JP2009217494A - Signal line generation circuit, signal line generation method, signal line generation program and communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate a signal line which can be loaded with large quantity of information, excellent in noise resistance, and discriminable even if superimposed, without complicating system configuration. <P>SOLUTION: The signal line generation circuit includes: a multiple M-line generation means 3 which generates a plurality of M lines which form a preferred pair when taken out by twos; a variable delay assignment means which assigns a delay to each of the plurality of generated M lines; an addition means which performs exclusive OR operation to the plurality of M lines with the delay assigned thereto, and outputs the resulting signal line; and a bit width extension means 4 which performs, for every P bits of the signal line output from the addition means, conversion to Q (Q>P) so that the ratios of "1" and "0" are biased after the conversion. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a signal sequence generation circuit, a signal sequence generation method, a signal sequence generation program, and a communication system, and can be applied to, for example, generation of unique individual data (ID) for identification or authentication of an article or an individual. It is.

  In recent years, there has been a need for efficient manufacturing process automation systems and physical distribution systems, and an efficient identification system for articles is required. An efficient identification system is (1) the identification medium added to the article is inexpensive, (2) less susceptible to the surrounding environment (noise, dirt, etc.), and (3) the system for identifying individual data is simple. It can be realized by having features such as low operating costs.

  The M-sequence is one of pseudo-random sequences and is used for spreading code communication and the like, and is a deterministic signal generated by a shift register, but its statistical property is similar to a true irregular signal. Such M series has already been used as individual data for identification and authentication of articles and individuals (see, for example, Patent Document 1).

There are systems using a bar code system or a wireless tag (RFID) as an identification system for articles and individuals used in inventory management and entrance / exit management. For example, when an M-sequence is applied to a system using a wireless tag, there are advantages such as less interference with other wireless tags and access to a plurality of wireless tags at a time.
JP 2004-143806 A

  As a signal used for generating individual data for identification or authentication of an individual, a signal capable of carrying a large amount of information and having high noise resistance is required.

  For example, in the case of a bar code system, if the surface on which the bar code is printed becomes dirty and noise is mixed in the signal read from the bar code, it may become impossible to recognize articles or individual items. Even in an RFID system, not only when there is a lot of electromagnetic noise, it is often possible that the radio wave signal is disturbed due to reflection or absorption by the surrounding environment and becomes indistinguishable.

  The M-sequence has higher noise resistance than other signal sequences, but even if the M-sequence is applied, noise may be a problem, and the amount of information that can be put on the M-sequence alone is not sufficient. There is also.

  Furthermore, in the case of a system that performs simultaneous reading of a plurality of RFID tags, such as an RFID system, even if each identification signal is unique, if many identification signals overlap due to simultaneous reading, There is a possibility that each identification signal cannot be discriminated.

  Incidentally, in a large-scale communication system represented by a mobile phone, it is possible to construct a system that is relatively resistant to noise, such as increasing the code length, but the system is complicated and requires a great deal of cost for operation.

  Therefore, a signal sequence generation circuit and a signal sequence that can generate a large amount of information without complicating the system configuration, have excellent noise resistance, and can generate a signal sequence that can be discriminated by superposition A generation method and a signal sequence generation program are desired, and a communication system to which such a signal sequence generation method is applied is desired.

  The signal sequence generation circuit according to the first aspect of the present invention includes: (1) a plurality of M sequence generation means for generating a plurality of M sequences that are preferred pairs when viewed two by two; and (2) generated Variable delay adding means for adding a delay to each of a plurality of M sequences; and (3) an adding means for performing an exclusive OR operation on the plurality of M sequences to which a delay has been added, and outputting a signal sequence after the calculation. (4) Bit width extending means for converting to Q (Q> P) bits so that the ratio of “1” and “0” is biased after conversion for each P bit of the signal sequence output from the adding means. It is characterized by comprising.

