JP5510829B2 - Signal receiver - Google Patents

Description

  The present invention relates to a signal receiver, and more particularly to a signal receiver that improves the extraction efficiency of fixed sentence data in a signal and improves the communication efficiency of simultaneous communication.

  Conventionally, communication using modulation techniques such as ASK and FSK has been performed (see, for example, Patent Documents 1 and 2). In recent years, this communication technique has been used for wireless communication such as ETC, keyless entry system, and Bluetooth communication. However, particularly when the transmitter is used for portable purposes or for animal monitoring purposes, the communication technology is reduced in size and saved. Electricity becomes an issue.

  In order to achieve miniaturization and power saving, it is effective to improve reception sensitivity, improve noise resistance, and shorten data length (message length). Therefore, for example, in the ones disclosed in Patent Documents 1 and 2, the reception sensitivity is improved by improving the characteristics of the wave height discrimination circuit on the receiver side and adjusting the wave height discrimination threshold.

JP 2006-229427 A JP 2009-302862 A

  However, in the conventional receiver, data extraction (noise removal) is performed by wave height discrimination based on a threshold value, and thus there is a limit to improvement in the S / N ratio. That is, if the threshold value is increased in response to the large noise component exceeding the threshold value, the data component may not be detected correctly. On the other hand, if the threshold value is lowered for reliable detection of the data component, a noise component may be erroneously detected as data this time. Therefore, there is a problem that it is difficult to set an appropriate threshold value and it is difficult to significantly improve the S / N ratio.

  As a measure for improving the S / N ratio, a method of increasing the data length of a fixed sentence or the like and reducing erroneous detection of data is also conceivable. However, if the data length is increased, the data becomes redundant and the communication efficiency is lowered, and it takes a long communication time to communicate the same amount of information, resulting in a large amount of power consumption. Occur. Furthermore, there is also a demand to achieve multiple access in highly sensitive and power saving communication as much as possible.

  The present invention has been made in view of the above circumstances, and can improve reception sensitivity and shorten data length without using wave height discrimination, thereby improving communication efficiency and S / N ratio. It is an exemplary object to provide a signal receiver that can contribute to downsizing and power saving of a transmitter.

  In order to solve the above problems, a signal receiver as an exemplary aspect of the present invention receives a signal including a data component including fixed sentence data and a noise component, performs frequency decomposition, and obtains a frequency spectrum. Calculation based on the receiving unit, the storage unit that stores the fixed sentence data in advance and stores the frequency spectrum and the acquisition time information acquired from the frequency spectrum, the frequency spectrum stored in the storage unit, and the acquisition time information acquired. A signal processing unit that executes processing and extracts a portion corresponding to fixed sentence data in a frequency spectrum, wherein the processing unit is configured to specify a signal intensity at a specific frequency and a specific acquisition time, and a specific A magnitude comparison step for comparing the magnitude of the signal strength at each frequency other than the frequency and / or the signal strength at each acquisition time other than the specific acquisition time; A size comparison pattern acquisition step for acquiring a frequency pattern size comparison pattern by changing the number and frequency of the specific acquisition time and / or the acquisition time to a different frequency and / or acquisition time and repeating the size comparison step, and a size comparison pattern And a predetermined condition pattern, and a fixed sentence data extracting step of extracting a part satisfying the predetermined condition pattern as a part corresponding to the fixed sentence data.

  Since the arithmetic processing unit executes the above-described size comparison process, the size comparison pattern acquisition process, and the fixed sentence data extraction process, the data component and the noise component can be discriminated with high accuracy. As a result, the S / N ratio of the signal receiver can be improved.

  Instead of simply distinguishing the data component from the noise component in the comparison with the threshold value of the signal amplitude, the signal intensity at the specific frequency and specific acquisition time is compared with the signal intensity at other frequencies / acquisition times, etc. The size comparison pattern is acquired by repeating the above. A portion (fixed sentence data candidate) corresponding to the fixed sentence data is specified and extracted using a pattern recognition method for determining whether the size comparison pattern matches a predetermined condition pattern set in advance.

  Therefore, even when the amplitude of the data component is small or the amplitude of the noise component is large, it is possible to realize extraction of fixed sentence data with high accuracy. The fixed sentence data is a part of the data component and is used for clock synchronization information, data frame synchronization information, frame start information, and the like. This fixed sentence data includes, for example, what is called a preamble (PR) or a unique word (UW).

