JP2009092653A - Standard wave receiving device, electric wave correcting timepiece, electronic apparatus, and time correcting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide accurate time information by eliminating errors in code judgment of each bit of a time code even in the case of degradation in reliability of the output of standard wave receiving means due to influences such as deterioration in receiving environment and noise. <P>SOLUTION: It is assumed, in each bit of a time code, that an actual probability 24 is a probability that is each code (0, 1 to n, marker) calculated by computation from an output waveform of receiving means 100 and a theoretical probability 25 is a statistical appearance probability of each code calculated in advance from definition of a time code for each bit. Computation and code judgment are performed by using these two probabilities. Further, the precision of code judgment is raised by adjusting the ratio between the two probabilities in accordance with stations, receiving environments, and the like. Furthermore, the probability of each code of subsequent bits are predicted based on the theoretical probability 25, the actual probability 24, and a result of judgment 28, and a receiving device is controlled by changing AGC, a level of AD conversion, and the like. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a standard radio wave receiving device that receives a standard radio wave including time information, a radio wave correction clock that corrects the time based on the time information included in the received standard radio wave, an electronic device incorporating the radio wave correction clock, and The present invention relates to a time correction method for correcting time based on time information included in a received standard radio wave.

[Explanation of standard radio wave and time code]
Standard radio waves are transmitted in a long wave band of several tens of kHz or a short wave band of 1 to 15 MHz in order to provide a frequency standard and a standard of time information in various countries around the world. This time information generally includes information such as time, date, year, day of the week, leap second, and daylight saving time. In Japan, the information is transmitted from two transmitting stations at 40 kHz and 60 kHz by the Independent Administrative Institution Information and Communication Organization.

  The standard radio wave is generally transmitted by a carrier wave by AM modulation, and when the amplitude at the time of non-modulation is 100%, the amplitude at the time of modulation is changed from about 25% to about 10% to represent the binary values of HIGH and LOW. Yes. The demodulated signal becomes a pulse signal with these two values. The standard radio wave transmits one bit every certain time, and one code is assigned to each bit. The code in the standard radio wave is defined by the pulse width of the pulse signal, and there are a plurality of codes. In the case of Japanese standard radio waves, three codes “0”, “1”, and “P” have pulse widths of 800 ms, 500 ms, and 200 ms, respectively. However, the definition of the pulse width and each code differs depending on the transmitting station.

  Time information varies from country to country, but taking Japanese standard radio waves as an example, information such as time and date is assigned to each block within a predetermined period (one minute), and each block has a bit width of several bits. have. One of the codes “0”, “1”, and “P” is assigned to each bit of each block. Information such as hours, minutes, and dates is expressed by the combination of codes. Therefore, time information of standard radio waves is also called a time code.

  In the code, “P” is called a position marker, which does not indicate information such as time, but indicates a specific place in the period of the time code such as the beginning of one period of the time code or the beginning of each block. Is. Although the definition of the time code varies depending on the transmitting station, the codes assigned to each bit of time information other than the marker in the time codes of many transmitting stations in the world are “0” and “1”. Information of each block is represented by the binary system used.

For example, in the case of Japanese standard radio waves, time information is represented by a method similar to a binary-coded decimal number (BCD). One bit is assigned to one second, and 0 to 59 bits are one time code period, that is, one minute is one time code period. Bits 1 to 8 are minute blocks, and the current minute is represented by adding the time information numerical values of the bits that are “1”. For example, the codes from bit 1 to bit 8 are {“0”, “1”, “0”, “0”, “0”, “1”, “0”, “1”}
In this case, 20 + 4 + 1 = 25 [minutes].

[Description of code judgment]
Since the time code is defined as described above, codes such as “0”, “1”, and “P” can be determined by measuring the pulse width of the signal demodulated by the receiving means. For example, as a simple method, the pulse width can be estimated by sampling a pulse signal at a constant frequency and measuring the number of HIGH times in a time corresponding to 1 bit.

[Characteristics and problems of time code]
There is no redundancy in the time information sent by standard radio waves, except for the parity check for limited information of some transmitting stations, and there is a method for detecting erroneous codes and means for correcting them. There is a fundamental problem of not. Therefore, when performing code determination for a certain bit, there is no information source other than the signal received at that time, and the accuracy of code determination depends only on the characteristics of the demodulated signal or pulse signal.