  The signal sequence generation method of the second aspect of the present invention includes a plurality of M sequence generation means, a variable delay addition means, an addition means, and a bit width expansion means. (1) The plurality of M sequence generation means takes out two by two. (2) the variable delay adding means adds a delay to each of the generated M series, and (3) the adding means , Performing an exclusive OR operation on a plurality of M sequences to which a delay has been applied, and outputting a signal sequence after the operation, (4) the bit width extending means outputs P of the signal sequence output from the adding means Each bit is converted into Q (Q> P) bits so that the ratio of “1” and “0” is biased after conversion.

  A signal sequence generation program according to a third aspect of the present invention includes: (1) a plurality of M sequence generation means for generating a plurality of M sequences that are preferred pairs when two computers are taken out and viewed; Variable delay applying means for adding a delay to each of the plurality of generated M sequences, and (3) performing an exclusive OR operation on the plurality of M sequences to which the delay is added, and outputting a signal sequence after the operation (4) a bit to be converted into Q (Q> P) bits so that the ratio of “1” and “0” is biased after conversion for each P bit of the signal sequence output from the adding means. It functions as a width expanding means.

  A communication system according to a fourth aspect of the present invention is characterized in that the individual data generated by the signal sequence generation circuit is used as an ID using the signal sequence generation circuit according to the first aspect of the present invention and communication means.

  According to the present invention, it is possible to put a large amount of information without complicating the system configuration and the like, and it is possible to generate a signal sequence that is excellent in noise resistance and can be discriminated by superposition, Alternatively, such a signal sequence can be used.

(A) Main Embodiments Hereinafter, embodiments of a signal sequence generation circuit, a signal sequence generation method, a signal sequence generation program, and a communication system according to the present invention will be described in detail with reference to the drawings.

(A-1) Configuration of Individual Data Writing Device for Wireless Tag An embodiment of a signal sequence generation circuit, a signal sequence generation method, and a signal sequence generation program is applied to an individual data writing device for a wireless tag.

  FIG. 1 is a block diagram showing a configuration of an individual data writing device for a wireless tag, and FIG. 3 is a block diagram showing a configuration of a signal sequence generation unit of FIG.

  In FIG. 1, an individual data writing device 1 for a wireless tag includes a management number / delay data conversion unit 2, a signal sequence generation unit 3, a bit width expansion unit 4, an individual data writing unit 5, and data correspondence according to the embodiment. A storage unit 6 and a control unit 7; The signal sequence generation unit 3 and the bit width expansion unit 4 correspond to the signal sequence generation circuit of the embodiment.

  The management number / delay data conversion unit 2 sets a management number given from the control unit 7 when a blank wireless tag in which individual data is not stored becomes a new write target. This is converted to R0 to Rr and given to the signal sequence generation unit 3.

  The signal sequence generation unit 3 may be configured as hardware, or may be configured as software in which functions are realized by the CPU executing a signal sequence generation program. 3 is functionally configured as shown in FIG. The detailed configuration will be described later. The signal sequence generation unit 3 generates individual data before extending the bit width, which is determined by a detailed configuration described later and a delay data group given from the management number / delay data conversion unit 2. Here, the individual data output from the signal sequence generation unit 3 has substantially the same frequency of “1” and “0” bits.

  The bit width expansion unit 4 expands the bit width of the individual data output from the signal sequence generation unit 3 and makes the ratio of “1” bits sufficiently smaller than the ratio of “0” bits. . A pulse position modulation (PPM) method can be applied as a bit width extension method by the bit width extension unit 4.

  FIG. 2 is an explanatory diagram of an example (PPM method) of the bit width extension method by the bit width extension unit 4. The example of FIG. 2 shows an example of expanding to a 16-bit width every 4 bits.

  Assume that the individual data output from the signal sequence generation unit 3 is “0000010100...” As shown in FIG. This individual data is divided into 4 bits. That is, it is divided into “0000”, “0101”, “00. Replace each 4 bits with hexadecimal notation 0-9, A (= 10) to F (= 15), and only the bit position represented by the number in hexadecimal notation is “1” in 16 bits, and the other bit positions are All are set to “0”. For example, since the first 4 bits are “0000”, it is “0” in hexadecimal notation. As shown in FIG. 2B, among bits 0 to F, hexadecimal notation “0” is set. It is converted into data in which bit 0 as the bit order takes “1” and other bits 1 to F take “0”. Since the second 4 bits are “0101”, it is “5” in hexadecimal notation. As shown in FIG. 2B, of bits 0 to F, hexadecimal notation “5” is bit. The order bit 5 is “1”, and the other bits 0 to 4 and bits 6 to F are converted to data “0”. That is, if the 4-bit hexadecimal notation is “x”, it is converted into data in which bit x takes “1” and all other bits take “0”. In the example of FIG. 2, the ratio 1/16 of the “1” bit is sufficiently smaller than the ratio 15/16 of the “0” bit.

