signal by the binarization circuit 137 and output to the decoding circuit 117. In the decoding circuit 117, data is read following the reverse procedure of the encoding processing circuit 112 described above, and stored in the reception buffer 107.

  The measurement of the radio wave intensity is performed by branching the signal after passing through the LPF 136 and inputting it to the amplitude detection circuit 138. The amplitude detection circuit 138 outputs a signal (radio wave intensity signal) corresponding to the intensity of the received radio wave to the AD circuit 139. The AD circuit 139 converts the input signal into a digital signal and outputs the digital signal to the level storage / setting circuit 140 and the comparison circuit 141. The level storage / setting circuit 140 stores the input signal in accordance with an instruction from the CPU 110, and outputs an upper limit value, a lower limit value, and a no-signal value to the comparison circuit 141 in accordance with the setting from the CPU 110. .

  The comparison circuit 141 converts the output value of the AD circuit 139 at that time and the average value over a certain period of time into a value readable by the CPU 110 and outputs the value. Further, the comparison circuit 141 outputs an intensity signal indicating which level of received radio wave intensity is in the set range to the decoding circuit 117, the error table 108, and the level storage / setting circuit 140. Thus, it is notified whether the radio wave being received is a radio wave from the terminal of its own system. Specifically, this intensity signal is a signal indicating whether it is below the no-signal level, within the upper and lower limits determined as the radio waves of the own system, or out of the range. The CPU 110 acquires the comparison result by the comparison circuit 141 via the level storage / setting circuit 140. Detailed description regarding the above-described measurement of the radio wave intensity and the analysis of the state of the received radio wave will be described later.

  Next, the configuration of the amplitude detection circuit 138 will be described. FIG. 5 is a circuit diagram showing a circuit configuration of the amplitude detection circuit 138 according to the present embodiment. The signal output from the LPF 136 is input to the non-inverting input terminal of the amplifier 142. The output terminal of the amplifier 142 is connected to one end of the diode 143. The inverting input terminal of the amplifier 142 is connected to the other end of the diode 143, one end of the switch 144, one end of the resistor 146, one end of the capacitor 147, and the non-inverting input terminal of the amplifier 148. The other end of the switch 144 is connected to one end of the resistor 145, and the other end of the resistor 145 is grounded. The other end of the resistor 146 and the other end of the capacitor 147 are also grounded. Both the inverting input terminal and the output terminal of the amplifier 148 are connected to the AD circuit 139.

  The operation of the amplitude detection circuit 138 is as follows. When the voltages of the diode 143, the capacitor 147, the resistor 146, and the switch 144 connected to the inverting input terminal of the amplifier 142 are lower than the voltage of the input signal, current is supplied through the diode 143, and the potential of the capacitor 147 increases. Conversely, when the above voltage is higher than the voltage of the input signal, the output voltage of the amplifier 142 decreases, but the diode 143 does not pass current, and the potential of the capacitor 147 is equal to the capacitance of the capacitor 147 and the resistance value of the resistor 146. It only decreases according to the time constant determined by. Peak detection is performed by this operation. At this time, the switch 144 is open. The resistance value of the resistor 145 is set to a value smaller than the resistance value of the resistor 146. Subsequently, when the switch 144 is closed, the charge of the capacitor 147 is discharged mainly through the resistor 145, so that the amplitude detection is performed. The output of the circuit 138 has almost the same value as the input signal.

  FIG. 6 shows the output of the amplitude detection circuit 138 when “0” is received as data (when data [D7] to [D0] = ‘0’). When “0” is received as data, HI does not become other than the start bit, but by setting the time constant longer than the reception period of the start bit, the radio wave intensity can be detected with high accuracy as shown in the figure. It becomes.

  Next, the timing for starting the reception operation will be described. FIG. 7 shows the state of the received signal. Here, a description will be given by taking as an example an operation in which the imaging device 1 periodically captures images and transmits image data to the display device 2. The imaging device 1 captures an image at a predetermined time and transmits image data. However, the display device 2 prepares for reception from the start of transmission of the image data by the imaging device 1 and transmits radio waves from the imaging device 1. The reception process is started from the time of reception. FIG. 7 shows a state in which noise from the peripheral device has occurred after the display device 2 has finished preparation for reception start and has entered a reception start waiting state.