  Further, in order to increase the reliability of the acquired information, it is necessary to receive a plurality of time codes and compare and correct the data of the same bit of the time code. As the reception environment gets worse, there is a problem that more data must be taken and the reception time becomes longer.

  The characteristics of the demodulated signal mainly depend on the electric field strength and the ratio (S / N ratio) between the signal component and the noise component. If the pulse rise position or pulse width on the time axis differs greatly from the transmitted original code due to a decrease in electric field strength or an increase in noise components, code determination and time information acquisition are performed accurately. However, it becomes the reception limit at that time.

Therefore, a technique for eliminating the influence of spike-like noise or the like generated during a pulse has been conventionally known (for example, see Patent Document 1). The prior art shown in Patent Document 1 divides 1 second into several sections, detects whether each section is HIGH or LOW, substantially estimates the pulse width of the code, and performs code determination. Yes.

JP 2003-222687 A

  In the above-mentioned Patent Document 1, a standard radio wave is received and demodulated, the demodulated signal is sampled at regular intervals, 1 bit is divided into several sections, and HIGH or LOW is determined for each section, and section determination is performed. The code determination of “0”, “1”, “P” is performed from the combination of the determination results of each section determined by the section.

  As shown in FIG. 5 and FIG. 7 of Patent Document 1, one bit is roughly divided into four sections of A section: 0 to 200 ms, B section: 200 to 500 ms, C section: 500 to 800 ms, and D section: 800 to 1000 ms. is doing. This is a section division corresponding to the modulation timing of the codes “0”, “1” and “P” defined in the standard radio wave. In each of these sections, the number of times of HIGH of data sampled at 32 Hz is counted. However, there is data that is not counted between the two sections, and these unused data sections are buffer sections that substantially absorb variations in pulse width and the like.

In each section of A, B, C, and D, if it becomes HIGH more than the predetermined number of sampling times, the section is HIGH. For example, the number of samplings in the C section is 6 times in total, and among these, if HIGH is 4 times or more, the C section is HIGH. Then, the code determination of “0”, “1”, “P” is performed by the combination of HIGH or LOW in each section. For example,
{A section, B section, C section} = {HIGH, HIGH, LOW}
If it is, the code determination unit determines “1”. In this case, since section A to section B are HIGH, it is determined that the pulse width of this pulse is approximately 500 ms, and “1” is determined. If the period from the A section to the C section is HIGH, it is determined that the pulse width is approximately 800 ms, and the determination result is “0”.

  If the demodulated pulse is an ideal rectangle and has a width of 680 ms, out of 32 samplings in 1 bit, the first to 21st or 22nd sampling is HIGH, and HIGH of C section The number of times is 4 or 5. The 22nd sampling data may easily change to HIGH or LOW due to the sampling timing shift with respect to the demodulated waveform and the influence of noise.

  As described above, in the definition of Japanese time code, the codes “0” and “1” have pulse widths of 800 ms and 500 ms, respectively, and therefore, a pulse width of about 650 ms, which is an intermediate region between these pulse widths. However, if the reception state deteriorates, the pulse width varies in the output of the receiving means, and the reliability of code determination based only on the pulse width decreases. Therefore, as in the prior art disclosed in Patent Document 1, in a reception state where code determination is difficult, it is necessary to provide an error code and avoid code determination in order to avoid erroneous determination.

  An object of the present invention is to provide a standard radio wave receiving apparatus that can accurately perform code determination, accurately convert time information, and correct time even in a reception state where code determination is difficult.

  In order to achieve the above object, the standard radio wave receiver of the present invention employs the following configuration.

  The standard radio wave receiver according to the present invention represents a plurality of codes by a plurality of rectangular pulse widths included in a predetermined cycle, and time information assigned to a predetermined bit is a time code defined by the plurality of codes. Receiving means for receiving and demodulating the standard radio wave, and outputting an analog signal; AD converting means for converting the analog signal output by the receiving means into a digital signal; and output by the AD converting means The actual probability of each code obtained by arithmetic processing of the digital signal, and the theoretical probability obtained from the appearance probability of each code of each bit constituting the time code, which is known in advance from the regularity of the time code, And code determination means for performing code determination using the code and decoding the time code based on the result of the code determination And wherein the door.

