JP4905531B2 - Time information acquisition device and radio clock - Google Patents

Description

  The present invention relates to a time information acquisition device that receives a standard time radio wave and acquires the time information, and a radio clock equipped with the time information acquisition device.

  Currently, in Japan, Germany, the United Kingdom, Switzerland, etc., long standard time radio waves are transmitted from transmitting stations. For example, in Japan, standard time radio waves with amplitude modulation of 40 kHz and 60 kHz are transmitted from transmitting stations in Fukushima Prefecture and Saga Prefecture, respectively. The standard time radio wave includes a sequence of codes constituting a time code indicating the year, month, day, hour and minute, and is transmitted in one cycle of 60 seconds. That is, the period of the time code is 60 seconds.

  A timepiece (radio timepiece) capable of receiving a standard time radio wave including such a time code, taking out the time code from the received standard time radio wave, and correcting the time has been put into practical use. The reception circuit of the radio clock accepts the standard time radio wave received by the antenna and demodulates the standard time radio signal amplitude-modulated by a band pass filter (BPF) for extracting only the standard time radio signal, envelope detection, etc. A demodulation circuit and a processing circuit that reads a time code included in the signal demodulated by the demodulation circuit are provided.

  The conventional processing circuit synchronizes at the rising edge of the demodulated signal, and then binarizes at a predetermined sampling period to obtain TCO data of a unit time length (1 second) which is a binary bit string. Further, the processing circuit measures the pulse width of the TCO data (that is, the time of bit “1” or the time of bit “0”), and codes “P”, “0” corresponding to the width. "Or" 1 "is determined, and time information is acquired based on the determined code sequence.

  In a conventional processing circuit, a process of second synchronization processing, minute synchronization processing, code acquisition, and matching determination is performed from the start of reception of standard time radio waves to acquisition of time information. When processing cannot be completed properly in each process, the processing circuit needs to start processing from the beginning. For this reason, processing may have to be performed again and again due to the influence of noise included in the signal, and the time until the time information can be acquired may be significantly increased.

  Second synchronization is to detect the rising of the code that arrives every second among the codes indicated by the TCO data. By repeating the second synchronization, it is possible to detect a portion where the position marker “P0” arranged at the end of the frame and the marker “M” arranged at the beginning of the frame are continuous. This continuous portion arrives every minute (60 seconds). The position of the marker “M” is the data of the first frame in the TCO data. Detecting this is called minute synchronization. Since the beginning of the frame is recognized by the above-mentioned minute synchronization, code acquisition is started thereafter, and after acquiring the data for one frame, the parity bit is checked, and an impossible value (year, month, day, and time cannot actually occur) Value) is determined (consistency determination). For example, minute synchronization finds the beginning of a frame and may take 60 seconds. Of course, it takes several times as long to detect the beginning of a frame over several frames.

  In Patent Document 1, TCO data obtained by binarizing a demodulated signal at a predetermined sampling interval (50 ms) is acquired, and a data group consisting of binary bit strings every second (20 samples) is listed. It becomes. The apparatus disclosed in Patent Document 1 includes this bit string, a binary bit string template representing the code “P: position marker”, a binary bit string template representing the code “1”, and a binary bit string representing the code “0”. Each of the templates is compared with each other to obtain the correlation, and it is determined by the correlation whether the bit string corresponds to the code “P”, “1”, or “0”.

JP 2005-249632 A

  In the technique disclosed in Patent Document 1, TCO data, which is a binary bit string, is acquired and matched with a template. In a state where the electric field strength is weak or a state where a lot of noise is mixed in the demodulated signal, many errors are included in the acquired TCO data. Therefore, it is necessary to finely adjust the filter for removing noise from the demodulated signal and the threshold of the AD converter to improve the quality of TCO data.

  If the data of the unit time length (1 second) only determines one of the codes “P”, “1”, and “0”, the start of the second, the start of the minute, etc. are again determined based on the determination result. Judgment processing needs to be performed. Here, if the beginning of the second or the beginning of the minute cannot be found properly, the processing must be performed again.

  In particular, in the detection of the start position of the second (second synchronization), if the accurate start position of the second is not detected, the detection of the start position of the minute and the decoding of the code executed thereafter are all invalidated. . Therefore, it is desired to accurately detect the start position of the second.

  The present invention can accurately identify the leading position of the second of the standard time radio wave under appropriate reception conditions of the standard time radio wave, and appropriately obtain the code included in the standard time radio wave to obtain the current time. It is an object of the present invention to provide a time information acquisition device capable of performing the above and a radio timepiece including the time information acquisition device.

An object of the present invention is to receive a standard time radio wave including a time code;
The signal including the time code output from the receiving means is sampled at a predetermined sampling period, and each sample point takes either a first value indicating a low level or a second value indicating a high level. And input waveform data generating means for generating input waveform data having one or more unit time lengths;
The data value of each sample point takes either the first value or the second value, has the same time length as the input waveform data, and the waveform shape is sequentially shifted by a predetermined sample. Predicted waveform data generating means for generating a plurality of predicted waveform data,
Correlation value calculation means for calculating a correlation value between the input waveform data and each of the plurality of predicted waveform data by calculating a sample point of the input waveform data and a corresponding sample point of the predicted waveform data The calculation of the first value in the input waveform data and the first value in the predicted waveform data, or the second value in the input waveform data and the second value in the predicted waveform data While calculating the first calculated value indicating a positive correlation, the calculation of the first value in the input waveform data and the second value in the predicted waveform data, or the second value in the input waveform data A correlation value calculating means that takes a second calculated value indicating a negative correlation by calculating the value and the first value in the predicted waveform data;
Correlation value comparison means for comparing the first calculated value and the second calculated value, which are correlation values calculated by the correlation value calculating means, and specifying the optimum value;
Control means for identifying the second pulse position in the time code based on the predicted waveform data indicating the optimum value,
The second pulse based on the optimum value of the correlation value repeatedly calculated between the input waveform data generated by the input waveform data generating unit and the predicted waveform data by the correlation value calculating unit. This is achieved by a time information acquisition device characterized by determining a specific continuation or cancellation of the position.

  In a preferred embodiment, when the control means indicates that the degree to which the optimum value shows a positive correlation is less than a predetermined value based on the optimum value of the correlation value calculated repeatedly, the second pulse Stop position identification.

  In a more preferred embodiment, the control means accumulates the optimum value of the correlation value to calculate an accumulated value, and refers to a threshold value storage means that stores a threshold value of the accumulated value corresponding to the number of repetitions. Then, it is determined whether the degree of showing the positive correlation is less than a predetermined value.

  In another preferred embodiment, the control means counts the number of predetermined correlation values indicating a positive correlation when calculating the correlation value, and based on the count value obtained by the counting, the second A specific continuation or cancellation of the pulse position is determined.

  In a more preferred embodiment, the control means refers to count value threshold storage means that stores a threshold value of a count value determined according to the number of repetitions of calculation of correlation value, and the count value is a predetermined value. When the count value is equal to or greater than the threshold value, the specification of the second pulse position is stopped.

  In a preferred embodiment, the control means calculates a level value indicating the reception level of the standard time radio wave based on the optimum value of the correlation value repeatedly calculated and displays it on the display means.

  In a more preferred embodiment, the control means increases or decreases the level value based on an increase or decrease in the degree of showing a positive correlation in the accumulated value with reference to the accumulated value of the optimum value. Let

  Further, in a preferred embodiment, the predicted waveform data generation means is configured so that each sample point has a first value indicating a low level in any predetermined section before and after the signal level change point, and before and after the change point. Any one of a second value indicating a high level in any other predetermined section and a third value in other sections other than the predetermined section, and the waveform shape is sequentially shifted by a predetermined sample. A plurality of predicted waveform data is generated.

  In another preferred embodiment, the predicted waveform data generating means generates a plurality of predicted waveform data whose waveform shape includes a predetermined code in a time code.

In another preferred embodiment, the control means is based on the second pulse position specified by the time information acquisition device and the signal level before and after the start position of the time code, and the minute start position in the time code. And obtaining the code included in the time code, and according to the value indicated by the code, obtaining the value of the code including the day, hour, and minute constituting the time code,
The current time is calculated based on the acquired code value.

Another object of the present invention is to provide the time information acquisition device,
An internal time measuring means for measuring the current time by an internal clock;
Time correction means for correcting the current time measured by the internal time measurement means according to the current time acquired by the time information acquisition device;
This is achieved by a radio-controlled timepiece comprising time display means for displaying the current time measured by the internal time measuring means or corrected by the time adjusting means.

  According to the present invention, it is possible to accurately identify the leading position of the second of the standard time radio wave under appropriate reception conditions of the standard time radio wave, and appropriately obtain the code included in the standard time radio wave to obtain the current time. It is possible to provide a time information acquisition device that can be obtained, and a radio timepiece including the time information acquisition device.