  The example of FIG. 2 shows an example in which every 4 bits are expanded to a 16-bit width, but it is needless to say that other expansion methods may be applied, such as an expansion to a 32-bit width every 5 bits.

  The individual data writing unit 5 is, for example, a first storage unit that initially stores blank wireless tags for a lot unit or a single wireless tag from the first storage unit and sets it at a writing position. Stores the feeding mechanism unit, the writing execution unit for writing the individual data after the bit width extension output from the bit width extension unit 4 to the blank wireless tag set at the writing position, and the wireless tag with the individual data written therein. A second storage unit, a moving mechanism unit for moving the wireless tag in which individual data is written from the writing position to the second storage unit, and the like are provided, and the individual data is written in the blank wireless tag. Note that at least a write execution unit for writing individual data may be provided.

  The data association storage unit 6 stores the delay data group (or management number) and the individual data after the bit width expansion in association with each other. The individual data after the bit width extension may be stored as it is. However, in this embodiment, each bit of the individual data after the bit width extension is set to the same value of 3 in consideration of the accuracy of the cross-correlation process described later. It is assumed that it is stored in a bit extended. That is, bit “0” of the individual data after the bit width extension is stored as “000”, and bit “1” of the individual data after the bit width extension is stored as “111”.

  The stored association data is used for identification or authentication by a data processing system that processes data from a wireless tag, such as a manufacturing process automation system or a distribution system. Note that a system that uses individual data after bit width expansion as an ID may be used, or a system that uses a delay data group (or management number) as an ID. A communication system and a communication method to be described later assume a system that uses individual data after bit width expansion as an ID.

  The control unit 7 controls the individual data writing device 1 as a whole, and writes the individual data after the bit width extension to the blank wireless tag as described above. Here, it is preferable that the control unit 7 writes a data portion for establishing synchronization such as a flag sequence in addition to the individual data after the bit width expansion to the blank wireless tag.

  As illustrated in FIG. 3, the signal sequence generation unit 3 of the embodiment includes M sequences from r + 1 M sequence generation units 10-0 to 10-r and all M sequence generation units 10-0 to 10-r. And an exclusive OR circuit 11 which is an adding means for taking the exclusive OR.

  Each of the M-sequence generation units 10-0 to 10-r includes an M-sequence generation body 20-0 to 20-r that is a plurality of M-sequence generation units, and variable delay units 21-0 to 21- that are variable delay addition units. r.

The M-sequence generation bodies 20-0 to 20-r generate M-sequences according to characteristic polynomials f ₀ (x) to f _r (x) having different orders n, and n-stage shift registers SR0 to SRr and , Has a well-known configuration of one or a plurality of exclusive OR circuits ExOR01 to ExORr1 that take an exclusive OR of the output of the stage determined by the characteristic polynomial.

  In the case of this embodiment, the r + 1 M sequences generated by the M sequence generation bodies 20-0 to 20-r are all in a preferred pair (preferred pair) relationship. Here, for M sequences, a pair of M sequences in which the maximum value of the cross-correlation function between the M sequences of the same order and the M sequences having different characteristic polynomials is referred to as a preferred pair. The preferred pair is described in, for example, Document A “D.V. Survate and MB Pursley,“ Crosslation Properties of Pseudorandom and Related Sequences ”, PROC. IEEE, Vol. 68, No. 5, pp. 59. 619, 1980. ”.