  The standard radio wave receiving apparatus according to the present invention further comprises a reception state determination unit that determines the strength of the standard radio wave received by the reception unit in the above invention, wherein the code determination unit includes the reception state determination unit. The code determination is performed by changing the calculation coefficient of the actual measurement probability and the calculation coefficient of the theoretical probability based on the determination result of the means.

  Further, in the standard radio wave receiver according to the present invention, in the above invention, the code determination unit calculates an effective probability of each code using the actual measurement probability and the theoretical probability, and based on the calculated effective probability. And performing code determination.

  Further, the standard radio wave receiving apparatus according to the present invention includes a storage unit that stores at least one of the actual measurement probability, the effective probability, and the code determination result in the above invention, wherein the code determination unit includes: For the predetermined bit of the time code, the theoretical probability, the measured probability of the period of the time code being received, and the time code before the period of the time code being received stored in the storage means The code determination is performed using at least one of the actual measurement probability, the effective probability, and the code determination result of the period.

  The standard radio wave receiving apparatus according to the present invention further comprises a reception state determination unit that determines the strength of the standard radio wave received by the reception unit in the above invention, wherein the code determination unit includes the reception state determination unit. Based on the determination result of the means, the calculation coefficient of the actual probability of the period of the time code being received, the calculation coefficient of the theoretical probability, and the period of the time code being received stored in the storage means Code determination is performed by changing at least one calculation coefficient of the actual measurement probability, the effective probability, and the code determination result of the same bit having the same period of the previous time code.

  Further, the standard radio wave receiving apparatus according to the present invention includes a storage unit that stores at least one of the actual measurement probability, the effective probability, and the code determination result in the above invention, wherein the code determination unit includes: For the predetermined bit of the time code, the theoretical probability and the measured probability, effective probability, and code determination of the period of the time code prior to the period of the received time code stored in the storage means The probability of each code of a predetermined bit after the next bit is calculated using at least one of the results, and the AD conversion means is controlled based on the calculation result.

  The standard radio wave receiving apparatus according to the present invention further comprises a reception state determination unit that determines the strength of the standard radio wave received by the reception unit in the above invention, wherein the code determination unit includes the reception state determination unit. Based on the determination result of the means, the calculation coefficient of the theoretical probability and the actually measured probability of the same bit of the time code period before the time code period being received stored in the storage means, The code determination is performed by changing at least one of the effective coefficient and the code determination result.

  The standard radio wave receiving apparatus according to the present invention is selected by the transmission station selection means for selecting an arbitrary transmission station from the plurality of transmission stations transmitting the standard radio wave, and the transmission station selection means. Transmitting station switching control means for controlling the receiving means so as to switch to a transmitting station that receives the standard radio wave, and the storage means calculates the theoretical probability for each of the plurality of transmitting stations to be received. And the code determination means extracts the theoretical probability corresponding to the selected transmission station from the storage means, and extracts the measured probability of the standard radio wave transmitted from the selected transmission station. The code determination is performed using the theoretical probability.

  A radio-controlled timepiece according to the present invention includes the standard radio wave receiver described in any one of the above.

  Further, the time correction method according to the present invention represents a plurality of codes by a plurality of rectangular pulse widths included in a predetermined cycle, and time information assigned to predetermined bits is defined by the plurality of codes. Receiving a standard radio wave containing the signal, demodulating and outputting an analog signal, an AD conversion step for converting the analog signal output by the reception step into a digital signal, and an output from the AD conversion step The theoretical probability obtained from the actual measurement probability of each code obtained by arithmetic processing of the obtained digital signal and the appearance probability of each code constituting each time code that is known in advance from the regularity of the time code And a code determination step of performing code determination using the code, and decoding the time code based on a result of the code determination. It is characterized in.

  According to the present invention, even when the reliability of the received signal is lowered in an environment where the electric field strength is low and the S / N ratio is low, it is possible to accurately determine the time code and correct the time correctly. There is an effect that a standard radio wave receiver is obtained.

  Exemplary embodiments of a standard radio wave receiver, a radio wave correction watch, an electronic device, and a time correction method according to the present invention will be described below in detail with reference to the accompanying drawings.