  The signal transmission / reception modulation method in the present invention may be FSK (frequency modulation method), ASK (amplitude modulation method), or PSK (phase modulation method). Therefore, a signal receiver receives a signal including a data component including fixed sentence data and a noise component, performs frequency decomposition, acquires a frequency spectrum, and stores the fixed sentence data in advance and the frequency. A storage unit that accumulates the spectrum and the acquisition time information acquired from the spectrum, and a calculation process based on the frequency spectrum stored in the storage unit and the acquisition time information acquired from the storage unit, and the fixed spectrum in the frequency spectrum An arithmetic processing unit that extracts a portion corresponding to sentence data, wherein the arithmetic processing unit includes a signal intensity at a specific frequency, a specific phase, and a specific acquisition time, and each frequency other than the specific frequency. Signal strength and / or signal strength at each phase other than the specific phase and / or signal strength at each acquisition time other than the specific acquisition time And a magnitude comparison step for performing magnitude comparison between the specific frequency, the specific phase and the frequency and / or phase and / or acquisition time of the specific acquisition time, and changing the size to a different frequency and / or phase and / or acquisition time. A size comparison pattern acquisition step for acquiring a magnitude comparison pattern of the frequency spectrum by repeating a comparison step, a comparison between the size comparison pattern and a predetermined condition pattern, and a portion satisfying the predetermined condition pattern as the fixed sentence A fixed sentence data extraction step of extracting as a portion corresponding to the data may be executed.

  The arithmetic processing unit is specified when the signal strength at the specific frequency and the specific acquisition time is greater than or equal to the signal intensity at each frequency other than the specific frequency and / or the signal strength at each acquisition time other than the specific acquisition time in the magnitude comparison process. The score value corresponding to the frequency and the specific acquisition time is added and aggregated, and the specific frequency and the specific acquisition time frequency and / or the acquisition time are changed to different frequencies and / or acquisition times in the magnitude comparison pattern acquisition step. A score value pattern for each frequency and each acquisition time is acquired by repeating the addition and aggregation of values, and in the fixed sentence data extraction step, the portion of the score value pattern where the score value is equal to or greater than the predetermined score threshold is the predetermined frequency In this case, the part may be extracted as a part corresponding to the fixed sentence data when it continues for a predetermined time or more.

  In the magnitude comparison step, the score values corresponding to the specific frequency and the specific acquisition time are totaled, and in the size comparison pattern acquisition step, the score pattern is acquired by changing the specific frequency and the specific acquisition time. Then, the score value pattern is compared with the score threshold value, and a portion where the portion that is equal to or greater than the score threshold value continues for a predetermined time or more is extracted as a portion corresponding to the fixed sentence data.

  This is a brief explanation of the concept. That is, the acquired frequency spectrum is divided into cells for each frequency and each acquisition time, and amplitude comparison is performed for each cell. The magnitude of the amplitude of the specific cell and the amplitude of the adjacent cell (of frequency or acquisition time) is determined, and if the amplitude of the specific cell is large, the score value corresponding to the specific cell is added. The size determination is performed between the specific cell and another cell other than the specific cell. The other cells may be a part or all of the cells in the frequency spectrum stored in the storage unit.

  Such size determination is performed with respect to other cells by sequentially changing specific cells, and a score value pattern for each cell is obtained. For example, when it is determined that the amplitude of the first specific cell is larger than that of the other 300 cells in the size comparison with the other cells, the score value of the first specific cell is 300. Further, when it is determined that another second specific cell has a larger amplitude than the other three cells in the size comparison with the other cells (that is, in this case, it is determined that the amplitude is smaller than most of the cells). The score value of the second specific cell is 3.

  When the score values for each cell are mapped in a matrix, a comparison with the score threshold is performed. For example, when the score threshold is 250, the first specific cell is equal to or higher than the score threshold (in this case, “◯” state), and the second specific cell is less than the score threshold (in this case, “×” state). ). Then, when the “◯” state continues for a predetermined time at a predetermined frequency, that is, when a predetermined number of “○” state cells continue in the time axis direction at a predetermined frequency, the portion is fixed. It is determined that the portion corresponds to the sentence data.

  If a portion corresponding to fixed sentence data is extracted by this determination procedure, whether or not the cell is in the “○” state based on a great deal of information such as the size determination of a specific cell and many other cells. It is possible to determine whether it is in a state. Since the portion corresponding to the fixed sentence data can be identified based on the highly accurate “O” and “X” judgment based on the large amount of information, the extraction of the portion corresponding to the fixed sentence data can be performed with a high S / The N ratio can be performed with high reliability.

  The signal has code data for error detection in the data component, and the storage unit stores in advance the entire structure of the data component including the fixed sentence data, and is extracted by the fixed sentence data extraction step. When it is determined that the part corresponding to the fixed sentence data is an error based on the code data and the entire structure of the data component, the part corresponding to the fixed sentence data may be discarded.

  By using the code data, it is possible to further ensure whether the judgment that the extracted part (candidate) is a part corresponding to the fixed sentence data is correct or incorrect. Therefore, it is possible to execute more accurate extraction of fixed sentence data. As a result, the score threshold can be lowered, and the leakage of data components relating to weak signals can be further reduced. As a result, the S / N ratio in discrimination between the data component and the noise component can be improved.

  In addition, in the magnitude comparison process, when the signal processing intensity at the specific frequency and the specific acquisition time is equal to or higher than the signal intensity at each frequency other than the specific frequency and / or the signal intensity at each acquisition time other than the specific acquisition time in the magnitude comparison process The score value corresponding to the specific frequency and the specific acquisition time is added and aggregated, and the frequency and / or acquisition time of the specific frequency and the specific acquisition time is changed to a different frequency and / or acquisition time in the magnitude comparison pattern acquisition step. The score value pattern for each frequency and each acquisition time is acquired by repeating the addition and counting of the score values, and in the fixed sentence data extraction step, the portion of the score value pattern where the score value is equal to or greater than a predetermined score threshold If the total number is greater than or equal to the predetermined reference number within the predetermined time interval, that portion is determined as the portion corresponding to the fixed sentence data It may put.