  Each of the variable delay devices 21-0 to 21-r delays the M sequence generated by the corresponding M sequence generation main body 20-0 to 20-r by the instructed amount and supplies the delayed delay to the exclusive OR circuit 11. It is. The delay amounts in the variable delay devices 21-0 to 21-r are not necessarily the same, and the combination of these delay amounts is one parameter that defines the uniqueness of the individual data generated by the signal sequence generation unit 3. .

In the case of this embodiment, each of the variable delay devices 21-0 to 21-r generates a corresponding M sequence so that an arbitrary delay amount shorter than the M sequence period 2 ⁿ −1 can be provided with a simple configuration. Exclusively the outputs of the multiplier groups D0 to Dr that multiply the values of the respective stages of the shift registers SR0 to SRr in the main bodies 20-0 to 20-r by the set values and the outputs of the corresponding multiplier groups D0 to Dr It consists of exclusive OR circuits ExOR02 to ExORr2 that take a logical sum.

The n pieces of data set in the multiplier groups D0 to Dr are delay data R0 to Rr given from the management number / delay data converter 2. For example, delay data R0 {r _0,0 ,..., R _{0, n−1} } is set in the multiplier group D0.

(A-2) Method for Obtaining Delayed M Sequence Next, the fact that the variable delay devices 21-0 to 21-r can be realized by the arithmetic configuration as shown in FIG. This will be described using a delayer model.

If an M-sequence is given an initial state of the n-stage shift register SR, all subsequent states are determined. Therefore, the M-sequence x ^d delayed by an arbitrary delay amount d is determined at each stage of the shift register SR. It can be seen that the content x ₀ ,..., X _n−1 is given by the linear combination represented by the expression (1).

x ^d = r ₀ x ₀ + r ₁ x ₁ + r ₂ x ₂ +... + r _n−1 x _n−1 (1)
The coefficient r _i (i is 0 to (n−1)) is “0” or “1”. If the coefficient r _i is known, it can be determined which stage of the shift register SR should be added.

The delay amount d can take a value in a range shorter than one cycle 2 ⁿ⁻¹ of the M sequence, and can take a value smaller than the number n of stages of the shift register SR, or can take a number n or more.

When the delay amount d is smaller than the number n of stages of the shift register SR, the delayed M series can be extracted from the stage j corresponding to the delay amount d of the shift register SR. In this case, only the coefficients r _j for content x _j of that stage j is "1", all of the coefficients for the contents of the other stages may be "0".

Consider a case where the delay amount d is greater than or equal to the number n of stages of the shift register SR. When the delayed M sequence ^xd is divided by the characteristic polynomial f (x) related to the M sequence generation body, the following equation (2) is established. In equation (2), Q (x) is a quotient, and R (x) is a remainder polynomial.

x ^d = Q (x) f (x) + R (x) (2)
Pay attention to the right side of equation (2). Here, the degree of the remainder polynomial R (x) is smaller than n, and the degree part entrusted to the remainder polynomial R (x) in Q (x) f (x) is zero. Here, considering the same order as the right side of equation (1), equation (2) can be written as equation (3).

x ^d = R (x) (3)
From the comparison between the equations (1) and (3), the coefficient of the remainder polynomial R (x) becomes r _{0 to} r _n−1 for forming the M sequence x ^d delayed by the delay amount d. Yes. That is, in order to form the M-sequence x ^d which is delayed by the time delay d may be taken out of the coefficients of x ^d a characteristic polynomial f (x) obtained by dividing obtained remainder polynomial R (x).

(A-3) Operation of Individual Data Writing Device for Wireless Tag Next, the operation of the individual data writing device for the wireless tag will be described.

  When a new blank wireless tag is to be written, the control unit 7 sets initial values in all the shift registers SR0 to SRr of the signal sequence generation unit 3 and manages the management number related to the wireless tag to be written. This is given to the number / delay data converter 2. The management number / delay data conversion unit 2 converts the management number into the delay data groups R0 to Rr and sets them in the multiplier groups D0 to Dr of the signal sequence generation unit 3.

  When such initialization processing ends, the control unit 7 causes the signal sequence generation unit 3 to start an operation based on the clock.