[Description of configuration of standard radio wave receiver]
First, the configuration of a radio-controlled timepiece and electronic equipment including a standard radio wave receiver according to an embodiment of the present invention will be described. FIG. 1 is a block diagram showing the configuration of a radio-controlled timepiece (or electronic device) according to the present invention. In FIG. 1, the radio-controlled timepiece includes a standard radio wave receiving device 10, an oscillation circuit 20, a frequency dividing circuit 30, a time measuring circuit 40, a display unit 50, an audio output unit 60, a time information output unit 70, It has.

  Here, the clock circuit 40 counts time using a signal transmitted by the oscillation circuit 20 and frequency-divided by the frequency divider circuit 30. The time measuring circuit 40 corrects the time using the time code output from the standard radio wave receiver 10. The timer circuit 40 also controls the standard radio wave reception start time of the standard radio wave receiver 10.

  The display unit 50 displays the time measured by the time measuring circuit 40. Specifically, digital display or analog display using a pointer may be used.

  The sound output unit 60 outputs the time information timed by the time measuring circuit 40 as sound. The audio output unit 60 may output audio information other than time information based on the time counted by the time measuring circuit 40.

  The time information output unit 70 outputs various information other than the time based on the time counted by the time measuring circuit 40. Alternatively, the information output may be switched based on the time counted by the timing circuit 40.

  FIG. 2 is an explanatory diagram showing an example of the hardware configuration of the standard radio wave receiver of the present invention. In FIG. 2, the standard radio wave receiving apparatus 10 includes, for example, a CPU 11, a ROM 12, and a RAM 13. When the CPU 11 executes a program stored in the ROM 12, each function of each unit illustrated in FIG. 3 to be described later is realized. To do.

  The ROM 12 stores in advance various data including data relating to a theoretical probability 25 described later. The RAM 13 temporarily stores data acquired by the standard radio wave receiver or calculated by the CPU 11, including data related to the actual measurement probability 24 described later. Further, although not shown, a rewritable storage means for storing various data may be provided.

  FIG. 3 is a block diagram showing the configuration of the standard radio wave receiver of the present invention. In FIG. 3, the standard radio wave receiver 10 includes a receiving unit 100, an AD converting unit 200, a code determining unit 300, a storage unit 400, a reception state determining unit 500, a transmitting station selecting unit 600, and a transmitting station switching. The control means 700 is included.

  The receiving means 100 receives the standard radio wave transmitted from the transmitting station and demodulates it. The demodulated demodulated signal (analog signal) is output to the AD conversion means 200. The standard radio wave is a radio wave that represents a plurality of codes by a plurality of rectangular pulse widths included in a predetermined cycle, and includes time code in which time information assigned to predetermined bits is defined by the plurality of codes.

  The AD conversion means 200 receives the demodulated signal output from the receiving means 100 and converts it into a digital signal. The converted digital signal is output to the code determination means 300. Specific processing contents of the AD conversion will be described later.

  The code determination means 300 is a bit that constitutes a time code that is known in advance from the actual measurement probability 24 of each code obtained by arithmetic processing of the digital signal output from the AD conversion means 200 and the regularity of the time code. The code is determined using the theoretical probability 25 obtained from the appearance probability of each code. Specifically, for example, the effective probability 27 of each code is calculated using the actual measurement probability 24 and the theoretical probability 25, and code determination is performed based on the calculated effective probability 27. Then, the time code is decoded based on the code determination result (determination result 28).

  The storage unit 400 includes information regarding the actual measurement probability 24 calculated by the code determination unit 300, information regarding the effective probability 27, information regarding the determination result of the code determined by the code determination unit 300, and reception received by the reception state determination unit 500. Various information such as information on the state and a theoretical probability 25 obtained in advance is stored. The storage unit 400 realizes its function by the ROM 12 and the RAM 13 shown in FIG. 2 or a rewritable storage unit (not shown).

  The reception state determination unit 500 determines the strength of the standard radio wave received by the reception unit 100. Specifically, for example, the reception state is determined by detecting a specific voltage value or the like inside the reception unit 100. The reception state may be determined by calculation from the demodulated signal or the code determination result. In this case, the reception state determination unit 500 is included in the code determination unit 300.