  In the reception start preparation state, as shown in FIG. 7, the display device 2 sets a no-signal value that is a level that does not cause an error in the received data if the noise is lower than that level, and the radio wave intensity at the previous reception. Based on the above, the upper limit value and the lower limit value determined as within the range of the transmission radio wave (radio wave intensity range) from the imaging device 1 are set. The upper limit value and the lower limit value are set by the CPU 210 based on the radio wave intensity in the previous communication and the elapsed time from the previous communication, and the radio wave intensity from the imaging device 1 when normal communication is performed. Is set to a value that falls between the upper and lower limits. Thereby, it is possible to distinguish between radio waves generated by the imaging apparatus 1 and noises generated by a radio wave transmission source different from the imaging apparatus 1.

  Moreover, CPU210 resets an upper limit and a lower limit at any time according to the average value of the received radio wave intensity after the start of the reception operation. Therefore, the display device 2 does not start the reception operation when noise occurs (period t0-t1, t2-t3), and starts the reception operation from the time (t4) when the radio wave intensity falls between the upper limit value and the lower limit value. Start. That is, the CPU 210 monitors the intensity of the received radio wave detected by the radio wave intensity detection circuit 216. If the radio wave intensity is not a value between the upper limit value and the lower limit value, the reception start waiting state is continued. On the other hand, when the radio field intensity reaches a value between the upper limit value and the lower limit value, the CPU 210 instructs each unit such as the wireless communication unit 211 to start receiving data. As the upper limit value and lower limit value at the start of operation immediately after the power is turned on, preset default values may be used, or the upper limit value and lower limit value at the time of communication performed before the power is turned off are stored. A value may be used.

  When an error occurs during the communication of the image data packet with the imaging device 1, the image data packet is retransferred from the imaging device 1 as will be described later. FIG. 8 shows a radio wave condition in a state where retransfer is performed. In FIG. 8, the transmission / reception operation of the image data packet is started from time t6. FIG. 8 shows that the first data packet transfer (DP0) and the result notification packet transfer (normal: ACK0) and the second data packet transfer (DP1) and the result notification packet transfer (normal: ACK1) are completed. This shows a situation in which noise occurs during the third data packet transfer (DP2), and the noise continues to be generated after the data packet transfer is completed.

  When the third data packet transfer is started and noise is generated at this time, the display device 2 monitors the radio wave intensity during reception as described above. , It is detected that an error has occurred in the received data. As shown in the figure, when the error period is long, the total processing time is shorter when the entire image data packet is retransmitted than when only the portion where the error is considered to be retransmitted. In that case, the display device 2 creates a result notification packet (abnormality: NACK2) having a command for requesting retransmission, and transmits the packet to the imaging device 1 after the reception is completed.

  In the reception of the image data packet in this embodiment, when the error is distributed to three or more places and when the total amount of errors exceeds 40H (error amount converted to a register value described later), the entire packet is retransmitted. Is called. In the example shown in FIG. 8, since the generation of noise continues even at the transmission end time (t8), the display device 2 waits for the noise to settle before transmitting the result notification packet (abnormal: NACK2). (T9). These detailed procedures will be described later.

  The imaging device 1 starts receiving the result notification packet immediately after the transmission ends (t8), but detects the occurrence of noise as in the display device 2, and is in a state of waiting for the noise to disappear. When the imaging apparatus 1 confirms that the radio wave intensity is less than the no-signal value and the noise generation is stopped (t9), the imaging apparatus 1 ends the noise disappearance wait and enters a normal result notification wait state. In normal result notification waiting, a timeout count is performed, and when the timeout period elapses, a timeout process is performed, and the process is restarted from the beginning. However, in the case of the present embodiment, the imaging apparatus 1 stops the timeout count while waiting for the noise to disappear, so the noise generation period (t8-t9) is longer than the timeout period. Must not.

  When the noise disappears, the radio wave intensity falls below the no-signal value on the display device 2 side at the same time, and the disappearance of the noise is confirmed. Therefore, a result notification packet (abnormality: NACK2) indicating a communication abnormality is captured from the display device 2. Sent immediately to the device 1. As described above, since the re-transmission request for the entire packet is written in the sent result notification packet, the imaging apparatus 1 re-transmits the same image data packet (DP2) as the previous time.