The M sequence generation body 20-0 of the M sequence generation unit 10-0 rewrites the contents of the stage of the shift register SR0 for each clock. The multiplier group D0 of the variable delay device 21-0 multiplies the contents of the stage of the shift register SR0 by the set value of the delay data group R0, and the multiplication result is added by the exclusive OR circuit ExOR02 ( And is output as an M series a ₀ (j + d ₀ ) delayed by a delay amount corresponding to the value of the delay data group R0.

The other M sequence generation units 10-1 to 10-r operate in the same manner, and output delayed M sequences a ₁ (j + d ₁ ) to a _r (j + d _r ).

The exclusive OR circuit 11 adds (exclusive OR) the delayed M sequences a ₀ (j + d ₀ ) to a _r (j + d _r ) from all the M sequence generators 10-0 to 10 -r. Output as individual data.

  In the output individual data, the bit width is expanded by the bit width expansion unit 4 and the ratio of “1” bits is made sufficiently smaller than the ratio of “0” bits.

  The individual data after the bit width extension is written into the wireless tag to be written by the individual data writing unit 5. Further, the data association storage unit 6 stores the delay data group (or management number) and the individual data after the bit width expansion in association with each other.

(A-4) Concept of signal generation As for the M sequence, the M sequence pair having the same order and the minimum value of the cross-correlation function with the M sequence having different characteristic polynomials is as described above. , Called the Preferred Pair. It has been found that the maximum value H of the number of M sequences that are mutually preferred pairs is as shown in FIG. 5 (see Document A above). However, it is not shown which pair is specifically a preferred pair.

  In this embodiment, attention is paid to the fact that sequences generated by combining M sequences that are preferred pairs with each other are sequences having a small correlation with each other.

In FIG. 5, suppose that the largest set (the number of elements is H) of a pair that is a preferred pair with each other is used for signal generation, more information can be sent as n × H is larger. Assuming that there are r combinations whose maximum value of aggregate elements that are mutually preferred pairs is H, the total amount of information that can be sent is r × 2 ^{n × H.}

  In this embodiment, unlike the Gold sequence using two M sequences and the Kasami sequence using three M sequences, all or most of the H M sequences that are preferred pairs with each other are used. This is a method for generating a signal sequence with less interference, in which the type of information to be inserted is increased by adding after delaying.

  According to FIG. 5, as the product of the order n of the M sequence and the maximum value H of the number of preferred pairs increases, the information to be loaded becomes larger. explain.

  As for the degree 7, since it is known that the total number of characteristic polynomials is 18, as a result of selecting 6 (maximum value H) from these and searching for a combination in which any pair of them is a preferred pair, The 18 M series shown in FIG. 6 were found.

In addition, the value which prescribes | regulates the characteristic polynomial in FIG. 6 is octal display, and represents the following. The order is not 7, but the case of characteristic polynomial f (x) = 1 + x ⁴ + x ⁵ + x ⁶ + x ⁸ is taken as an example. In this case, when each power coefficient is represented by 0 and 1, and only the coefficient is extracted and represented, the characteristic polynomial f (x) can be represented as f (x) = 1000011101 (binary number). When such a binary display is displayed in octal, the characteristic polynomial f (x) can be expressed as f (x) = 435 (octal number). FIG. 6 applies such octal display.

6 is selected, and r + 1 pieces forming the signal sequence generation unit 3 in FIG. 3 so as to follow the six characteristic polynomials f ₀ (x) to f ₅ (x) in the one set. (= H = 6) seventh-order M-sequence generators 10-0 to 10-r are formed. The delay data groups R0 to Rr are also obtained by using the selected set of six characteristic polynomials f ₀ (x) to f ₅ (x).

Signal generation when the 7th order M-sequence is used is expressed by the following equation (4) because the number of M-sequence generation units 10-0 to 10-r is six.

  The individual data output from the signal sequence generation unit 3 is a signal sequence with good noise resistance that can carry a large amount of information with little interference. However, since this signal sequence includes approximately the same amount of “1” and “0”, when this signal sequence is applied to a system in which the wireless tag reader can simultaneously read a plurality of wireless tags, The signals “1” overlap, making it difficult to distinguish each signal from the received signal.

  For this reason, the bit width extension unit 4 extends the bit width so that the ratio of “1” bits is sufficiently smaller than the ratio of “0” bits.