FIG. 1 is a block diagram showing the configuration of the radio timepiece according to the present embodiment. FIG. 2 is a block diagram showing a configuration example of the receiving circuit according to the present embodiment. FIG. 3 is a block diagram showing the configuration of the signal comparison circuit according to the present embodiment. FIG. 4 is a flowchart showing an outline of processing executed in the radio timepiece according to the present embodiment. FIG. 5 is a diagram for explaining the standard of the standard time radio signal. FIGS. 6A to 6C are diagrams illustrating examples of codes according to JJY, WWVB, and MSF standards, respectively. FIG. 7 is a diagram exemplifying a portion of predicted waveform data used in the second synchronization according to the present embodiment. FIG. 8 is a flowchart showing in more detail the detection of the second pulse position (second synchronization) according to the present embodiment. FIG. 9 is a flowchart illustrating an example of a covariance value calculation process in the second pulse position detection process. FIG. 10 is a diagram schematically illustrating second pulse position detection processing according to the present embodiment. FIG. 11 is a diagram for explaining an example of calculating a covariance value according to the present embodiment. FIG. 12 is a flowchart illustrating an example of reception level calculation / display processing according to the present embodiment. FIGS. 13A and 13B are diagrams illustrating an example of a portion of input waveform data based on JJY. FIG. 14 is a diagram illustrating an example of the accumulated value of the covariance values based on the input waveform data illustrated in FIG. FIG. 15 is a diagram illustrating an example of the accumulated value of the covariance values based on the input waveform data illustrated in FIG. FIG. 16 is a flowchart illustrating an example of the cancellation condition acquisition process according to the present embodiment. FIG. 17A is a diagram illustrating a configuration example of a count value cancellation condition table according to the present embodiment, and FIG. 17B is a diagram illustrating a configuration example of a maximum value cancellation table according to the present embodiment. . FIG. 18 is a diagram illustrating an example of the accumulated value of the covariance values based on the input waveform data illustrated in FIG. FIG. 19 is a diagram illustrating an example of accumulated values of covariance values based on the input waveform data illustrated in FIG. FIG. 20 is a flowchart showing in more detail the detection (minute synchronization) of the minute head position according to the present embodiment. FIG. 21 is a diagram for explaining input waveform data and predicted waveform data in the detection of the leading position according to the present embodiment. FIGS. 22A and 22B are diagrams for explaining the feature sections in each code of JJY. FIG. 23 is a flowchart showing an example of a fractional detection process according to the embodiment of the present invention. FIG. 24 is a diagram illustrating a covariance value between input waveform data and predicted waveform data. FIG. 25 is a flowchart showing in more detail the detection of the second pulse position (second synchronization) according to the second embodiment of the present invention. FIG. 25 is a flowchart showing in more detail a flowchart showing an example of a covariance value calculation process in the detection of the second pulse position according to the second embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In the embodiment of the present invention, a standard time radio wave in a long wave band is received, the signal is detected, a sequence of codes indicating a time code included in the signal is extracted, and based on the sequence of the codes The radio timepiece for correcting the time is provided with the time information acquisition device according to the present invention.

  Currently, standard time radio waves are transmitted from a predetermined transmitting station in Japan, Germany, the United Kingdom, Switzerland, and the like. For example, in Japan, standard time radio waves with amplitude modulation of 40 kHz and 60 kHz are transmitted from transmitting stations in Fukushima Prefecture and Saga Prefecture, respectively. The standard time radio wave includes a string of codes constituting a time code indicating the year, month, day, hour and minute, and is transmitted in one cycle of 60 seconds. Since one code has a unit time length (1 second), one cycle can include 60 codes.

  FIG. 1 is a block diagram showing the configuration of the radio timepiece according to the present embodiment. As shown in FIG. 1, the radio timepiece 10 includes a CPU 11, an input unit 12, a display unit 13, a ROM 14, a RAM 15, a receiving circuit 16, an internal timing circuit 17, and a signal comparison circuit 18.

  The CPU 11 reads out a program stored in the ROM 14 at a predetermined timing or in response to an operation signal input from the input unit 12, expands the program in the RAM 15, and configures the radio clock 10 based on the program. Execute instructions and data transfer. Specifically, for example, by receiving the standard time radio wave by controlling the receiving circuit 16 every predetermined time, a sequence of codes included in the standard time radio signal is obtained from digital data based on the signal obtained from the receiving circuit 16. Specific processing is performed to correct the current time measured by the internal clock circuit 17 based on this sequence of codes, and to transfer the current time clocked by the internal clock circuit 17 to the display unit 13. In the present embodiment, one or more unit time lengths of predicted waveform data in a predetermined form are generated, and the predicted waveform data and input waveform data obtained from the standard time radio wave received by the receiving circuit 16 are obtained. By comparing, the beginning of the second is specified.

  Also in the present embodiment, for example, by comparing the predicted waveform data with the input waveform data, the value of various codes including the beginning of the minute, hour, minute, and date is specified. ing. By specifying the date and time, the error in the internal clock circuit 17 is calculated, and the current time in the internal clock circuit 17 can be corrected.

  The input unit 12 includes a switch for instructing execution of various functions of the radio timepiece 10, and outputs a corresponding operation signal to the CPU 11 when the switch is operated. The display unit 13 includes a dial, an analog pointer mechanism controlled by the CPU 11, and a liquid crystal display device, and displays the current time measured by the internal clock circuit 17. In addition to displaying the current time, the liquid crystal display device can display the reception level of the standard time radio wave received by the radio clock. The ROM 14 stores a system program, an application program, and the like for operating the radio timepiece 10 and realizing a predetermined function. The program for realizing the predetermined function includes a program for controlling the signal comparison circuit 18 for second pulse position detection processing, which will be described later, and a program for controlling the signal comparison circuit 18 for the minute leading position and code decoding processing. Is also included. The RAM 15 is used as a work area for the CPU 11 and temporarily stores programs and data read from the ROM 14, data processed by the CPU 11, and the like.

  The reception circuit 16 includes an antenna circuit, a detection circuit, and the like, obtains a signal demodulated from the standard time radio wave received by the antenna circuit, and outputs the signal to the signal comparison circuit 18. The internal clock circuit 17 includes an oscillation circuit, counts clock signals output from the oscillation circuit, counts the current time, and outputs current time data to the CPU 11.

  FIG. 2 is a block diagram showing a configuration example of the receiving circuit 16 according to the present embodiment. As shown in FIG. 2, the receiving circuit 16 includes an antenna circuit 50 that receives standard time radio waves, a filter circuit 51 that removes noise of a standard time radio signal (standard time radio signal) received by the antenna circuit 50, and a filter An RF amplification circuit 52 that amplifies a high-frequency signal that is an output of the circuit 51, and a detection circuit 53 that detects a signal output from the RF amplification circuit 52 and demodulates a standard time radio signal, and is demodulated by the detection circuit 53. The signal is output to the signal comparison circuit 18.

  FIG. 3 is a block diagram showing the configuration of the signal comparison circuit according to the present embodiment. As shown in FIG. 3, the signal comparison circuit 18 according to this exemplary embodiment includes an input waveform data generation unit 21, a reception waveform data buffer 22, a predicted waveform data generation unit 23, a waveform cutout unit 24, a correlation value calculation unit 25, A correlation value comparison unit 26, a reception level calculation unit 27, and a cancellation determination unit 28 are included.

  The input waveform data generation unit 21 converts the signal output from the receiving circuit 16 into digital data whose value takes any one of a plurality of values at a predetermined sampling interval and outputs the digital data. For example, the sampling interval is 50 ms, and data of 20 samples per second can be acquired. The value of the digital data according to this embodiment will be described in detail later. The reception waveform data memory 22 sequentially stores the data generated in the input waveform data generation unit 21. The reception waveform data memory 22 can store a plurality of unit time length (1 second) data (for example, 10 unit time (10 seconds)). Erase.

  The predicted waveform data generation unit 23 generates predicted waveform data having a predetermined time length to be compared and used in each process described later. The predicted waveform data generated by the predicted waveform data generation unit 23 will be described in each of the second pulse position detection process, the minute leading position detection process, and the code decoding process. The waveform cutout unit 24 extracts input waveform data having the same time length as the predicted waveform data from the received waveform data buffer 22.

  The correlation value calculation unit 25 calculates a correlation value between each of the plurality of predicted waveform data and the input waveform data. In the present embodiment, covariance is adopted to obtain a correlation as will be described later. The correlation value comparison unit 26 compares the correlation values (covariance values) calculated by the correlation value calculation unit 25 and identifies the optimum value.

  The reception level calculation unit 27 calculates the level value of the signal level of the standard time radio signal based on the covariance value calculated by the correlation value calculation unit 25 and outputs it to the CPU 11. Further, the cancellation determination unit 28 determines whether or not to continue the second pulse position detection process based on the covariance value.

  FIG. 4 is a flowchart showing an outline of processing executed in the radio timepiece according to the present embodiment. The process shown in FIG. 4 is mainly executed by the CPU 11 and the signal comparison circuit 18 based on instructions from the CPU 11. As shown in FIG. 4, the CPU 11 and the signal comparison circuit 18 (hereinafter also referred to as “CPU 11 or the like” for convenience of description) detect the second pulse position (step 401). The process of detecting the second pulse position is also referred to as second synchronization. FIG. 5 is a diagram for explaining the standard of the standard time radio signal. As shown in FIG. 5, the standard time radio signal is transmitted according to a predetermined standard. In the standard time radio signal, symbols indicating “P”, “1”, and “0” having a unit time length of 1 second are connected. The standard time radio wave has 60 seconds as one frame, and one frame includes 60 codes. Further, in the standard time radio wave, the position marker “P1”, “P2”,... Or the marker “M” arrives every 10 seconds, and the position marker “P0” and the frame arranged at the end of the frame. By detecting the portion where the marker “M” arranged at the head of the frame continues, the head of the frame that arrives every 60 seconds, that is, the head position of the minute can be found.