  As described above, immediately after the transmission of the image data packet is completed, when the imaging apparatus 1 determines that noise is generated as a result of the radio field intensity measurement, the imaging apparatus 1 stops time measurement for timeout processing, Become. As a result, even if the noise generation period is longer than the timeout start period, the waiting time due to noise is excluded from the timeout measurement time, so the imaging device 1 receives the result notification packet after the noise ends. The communication sequence is continued.

  Next, with reference to FIG. 9 and FIG. 10, a re-transfer process when a reception error occurs in the image data packet reception operation by the display device 2 will be described. In particular, a description will be given of a process in which the display device 2 designates data in which an error has occurred and performs retransfer. FIG. 9 shows a change in radio wave intensity when an image data packet is received. The error table 208 stores a result signal from the comparison circuit of the wireless communication unit 211 (the same configuration as the comparison circuit 141) in association with the data position being received. In this case, the error table 208 stores the radio wave intensity for each bit unit of data.

  In the example shown in FIG. 9, noise occurs twice (error 1 and error 2) during reception of the image data packet. In this case, as described above, the position of the error data is stored in the memory in the error table 208, and an error is indicated by an error sorting circuit (not shown) in the error table 208 immediately after the end of the reception period (t15). The occurrence start position and length of “1” are detected and written to the register in the error table 208.

  FIG. 10 shows the state of the registers in the error table 208 described above. As shown in FIG. 10, in the error table 208, the error position is stored in units of bits, including the start bit, corresponding to the received data string. However, since the retransmission unit is handled in units of bytes, The error occurrence position and length are displayed in units of bytes excluding the start bit. Therefore, if an error is included even in 1 bit in the data in byte units excluding the start bit, the byte is handled as an error byte (if noise is generated at the start bit position, the subsequent 8 bits are handled. Is determined to have an error).

  The above register value is read by the CPU 210. The CPU 210 selects the re-transfer method according to the register value. However, in the error occurrence state as shown in FIG. 9, the error amount is small, so the method for re-transfer by partially specifying the data is selected. To do. In this case, a value indicating the number of errors and the start position and length of each error is written and transmitted in the result notification packet.

  Upon receiving the result notification packet, the imaging apparatus 1 analyzes the content, reads only the requested data from the work memory 102, creates a retransmission packet with a header, and transmits it. When the display device 2 receives the retransfer packet, the display device 2 analyzes the content, replaces the retransmitted data with the error portion written on the work memory 202, reconfigures the data packet, and reconfigures the data. After confirming that there is no error by passing the packet through the error detection circuit 205, a result notification packet (normal: ACK) for requesting transmission of the next packet is transmitted to the imaging apparatus 1. When an error is detected by the error detection circuit 205, the error position cannot be specified, and the display device 2 transmits a result notification packet (abnormality: NACK) requesting retransmission of the entire packet.

  Next, the image data packet re-transfer process performed when the amount of errors is large will be described with reference to FIGS. Hereinafter, a reception process of the display device 2 when an error occurs in the image data packet transferred from the imaging device 1 and retransfer is performed will be described. If the amount of error is large, the previously received image data packet is retransmitted as it is. In this case, since it is determined that the communication status has deteriorated, the display device 2 determines that no error has occurred in the data received in the first transfer and the data received in the retransfer. To create received data. The reception data after creation is passed through the error detection circuit 205 as in the case described with reference to FIGS. 9 and 10, and it is confirmed that there is no error.

  Hereinafter, with reference to FIG. 11 and FIG. 12, an error occurrence state in the first transfer and an example of a register value corresponding thereto will be described. Also in this example, it is assumed that noise occurs twice during packet reception (error 3 and error 4), and the register values in the error table 208 indicating the noise occurrence position and length are shown in FIG. It is like that. In this case, the CPU 210 of the display device 2 reads the register value and confirms the noise generation status. Since the amount of data to be retransmitted is large, the CPU 210 selects to retransmit the entire packet and generates a result notification packet (abnormality: NACK). The display device 2 notifies the re-transfer request to the imaging device 1 by transmitting the result notification packet. In response to the request indicated by the received result notification packet (abnormality: NACK), the imaging device 1 performs retransfer of the entire packet.