(A-5) Wireless Tag Communication System and Communication Method FIG. 7 shows a configuration of a wireless tag communication system that performs communication with the wireless tag in which the extended individual data is written by the individual data writing device 10 described above. It is a block diagram.

  In FIG. 7, the wireless tag communication system 30 includes a wireless tag 31, a wireless tag reader 32, and a host device 33.

  The wireless tag 31 is written with the individual data expanded by the individual data writing device 10 described above, and attached to the article or individual for management such as identification or authentication of the article or individual. It is something that an individual possesses. The wireless tag 31 includes a loop transmission / reception antenna 40, an individual data memory 41 that records expanded individual data, a control unit 42 that controls the operation of the wireless tag 31, and an inquiry signal from the wireless tag reader 32. Is received and given to the control unit 42, and the control unit 42 includes a transmission / reception unit 43 that transmits the expanded individual data read from the individual data memory 41.

  For example, a resonance circuit (for example, an LC resonance circuit) that resonates with the carrier frequency of the interrogation signal is configured by the loop-shaped transmission / reception antenna 40 and a part of the constituent elements of the transmission / reception unit 43 or the control unit 42. An operating power supply for the tag 31 is obtained. The individual data memory 41 is preferably a nonvolatile memory. The digital modulation method between the wireless tag 31 and the wireless tag reader 32 is not limited. For example, an ASK (amplitude shift keying) modulation method, an FSK (frequency shift keying) modulation method, and a PSK (phase shift keying) modulation method are used. Applicable.

  The wireless tag reader 32 radiates an inquiry signal to its surroundings under the control of the host device 33 and acquires expanded individual data of the wireless tag 31 existing in the vicinity of the wireless tag reader 32. is there. The wireless tag reader 32 digitally modulates the non-directional or directional transmission / reception antenna 50, the duplex unit 51 that separates the transmission system and the reception system, and the baseband interrogation signal given from the control unit 54 to the duplex unit 51. A transmission unit 52 for giving, a reception signal from the duplex unit 51 to a baseband signal, a reception unit 53 for converting to a binary (digital value) signal, a query signal to be radiated, and a radio tag reader 32 A control unit 54 for identifying the expanded individual data assigned to the wireless tag 31 existing in the vicinity, and a delay data group (or management number) and bits similar to the data association storage unit 6 described above During the identification processing of the reference database 55 storing the association information with the individual data after the width expansion and the control unit 54 Compiled individual data or delay data group after the bit width extension candidates (or control number) and a candidate storage unit 56 for buffering.

  The wireless tag reader 32 may include at least the transmission / reception antenna 50, the transmission unit 52, the reception unit 53, and the control unit 54.

  In this embodiment, the receiving unit 53 converts the baseband signal into a binary (digital value) signal as a sampling rate of 3 of the sampling rate of the individual data after the bit width extension output from the wireless tag 31. A double rate (which may be another integer multiple of 2 or more) is applied. The individual data sampled at the triple rate is output to the control unit 54 as it is, or is output to the control unit 54 after performing noise removal processing. When the baseband signal obtained by the receiving unit 53 is as shown in FIG. 8, it is sampled at the sampling timing indicated by the vertical line. In the case of FIG. 8, the noises NI1 and NI2 are removed by this sampling, but it is assumed that “1” is sampled. For example, if the noise removal rule that “1” is replaced with “0” if any of the preceding and following is not “1”, even if the noises NI1 and NI2 are sampled as “1”, it is set to “0”. It is replaced and noise is removed.

  The controller 54 identifies the expanded individual data assigned to the wireless tag 31 existing in the vicinity as follows. The control unit 54 internally buffers the sampling data given from the receiving unit 53. Here, for example, buffering is performed after “1” arrives.

  First, assuming that the first buffered “1” is a value at the position of bit 0 (see FIG. 2) in the extended individual data, the post-extension stored in the reference database 55 is assumed. Of individual data (sampling rate is tripled), obtain a correlation value with the bit 0 position value of “1”, and candidates whose correlation value is greater than or equal to the threshold value Store in the storage unit 56.