  According to the above-described configuration of “extracting the relevant part as the part corresponding to the fixed sentence data when it continues for a predetermined time or longer”, the part where the score value is equal to or higher than the predetermined scoring threshold is intermittent in time. In the case of a large number, extraction as a portion corresponding to fixed sentence data is not performed. In other words, if a portion that is partly below the scoring threshold due to noise or the like is included in the duration even though it is a part that originally corresponds to the fixed sentence data, the part corresponding to the fixed sentence data Cannot be extracted as a candidate.

  However, as in this configuration, a predetermined time interval is set, and it is determined whether the total number of portions (“◯” state) that are equal to or higher than the score threshold within the predetermined time interval is greater than or less than a predetermined reference number Even if a portion that is partially less than the score threshold is included due to noise, if the total number of portions that exceed the score threshold as a whole is greater than or equal to the predetermined reference number, that portion is fixed. It can be extracted as a part corresponding to the data.

  This predetermined time interval is determined by the baud rate of data to be transmitted and received and the frequency sampling rate in the signal receiver. For example, when the frequency sampling rate is 50 times the baud rate (speed), sampling is performed 50 times for one piece of data (“0” or “1”). Therefore, there should be 50 consecutive portions (“◯” state) that are equal to or higher than the score threshold.

  However, for example, as described above, when the sampling rate is somewhat higher than the baud rate, 40 times (predetermined reference number) or more out of 50 samplings is the score threshold value ("○" state) If so, it may be determined that the data. In such a case, even if it does not necessarily exceed the score threshold value 50 times continuously, if 40 times or more out of the 50 samplings are the score threshold value (“◯” state), that portion is data. You may judge that there is. In this case, if the total number of samplings not less than the score threshold within a predetermined time interval is less than 40 (predetermined reference number), it is discarded as noise. Therefore, even if the “◯” state occurs 5 or 6 times due to noise within a predetermined time interval, erroneous recognition that it is data is prevented. That is, it is desirable that the sampling rate be higher than the baud rate so as not to be affected by noise.

  Note that how many times the sampling rate is set to be higher than the baud rate can be set as appropriate according to the processing load, noise resistance, and the like. Depending on the situation of the signal transmission / reception system, for example, it may be set to about 5 to 100 times. When the influence of noise is small, it may be about 5 to 10 times for reducing the processing load, and about 30 to 100 times for the purpose of improving the S / N ratio.

  The present invention can also be configured as follows. For example, a condition range that can be taken as data (fixed sentence data or text data) is stored in the storage unit in advance, and is extracted as a candidate for fixed sentence data based on the condition range and the above configuration (the fixed sentence data itself) Or body data corresponding to the fixed sentence data). If the extracted fixed sentence data or the corresponding data body is out of the condition range stored in the storage unit, the extracted fixed sentence data candidates are discarded as the extraction judgment is incorrect. May be.

  Here, as a condition range that can be taken as fixed sentence data, for example, a time length range to be continued as fixed sentence data (for example, a “1” duration length range or a “0” duration length range) The range of duration of the combination of “0” and “1” as a unique word, and the upper and lower limit values of the score value of the cell can be considered.

  The text data is the data body itself that is desired to be received by signal transmission / reception, for example, measured value data when the transmitter is a sensor terminal. As the body data, for example, body temperature data, temperature data, acceleration data, humidity data, and the like can be considered. For example, as body temperature data, a measured value of less than 0 ° C. or 50 ° C. or more is usually not possible. Moreover, as humidity data, measured values of less than 0% or 100% or more are usually not possible.

  Therefore, when the body data is body temperature data, for example, 0 ° C. or more and less than 50 ° C. can be set as the “condition range that can be taken”. When the text data is humidity data, 0% or more and less than 100% can be set as the “acceptable condition range”. When a candidate for fixed sentence data is extracted and the corresponding body data deviates from the “acceptable condition range”, the candidate is determined based on the determination that the extraction of the fixed sentence data is incorrect. May be discarded.

  Further, according to the present invention, it is possible to receive data without any problem even when the communication baud rate is unknown. In other words, if the communication baud rate and the number of samplings in the frequency spectrum decomposition of the signal are not an integer multiple of each other, the difference between the baud rate and the number of samplings gradually accumulates as the data frame of the fixed sentence data advances, A data error occurs in a specific data frame (originally “0” or “1” but becomes “1” or “0”).

  For example, in this configuration, fixed sentence data is stored in advance in the storage unit, and it is known in which data frame of fixed sentence data a data error occurs corresponding to each of a plurality of different baud rates. Then, a fixed sentence data candidate is extracted from the received signal based on the above method, and the data error is detected in what data frame by comparing the fixed data candidate with the fixed sentence data stored in the storage unit. Can be determined based on the data frame number in which the data error has occurred, to determine what the baud rate of the received signal is.