  FIGS. 6A to 6C are diagrams illustrating examples of codes according to JJY, WWVB, and MSF standards, respectively. As shown in FIG. 5 and FIG. 6A, JJY includes three codes indicating “0”, “1”, and “P”, respectively. The code of JJY is a code of unit time length (1 second), and rises from the low level to the high level at the head of the second. The code “0” of JJY becomes the high level only for the first 800 ms, and becomes the low level in the subsequent 200 ms. That is, the code “0” is an 80% duty signal. The code “1” becomes a high level only for the first 500 ms, and becomes a low level in the subsequent 500 ms. That is, the code “1” is a 50% duty signal. The code “P” is a code used as a position marker or a marker, and becomes a high level only for the first 200 ms and becomes a low level in the subsequent 800 ms. That is, the symbol “P” is a signal with a 20 percent duty.

  As will be described in detail later, in the present embodiment, in order to accurately detect that the JJY signal rises from a low level to a high level at the beginning of a second, a waveform of a unit time length having a predetermined data value A plurality of pieces of predicted waveform data are generated in which a predetermined number of data (four in the present embodiment) are continuous and shifted by 50 ms. The correlation value between the plurality of predicted waveform data and the input waveform data is calculated, and the change point indicating the rising from the low level to the high level of the predicted waveform data indicating the optimum correlation value is represented by the second pulse position (second The first position of

  Next, the CPU 11 detects the start position of the minute, that is, the start position of the standard time radio signal of the one frame (step 402).

  Thereafter, the CPU 11 or the like uses various codes of the standard time radio signal (the fractional part code (M1), the fractional part code (M10), other codes such as date, day of the week, etc.) as predicted waveforms. Decoding is performed based on the comparison between the data and the input waveform data (step 403).

  In the present embodiment, a case where a standard radio signal according to JJY is received and the second synchronization is performed will be described first. However, when a standard radio signal according to another standard, for example, WWVB or MSF is received. It can also be applied to. Here, the symbols according to WWVB and MSF are also briefly described.

  FIG. 6B is a diagram illustrating a code included in the WWVB of the United States. As shown in FIG. 6B, WWVB includes three codes indicating “0”, “1”, and “P”, respectively. The sign of WWVB falls from the high level to the low level at the beginning of the second. The code “0” of WWVB becomes a low level only for the first 200 ms, and becomes a high level in the subsequent 800 ms. The code “1” becomes a low level only for the first 500 ms, and becomes a high level in the subsequent 500 ms. Further, the code “P” becomes a low level only for the first 800 ms, and becomes a high level in the subsequent 200 ms.

FIG. 6C is a diagram showing symbols included in the UK MSF. Unlike JJY and WWVB, MSF has five codes, and four of them can represent the values of two bits (A, B). The sign of MSF falls from high level to low level at the beginning of the second. The code corresponding to “A = 0, B = 0” becomes a low level only for the first 100 ms, and becomes a high level in the subsequent 900 ms. The code corresponding to “A = 1, B = 0” becomes a low level only for the first 200 ms, and becomes a high level in the subsequent 800 ms. Further, the code “M” corresponding to the marker becomes a low level only for the first 500 ms, and becomes a high level in the subsequent 500 ms. A code corresponding to “A = 0, B = 1” sequentially becomes a low level, a high level, and a low level by 100 ms in the first 300 ms, and then becomes a high level in 700 ms thereafter. Further, the code corresponding to “A = 1, B = 1” becomes a low level only for the first 300 ms, and becomes a high level in the subsequent 700 ms.

  Hereinafter, the second pulse position detection process (step 401) according to the present embodiment will be described in more detail. FIG. 7 is a diagram illustrating a portion of predicted waveform data used in the second synchronization according to the present embodiment. In FIG. 7, one second corresponding to the initial unit time length of each predicted waveform data is displayed. A broken line indicated by reference numeral 700 indicates the beginning of the predicted waveform data. Actually, in the present embodiment, four unit time lengths, ie, four unit time lengths, that is, four seconds of predicted waveform data shown in FIG. 23. Further, in the present embodiment, 20 pieces of predicted waveform data P (1, j) to P (20, j) in which the position of the head of data (rise from low level to high level) is shifted by 50 ms each. Is generated by the predicted waveform data generation unit 23.

  As shown in FIG. 7, the first predicted waveform data P (1, j) rises from a low level to a high level at the beginning of the data (see reference numeral 700). In the predicted waveform data according to the present embodiment, the low level is set only for a predetermined interval in front of the point rising from the low level to the high level (the point indicated by reference numeral 700 in the first predicted waveform data). And a second value indicating a high level only for a predetermined interval behind the point (a new side in time). Other than the predetermined section before and after the point, another third value indicating “0” is provided. In the example of FIG. 7, “−1” is used as the first value, “1” is used as the second value, and “0” is used as the third value. In the present embodiment, the predetermined interval of the first value indicating the low level and the predetermined interval of the second value indicating the high level are both 50 ms.

  In the actual calculation, in the portion having the first value and the portion having the second value, that is, in the first predicted waveform data P (1, j) (see reference numeral 701), reference numerals 711 and 712 are given. In the portion shown, the second predicted waveform data P (2, j) to the twentieth predicted waveform data P (20, j), only the operations indicated by the reference numerals 721, 731, 741, and 751 are substantially performed. It becomes effective.

  As can be understood from FIG. 7, the second predicted waveform data P (2, j) (see reference numeral 702) rises from the low level to the high level at a position where 50 ms has elapsed from the top of the data. Hereinafter, in the third predicted waveform data P (3, j), the fourth predicted waveform data P (4, j),..., The rising position from the low level to the high level corresponds to 50 ms. Only the position goes back sequentially.

  FIG. 8 is a flowchart showing in more detail the detection (second synchronization) of the second pulse position according to the present embodiment, and FIG. 9 is a flowchart showing an example of a covariance value calculation process in the second pulse position detection process. . FIG. 10 is a diagram schematically illustrating the second pulse position detection process according to the present embodiment.

  As shown in FIG. 8, the predicted waveform data generation unit 23 rises from the low level to the high level by 50 ms each in 4 unit time length (4 seconds) as described above according to the instruction of the CPU 11. Twenty pieces of predicted waveform data P (1, j) to P (20, j) whose positions are shifted are generated (step 801, reference numeral 1001 in FIG. 10). As described with reference to FIG. 7, the value of the predicted waveform data is any one of the first value, the second value, and the third value.

  Next, covariance value calculation processing is executed in the signal comparison circuit 18 (step 802). As shown in FIG. 9, in accordance with an instruction from the CPU 11, the waveform cutout unit 24 cuts out data having a unit time length (4 seconds) from the received waveform data buffer 22 to generate input waveform data Sn (j). (Step 901, reference numeral 1011 in FIG. 10). In this embodiment, since 20 samples of data are acquired per second, Sn (j) is data including 80 samples. In order to increase the processing speed or reduce the size of the received waveform data buffer 22, the waveform cutout unit 24 is configured so that all of the data of four unit time lengths are not stored in the received waveform data buffer 22. Sample data may be taken out in order of (1), Sn (2),.

In the present embodiment, the input waveform data generation unit 21 binarizes the analog signal (see reference numeral 1010 in FIG. 10) output from the reception circuit 16 with a predetermined level as a threshold value. At the time of binarization, the first value “−1” is given as the data value when the level is low, and the second value “1” is given as the data value when the level is high. Therefore, the received waveform data buffer 22 stores digital data composed of the first value and the second value. Therefore, the data value of the input waveform data Sn (j) extracted by the waveform cutout unit 24 also takes either the first value or the second value.

  Next, the correlation value calculation unit 25 initializes a parameter p for specifying the predicted waveform data to “1” in accordance with an instruction from the CPU 11 (step 902), the input waveform data Sn (j), and the predicted waveform data P (p, The correlation value (covariance value) C (p) between each of j) is calculated (step 903). Further, the correlation value calculating unit 25 calculates an accumulated value Ca (p) of the covariance value C (p) (step 904).

  In the present embodiment, the correlation value calculation unit 25 includes the data value Sn (j) of the input waveform data, its average value Sm, the data value P (p, j) value of the predicted waveform data, and its average value Pm. Is used to calculate the covariance value C (p) according to the following equation. In FIG. 10, by calculating the covariance values of Sn (j) and each of P (1, j), P (2, j),..., P (20, j), C (1), C (2),..., C (20) are obtained.

C (p) = (1 / N) * Σ ((Sn (j) −Sm) * (P (p, j) −Pm))
Sm = (1 / N) * Σ (Sn (j)), Pm = (1 / N) * Σ (P (p, j))
The sigma is for j = 1 to N. As described above, when the waveform cutout unit 24 sequentially extracts sample data in the order of Sn (1), Sn (2),. All Sn (j) (j = 1 to N) is not acquired at the beginning of step 703. Therefore, in the initial stage of Step 903, the average value Sm = (1 / N) * Σ (Sn (j)) cannot be obtained.