  Here, since the sampling rate is tripled, the position of bit 0 is also divided into three equal parts, the position of the first three equal parts of bit 0, the position of the second three equal parts of bit 0, A candidate may be obtained by obtaining a correlation for each of the last three equal positions.

  In addition, when the correlation value for the entire period is obtained, if there are many wireless tags 31 around the wireless tag reader 32, the correlation value with the individual data of the corresponding wireless tag 31 becomes small. . Therefore, the correlation value may be obtained by limiting (only masking) only the period in which the individual data stored in the reference database 55 is “1” with the individual data on the reference side. .

  Next, it is assumed that the buffered leading “1” is the value at the position of bit 1 (see FIG. 2) in the extended individual data, and the post-extension stored in the reference database 55 Of the individual data, the correlation value with the value of the position of bit 1 being “1” is obtained, and the correlation value is equal to or greater than the threshold value and stored in the candidate storage unit 56.

  Thereafter, similarly, the buffered leading “1” is stored in the reference database 55 on the assumption that the value is a bit x (x = 2 to 15) in the expanded individual data. Of the individual data after expansion, a correlation value with the value of the position of the bit x being “1” is obtained, and those having a correlation value equal to or greater than the threshold value are stored in the candidate storage unit 56.

  When the candidate search at bit 15 is completed, the control unit 54 sends the candidate data stored in the candidate storage unit 56 to the host device 33. It should be noted that the transmission of the question signal and the candidate search may be executed a plurality of times, and the candidates that have been candidates a predetermined number of times (for example, a majority) or more in a plurality of searches may be sent to the host device 33.

  In the above description, the wireless tag reader 32 executes the process of identifying the individual data from the received baseband signal. However, the host device 33 may execute the process of identifying the individual data. .

(A-6) Effect of Embodiment The above embodiment uses H sequences that are easy to generate and use H (preferably 7th order, H = 6, 11th order, H = 4) After adding a delay to each of the M-sequence, a signal sequence (individual data before expansion) is obtained by adding by exclusive OR, and then the individual data to be output with the bit width expanded (after expansion) (Individual data) is generated, so that it is possible to generate a signal sequence with good noise resistance that can carry a large amount of information with small cross-correlation and little interference.

For example, when a 7th order M-sequence (sequence length 127) is used, the amount of information to be placed is 18 × ²⁴² pieces of information, and an extremely large amount of information can be placed.

  Moreover, since this sequence has a small correlation with other sequences having different information and excellent noise resistance characteristics, it can be used for an article or individual identification or authentication system using a wireless tag as in the above embodiment. When applied, it can produce extremely large effects.

  In particular, even when the reader has a function for simultaneously reading a plurality of wireless tags, the bit expansion can eliminate collisions in the “1” section, and can identify an article or an individual using a wireless tag or the like. Or, when applied to an authentication system or the like, an extremely large effect can be obtained.

(B) Other Embodiments In the above description, the signal sequence generation circuit of the present invention is applied to an individual data writing device for a wireless tag. However, the use of the signal sequence generation circuit of the present invention is limited to this. It is not something. For example, the signal sequence generation circuit of the present invention can be applied to a device on the authentication side. For example, authentication or identification is performed by inputting a password or ID consisting of a delay data group from a keyboard or the like, and collating a signal sequence generated from the input delay data group with a signal sequence read from a wireless tag. Anyway. Further, for example, a signal sequence to be described as a barcode may be generated by the signal sequence generation circuit of the present invention.

  In the above-described embodiment, the configuration in which the generated M sequence is delayed includes the multiplier group and the exclusive OR. However, other variable delay configurations may be applied. For example, if the range of the delay amount is narrow, a configuration in which a delay shift register and an output of an arbitrary stage of the delay shift register are taken out may be a variable delay configuration.

  Further, in the above-described embodiment, the maximum number (H) of M sequences that are preferred pairs with each other is generated and added with a delay, but the maximum number (H) is generated. The number of occurrences may be reduced, and the number of occurrences may be variable.