  Hereinafter, with reference to FIGS. 13 and 14, an example of an error occurrence state in re-transfer and a corresponding register value will be described. When the error occurrence status at the time of re-transfer (noise occurs once (error 5)) and the corresponding register values are as shown in FIG. 13 and FIG. 14, the CPU 210 of the display device 2 It is determined whether or not the entire data can be reconstructed based on the data received at the time of transfer and the data determined to have no error among the data received at the time of retransfer. In this example, the addresses: 0H to 4FH, 60H to 6FH, and E0H to 112H are determined to be normal in the first transfer, and the addresses: 0H to 1FH and 40H to 112H are determined to be normal in the retransfer. In this case, the CPU 210 reconstructs the data packet by replacing the data of 20H to 3FH determined to have an error at the time of the retransfer with the data received at the time of the first transfer, and then transmits the data packet to the error detection circuit 205. The data is output, and it is confirmed by the processing of the error detection circuit 205 that there is no error in the data.

  If the error does not disappear even after re-transfer, repeat the re-transfer process according to the above procedure to eliminate the error part. However, there is a limit on the number of retransfer processes, and retransfer does not continue indefinitely. If the error does not disappear even if the upper limit of the number of retransmissions is exceeded, the imaging device 1 determines that the communication path has deteriorated and stops packet transfer. In addition, when an error is detected by the error detection circuit 205 in the inspection of the reconstructed data packet, as in the case where a large number of errors are found in the normally transferred packet, the entire packet is checked. Retransfer is performed.

  Next, reception processing performed by the CPU 210 of the display device 2 will be described with reference to FIGS. 15 and 16. FIG. 15 shows received data confirmation processing, and FIG. 16 shows error determination processing called as a subroutine during received data confirmation processing. The reception data confirmation process is performed after the reception of the normal image data packet and the re-transfer packet, based on the radio wave condition being received and the error detection result of the received data, the CPU 210 of the display device 2 displays the transfer result. This is a process of creating a “result notification packet” for informing the imaging apparatus 1. Depending on the content of the “result notification packet”, the content of the packet transmitted from the imaging apparatus 1 in the next communication is determined.

  In the image data reception confirmation process, the CPU 210 first reads out the packet transferred from the imaging device 1 from the work memory 202 and confirms the type of the packet from the header information (step S301). As a result of the confirmation, if the transferred packet is a normal image data packet, an error determination process is called and executed (step S302), and then the process ends. On the other hand, when the transferred packet is a retransfer packet, the CPU 210 reconstructs the data packet on the work memory 202 (step S303).

  Subsequently, the CPU 210 determines whether or not all error data has been replaced by the retransferred data (step S304). If it is determined that all the error data has been replaced, the CPU 210 inputs the reconstructed data packet to the error detection circuit 205 via the data bus 204, and the error that could not be found by observation of the radio field intensity. Is confirmed in the data packet (step S305). Subsequently, the CPU 210 calls an error determination processing subroutine to perform error determination processing (step S302), and then ends the processing.

  If it is determined in step S304 that all error data cannot be replaced and an error remains, the CPU 210 checks whether the number of retransmissions exceeds the allowable number of retransmissions (step S306). When the number of retransmissions does not exceed the allowable limit number, the CPU 210 reads information on the number, position, and length of error data from the error table 208, and based on the information, the time required for the retransmission process And a re-transfer method is selected (step S307).

  If the error amount is large, that is, if the process of requesting retransmission by specifying the entire packet (entire retransmission) takes less time, the CPU 210 creates a result notification packet for performing the entire retransmission. (Step S308). When the amount of errors is small, that is, when the process of requesting retransmission by specifying error data (partial retransmission) can be completed in a shorter time, the CPU 210 sends a result notification packet for performing partial retransmission. Is created (step S309). The result notification packet for causing the imaging apparatus 1 to perform partial re-transfer includes the number of errors, the start position when an error occurs in the received data (error occurrence start position), and the length of the duration of the error. Information indicating the length (error length) or the length of data received during the duration of the error is recorded. The CPU 210 reads a register value from a register in the error table 208 and generates the above information based on the register value.