  According to this configuration, multiple-access data communication using different baud rates is performed between one signal transmitter and a plurality of signal receivers, or between a plurality of signal transmitters and one signal receiver. Can be realized. If the communication timing is not simultaneous, there is no problem even if data communication of multiple access is performed at the same carrier frequency.

  Further objects and other features of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  According to the present invention, it is possible to improve reception sensitivity and shorten data length without using wave height discrimination. As a result, it is possible to improve the communication efficiency and the S / N ratio, thereby realizing downsizing and power saving of the transmitter.

It is a figure for demonstrating the outline | summary of the sensor network system which concerns on Embodiment 1 of this invention. 2 shows a transmission data format often used in wireless communication. 2 illustrates an example of a frame configuration of a signal transmitted from a wireless sensor terminal to a receiving device. It is a block diagram which shows the outline of an internal structure of a receiver. It is a graph which shows the example of the frequency spectrum acquired by the FFT circuit. FIG. 5 is an explanatory diagram schematically showing the graph shown in FIG. 4 divided into a plurality of cells C; It is the figure which showed the example which made the explanatory drawing of FIG. 5A the score value pattern. It is the figure which showed the example of the winning / losing pattern which shows the result of having performed the magnitude comparison of the score value of each cell, and a score threshold value. It is the figure which showed the winning / losing pattern which concerns on Embodiment 2 of this invention. It is the figure which showed the winning / losing pattern which concerns on Embodiment 3 of this invention.

[Embodiment 1]
Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining an outline of a sensor network system 100 described in detail below. The sensor network system 100 includes a plurality of wireless sensor terminals 102 as transmitters and at least one receiving device (signal receiver) 104. Various sensors are incorporated in the wireless sensor terminal 102 and configured to transmit measured data to the receiving device 104 using the wireless medium 106.

  Such a sensor network system is widely used for remote monitoring of various facilities, but can also be used for remote monitoring of organisms. An example of an animal health management system using a sensor network system is described in Japanese Patent Application Laid-Open No. 2007-306804. As will be described below, the sensor network system 100 introduced herein is also particularly suitably designed for monitoring livestock and the like. Of course, the field of application of the sensor network system 100 is not limited to animal monitoring. The gist of the present invention is not limited to wireless communication, and can of course be applied to wired communication.

  The wireless sensor terminal 102 is preferably configured to be small and light so that a human or animal can be worn for a long time without any discomfort. More preferably, it is preferable to reduce the size and weight so that it can be attached to a small bird such as a chicken. In addition, when there are a large number of individuals to which the wireless sensor terminals 102 are attached, the less the frequency of battery replacement, the more convenient it is for the administrator to reduce the amount of work, so it is desirable that the power consumption be as low as possible. As described below, the wireless sensor terminal 102 is devised in various ways to reduce power consumption as much as possible. The wireless sensor terminal 102 includes, for example, a sensor element such as a vibration sensor or a temperature sensor, a transmission circuit that converts sensor data into a transmission signal, an antenna that radiates a transmission signal, a driving source that drives various elements and circuits, and the like. However, detailed description thereof will be omitted.

  FIG. 2A illustrates a transmission data format often used in wireless communication. One frame 800 of transmission data is roughly divided into five parts: a preamble 802 for clock synchronization, a unique word 804 for frame synchronization, an individual identification information 806, a data portion 808, and an error detection / correction information portion 810. Consists of Of these, for example, a total of 40 bits of 16 bits, 16 bits, and 8 bits are often used for the preamble 802, the unique word 804, and the individual identification information 806, respectively. However, in the sensor network system 100 according to the present invention, it is unnecessary to include clock synchronization information and frame synchronization information, and it is also possible to eliminate the need to include individual identification information. Since the receiving device 104 only needs to be able to determine the start of a frame, the 40 bits of the portions 802 to 806 can be replaced with, for example, only 2 bits of frame start information. Needless to say, the sensor network system 100 may include individual identification information. Of course, the frame synchronization information may be used as the frame start information.

  The power required for transmission is approximately proportional to the number of bits. Therefore, the fact that 40 bits can be shortened to 2 bits means that the transmission power has been successfully reduced to about 1/20. Of course, the transmission signal includes information to be transmitted (for example, temperature) and error detection information in addition to the frame start information, etc., so the number of bits of the entire frame is reduced to 1/20. I can't do that. However, regarding the header part transmitted prior to the data part, the number of bits can be reduced to 1/20, and the transmission power can be reduced to approximately 1/20 for that part.

  FIG. 2B illustrates an example of a frame configuration of a signal transmitted from the wireless sensor terminal 102 to the receiving device 104. In this example, one frame 820 includes a 2-bit unique word (frame start information, fixed sentence data) 822 for teaching the start of the frame, an 8-bit data portion 824, and a 1-bit parity for error detection. Bits (code data for error detection) 826. In order to reduce the number of bits as much as possible, parity information, which requires only one bit, is used for error detection information. As a result, even if 8 bits are used for the data portion, the number of bits per frame can be suppressed to 11 bits. In the example of FIG. 2A, since the number of bits per frame is 60 bits, it is possible to reduce the number of bits by approximately 82% and save transmission power corresponding to the number of bits. It goes without saying that this frame configuration is merely an example.