  Then, the code determination unit 300 may perform code determination by changing the calculation coefficient of the actual measurement probability 24 and the calculation coefficient of the theoretical probability 25 based on the determination result of the reception state determination unit 500. . Details of the calculation coefficient will be described later (see FIGS. 9 and 12).

  The code determination means 300 uses the theoretical probability 25 and the time code being received for a predetermined bit of the time code (it may be performed for the entire bit or may be performed only for the predetermined bit). And at least the actual measurement probability 24, the effective probability 27, and the code determination result (determination result 28) of the time code period prior to the time code period being received stored in the storage unit 400. Any one of them may be used for code determination.

  Here, the theoretical probability 25 and the actual measurement probability 24 of the period of the time code being received are always used, but the actual measurement probability 24, the effective probability 27 of the period of the time code prior to the period of the time code being received, For the determination result 28, the actual measurement probability 24 may be used, the effective probability 27 may be used, or the determination result 28 may be used. Any one of them may be used alone, any two of them may be used in combination, or code determination may be performed using all three. In the flowchart of FIG. 11 described later, only the effective probability 27 is used.

  Further, in this case, the code determination means 300, based on the determination result of the reception state determination means 500, the calculation coefficient of the actual measurement probability 24 of the period of the time code being received, the calculation coefficient of the theoretical probability 25, and the storage means 400, at least one calculation coefficient of an actual measurement probability 24, an effective probability 27, and a code determination result (determination result 28) of the same bit of the time code period prior to the received time code period; , May be changed to perform code determination.

  Here, the calculation coefficient of the actual measurement probability 24 during reception and the calculation coefficient of the theoretical probability 25 are set independently, but the actual measurement probability 24 of the same bit in the period of the time code prior to the period of the time code being received. The calculation coefficients of the effective probability 27 and the determination result 28 may be set independently, or one calculation coefficient may be applied to each. In the flowchart of FIG. 11 described later, only the effective probability 27 is used, and only the calculation coefficient (calculation coefficient c) of the effective probability 27 is set.

  In addition, the code determination unit 300 has a theoretical probability 25 for a predetermined bit of the time code, an actual measurement probability 24 of the period of the time code prior to the period of the time code being received stored in the storage unit 400, effective Using at least one of the probability 27 and the code determination result (determination result 28), the probability of each code of a predetermined bit after the next bit is calculated, and the AD conversion means 200 is operated based on the calculation result. Control.

  Here, the theoretical probability 25 and the actual measurement probability 24 of the time code period being received are always used, but the actual probability 24 of the time code period prior to the period of the time code being received 24, the effective probability 27, and the determination For the result 28, the actual measurement probability 24 may be used, the effective probability 27 may be used, or the determination result 28 may be used. Any one of them may be used alone, any two of them may be used in combination, or code determination may be performed using all three. In the flowchart of FIG. 11 described later, only the effective probability 27 is used.

  Further, in this case, the code determination unit 300 is based on the determination result of the reception state determination unit 500 and the calculation coefficient of the theoretical probability 25 and the period of the time code being received stored in the storage unit 400. The code determination may be performed by changing at least one of the actual measurement probability 24, the effective probability 27, and the code determination result (determination result 28) of the bits having the same time code period.

  Here, the calculation coefficient of the actual measurement probability 24 during reception and the calculation coefficient of the theoretical probability 25 are set independently, but the actual measurement probability 24 of the same bit in the period of the time code prior to the period of the time code being received. The calculation coefficients of the effective probability 27 and the determination result 28 may be set independently, or one calculation coefficient may be applied to each. In the flowchart of FIG. 11 described later, only the effective probability 27 is used, and only the calculation coefficient (calculation coefficient c) of the effective probability 27 is set.

  The transmission station selection means 600 selects an arbitrary transmission station from a plurality of transmission stations that transmit standard radio waves. At that time, the tuning circuit 102 shown in FIG. 4 to be described later is switched to the standard radio wave frequency of each transmitting station to determine whether the standard radio wave of each transmitting station can be received. Then, an arbitrary transmitting station is selected from transmitting stations that transmit receivable standard radio waves. As a selection method, for example, a method of selecting a transmitting station with strong standard radio waves, a method of selecting a transmitting station that has received standard radio waves immediately before, a method of selecting a transmitting station that has received many standard radio waves in the past, etc. And so on.