  On the other hand, if it is determined in step S306 that the number of retransmissions has reached the allowable limit number, the CPU 210 determines that the state of the communication path has deteriorated and results for canceling the transfer of the data packet during communication. A notification packet is created (step S310). When the creation of each result notification packet ends, the image data reception confirmation process ends. After completion of the reception confirmation process, each result notification packet is transmitted to the imaging apparatus 1.

  Hereinafter, details of the error determination process in step S302 will be described with reference to FIG. First, the CPU 210 determines whether there is data received when radio wave intensity abnormality has occurred in the image data written in the work memory 202 (or radio wave intensity abnormality has occurred during reception of image data). Whether or not) (step S3021). When performing an error determination process after receiving a normal packet, the CPU 210 reads a register value from a register in the error table 208 and makes a determination based on the register value. Further, when the error determination process is performed after receiving the retransfer packet, the error determination process subroutine is called after the completion of the error as shown in FIG. The received image data is processed when it is determined that there is no data received when the radio wave strength abnormality occurred (or no radio wave strength abnormality occurred during reception of the image data). .

  When it is determined that there is no data received when the radio wave intensity abnormality has occurred (or no radio wave intensity abnormality has occurred during reception), the CPU 210 reads the detection result from the register of the error detection circuit 205. Then, it is confirmed whether or not there is an error in the data packet that could not be found by observation of the radio field intensity (step S3022). In the case of normal (not retransfer) data, the data is sent to the error detection circuit 205 at the time of reception. In the case of retransfer data, the data is sent to the error detection circuit 205 before calling the error determination process. Therefore, the CPU 210 executes the above process by confirming the register value of the error detection circuit 205.

  If it is determined in step S3022 that there is no error, the CPU 210 creates a result notification packet for transferring the next packet (step S3023). If it is determined that there is an error, it is impossible to specify where the error has occurred in the data, and thus the CPU 210 creates a result notification packet for performing the entire retransmission (step S3024).

  On the other hand, if it is determined in step S3021 that there is data received when a radio field intensity abnormality has occurred (or a radio field intensity abnormality has occurred during reception), the CPU 210 registers from the register of the error table 208. A value is read out, a time required for the retransfer process is calculated based on the value, and a retransfer method is selected (step S3025). If the error amount is large, that is, if the process of requesting retransmission by specifying the entire packet (entire retransmission) takes less time, the CPU 210 creates a result notification packet for performing the entire retransmission. (Step S3024). When the amount of errors is small, that is, when the process of requesting retransmission by specifying error data (partial retransmission) can be completed in a shorter time, the CPU 210 sends a result notification packet for performing partial retransmission. Is created (step S3026). When the creation of the result notification packet is completed, return processing is performed.

  In the above description, transmission / reception of image data packets has been described as an example. However, in the data communication system according to the present embodiment, a control packet for setting imaging conditions in the imaging apparatus 1 is also used. This control packet is a packet transmitted from the display device 2 to the imaging device 1 and has a shorter packet length because the data amount is smaller than that of the image data packet. In addition, since the influence when the contents are erroneously transmitted is large, the processing in the transmission / reception of the control packet is different from the case of the image data packet described above. Specifically, when noise generation is detected by radio field intensity measurement during reception of a control packet, re-transfer of the entire packet is requested unconditionally. This reduces the possibility of information being transmitted by mistake. The detailed operation described above is the same as the processing performed when a lot of noise is detected in the image data packet being received, which has been described with reference to FIGS.

  In the present embodiment, the case of amplitude modulation has been described as an example. However, the measurement of radio wave intensity is not limited to amplitude modulation. In the case of frequency modulation or phase modulation, radio wave intensity can be easily detected because there is no change in the amplitude of the carrier signal due to data. For example, a combination of a rectifier circuit and a peak detection circuit may be used as in the case of this embodiment, or a simple LPF (low-pass filter) circuit may be used.

  In this embodiment, the case where image data is transmitted and received between the imaging device 1 and the display device 2 has been described as an example. However, the system configuration is not limited to this. For example, the present embodiment may be applied to a system in which data communication apparatuses having the same configuration perform data transmission / reception or a data communication terminal downloads data from a server. Further, the data transmitted and received is not limited to image data.