  At least one receiving device 104 is provided in the sensor network system 100 and receives data from a plurality of wireless sensor terminals 102. The receiving device 104 can be a computer device that can analyze received data alone, and depending on the embodiment, the analysis result can be displayed on a built-in or external display, printed on a printer, It can be configured to output to a removable medium such as a CD-R or to transmit to an external computer through various interfaces. In another embodiment, the receiving device 104 may be a device that transmits the received data to another computer without analyzing the data (or performing some analysis). Therefore, the receiving device 104 may be connected to the computer network system by wire or wireless.

  FIG. 3 is a block diagram showing an outline of the internal configuration of the receiving apparatus 104. The receiving device 104 has a receiving antenna 2, a receiving circuit 4, an A / D conversion circuit 6, an FFT circuit 8, a memory (storage unit) 10, and an arithmetic processing unit 12.

  The receiving antenna 2 has a function of receiving a radio wave transmitted from the wireless sensor terminal 102 and sending it to the receiving circuit 4 as a signal. As shown in FIG. 3, the reception circuit 4 typically includes an LPF (low-pass filter) and an IF amplifier (intermediate frequency amplifier), and has a reception signal (having the same frequency as the carrier wave and a phase of 90). It has a function of amplifying the signal by cutting off the high frequency of the signal obtained by multiplying the shifted signal.

  The A / D conversion circuit 6 has a function of A / D converting the reception signal from the reception circuit 4 and converting it into digital data. In the first embodiment, for example, as shown in FIG. 3, the A / D conversion circuit 6 A / D converts the received signal into 12-bit digital data.

  The FFT circuit 8 has a function of performing frequency conversion (frequency decomposition) on the received signal after A / D conversion and acquiring a frequency spectrum. In the first embodiment, for example, as shown in FIG. 3, the FFT circuit 8 is configured using an integrated circuit called FPGA (Field-Programmable Gate Array). The signal receiving unit according to the first embodiment includes the receiving circuit 4, the A / D conversion circuit 6, and the FFT circuit 8.

  The memory 10 is a storage unit having a plurality of storage areas therein. For example, in the first storage area 10a in the memory 10, the frequency spectrum acquired by the FFT circuit 8 is stored together with the acquisition time information. FIG. 4 is a graph showing an example of the frequency spectrum acquired by the FFT circuit 8. In this graph, the horizontal axis is frequency, and the vertical axis is amplitude (signal strength). FIG. 4 shows a frequency spectrum acquired at a specific acquisition time. In reality, since the signal is received by the receiving device 104 from moment to moment, a plurality of frequency spectra are sequentially stored in the first storage area 10a at each acquisition time (at each sampling time of the A / D conversion circuit 6 and the FFT circuit 8). Will be. That is, the graph shown in FIG. 4 is an image in which many sheets are stored in the first storage area 10a at each acquisition time. When the storage capacity of the first storage area 10a is full, the frequency spectrum corresponding to the old acquisition time is sequentially discarded, and the frequency spectrum corresponding to the new acquisition time is accumulated.

  In the second storage area 10b of the memory 10, the unique word UW1 is stored. This unique word UW1 is for collation with the unique word 822 in the received data. In the third storage area 10c, information on a score threshold ST described later is stored. The fourth storage area 10d stores duration information TC as a predetermined condition pattern. This duration information TC is determined to be a portion corresponding to fixed sentence data when a portion where a later-described cell score value SC (see FIG. 5B) is greater than or equal to a score threshold ST continues for a duration at a predetermined frequency. It is a criterion for doing this.

  The arithmetic processing unit 12 has a function of executing a calculation process based on the frequency spectrum stored in the memory 10 and the acquisition time information acquired from the frequency spectrum, and extracting a candidate portion corresponding to the unique word 822 in the frequency spectrum. The arithmetic processing unit 12 may be an MCU (Micro Control Unit) as shown in FIG. 2 or a PC connected to the FFT circuit 8.

  The arithmetic processing unit 12 functions as a size comparison unit 12a, a size comparison pattern acquisition unit 12b, and a unique word extraction unit 12c. Each function will be described below.

  The magnitude comparison unit 12a compares the signal amplitude at the specific frequency and the specific acquisition time in the frequency spectrum accumulated in the first storage area 10a with the signal amplitude at the other frequencies and the acquisition time, and performs size comparison. More specifically, when the signal amplitude at the specific frequency and the specific acquisition time is equal to or higher than the signal amplitude at the other frequency and the acquisition time, the score value SC is added corresponding to the specific frequency and the specific acquisition time.