However, the above C (p) is
C (p) = (1 / N) Σ (Sn (j) * P (p, j)) − Sm * Pm
And transformed. Therefore, every time the waveform cutout unit 24 acquires the sample data Sn (j), the correlation value calculation unit 25 calculates Sn (j) * P (p, j) and obtains the calculated value as the multiplication result. When the last sample data Sn (N) is obtained, the correlation value calculation unit 25 calculates the average value Sm, and calculates Sm * Pm from the accumulation result. Subtract.

  Further, in the present embodiment, when Sn (j) is the first value “−1” and P (p, j) is the first value “−1”, Sn (j) * P (p , J) becomes “1”. Similarly, when Sn (j) is the second value “1” and P (p, j) is the second value “1”, Sn (j) * P (p, j) is “ 1 ". In other words, when P (p, j) takes the first value or the second value and Sn (j) and P (p, j) match, the predetermined value indicates a positive correlation. (“1” in this embodiment).

  On the other hand, when Sn (j) is the first value “−1” and P (p, j) is the second value “1”, Sn (j) * P (p, j) is “− 1 ". Similarly, when Sn (j) is the second value “1” and P (p, j) is the first value “−1”, Sn (j) * P (p, j) is “−1”. That is, when P (p, j) takes the first value or the second value and Sn (j) and P (p, j) do not match, a negative predetermined value indicating a negative correlation (In this embodiment, “−1”).

  Further, when P (p, j) is the third value “0”, Sn (j) * P (p, j) affects the calculation of the covariance value regardless of the value of Sn (j). The value not to be “0”.

  FIG. 11 is a diagram for explaining an example of calculating a covariance value according to the present embodiment. In the example of FIG. 11, the first one second (j = 1 to 20) is shown in the input waveform data and the predicted waveform data. Further, C (1) to C (6) displayed on the right side indicate the accumulated value of Sn (j) * P (p, j), not the covariance value itself. In the input waveform data Sn (j), when j = 4, 5, the input waveform data Sn (j) is at the high level and indicates the second value “1”. Otherwise, it is at a low level, indicating the first value “−1”.

  In the predicted waveform data P (1, j) to P (3, j), C (1) to C (3) are “0”, respectively. On the other hand, in the predicted waveform data P (4, j) whose waveform rising position matches the waveform rising position of the input waveform data Sn (j), C (4) is “2”. On the other hand, in the predicted waveform data P (6, j) in which the rising position of the waveform matches the falling position of the waveform of the input waveform data Sn (j), C (6) is “−2”. Thus, in this embodiment, when the rising position of the input waveform data matches the rising position of the predicted waveform, a larger covariance value appears to indicate that there is a stronger correlation. In addition, when the falling position of the input waveform data matches the rising position of the predicted waveform, that is, when the waveform has an opposite phase, a negative covariance value indicating a negative correlation appears. On the other hand, a value “0” that does not affect the calculation result appears except for the rising position of the predicted waveform data.

  Also, the covariance value C (p) = (1 / N) * (Σ (Sn (j) * P (p, j)) − Sm * Pm, and the calculated value Sn that is the product of the data values of the sample points. The sum Σ (Sn (j) * P (p, j)) of (j) * P (p, j) is divided by the number of samples N. However, in this embodiment, the covariance value itself Is used to specify the optimum value of the covariance value (the maximum value in the present embodiment) by comparison as will be described later, and therefore division of N can be omitted. In this embodiment, since the average value of the predicted waveform data P (i, j) is “0”, Sm * Pm is also “0”.

  Therefore, (Σ (Sn (j) * P (p, j)) can be used as the covariance value C (p) in the present embodiment.

  If the parameter p is smaller than “20” (No in step 905), the parameter p is incremented (step 906), and the process returns to step 903. When the covariance values C (1) to C (20) are acquired for all the parameters p (Yes in step 905), the process is terminated.

  Next, the reception level calculation unit 27 calculates a reception level value in accordance with an instruction from the CPU 11, and the CPU 11 displays the reception level value on the liquid crystal display device (step 803). FIG. 12 is a flowchart illustrating an example of reception level calculation / display processing according to the present embodiment.

As illustrated in FIG. 12, the reception level calculation unit 27 determines the maximum value Camax _t−1 (accumulation value Ca (p) _t−1 (p: 1 to 20) of the covariance value obtained by the previous process. t is a parameter indicating processing time) and the maximum value Camax _{t of} the covariance accumulated value Ca (p) _t calculated in the current step 802 (step 1201), and the current maximum value It is determined whether Camax _t has increased, that is, whether Camax _t > Camax _t−1 (step 1202).

  When it is determined Yes in step 1202, the reception level calculation unit 27 increments the value of the reception level (step 1203). Next, it is determined whether or not the value of the reception level is greater than the maximum set value (for example, “5”) (step 1204). If the value is larger (Yes in step 1204), the reception level calculation unit 27 Is the maximum set value (step 1205). Thereafter, the reception level calculation unit 27 outputs the calculated reception level value to the CPU 11. The CPU 11 displays the reception level value on the screen of the liquid crystal display device (step 1206). On the screen of the liquid crystal display device, the level value (0 to 5) may be displayed as a bar (for example, see reference numeral 1401 in FIG. 14), or the corresponding number may be displayed as it is.

If it is determined No in step 1202, the reception level calculation unit 27 decrements the value of the reception level (step 1207). Next, it is determined whether or not the value of the reception level is smaller than the minimum setting value “0” (step 1208). If it is smaller (Yes in step 1208) , the reception level calculation unit 27 sets the value of the reception level to “ 0 "(step 1209). Then, it progresses to step 1206.

  FIGS. 13A and 13B are diagrams illustrating an example of a portion of input waveform data based on JJY. In each of them, only the first one second of the input waveform data is shown. In each of FIGS. 13A and 13B, input waveform data is acquired a plurality of times (5 times in the example of FIG. 13). FIG. 13A shows an example in which the input waveform data has a lot of noise, and FIG. 13B shows an example in which the input waveform data has a little noise. As shown in FIG. 13B, in the input waveform data with little noise, for example, the leading rising positions are substantially coincident (see arrow 1310). On the other hand, as shown in FIG. 13A, in the case of input waveform data with a lot of noise, for example, the leading rising positions do not match (see arrows 1301 to 1303).

  FIG. 14 is a diagram illustrating an example of the accumulated value of the covariance values based on the input waveform data illustrated in FIG. In the example of FIG. 14, for convenience of explanation, the covariance value C (p) is calculated based on the input waveform data portion for one second shown in FIG. 13A, and the cumulative value of each covariance value in each process is calculated. The calculated value Ca (p) is shown as a histogram. In FIG. 14, the maximum values Camax of the accumulated values from the first time to the fifth time are “2”, “2”, “4”, “6”, and “6”. As shown in FIG. 14, the level values of the reception level based on the maximum value of the accumulated value are “1”, “0”, “1”, “2”, and “1”, respectively.

  FIG. 15 is a diagram illustrating an example of the accumulated value of the covariance values based on the input waveform data illustrated in FIG. In the example of FIG. 15 as well, for convenience of explanation, the covariance value C (p) is calculated based on the input waveform data portion for one second shown in FIG. The calculated value Ca (p) is shown as a histogram. In FIG. 15, the maximum values Camax of the accumulated values from the first time to the fifth time are “2”, “4”, “6”, “8”, and “10”. As shown in FIG. 15, the level values of the reception level based on the maximum value of the accumulated value are “1”, “2”, “3”, “4”, and “5”, respectively.

  Thus, in this embodiment, the level value of the reception level is increased when the maximum value of the accumulated value is increased with reference to the accumulated value of the covariance value for each process. The maximum accumulated value of the covariance values indicates the degree of coincidence between the rising edges of the input waveform data and the predicted waveform data. Therefore, a large maximum accumulated value indicates that a signal with relatively little noise is received. An increase in the maximum accumulated value indicates that a signal with relatively little noise is repeatedly received. Therefore, in the present embodiment, the level value of the reception level is increased when the maximum accumulated value increases.

Next, the cancellation determination unit 28 executes a cancellation condition acquisition process according to an instruction from the CPU 11 (step 804). FIG. 16 is a flowchart illustrating an example of the cancellation condition acquisition process according to the present embodiment. As illustrated in FIG. 16, the cancellation determination unit 28 refers to the accumulated value Ca (p) _t of the covariance value, and the number of positions p at which the accumulated value is equal to or greater than a predetermined value indicating a positive correlation. Are counted (step 1601). Similar to the calculation / display of the reception level, when the portion of the input waveform data for one second is considered, the predetermined value can be set to “2”, for example. In the present embodiment, the covariance value of “2” means that the rising position of the pulse is between the input waveform data portion for 1 second and the corresponding predicted waveform data portion for 1 second. It shows that they match. Therefore, the accumulated value of the covariance values is “2”, and it is expected that the rising positions of the pulses coincide with each other in the process.

  In addition, the cancellation determination unit 28 acquires the maximum value Camax of the accumulated value Ca (p) of the covariance value (step 1602). Next, the cancellation determination unit 28 refers to the count value cancellation condition table stored in the ROM 14 and acquires the determination result of the first cancellation condition (step 1603). FIG. 17A is a diagram illustrating a configuration example of a count value stop condition table according to the present embodiment. As shown in FIG. 17A, the count value stop condition table 1700 stores count values (table count values) in association with the number of processing times.