  As described above, in the present embodiment, the radio field intensity range (upper limit value and lower limit value in the above-described example) that is permitted as the intensity of the received radio wave for normal communication in the data communication system, and the intensity of the received radio wave By comparing, it is detected whether or not a noise component is included in the received radio wave, and communication with another data communication device (communication partner device) is controlled based on the detection result. As a result, it is possible to more correctly determine the occurrence of a reception failure due to an external radio wave, so that it is possible to reliably detect the radio wave transmitted from the communication partner device and start the reception operation. In addition, by performing processing corresponding to the state of failure, even in an environment where devices that perform wireless communication or devices that emit strong noise exist in the vicinity, the influence of radio waves generated by external devices is minimized, Communication efficiency can be improved.

  In addition, by setting the reference value of the radio field intensity that determines the radio field intensity range used for the comparison of the radio field intensity based on the normal radio field intensity at the time of past communication, for example, a moving speed such as a capsule endoscope In communication with other communication terminals that have a higher communication frequency compared to, the accuracy of detecting transmissions from the communication terminal of its own system can be increased. Improvements can be made.

  In addition, as a result of comparison between the value defining the predetermined radio wave intensity range and the received radio wave intensity, if the received radio wave intensity does not exist within the radio wave intensity range before the start of communication such as transmission and reception of the result notification packet, When the timeout count is stopped and the received signal strength is within the signal strength range, communication such as transmission / reception of the result notification packet with the communication partner device is started, and communication is usually terminated due to timeout. However, the communication sequence is continued without being reset. Therefore, occurrence of communication delay due to noise can be minimized. In particular, in a medical field, noise with a long bursty period is generated by an electric knife or the like, and it is important to avoid the influence. According to this embodiment, noise with a long bursty period is used. It is possible to reliably avoid occurrence of timeout due to.

  In addition, if the received radio wave strength does not fall within the radio wave strength range during data reception, the error period when the radio wave strength falls outside the radio wave strength range is stored, and the data that should have been received during that error period is stored in the communication partner By retransfer from the apparatus, it is possible to accurately detect an error occurrence position during data reception, and as a result, an efficient retransfer process can be performed, thereby improving communication efficiency. Furthermore, even if ECC (Error Correction Code) or CRC (Cyclic Redundancy Code) with low detection capability is used, the probability of erroneous correction or erroneous detection can be reduced, so that the amount of additional data can be reduced. The improvement of the communication efficiency from can also be expected.

  In addition, when retransmitting data, by specifying only the data in error and performing retransfer (partial retransfer), the amount of retransfer data is reduced and efficient communication can be performed. . Furthermore, to improve transfer efficiency, even if transfer is performed with a large packet, re-transfer when an error occurs can be improved by changing the size of the packet and transferring the packet with an optimal size. .

  In addition, when performing data re-transfer, if the amount of data in error is increased by re-transferring all data in units of reception (packet unit in this embodiment) (overall re-transfer), It can cope with quick reproduction of data.

  Further, by making it possible to select partial re-transfer and full re-transfer, when there are few errors, the amount of data that has become an error, or the amount of data transferred in one packet, such as control data, can be reduced. When retransmitting a small number of packets, there are various situations that occur in communication systems in which image data and control data are transmitted and received, such as when the entire packet is simply retransmitted without specifying the position, etc. Corresponding to the case, the efficiency of the retransfer process can be improved.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings, but the specific configuration is not limited to these embodiments, and includes design changes and the like within a scope not departing from the gist of the present invention. It is.