  This concept will be described with reference to FIG. FIG. 5A is an explanatory diagram schematically showing the graph of FIG. 4 divided into a plurality of cells C. FIG. One cell C is a unit area divided for each frequency resolution and for each acquisition time, and the signal amplitude A corresponds to each cell. For example, the frequency resolution of one cell is set to 1 MHz for a frequency spectrum from 305 MHz to 320 MHz. The acquisition time for one cell is 10 μs. That is, one signal amplitude A is stored corresponding to the cell C of 1 MHz and 10 μs. The signal amplitude A is an intensity value having a resolution of 12 bits. Assuming that the frequency spectrum corresponding to the acquisition time for 1 ms is stored in the first storage area 10a, it is divided into 15 × 100 = 1500 cells.

  An arbitrary specific cell CS among the cells C is selected. The specific cell CS is a cell at a specific frequency and a specific acquisition time. In practice, the specific cell CS is generally selected in the order stored in the first storage area 10a. It is assumed that the signal amplitude A of the specific cell CS has a value of “1000”, for example. The signal amplitude A of the specific cell CS is compared with the signal amplitude A of the adjacent cell CR (“50” in FIG. 5). When the signal amplitude A of the specific cell CS is equal to or greater than the signal amplitude A of the adjacent cell CR, the score value = 1 is added to the specific cell CS. When the signal amplitude A of the specific cell CS is less than the signal amplitude A of the adjacent cell CR, the score value SC is not added to the specific cell CS.

  The signal amplitude A of all cells C of the frequency spectrum stored in the first storage area 10a as well as the adjacent cell CR is compared in magnitude with the signal amplitude A of the specific cell CS, and the score value SC of the specific cell CS Is added. When the signal amplitude A of the specific cell CS is greater than or equal to the signal amplitude A of the other 300 cells C, the score value SC of the specific cell CS is 300 (see FIG. 5B).

  The size comparison pattern acquisition unit 12b changes the specific cell CS to a cell C corresponding to a different frequency and acquisition time, and adds and counts the score values SC in the new specific cell CS. By repeatedly changing the cell C, the score values SC of all the cells C are calculated, and the score value pattern P in the entire frequency spectrum data accumulated in the first storage area 10a is obtained. FIG. 5B shows an example of the score value pattern P.

  The unique word extraction unit 12c compares the score value SC of each cell C in the score value pattern P with the score threshold value ST stored in the third storage area 10c, and the score value SC of the cell C is determined as the score threshold value. If it is equal to or greater than ST, a flag “◯” is set for the cell C, and if the score value SC of the cell C is less than the score threshold ST, a flag “x” is set for the cell C. . FIG. 5C is a diagram showing an example of a win / loss pattern P2 showing the result of comparing the score value SC of each cell C with the score threshold ST.

  The winning / losing pattern P2 in FIG. 5C includes a pattern in which the “◯” state continues for a predetermined time at a certain frequency. In the first embodiment, since the modulation method is the FSK modulation method, the channel, “0”, “1”, or guard band is predetermined for each frequency. For example, in FIG. 5C, 310 MHz is a guard band, 311 MHz is “0” of channel 10, 312 MHz is “1” of channel 10, 313 MHz is a guard band, 314 MHz is “0” of channel 11, and 315 MHz is “channel 11”. 1 ", 316 MHz is a guard band. Thus, each channel of the plurality of channels has a frequency corresponding to “0” and “1”, and a guard band is set for each channel.

  A continuous pattern of five “O” states in “0” of channel 10 (that is, a pattern in which the “O” state continues for 50 μs) S0 is included. The unique word extraction unit 12c compares the duration information TC in the fourth storage area 10d with the continuous pattern S0. The continuation time information TC is information of a determination criterion that can be determined as a data component when the “◯” state continues for that time or longer, and is, for example, 50 μs in the first embodiment.

  Since the continuous pattern S0 is equal to or longer than the duration information TC, it can be determined that the continuous pattern S0 is “0” data as a data component. Even if the continuous pattern S0 is a case where six or more “◯” states continue, it can be determined that the data is “0” data. On the other hand, if the continuous pattern S0 has only four continuous “o” states, it is determined that it is not a data component.

  A continuous pattern S1 in which six “O” states are consecutive in “1” of the channel 10 is included. The unique word extraction unit 12c compares the continuous pattern S1 with the duration information TC and determines that the continuous pattern S1 is “1” data. Thus, in channel 10, it is determined that the portions of the continuous patterns S0 and S1 are “01” data.

  The unique word extraction unit 12c compares the unique word UW1 in the second storage area 10b with the portions of the continuous patterns S0 and S1. Information on the unique word UW1 is stored in the second storage area 10b. In the first embodiment, the unique word UW1 is “01”. Therefore, since the unique word “UW1” “01” matches the “01” corresponding to the portions of the continuous patterns S0 and S1, the unique word extraction unit 12c is a candidate for the unique word 822 where the portions of the continuous patterns S0 and S1 are the same. Extract as part.