  If the count value calculated in step 1601 is greater than or equal to the table count value associated with the number of processes shown in FIG. 17A, the stop determination unit 18 determines that the determination result of the first stop condition is “stop ". On the other hand, if the count value calculated in step 1601 is smaller than the table count value, the determination result of the first stop condition indicates “continuation”.

  In the count value stop condition table shown in FIG. 17A, the number of positions p where the accumulated value is equal to or greater than a predetermined value indicates variations in predicted waveform data whose rising edge coincides with the input waveform data. That is, as the count value (number) increases, the number of predicted waveform data whose rising edge matches the input waveform data increases. It is desirable that this count value (number) does not increase despite the repeated processing. That is, it is the most desirable state that the accumulated value increases only at one certain position and the accumulated value does not increase at the other position. In this case, the counted value does not increase.

  Therefore, it is acceptable that the count value increases within a certain range as the processing is repeated, and the count value stop condition table 1700 stores the allowable table count values.

  Next, the cancellation determination unit 18 refers to the maximum value cancellation condition table stored in the ROM 14 and acquires the determination result of the second cancellation condition (step 1604). FIG. 17B is a diagram illustrating a configuration example of the maximum value cancellation table according to the present embodiment. As illustrated in FIG. 17B, the maximum value cancellation condition table 1710 stores a maximum value (table maximum value) in association with the number of processes.

  If the maximum value Camax acquired in step 1602 is equal to or smaller than the table maximum value associated with the number of processes shown in FIG. 17B, the cancellation determination unit 18 determines that the determination result of the second cancellation condition is “cancel ". On the other hand, if the maximum value Camax acquired in step 1602 is larger than the table maximum value, the determination result of the second stop condition indicates “continuation”.

  The maximum value Camax acquired in step 1602 indicates the degree of coincidence of the rise in the predicted waveform data whose rise coincides with the input waveform data. The maximum value is desirably increased as the process is repeated.

  Therefore, assuming that the maximum value increases as the processing is repeated, the minimum value of the maximum value to be increased is stored in the maximum value cancellation condition table 1710, and the acquired maximum value is The process is stopped when the value is less than the allowable value.

  Thereafter, the cancellation determination unit 18 determines whether to stop or continue the final second synchronization process based on the determination result of the first cancellation condition and the determination result of the second cancellation condition (step 1605). In the present embodiment, if either of the determination result of the first stop condition or the determination result of the second stop condition is “stop”, it is determined that the process should be stopped. To do. When it is determined that the process can be continued by the cancellation condition acquisition process shown in FIG. 16 (step 805), the CPU 11 determines whether the number of processes for calculating the covariance value (step 802) has reached a predetermined number. (Step 806). If NO is determined in step 806, the process returns to step 802.

  If it is determined No in step 805, the second pulse position detection process is terminated. In this case, detection of the leading position and decoding of the code are not executed as much as described below.

  FIG. 18 is a diagram illustrating an example of the accumulated value of the covariance values based on the input waveform data illustrated in FIG. 13A, and is similar to the example of FIG. Accordingly, in the example of FIG. 18 as well, for convenience of explanation, the covariance value C (p) is calculated based on the input waveform data portion for one second shown in FIG. The accumulated value Ca (p) is shown as a histogram. In FIG. 18, the respective count values from the first time to the fifth time are “2”, “3”, “3”, “4”, “7”, and the maximum value Camax of the accumulated value is “2”, “2”, “4”, “6”, “6”. In this example, in the fifth processing, the count value is “7”, and “continuation” is indicated in the first cancellation condition, while the maximum value Camax is “6”, and “ "Cancel" is indicated. Therefore, it is finally determined in step 1605 that the second synchronization is stopped in the fifth process.

  FIG. 19 is a diagram illustrating an example of the accumulated value of the covariance values based on the input waveform data illustrated in FIG. 13B, and is similar to the example of FIG. Accordingly, in the example of FIG. 19 as well, for convenience of explanation, the covariance value C (p) is calculated based on the input waveform data portion for 1 second shown in FIG. The accumulated value Ca (p) is shown as a histogram. In FIG. 19, the respective count values from the first time to the fifth time are “1”, “1”, “1”, “1”, “2”, and the maximum value Camax of the accumulated value is “2”, “4”, “6”, “8”, “10”. Accordingly, it is determined that the second synchronization should be continued in each of the five processes.

  When it is determined Yes in step 806, the correlation value comparison unit 26 compares the accumulated values Ca (1) to Ca (20) of the correlation values to determine the optimum value (in this case, the maximum value) C. Find (x) (step 807). The CPU 11 receives the optimum value C (x) and determines whether or not the optimum value is valid (step 808).

Among the obtained covariance values C (p), C (x) indicating the maximum value is a predicted waveform having the highest correlation. However, in a covariance value obtained from a sample with insufficient parameters, noise The maximum value may appear due to an accidental factor. For the purpose of eliminating such a case, for example, in step 808, for example, the following criteria are provided to avoid erroneous detection.
(1) The number of input waveform data used for covariance calculation is greater than or equal to a predetermined number. (2) The value of x indicating C (x) appears multiple times, and the value of the multiple times x is equal. The frequency is higher than others. (X is the mode)
(3) The value of x is continuously equal to the predetermined number of times. (Continuity of mode)
(4) The variance of C (p) is below a specified value,
(5) Calculate kurtosis or skewness, which is a statistic of C (p) , or an evaluation function equivalent thereto, and determine whether the result reaches a specified value.

  Of course, the judgment of effectiveness is not limited to the above-described method, and the average value or standard deviation of the correlation value is used, for example, even if the correlation value is the maximum value, the value smaller than the average value is not significant. Judgment may be made, or a general significance level (for example, 5%) in statistics may be used.

  If the optimum value C (x) is valid (Yes in step 808), the CPU 11 starts from the change point of the signal level in the predicted waveform data indicated by the optimum value C (x), that is, the first value indicating the low level. The position that changes to the second value indicating the high level is determined as the second pulse position (step 809). The CPU 11 stores second pulse position information in the RAM 15. This second pulse position is used in processing such as detection of the leading position as described below.

  When the second pulse position is detected (step 401), that is, when the second synchronization is completed, the minute leading position is detected (step 402). Detection of the minute start position is also referred to as minute synchronization. In step 401, the second pulse position (first position of the second) has already been determined. Also, in JJY, as shown in FIG. 5, in one frame, a code indicating the position marker “P0” is arranged at the end, and a code indicating the marker “M” is arranged at the top. Both the position marker “P0” and the marker “M” have a sign “P” with a duty of 20%. Therefore, in the minute synchronization, predicted waveform data having a unit time length of 2 units in a form in which the code “P” having a duty of 20% is generated is generated. In addition, 60 pieces of input waveform data of 2 unit time length (2 seconds) starting from the second pulse position (that is, the second head position) are generated. By calculating the correlation value between the predicted waveform data and each of the 60 input waveform data, 60 correlation values (covariance values) C (1) to C (60) can be obtained.

  FIG. 20 is a flowchart showing in more detail the detection (minute synchronization) of the minute head position according to the present embodiment. FIG. 21 is a diagram for explaining input waveform data and predicted waveform data in the detection of the leading position according to this embodiment. With the second synchronization, the second pulse position (second head position) has already been determined.

  The predicted waveform data generation unit 23 generates predicted waveform data P (j) having a 2-unit time length in a form in which two symbols “P” are connected in accordance with an instruction from the CPU 11 (step 2001). As shown in FIG. 21, this predicted waveform data (see reference numeral 2100) has two waveforms in which the first 200 ms (20%) is high level and the rest is low level in unit time length (1 second). It is a thing.

  The predicted waveform data generation unit 23 extracts data values (feature values) belonging to the feature section of the generated predicted waveform data P (j) (step 2002). FIGS. 22A and 22B are diagrams for explaining the feature sections in each code of JJY. As shown in FIG. 22 (a), in code “P” (see symbol 2201), code “1” (see symbol 2202), and code “0” (see symbol 2203), the value is the value of another code. There are sections with unique values that are different from For example, in the code “P”, an interval from 200 ms to 500 ms (see reference 2211) is a low level (data value “−1”), and this interval has a unique value “−1” different from others. ing.

Therefore, in the present embodiment, the section of 200 ms to 500 ms is the feature section in the code “P”. In the predicted waveform data P (j) shown in FIG. 21 , if the number of samples of unit time length is 20, j = 1 to 40. In this case, the predicted waveform data generation unit 23 uses, as the feature value, data values in a section of 200 ms to 500 ms and a section of 1200 ms to 1500 ms, that is, P (5) to P (10) and P (25) to P Only (30) is extracted.

  As will be described later, the feature value of the feature section of the predicted waveform data is also used in the code decoding process. In the code decoding process, it is only necessary to determine whether the code is “0” or “1”. That is, since the minute synchronization has been completed, it is not necessary to determine the code “P”.

  As shown in FIG. 22B, in the code “1”, the section (see the code 2212) from 500 ms to 800 ms is at the low level (data value “−1”). And a unique value “−1”. On the other hand, in the code “0”, an interval from 500 ms to 800 ms (refer to the code 2213) is a high level (data value “1”), and a unique value “1” different from the other codes “1” in this interval. "have. Therefore, in the codes “1” and “0”, a section of 500 ms to 800 ms is a feature section. Further, the feature value in the feature section with the code “1” is “−1”, and the feature value in the feature section with the code “0” is “1”.