It is a block diagram which shows the structure of the imaging device by one Embodiment of this invention. It is a block diagram which shows the structure of the display apparatus by the embodiment. FIG. 5 is a conceptual diagram for explaining a procedure for converting compressed image data into communication data and a method for adding a start bit in the embodiment. It is a block diagram which shows the structure of the radio | wireless communication unit by the embodiment. FIG. 3 is a circuit diagram showing a circuit configuration of an amplitude detection circuit according to the same embodiment. It is a reference figure showing the output of the amplitude detection circuit by the embodiment. FIG. 6 is a reference diagram for explaining a reception start timing in the same embodiment. FIG. 6 is a reference diagram for explaining an operation at the time of noise detection in the same embodiment. FIG. 6 is a reference diagram for explaining an operation at the time of noise detection in the same embodiment. It is a reference figure showing the state of the register in the error table at the time of noise detection in the embodiment. FIG. 6 is a reference diagram for explaining an operation at the time of noise detection in the same embodiment. It is a reference figure showing the state of the register in the error table at the time of noise detection in the embodiment. FIG. 6 is a reference diagram for explaining an operation at the time of retransfer of an image data packet in the embodiment. FIG. 8 is a reference diagram illustrating a state of a register in an error table at the time of retransfer of an image data packet in the same embodiment. It is a flowchart which shows the procedure of the reception confirmation process which CPU of the display apparatus by the embodiment performs. It is a flowchart which shows the procedure of the error determination process which CPU of the display apparatus by the same embodiment performs during a reception confirmation process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Imaging device, 2 ... Display device, 101 ... Imaging unit, 102, 202 ... Work memory, 103 ... Image compression circuit, 104, 204 ... Data bus, 105, 205 ... Error detection circuit, 106, 206 ... Transmission buffer, 107, 207 ... Reception buffer, 108, 208 ... Error table (storage means), 109, 209 ... Clock circuit, 110, 210 ... CPU (communication control means), 111, 211 ... wireless communication units, 112, 212 ... coding circuit, 113, 213 ... modulation circuit, 114, 214 ... antenna, 115, 215 ... Demodulation circuit, 116, 216 ... Radio wave intensity detection circuit, 117,217 ... Decoding circuit, 129 ... Analogization circuit, 130 ... BPF, 131・ Oscillator circuit, 132, mixer, 133, buffer, 134, buffer amplifier, 135, rectifier circuit, 136, LPF, 137, binarization circuit, 138, amplitude Detection circuit (radio wave intensity detection means), 139 ... AD circuit, 140 ... level storage / setting circuit, 141 ... comparison circuit (noise detection means), 142, 148 ... amplifier, 143 ... Diodes, 144, switches, 145, 146, resistors, 147, capacitors, 218, LCD, 219, display circuits, 220, image expansion circuits.

Claims (7)

In a data communication device that performs data communication with a communication partner device using radio waves,
Radio wave intensity detecting means for generating a radio wave intensity signal based on the intensity of the received radio wave;
A radio wave intensity range set to distinguish a radio wave generated by the communication partner apparatus from a noise generated by a radio wave transmission source different from the communication counterpart apparatus, and the received radio wave indicated by the radio wave intensity signal Noise detection means for comparing whether the noise is included in the received radio wave,
Communication control means for controlling communication with the communication partner device based on the detection result of the noise by the noise detection means;
A data communication apparatus comprising:   The data communication apparatus according to claim 1, wherein the communication control unit sets the radio field intensity range based on the radio field intensity signal at the time of past communication with the communication partner apparatus.   2. The communication control unit starts communication with the communication partner device when the intensity of the received radio wave is within the radio wave intensity range as a result of the comparison by the noise detection unit. The data communication apparatus according to 1. Storage means for storing an error period in which the intensity of the received radio wave is out of the radio wave intensity range during a predetermined period;
The data communication apparatus according to claim 1, wherein the communication control unit executes a retransfer process for retransmitting data corresponding to the error period from the communication partner apparatus.   The communication control means receives information specifying the number of times that the intensity of the received radio wave is out of the radio wave intensity range and the head position and length of data corresponding to the error period as the re-transfer process. 5. The data communication apparatus according to claim 4, wherein necessary data is re-transferred from the communication partner apparatus by transmitting to.   The communication control means, as the re-transfer processing, transmits necessary data from the communication partner device by transmitting information specifying the entire data of a reception unit to the communication partner device. Item 5. The data communication device according to Item 4. The communication control means, as the re-transfer process,
By transmitting information specifying the number of times the received radio wave intensity is out of the radio wave intensity range and the start position and length of data corresponding to the error period to the communication partner apparatus, the necessary data is transmitted to the communication partner device. Partial re-transfer processing to re-transfer from the other device,
An overall re-transmission process for re-transmitting necessary data from the communication counterpart device by transmitting information specifying the entire data in a reception unit to the communication counterpart device;
According to the type of data, the number of times the received radio wave intensity is out of the radio wave intensity range, or the amount of data received from the communication counterpart device during the error period. The data communication apparatus according to claim 4, wherein one of the transfer process and the entire retransfer process is selected and executed.

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