  In the first embodiment, the communication baud rate can be estimated according to the number of cells (ie, time) in which the “◯” state continues. That is, in the above description, the number of continuous cells in which one data is in the “◯” state is five (50 μs). Therefore, the baud rate of the wireless sensor terminal 102 in this communication is 20 kbps. On the other hand, if the number of consecutive “◯” states of the received data is four, it can be determined that the baud rate of the wireless sensor terminal 102 is 25 kbps, which is 1.25 times the original baud rate. If the number of consecutive “◯” states of the received data is 3, it can be determined that the baud rate of the wireless sensor terminal 102 is 33 kbps, which is 5/3 times the original baud rate.

  In this way, the baud rate of the wireless sensor terminal 102 can be estimated according to the number of continuous cells that are in the “◯” state. Therefore, the signal receiver 104 can perform signal transmission / reception with a plurality of wireless sensor terminals 102 having different baud rates at the same time. Since each wireless sensor terminal 102 can be discriminated based on the estimated baud rate, each wireless sensor terminal 102 can identify each wireless data based on the estimated baud rate value without adding ID information as identification information to the transmission data from each wireless sensor terminal 102. The sensor terminal 102 can be identified. That is, a different baud rate value for each wireless sensor terminal 102 can be used instead of ID information, and the amount of communication data can be reduced by deleting the ID information from the communication data. As a result, it contributes to power saving and miniaturization of the wireless sensor terminal 102.

[Embodiment 2]
FIG. 6 shows a win / loss pattern P22 according to Embodiment 2 of the present invention. In the first embodiment, the example using the FSK modulation method as the modulation method has been described. In the second embodiment, an example using the ASK modulation method as the modulation method will be described. The apparatus configuration other than the modulation scheme is the same as that of the first embodiment, and thus the description thereof is omitted.

  Also in the second embodiment, the receiving apparatus 104 performs frequency decomposition on the received signal and accumulates it in the first storage area 10a. Then, the specific cell CS and another cell C are compared in size, the score value SC is added and tabulated, and the size comparison with the score threshold ST is performed. Here, in the second embodiment, since the ASK modulation method is adopted, for example, 310 MHz is a guard band, 311 MHz is a channel 10, 312 MHz is a guard band, and 313 MHz is a channel 11. A portion where five or more “O” states continue in the channel 10 is a data component of “1” data, and a portion where five or more “×” states continue is a data component of “0” data.

  In the ASK modulation method, the modulation is performed using the signal amplitude, so that it is not possible to distinguish the silent portion from the “0” data portion. Therefore, the unique word UW1 needs to be information starting from “1” data corresponding to the “◯” state. For example, in the second embodiment, the unique word UW1 is “10”. If there is a portion in which five or more “O” states continue in the channel 10 following a portion in which five or more “O” states continue, the portion is extracted as a candidate portion of the unique word 822.

[Embodiment 3]
FIG. 7 is a diagram showing a win / loss pattern P23 according to Embodiment 3 of the present invention. In the first embodiment, the example in which the FSK modulation scheme is used as the modulation scheme has been described. In the third embodiment, an example in which the PSK modulation scheme is used as the modulation scheme will be described. The apparatus configuration other than the modulation scheme is the same as that of the first embodiment, and thus the description thereof is omitted.

Also in the third embodiment, the receiving device 104 performs frequency decomposition on the received signal to obtain the first
Accumulate in the storage area 10a. Then, the specific cell CS and another cell C are compared in size, the score value SC is added and tabulated, and the size comparison with the score threshold ST is performed. Here, in the third embodiment, since the PSK modulation method is adopted, it is necessary to accumulate the signal amplitude for each frequency, phase, and acquisition time of the received signal when accumulating in the first storage area 10a. is there. And it is necessary to divide a cell for every frequency, phase, and acquisition time.

  In the second embodiment, for example, 310 MHz is a guard band, 311 MHz is a channel 10, 312 MHz is a guard band, and 313 MHz is a channel 11. Then, the 0 ° phase signal in the channel 10 is “0”, and the 90 ° phase signal obtained by shifting the phase by 90 ° with respect to the 0 ° phase signal is “1”. In channel 10, a portion where 5 or more “O” states continue in a cell with a phase of 0 ° becomes a data component of “0” data, and a portion where 5 or more “O” states continue in a cell with a phase of 90 ° is “ It becomes the data component of 1 "data.

  In the PSK modulation method, modulation is performed using the phase of a signal, and therefore it is necessary to maintain a reference phase on the receiving device 104 side. Then, for example, “0” is a signal having the same phase as the reference phase, “1” is a signal having a phase shifted by 90 ° from the reference phase, and “0” or “1” is determined based on the relative phase shift. Identify.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these, A various deformation | transformation and change are possible within the range of the summary.

  For example, in the first embodiment, the unique word is “01” data, but “10” data may of course be used. By using a different unique word for each wireless sensor terminal 102, the unique word can be used as substitute information for ID information. By using the wireless sensor terminal 102 with the unique word “01” and the wireless sensor terminal 102 with the unique word “10” in the sensor network system 100, it is possible to identify twice as many wireless sensor terminals 102. .