Next, the parameter i for specifying the second head position is initialized, and in accordance with an instruction from the CPU 11, the waveform cutout unit 24 inputs an input waveform having a unit time length (2 seconds) from the second head position from the received waveform data buffer 22. Data Sn (i, j) is generated (step 2004). Further, the waveform cutout unit 24 extracts data values belonging to the feature section of Sn (i, j) so as to correspond to the feature section of the predicted waveform data (step 2005). When i = 1, the waveform cutout unit 24 extracts Sn (1,5) to Sn (1,10) and Sn (1,25) to Sn (1,30) as data values belonging to the feature section. . In general,
Sn (i, 5) -S (i, 10), and
Sn (i, 25) to S (i, 30) are extracted as data belonging to the feature section.

  Next, the correlation value calculation unit 25 calculates a correlation value (covariance value) C (i) between the input waveform data Sn (i, j) belonging to the feature section and the predicted waveform data P (j) belonging to the feature section. (Step 2006). Since the calculation of the covariance value is the same as that of the second synchronization process, only the balance with the feature section will be described. In the present embodiment, Sn (i, 5) to S (i, 10) and Sn (i, 25) to S (i, 30) are input waveform data as data values belonging to the feature section. Extracted. Further, P (5) to P (10) and P (25) to (P30) are also extracted from the predicted waveform data.

Therefore, when calculating the covariance value C (i), the sum of the product values of the input waveform data and the data value of the predicted waveform data ΣSn (i, j) * P (j), j = 5 -10, 25-30. Here, as described with reference to FIG. 22A, the data value (feature value) of the feature section with the symbol “P” is “−1”. Therefore, the prediction waveform data P (j) (j = 5 to 10, 25 to 30) in the prediction section is “−1”. Therefore, when calculating the total sum of the multiplication values, Sn (i, j) (j = 5 to 10, 25 to 30) may be obtained and multiplied by the feature value “−1”.

  Next, the CPU 11 determines whether or not the parameter i is 60 (step 2007). If it is determined No in step 2007, the CPU 11 increments the parameter i (step 2008). In the subsequent step 2004, in accordance with the instruction from the CPU 11, the waveform cutout unit 24 sets the unit time length (2) from the next second start position (that is, a position 20 samples after the second start position of the previous input waveform data). Second) input waveform data Sn (i, j). Hereinafter, a covariance value is calculated between the newly acquired input waveform data Sn (i, j) and the predicted waveform data P (j).

  As shown in FIG. 21, the input waveform data Sn (1, j) is composed of data 2101 and 2102 of 2 unit time length from a certain second head position. The next input waveform data Sn (2, j) is composed of data 2102 and 2103 having a length of 2 unit time from the next second head position. Thus, Sn (n-1, j) and Sn (n, j) are data in which the second head position is shifted by the unit time length (1 second). The last input waveform data Sn (60, j) is composed of data 2159 and 2160 having a length of 2 unit time shifted by 59 seconds from the first input waveform data Sn (1, j).

  The data value belonging to the feature section of the input waveform data Sn (1, j), Sn (2, j), Sn (3, j),..., Sn (60, j) and the feature section space of the predicted waveform data Are used to calculate the respective covariance values. In FIG. 21, for convenience of illustration, prediction for calculating covariance among Sn (1, j), Sn (2, j), Sn (3, j),..., Sn (60, j). The waveform data is P (1, j), P (2, j), P (3, j),..., P (60, j), but these are actually the same value P (j). It is.

  When all the correlation values (covariance values) C (1) to C (60) are acquired, the correlation value comparison unit 26 compares the covariance values C (1) to C (60) to determine the optimum value. (Maximum value in this case) C (x) is found (step 2009). The CPU 11 accepts the optimum value C (x) and determines whether or not the optimum value is valid (step 2010). Whether it is valid or not is also the same as in the case of the second synchronization process (step 808 in FIG. 8). In the determination of the validity of the optimum value related to step 808, when (1) to (3) are applied, the processing set of steps 2003 to 2009 is executed a plurality of times.

  If NO is determined in step 2010, the process returns to step 2003, and the waveform cutout unit 24 is different from the data used for the previous processing stored in the reception waveform buffer 22 in accordance with the instruction from the CPU 11. Get input waveform data.

  When it is determined Yes in step 2010, the CPU 11 changes the head position of the second code “P” in the input waveform data indicated by the optimum value C (x), that is, from the second low level to the high level. Is determined to be the leading position of the minute (step 2011). The CPU 11 stores information on the start position of the minute in the RAM 15.

  When the minute leading position is detected (step 402), that is, when the minute synchronization is completed, codes such as minutes, hours, and days of the week are decoded (step 403). In the minute decoding, one-minute decoding and ten-minute decoding are executed. In the hour decoding, the hour's first digit and the hour's tenth digit are executed. In the following, the decoding of fractions will be described.

  FIG. 23 is a flowchart showing an example of a fractional detection process according to the embodiment of the present invention. In this embodiment, the waveform cutout unit 24 acquires the input waveform data Sn (j) having a length of 4 unit time from the head position of the code (fractional place) (step 2301). If it is 20 samples per second, input waveform data of 80 samples (j = 1 to 80) can be obtained.

Next, the waveform cutout unit 24 extracts a feature section of the input waveform data Sn (j) (step 2302). As shown in FIG. 22B, the feature sections for the codes “0” and “1” based on JJY are positions from the position of 500 ms from the head of the code to the position of 800 ms. Therefore, the characteristic section of the input waveform data Sn (j) is
It is a section of data values of Sn (10) to Sn (16), Sn (30) to Sn (36), Sn (50) to Sn (56), and Sn (70) to Sn (76).

Next, the parameter BCD that specifies the value of the fractional part represented by BCD is initialized to “0000” (step 2303). The predicted waveform data generation unit 23 generates predicted waveform data P (j) having a 4-unit time length corresponding to the code indicated by the parameter BCD (step 2304). Further, the predicted waveform data generation unit 23 extracts a feature section of the predicted waveform data P (j) (step 2305). This feature section is
This is a section of data values P (10) to P (16), P (30) to P (36), P (50) to P (56), and P (70) to P (76).

Next, the correlation value calculation unit 25 obtains an operation value by multiplying the data value of the feature section of Sn (j) and the corresponding data value (feature value) of the feature section of P (j). A covariance value C (p) is calculated based on the calculated value (step 2306). Note that there are four characteristic sections of the predicted waveform data P (j), and each data value is “1” or “0”. Therefore, the multiplication of data values can be obtained as follows.
(Feature value of feature section (P (10) to P (16))) × Σ (Sn (10) to Sn (16)) + (Feature value of feature section (P (30) to P (36))) × Σ (Sn (30) to Sn (36)) + (feature value of feature section (P (50) to P (56))) × Σ (Sn (50) to Sn (56)) + (feature section ( Characteristic value of P (70) to P (76)) × Σ (Sn (70) to Sn (76))
Therefore, there is no need to obtain the sum of the multiplication values of all data values.

  If the parameter is smaller than “BCD = 1001” (step 2307), the parameter BCD is incremented (step 2308) and the process returns to step 2304. If it is determined YES in step 2307, the process proceeds to step 2309.

  When all the correlation values (covariance values) C (1) to C (10) are acquired, the correlation value comparison unit 26 compares the covariance values C (1) to C (10) to determine the optimum value. (Maximum value in this case) C (x) is found (step 2309). The CPU 11 receives the optimum value C (x) and determines whether or not the optimum value is valid (step 2310). Whether it is valid or not is also the same as in the case of the second synchronization process (step 808 in FIG. 8). If NO is determined in step 2310, the process returns to step 2301. On the other hand, if “Yes” is issued in step 2310, the CPU 11 determines that the value (BCD) indicated by the predicted waveform data indicated by the optimum value C (x) is a fractional value (step). 2311). The CPU 11 stores a fractional value in the RAM 15.

  Decoding of other codes such as the tenths of a minute, the hours of the hour, the tens of the digits, and the day of the week can also be realized by the same processing as the ones of the minutes. When the time information including the current date and time, the day of the week, the current time, and the like is acquired by decoding the code, the CPU 11 stores the obtained time information in the RAM 15. Further, the CPU 11 corrects the current time measured by the internal clock circuit 17 based on the current time obtained from the code, and displays the obtained current time on the display unit 13 (step 404).

  Although second synchronization, minute synchronization, and code decoding have been described for the JJY signal, second synchronization, minute synchronization, and code decoding are also possible for other standards such as WWVB and MSF.

  Second synchronization in the case of WWVB or MSF will be described. As shown in FIGS. 6B and 6C, WWVB and MSF fall from the high level to the low level at the beginning of the second. The case where the predicted waveform data applied to JJY is applied to the signal that falls at the head in this way will be described. FIG. 24 is a diagram illustrating a covariance value between input waveform data and predicted waveform data. In FIG. 24 (a), input waveform data Sn (j) rises from a low level to a high level at the start position of the second (see reference numeral 2400). Predicted waveform data P (j) that takes a first value corresponding to a low level before the rising point and takes a second value corresponding to a high level after the rising point; Considering the covariance value C with the input waveform data Sn (j), the maximum value is “2”. Note that the covariance value is simply the sum of the product of the data value of the predicted waveform data and the data value of the input waveform data for ease of explanation.