  The wireless tag used in the present invention is not particularly limited, but a tag that has a built-in battery and transmits radio waves by itself or a tag that exchanges data using external radio waves can be used. Furthermore, the thing using electromagnetic induction, the thing using a radiated electromagnetic field, etc. can be used. Examples of the electric circuit (antenna circuit) in the wireless tag include a coil shape and a dipole type.

  In the communication system of the above-described embodiment, the extended individual data is stored in the wireless tag. However, the expanded individual data sampling rate is stored and transmitted when the interrogation signal arrives. You may do it. Also, instead of storing individual data in the wireless tag, a signal sequence generation circuit is mounted on the wireless tag, and a delayed data group is stored, and when an interrogation signal arrives, individual data is generated and transmitted. Anyway.

  The communication system of the present invention is not limited to the wireless tag communication system. For example, the present invention can be applied to a communication system that reads and processes a signal sequence from a barcode.

It is a block diagram which shows the structure of the separate data writing apparatus of a radio | wireless tag to which the signal series generation circuit which concerns on embodiment is applied. It is explanatory drawing of the bit width expansion method in the bit width expansion part which concerns on embodiment. It is a block diagram which shows the structure of the signal series production | generation part which concerns on embodiment. It is a block diagram which shows the model of the M series production | generation main body and variable delay device for demonstrating the method to obtain the delayed M series in embodiment. It is explanatory drawing which shows the relationship between the order of M series, and the maximum number of M series which become a preferred pair mutually. It is explanatory drawing which shows the characteristic polynomial of the maximum number of M series which becomes a preferred pair mutually in order 7 M series. It is a block diagram which shows the structure of the communication system which concerns on embodiment. It is explanatory drawing of the sampling process of the receiving part of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 3 ... Signal sequence production | generation part, 4 ... Bit width expansion part, 6 ... Data matching memory | storage part, 10-0-10-r ... M series production | generation part, 11 ... Exclusive OR circuit, 20-0-20-r ... M-sequence generation main body, 21-0 to 21-r ... variable delay device, 30 ... wireless tag communication system, 31 ... wireless tag, 32 ... wireless tag reader.

Claims (6)

A plurality of M-sequence generating means for generating a plurality of M-sequences that are paired with each other when viewed two by two;
Variable delay providing means for adding a delay to each of the plurality of generated M sequences;
Adding means for performing an exclusive OR operation on a plurality of M sequences to which a delay is added, and outputting a signal sequence after the operation;
Bit width extending means for converting each bit of the signal sequence output from the adding means into Q (Q> P) bits so that the ratio of “1” and “0” is biased after conversion. A signal sequence generation circuit.   2. The signal sequence according to claim 1, wherein the number of M sequences subjected to the exclusive OR operation is equal to a maximum number that becomes a preferred pair with each other when the two sequences are taken out. Generation circuit. A plurality of M sequence generation means, variable delay provision means, addition means and bit width expansion means;
The plurality of M-sequence generating means generates a plurality of M-sequences that are preferred pairs when viewed two by two,
The variable delay giving means gives a delay to each of the generated M sequences,
The adding means performs an exclusive OR operation on a plurality of M sequences to which a delay is given, and outputs a signal sequence after the operation,
The bit width extending means converts each P bit of the signal sequence output from the adding means into Q (Q> P) bits so that the ratio of “1” and “0” is biased after conversion. A signal sequence generation method characterized by the above. Computer
A plurality of M-sequence generating means for generating a plurality of M-sequences that are paired with each other when viewed two by two;
Variable delay providing means for adding a delay to each of the plurality of generated M sequences;
Adding means for performing an exclusive OR operation on a plurality of M sequences to which a delay is added, and outputting a signal sequence after the operation;
Functions as a bit width expansion unit that converts each P bit of the signal sequence output from the addition unit into Q (Q> P) bits so that the ratio of “1” and “0” is biased after conversion. A signal sequence generation program characterized in that Using the signal sequence generation circuit according to claim 1 and communication means,
A communication system using the individual data generated by the signal sequence generation circuit as an ID.   6. The communication system according to claim 5, wherein when the individual data as the ID is collated with a plurality of pieces of reference individual data stored in advance, the collation is performed by increasing the sampling rate.

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