  The transmission station switching control means 700 controls the reception means 100 so that the standard radio wave is switched and received by switching to the transmission station selected by the transmission station selection means 600. Specifically, the tuning circuit 102 is adjusted so that a radio wave having the standard radio frequency of the selected transmission station can be received.

  The storage unit 400 stores a theoretical probability 25 in advance for each of a plurality of transmission stations to be received. In addition, the code determination unit 300 extracts the theoretical probability 25 corresponding to the selected transmission station from the storage unit 400, and extracts the actual probability 24 of the standard radio wave transmitted from the selected transmission station and the storage unit 400. The code is determined using the theoretical probability 25. When the standard radio wave time code is different, the theoretical probability 25 is different. Therefore, it is extremely effective to store the theoretical probability 25 in the storage means 400 for each transmitting station (or each standard radio wave type).

  At this time, it is preferable to store the calculation coefficient to which the theoretical probability 25 of each transmitting station is applied in the storage unit 400. Since reception conditions such as the radio wave intensity of the standard radio wave are different for each transmission station, it is possible to perform more reliable code determination by changing the ratio at which the theoretical probability 25 is applied.

[Circuit configuration of receiving means]
FIG. 4 is a block diagram illustrating the circuit configuration of the receiving means of the standard radio wave receiver of the present invention. In FIG. 4, 101 is an antenna, 102 is a tuning circuit, 103 is an amplifier circuit, 104 is a filter circuit, 105 is a demodulation circuit, and 106 is an AGC control circuit.

  The frequency of the standard radio wave received by the antenna 101 is selected by the tuning circuit 102, the selected signal is amplified by the amplifier circuit 103, and noise is removed by the filter circuit 104. The demodulating circuit 105 demodulates the AM modulated wave and outputs it as a demodulated waveform reflecting a time code pulse. The reception state determination unit 500 determines the reception state by reading the voltage of the AGC control circuit 106 that works to complement the strength of the reception signal.

[Code determination in standard radio wave receiver (part 1)]
Next, the contents of another code determination in the standard radio wave receiver 10 of the present invention will be described. The following explanation shows a mathematical calculation procedure for obtaining the theoretical probability 25, and the code determination means 300 in the actual standard radio wave receiving apparatus calculates the theoretical probability 25 stored in advance in the storage means 400 and the timely calculation. The code determination is performed using the actual measurement probability 24 obtained by the above.

  FIG. 5 is a flowchart for explaining the code determination procedure of the standard radio wave receiver of the present invention. In the flowchart of FIG. 5, the demodulated waveform 21 demodulated by the demodulation circuit 105 of the receiving means 100 is AD converted by the AD converting means 200 to obtain a pulse signal 22 (step S1). The demodulated waveform 21 is, for example, an analog signal shown in FIG. The pulse signal 22 is a digital signal shown in FIG. 13 (b) or (c). The pulse signal 22 obtained in the AD conversion means 200 is sent to the code determination means 300.

  Next, the second synchronization processing is performed based on the obtained pulse signal 22 (step S2). In order to know the pulse width of each bit from the pulse waveform, it is necessary to find the timing of the beginning of the bit. Since 1 bit is assigned to 1 second, this process is called second synchronization. The code determination unit 300 detects the rising position of the pulse signal 22 as second synchronization, and sets the rising position as the start of each second, that is, each bit in the pulse signal 22. Then, the time to fall from that position is calculated as the pulse width 23.

[Calculation processing of actual probability]
Next, the actual measurement probability 24 is calculated (step S3). For the actual measurement probability 24, any numerical value can be used as long as it quantitatively indicates “each code“ likeness ”” obtained from the digital signal output from the AD conversion means 200 for a certain bit. .

A case of Japanese standard radio waves will be described as an example. FIG. 6 is a diagram for explaining the pulse widths of “0”, “1”, and “P” codes in the time code of Japanese standard radio waves. For example, when AD conversion is binary, the measured pulse width of each code of “0”, “1”, “P” by the receiving means 100 is centered on the pulse width value in the time code definition shown in FIG. If it is known that the value has a characteristic that has a normal distribution as a value, it is possible to statistically obtain the probability of each code for the measured pulse width of a certain bit. Assuming that the probability of each code of a received bit obtained from the normal distribution characteristic of the receiving means 100 is Q ⁱ _m , the actual measurement probability P ⁱ _m is expressed by the following equation (1).