  On the other hand, as shown in FIG. 24B, consider input waveform data S′n (j) that falls from a high level to a low level at the start position (second pulse position) of the second. Considering the covariance value C between the input waveform data S′n (j) and the predicted waveform data P (j), the minimum value is “−2”. In other words, for data that falls from the high level to the low level at the start position of the second, such as WWBV and MSF, the process shown in FIG. 8, particularly in step 807, is optimal for detecting the start position of the second. As the value, the minimum covariance value may be selected.

  In the calculation of the reception level (FIG. 12), it is determined in step 1202 whether the minimum value of the accumulated value has decreased. Also in the cancellation condition acquisition process (FIG. 16), the minimum negative covariance value and the minimum negative accumulated value are used. For FIG. 16, the following steps are modified.

In step 1601, positions where the accumulated value Ca (p) _t is equal to or less than a predetermined negative value are counted. In step 1602, the minimum value Camin of the accumulated value Ca (p) _t is acquired. The table referred to in step 1604 is a minimum value cancellation condition table, in which the minimum accumulated value for each processing count is stored. In step 1605, if the minimum value Camin acquired in step 1602 is greater than or equal to the table minimum value, the cancellation determination unit 18 indicates that the determination result of the second cancellation condition is “stop”. On the other hand, if the minimum value Camin acquired in step 1602 is smaller than the table minimum value, the determination result of the second stop condition indicates “continuation”.

  Alternatively, in order to detect the leading position of the second of the data that falls from the high level to the low level at the leading position of the second, such as WWVB or MSF, the above-described predicted waveform data P (p, j) is inverted Other predicted waveform data may be applied. In FIG. 24C, the input waveform data S′n (j) is the same as that in FIG. The predicted waveform data P ′ (j) is obtained by inverting the predicted waveform data P (j) shown in FIG. In this case, the covariance value C (2) when p = 2 takes the maximum value. Therefore, the second position of the second may be determined based on the predicted waveform data P (2) and the input waveform data Sn (2).

  In the present embodiment, the cancellation determination unit 28 is based on the correlation value repeatedly calculated by the correlation value calculation unit 25 between the input waveform data generated by the input waveform data generation unit and the predicted waveform data. The specific continuation or cancellation of the second pulse position is determined. The optimum correlation value indicates the largest positive correlation. Therefore, by referring to the optimum value, it is possible to determine the amount of noise in the input waveform data, and it is possible to realize accurate second synchronization using the input waveform data with relatively little noise contamination.

  In the present embodiment, the cancellation determination unit 28 determines the second pulse when the degree of the positive value indicating the positive correlation is less than a predetermined value based on the optimal value of the correlation value calculated repeatedly. Stop position identification. For the optimum value indicating the strongest correlation, a decrease in the degree of positive correlation means that the degree of noise mixing in the input waveform data is increased. Therefore, in this case, the second synchronization is stopped and the detection of an inappropriate second head position is eliminated.

  In particular, in the present embodiment, the cancellation determination unit 28 calculates the accumulated value by accumulating the optimum value of the correlation value, and stores the threshold value of the accumulated value corresponding to the number of repetitions. Referring to 1710, it is determined whether the degree of showing a positive correlation is less than a predetermined value. When the optimum value is the maximum value, the accumulated value of the optimum value (maximum value) increases as the processing is repeated for input waveform data with relatively little noise contamination. Therefore, the maximum value cancellation condition table 1710 stores the minimum allowable value of the increasing maximum value, and the processing is stopped when the acquired maximum value is equal to or less than the allowable value. As a result, it is possible to appropriately stop the second synchronization without performing complicated calculations.

  Further, in the present embodiment, when determining the correlation value, the cancellation determination unit 28 counts the number of predetermined correlation values indicating a positive correlation, and based on the count value obtained by the counting, the second pulse Determine the specific continuation or cancellation of the position. The number of predetermined correlation values indicating a positive correlation indicates the number of positions that may be determined as second pulse positions. Therefore, as the number of correlation values increases, the position that can be determined as the second pulse position increases, and it is difficult to specify the accurate second pulse position. Therefore, by counting the number of positive correlation values and determining whether the process is to be continued or stopped based on the counted value, accurate second pulse position specification can be reliably realized.

  In particular, in the present embodiment, the cancellation determination unit 28 refers to the count value cancellation condition table 1700 that stores a threshold value of the count value determined according to the number of repetitions of the calculation of the correlation value. When it is equal to or greater than a predetermined count value threshold, the specification of the second pulse position is stopped. As the processing is repeated, it is acceptable that the count value increases within a certain range, and the count value stop condition table stores the count value of the allowable limit, and is greater than or equal to the count value stored in the table. In such a case, the specification of the accurate second pulse position is reliably realized by stopping the specification of the second position.

  Further, in the present embodiment, the reception level calculation unit 27 calculates a level value indicating the reception level of the standard time radio wave based on the optimal value of the correlation value that is repeatedly calculated, indicate. Therefore, a device including the time information acquisition device, for example, a user of an electronic timepiece can appropriately grasp the status of the standard time radio wave currently received by the device.

  In particular, the reception level calculation unit 27 refers to the accumulated value of the optimum value, and increases or decreases the level value based on an increase or decrease in the degree indicating a positive correlation in the accumulated value. Thereby, it is possible to appropriately acquire the increase / decrease in the level value of the reception level over time.

  For example, in the present embodiment, the predicted waveform data generation unit 23 is configured so that each sample point is a first value indicating a low level in any predetermined section before and after the signal level change point, and before and after the change point. Any one of the second value indicating the high level in any other predetermined section and the third value in the other section other than the predetermined section, and the waveform shape is sequentially shifted by a predetermined sample. A plurality of predicted waveform data are generated, and the correlation value calculation unit 25 calculates a correlation value between the predicted waveform data and the input waveform data.

  When the predicted waveform data has the above-described value, a value indicating a larger positive correlation is output when the rising positions of the predicted waveform data and the input waveform data match. Therefore, it is possible to specify the second head position with high accuracy.

  In this embodiment, based on the second pulse position specified by the above-described processing and the signal level before and after the start position of the time code, the start position of the minute in the time code is specified and the code included in the time code is acquired. Then, according to the value indicated by the code, the code value including the date, hour, and minute constituting the time code is acquired, and the current time is calculated based on the acquired code value. Therefore, it is possible to correct the time obtained in the internal clock circuit 17 with the calculated current time.

  The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

  For example, in the above-described embodiment, when the second pulse position is detected, the first value “−” indicating the low level only for a predetermined interval in front of the point rising from the low level to the high level (the older side in time). 1 ”, a second value“ 1 ”indicating a high level only in a predetermined section behind the point (a new side in time), and other than the predetermined section before and after the point, Predicted waveform data having another third value indicating “0” is used. However, the present invention is not limited to this, and predicted waveform data in a form in which a code constituting a time code, for example, a code “0” is repeated may be used.

  FIG. 25 is a flowchart showing in more detail the detection of the second pulse position (second synchronization) according to the second embodiment of the present invention. As shown in FIG. 25, the predicted waveform data generation unit 23 follows the instruction of the CPU 11 and has a unit time length of 4 units (4 seconds), 50 ms each, and the head of the code “0” (from low level to high level) Twenty pieces of predicted waveform data P (1, j) to P (20, j) whose positions of (rising) are shifted are generated (step 2501).

  Next, the predicted waveform data generation unit 23 extracts feature sections of the predicted waveform data P (1, j) to P (20, j) (step 2502). As described above, in the code “0”, as shown in FIG. 22B, the feature section extends from the head of the code to the position of 500 ms to the position of 800 ms, and the feature value in the feature section is “1”. It is. Therefore, the feature section extraction unit 28 specifies the position of 500 ms to 800 ms from the beginning of the code “0” in each of the predicted waveform data P (1, j) to P (20, j).

For example, the feature section of the predicted waveform data P (1, j) is
P (1,10) -P (1,16), P (1,30) -P (1,36), P (1,50) -P (1,56), and P (1,70) To P (1,76), and the characteristic section of the predicted waveform data P (2, j) is
P (1,11) -P (1,17), P (1,31) -P (1,37), P (1,51) -P (1,57), and P (1,71) This is a section of data values of .about.P (1, 77).

In general, the characteristic section of the predicted waveform data (p, j) is
P (p, 10 + (p-1)) to P (p, 16 + (p-1)), P (p, 30 + (p-1)) to P (p, 36 + (p-1)), P ( p, 50 + (p-1)) to P (p, 56 + (p-1)) and P (p, 70 + (p-1)) to P (p, 76 + (p-1)) It becomes the section. In P (p, j), when the right number j> 80, (j−80) is obtained. In addition, the data value (feature value) of the feature section is “1” as shown in FIG.

  Next, a covariance value calculation process is executed (step 2503). FIG. 26 is a flowchart illustrating an example of covariance value calculation processing according to the second embodiment. As shown in FIG. 26, in accordance with an instruction from the CPU 11, the waveform cutout unit 24 cuts out data of 4 unit time length (4 seconds) from the received waveform data buffer 22 to generate input waveform data Sn (j). (Step 2601). Also in the second embodiment, since 20 samples of data are acquired per second, Sn (j) is data including 80 samples. Next, the CPU 11 initializes a parameter p for specifying the predicted waveform data to “1” (step 2602).