  For example, the sensor network system 100 can have two wireless sensor terminals 102 having the same carrier frequency and the same baud rate, those having the unique word “01” and those having the unique word “10”. Therefore, when the sensor network system 100 has 100 wireless sensor terminals 102 that can be distinguished from each other based on the difference in carrier frequency and / or baud rate using the same unique word “01”, the unique word “10” is set. It is possible to add 100 wireless sensor terminals 102 to be used.

  The wireless sensor terminal 102 can be easily added without increasing the number of data. Of course, if the increase in the number of bits can be allowed, information of “0101” or “1010” can be applied as a unique word.

  Further, in the first embodiment, the duration information TC is stored in the fourth storage area 10d, and the data based on whether the portion where the score value of the cell C is equal to or greater than the score threshold has continued for the duration TC or more. Judging.

  However, the predetermined time interval information and the predetermined reference number information are stored in the fourth storage area 10d, and at a specific frequency (for example, 311 MHz in FIG. 5C, that is, “0” of the channel 10), the score threshold value or more (“◯”). It may be determined whether or not the portion is “0” data based on whether or not the portion in the state is equal to or greater than a predetermined reference number within a predetermined time interval. For example, when the predetermined time interval information is 50 μs (for five cells on the vertical axis in FIG. 5C) and the predetermined reference number information is 4, even if the “◯” state does not become five consecutive, If four cells among the consecutive five cells are intermittent even if they are intermittent, it is determined that the portion is data.

  The predetermined time interval information in this case is determined by the communication baud rate, the frequency sampling rate of the signal receiver, and the like. When the start cell of the predetermined time interval is determined, the time corresponding to the predetermined time interval sequentially from the start cell. The windows are set continuously without overlap or separation.

Signal amplitude: A
Cell: C
Specific cell: CS
Adjacent cell: CR
Score value pattern: P
Win / Lose Pattern: P2, P22, P23
Continuous pattern: S0, S1
Score value: SC
Score threshold: ST
Duration information: TC
Receiving antenna: 2
Receiver circuit (part of signal receiver): 4
A / D conversion circuit (part of signal receiver): 6
FFT circuit (part of signal receiver): 8
Memory (storage unit): 10
First storage area: 10a
Second storage area: 10b
Third storage area: 10c
Fourth storage area: 10d
Arithmetic processing part: 12
Large / small comparison part: 12a
Large / small comparison pattern acquisition unit: 12b
Unique word extraction unit: 12c
Sensor network system: 100
Wireless sensor terminal (transmitter): 102
Receiver (signal receiver): 104
Wireless medium: 106
Frame: 800,820
Preamble: 802
Unique word (fixed sentence data): 804, 822, UW1
Individual identification information: 806
Data part: 808, 824
Error detection / correction information section: 810
Parity bit (code data for error detection): 826

Claims (3)

A signal receiving unit that receives a signal including a data component including fixed sentence data and a noise component, performs frequency decomposition, and obtains a frequency spectrum;
A storage unit that stores the fixed sentence data in advance and accumulates the frequency spectrum and the acquisition time information obtained from the frequency spectrum;
An arithmetic processing unit that performs arithmetic processing based on the frequency spectrum stored in the storage unit and the acquisition time information that acquired the frequency spectrum, and extracts a portion corresponding to the fixed sentence data in the frequency spectrum; A receiver,
The arithmetic processing unit includes:
A magnitude comparison step for comparing the magnitude of the signal intensity at the specific frequency and the specific acquisition time with the signal intensity at each frequency other than the specific frequency and / or the signal intensity at each acquisition time other than the specific acquisition time;
A magnitude comparison pattern acquisition step of acquiring a magnitude comparison pattern of the frequency spectrum by changing the frequency and / or acquisition time of the specific frequency and the specific acquisition time to a different frequency and / or acquisition time and repeating the magnitude comparison step; ,
A signal receiver that performs a fixed sentence data extraction step of collating the size comparison pattern with a predetermined condition pattern and extracting a portion satisfying the predetermined condition pattern as a portion corresponding to the fixed sentence data. The arithmetic processing unit is
In the size comparison step, when the signal strength at the specific frequency and the specific acquisition time is equal to or higher than the signal strength at each frequency other than the specific frequency and / or the signal strength at each acquisition time other than the specific acquisition time, the specific Add the score values corresponding to the frequency and the specific acquisition time,
In the size comparison pattern acquisition step, the frequency and / or acquisition time of the specific frequency and / or specific acquisition time is changed to a different frequency and / or acquisition time, and the addition and counting of the score values are repeated for each frequency and acquisition time Get the score pattern for each
In the fixed sentence data extraction step, when a part of the score value pattern where the score value is equal to or higher than a predetermined score threshold continues for a predetermined time at a predetermined frequency, the corresponding part corresponds to the fixed sentence data The signal receiver according to claim 1, wherein the signal receiver is extracted as a portion to be processed. The signal has code data for error detection in the data component;
The storage unit stores in advance the entire structure of the data component including the fixed sentence data,
The part corresponding to the fixed sentence data when it is determined that the part corresponding to the fixed sentence data extracted by the fixed sentence data extraction step is an error based on the code data and the entire structure of the data component The signal receiver according to claim 1, wherein the signal receiver is discarded.

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