  Here, i is an index corresponding to each code, and “0”, “1”, or “P” is entered in the case of Japanese standard radio waves. When the AD conversion output is multi-valued, it is possible to calculate a more precise “each code“ likeness ””. Even if the AD conversion is binary, the “each code“ likeness ”” is precisely calculated by combining a plurality of pieces of information such as the pulse width and the pulse fall time, and the above equation (1) is used. It is also possible to obtain the actual measurement probability 24.

[How to find theoretical probability]
Next, how to obtain the theoretical probability 25 will be described. The appearance probability (theoretical probability 25) of each code in each bit of the time code is determined for each definition of the time code, and is different for each transmitting station. In the following explanation, Japanese standard radio waves are shown as an example. FIG. 7 is a diagram for explaining the time code of Japanese standard radio waves. FIG. 8 is a chart showing theoretical probabilities 25 of “0”, “1”, “P” in the time code of Japanese standard radio waves. Each time information numerical value and each theoretical probability 25 of “0”, “1”, “P” are associated with each other.

  Since any one of “0”, “1”, and “P” is entered, the sum of the theoretical probabilities 25 of “0”, “1”, and “P” is all “1.00”. For the sake of convenience, the theoretical probability 25 shown in FIG. 8 is neglected when the probability of appearing is very low. The theoretical probability 25 obtained in this way is stored in advance in the storage means 400 (specifically, ROM 12 or the like), and is used for numerical processing in code determination.

  As an example of how to determine the appearance probability of each code, the “1” bit (bit No. 8 in FIG. 8) of “minute” of the time shown in FIG. 7 will be described. The “minute” of the time is an integer value from 00 minutes to 59 minutes, and is incremented by 1 every fixed time of 60 seconds, and the next 59 minutes returns to 00 minutes. Thirty even and odd numbers appear alternately in the 1 / 59-59 period. That is, the probability that an even number or an odd number appears is ½. All the time information numerical values of bits other than the “1” bit of the “minute” are even numbers, and it is the “1” bit of the “minute” that determines the odd and even number of minutes. Therefore, the probability that the “1” bit of “minute” is “0” or “1” is ½ (theoretical probability: 0.50).

  On the other hand, the “40” bit (bit No. 1 in FIG. 8) of “minute” becomes “1” when the minute has a value of 40 or more, and is between 40 minutes and 59 minutes. The probability that “1” appears in 40 bits is (59−39) / 60 = 1/3. Therefore, the probability that 40 bits of the minute are “0” is 2/3 (theoretical probability: 0.67).

  In the same manner, the appearance probability of each code in each bit such as a time block and a calendar block can be obtained. A fixed bit of “P” or “0” inevitably has a probability that the bit appears 100% (theoretical probability 25: 1.00), and the probability that another code appears is 0 (theoretical probability 25: 0.00). On the other hand, as in the above example, the appearance probability of “P” in the bit to which time information is assigned and fluctuates is zero.

[Effective probability calculation process]
Next, an effective probability 27 calculation process (step S4) and a code determination process (step S5) are performed. As described above, when the actual measurement probability 24 and the theoretical probability 25 are obtained, the effective probability 27 that is directly used for code determination can be obtained by the equation (2) (step S4). The reception state 26 will be described later.

Here, P ⁱ _e , P ⁱ _t , and P ⁱ _m are an effective probability 27, a theoretical probability 25, and an actual measurement probability 24, respectively, and i is an index corresponding to a code. ",""1", or "P" is entered. The calculation coefficients a and b are calculation coefficients of the theoretical probability 25 and the actual measurement probability 24, respectively. The effective probability 27 is obtained for each code, and a code determination process is performed in which the code having the highest effective probability 27 is determined as a determination result 28 (step S5).

  FIG. 10 is a diagram for explaining a difference between code determination using only the actual measurement probability 24 and code determination using the actual measurement probability 24 and the theoretical probability 25. In FIG. 10, for example, as a result of the measurement probability 24, if the pulse width is around 800 ms, it is “0”, if the pulse width is around 500 ms, it is “1”, and if the pulse width is around 200 ms, It can be determined that it is “P”, but if the pulse width is 650 ms as in “bit No. 5”, it is exactly halfway between 800 ms and 500 ms, and neither “0” nor “1” can be determined. . Therefore, only with the actual measurement probability 24, the code determination is NG.