Next, the waveform cutout unit 24 acquires the data value of the feature section corresponding to the feature section of the predicted waveform data in the input waveform data Sn (j) (step 2603). In step 2603, corresponding to the predicted waveform data P (p, j), the data value of the feature section of the input waveform data Sn (j) is
Sn (10+ (p-1)) to Sn (16+ (p-1)), Sn (30+ (p-1)) to Sn (36+ (p-1)), Sn (50+ (p-1)) to Sn (56+ (p-1)) and Sn (70+ (p-1)) to Sn (76+ (p-1)).

  Next, the correlation value calculation unit 27 obtains an operation value by multiplying the data value of the feature section of Sn (j) and the corresponding data value (feature value) of the feature section of P (p, j). A covariance value is calculated based on the calculated value (step 2604). As described above, the data value of the feature section of the predicted waveform data P (p, j) is “1”. Therefore, in the multiplication of the data value of the feature section of Sn (j) and the corresponding data value (feature value) of the feature section of P (p, j), the data value of the feature section of Sn (j) is accumulated. It is only necessary to calculate and obtain ΣSn (j). Further, the correlation value calculation unit 27 calculates an accumulated value Ca (p) of the covariance value C (p) (step 2605).

If the parameter p is smaller than 20 (No in Step 2606), the parameter p is incremented (Step 2607) , and the process returns to Step 2603. If it is determined YES in step 2606, the process ends.

  Subsequent reception level calculation / display processing (step 2504) and stop condition acquisition processing (step 2505) are the same as steps 803 and 804 in FIG. Steps 2506 to 2510 are the same as steps 805 to 809 in FIG.

  As described above, in the second embodiment, the predicted waveform data generation unit 23 generates a plurality of predicted waveform data whose waveform shape includes a predetermined code in the time code, for example, the code “0”, The correlation value calculator 25 calculates a correlation value between the predicted waveform data and the input waveform data. Even when such predicted waveform data is used, accurate second synchronization can be reliably specified.

  In the reception level calculation / display process according to the embodiment, the maximum value of the covariance accumulated value Ca (p) is compared to determine whether the maximum value is increasing. When determining the maximum value, the index value V (p) is calculated using another index value V (p) = Ca (p−1) + C (p) + C (p + 1) in consideration of the accumulated values before and after. It may be determined whether the maximum value of is increasing.

  Further, in the reception level calculation / display processing according to the embodiment, the maximum value of the accumulated value Ca (p) is normalized by dividing by the number of processing times, and normalized with respect to a predetermined value corresponding to the maximum level. The ratio of the values may be the reception level value.

  Furthermore, in the cancellation condition acquisition process according to the embodiment, the maximum value Camax of the accumulated value is acquired, and the second cancellation condition is determined based on the acquired maximum value. However, the present invention is not limited to this, and the second stop condition is determined based on another index value V (p) = Ca (p−1) + C (p) + C (p + 1) in consideration of the previous and subsequent accumulated values. May be.

  Further, in the above-described embodiment, when the determination result “stop” is given in either the first stop condition or the second stop condition, the specification of the second head position is stopped. However, the present invention is not limited to this, and it may be configured to stop the specification of the second head position when a determination result of “stop” is obtained in both the first stop condition and the second stop condition.

In the embodiment, the first value indicating the low level is “−1”, the second value indicating the high level is “1”, and the other third values are “0”. However, the present invention is not limited to this. The first value and the second value may be as follows.
(1) When the first value appears in the input waveform data and the first value appears in the predicted waveform data, or the second value appears in the input waveform data and the second value in the predicted waveform data When a value of 現 れ appears, a predetermined positive calculation value indicating that there is a positive correlation is calculated by calculation. That is, when the same value appears in the input waveform data and the predicted waveform data, a predetermined positive calculation value is calculated.
(2) When the first value appears in the input waveform data and the second value appears in the predicted waveform data, or the second value appears in the input waveform data and the first value in the predicted waveform data When a value of 現 れ appears, a predetermined negative calculation value indicating that there is a negative correlation is calculated by calculation. That is, when different values appear in the input waveform data and the predicted waveform data, a predetermined negative calculation value is calculated. Further, it is desirable that the predetermined negative calculation value is obtained by setting the sign of the predetermined positive value to “− (minus)”.

  In addition, the third value may not be “0”, but when the first value is calculated and the second value is calculated, the correlation value such as the covariance value is affected. There must be no value.

  Moreover, in the said embodiment, although the covariance value was utilized as a correlation value, it is not limited to this. For example, a residual that is the sum of absolute values of differences may be used as the correlation value. Alternatively, a cross-correlation coefficient may be used instead of covariance or residual.

10 radio time clock 11 CPU
12 Input unit 13 Display unit 14 ROM
15 RAM
DESCRIPTION OF SYMBOLS 16 Reception circuit 17 Internal clock circuit 18 Signal comparison circuit 21 Input waveform data generation part 22 Reception waveform data buffer 23 Predicted waveform data generation part 24 Waveform cut-out part 25 Correlation value calculation part 26 Correlation value comparison part 27 Reception level calculation part 28 Stop determination Part

Claims (11)

A receiving means for receiving a standard time radio wave including a time code;
The signal including the time code output from the receiving means is sampled at a predetermined sampling period, and each sample point takes either a first value indicating a low level or a second value indicating a high level. And input waveform data generating means for generating input waveform data having one or more unit time lengths;
The data value of each sample point takes either the first value or the second value, has the same time length as the input waveform data, and the waveform shape is sequentially shifted by a predetermined sample. Predicted waveform data generating means for generating a plurality of predicted waveform data,
Correlation value calculation means for calculating a correlation value between the input waveform data and each of the plurality of predicted waveform data by calculating a sample point of the input waveform data and a corresponding sample point of the predicted waveform data The calculation of the first value in the input waveform data and the first value in the predicted waveform data, or the second value in the input waveform data and the second value in the predicted waveform data While calculating the first calculated value indicating a positive correlation, the calculation of the first value in the input waveform data and the second value in the predicted waveform data, or the second value in the input waveform data A correlation value calculating means that takes a second calculated value indicating a negative correlation by calculating the value and the first value in the predicted waveform data;
Correlation value comparison means for comparing the first calculated value and the second calculated value, which are correlation values calculated by the correlation value calculating means, and specifying the optimum value;
Control means for identifying the second pulse position in the time code based on the predicted waveform data indicating the optimum value,
The second pulse based on the optimum value of the correlation value repeatedly calculated between the input waveform data generated by the input waveform data generating unit and the predicted waveform data by the correlation value calculating unit. A time information acquisition apparatus characterized by determining a specific continuation or cancellation of a position.   When the control means indicates that the degree to which the optimum value shows a positive correlation is less than a predetermined value based on the repeatedly calculated optimum value of the correlation value, the specification of the second pulse position is stopped. The time information acquisition apparatus according to claim 1.   The control means accumulates the optimum value of the correlation value to calculate an accumulated value, and refers to a threshold value storage means that stores a threshold value of the accumulated value corresponding to the number of repetitions. The time information acquisition device according to claim 2, wherein it is determined whether the degree of indication is less than a predetermined value.   When the control means calculates the correlation value, it counts the number of predetermined correlation values indicating a positive correlation, and based on the count value obtained by the counting, the second pulse position is specifically continued or stopped. The time information acquisition apparatus according to claim 1, wherein:   The control means refers to a count value threshold storage means that stores a count value threshold determined in accordance with the number of iterations of calculation of correlation value calculation, and the count value is equal to or greater than a predetermined count value threshold. In such a case, the time information acquisition device according to claim 4, wherein the second pulse position specification is stopped.   6. The control unit according to claim 1, wherein the control unit calculates a level value indicating the reception level of the standard time radio wave based on the optimum value of the correlation value repeatedly calculated, and displays the level value on a display unit. The time information acquisition device according to any one of the above.   The control means refers to the accumulated value of the optimum value, and increases or decreases the level value based on an increase or decrease of a degree indicating a positive correlation in the accumulated value. Item 7. The time information acquisition device according to Item 6.   The predicted waveform data generation means is configured such that each sample point has a first value indicating a low level in any predetermined section before and after the change point of the signal level, and in any other predetermined section before and after the change point. One of the second value indicating the high level and the third value in other sections other than the predetermined section is taken, and a plurality of predicted waveform data whose waveform shapes are sequentially shifted by a predetermined sample are generated. The time information acquisition device according to claim 1, wherein the time information acquisition device is a time information acquisition device.   8. The time information acquisition apparatus according to claim 1, wherein the predicted waveform data generation unit generates a plurality of predicted waveform data whose waveform shape includes a predetermined code in a time code. . The control means specifies the minute start position in the time code based on the second pulse position specified by the time information acquisition device and the signal level before and after the start position of the time code, and the time code includes Acquire a code, and according to the value indicated by the code, acquire the value of the code including the day, hour, and minute constituting the time code,
The time information acquisition apparatus according to any one of claims 1 to 9, wherein the current time is calculated based on the acquired code value. A time information acquisition device according to claim 10;
An internal time measuring means for measuring the current time by an internal clock;
Time correction means for correcting the current time measured by the internal time measurement means according to the current time acquired by the time information acquisition device;
A radio-controlled timepiece comprising: time display means for displaying the current time measured by the internal time measuring means or corrected by the time adjusting means.

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