  Therefore, in consideration of the theoretical probability 25, the theoretical probability 25 in “bit No. 5” is as shown in FIG. 8 where the theoretical probability 25 of “0” is 0.80 and the theoretical probability of “1”. Since the probability 25 is 0.20, it is determined that it is “0” in consideration of it. In this way, it is possible to more accurately determine the bit that causes an error only by the actual measurement probability 24.

  Further, the calculation coefficients a and b can be used as fixed values depending on the characteristics of the receiving means 100. However, an accurate code determination is performed by making the calculation coefficient a or the calculation coefficient b variable according to the reception state 26. Is possible. As an example of making the calculation coefficient variable, a variable method corresponding to the reception state 26 is shown in FIG. FIG. 9 shows an example of a typical combination of calculation coefficients a and b when the reception state determination unit 500 can determine the reception state 26 in three stages.

  FIG. 9 is a diagram for explaining a combination of the reception state 26 and the calculation coefficients a and b. In FIG. 9, for example, the reception state 26 is divided into three stages of “good”, “normal”, and “bad”, respectively. The numerical values of the coefficients a and b are changed. When the reception state 26 is “good”, an accurate determination can be made only with the actual measurement probability 24. Therefore, the calculation coefficient a = 0.00, the calculation coefficient b = 1.00, and the theoretical probability 25 is not used.

  On the other hand, when the reception state 26 is “bad”, it is determined that an accurate determination cannot be made with only the actual measurement probability 24, the calculation coefficient a = 0.25, the calculation coefficient b = 0.75, and the theoretical probability. It is possible to increase the ratio of using 25 and avoid a state where determination is impossible as much as possible. When the reception state 26 is “normal”, the numerical values of the calculation coefficients a and b are set so that the ratio is between the “good” case and the “bad” case.

  When the reception state 26 is good, the reliability of the digital signal that is the output signal of the AD conversion means 200 is high, and sufficient code determination can be performed with only the actual measurement probability 24. Since the reliability of the digital signal decreases as the reception state 26 becomes worse, the code determination accuracy is maintained by increasing the specific gravity of the theoretical probability 25.

  In addition, the reception state 26 may include conditions of the transmitting station. As the transmission condition, for example, in the case of Japanese standard radio waves, the calculation coefficients a and b may be made variable depending on which radio wave is received from two transmitting stations of 40 kHz and 60 kHz. In this case, in the case of reception from the previously received transmission station or from the transmission station that has received many in the past, the ratio of the calculation coefficients a and b is increased, and conversely, the transmission station other than the previously received transmission station or the past In the case where the number of times of reception is smaller than that of other transmitting stations, the ratio of the arithmetic coefficients a and b can be lowered.

  Further, the current position detection function such as GPS may be used to acquire the distance between the current position and the transmitting station, and the calculation coefficients a and b may be made variable according to the acquired distance. In this case, a predetermined threshold value is provided for the distance, and if the distance is closer than the threshold value, the ratio of the calculation coefficients a and b is increased. Conversely, if the distance is greater than the threshold value, the ratio of the calculation coefficients a and b is decreased. it can.

  In the case of a standard radio wave receiver mounted on a portable information processing apparatus such as a wristwatch, it is effective to perform an effective probability calculation process in consideration of the reception state 26 described above. Data relating to the reception state 26 and a program to which the data is applied are stored in the storage unit 400 shown in FIG. 3 (specifically, the ROM 12 or the RAM 13 or other storage unit shown in FIG. 2).

[Code determination in standard radio wave receiver (part 2)]
Next, the contents of code determination in the standard radio wave receiver 10 of the present invention will be described. As described above, the code determination unit 300 in the actual standard radio wave receiver 10 simply performs code determination using the theoretical probability 25 stored in advance in the storage unit 400 and the actual measurement probability 24 obtained by occasional calculation. Rather, it performs code determination using data obtained during reception. When receiving two or more time codes, the effective probability 24 of each bit obtained in the time code period before the time code period being received, the code determination result 28, etc. are stored in the storage means 400, Can be used to determine the code in the bit being received.

  FIG. 11 is a flowchart for explaining another procedure of code determination of the standard radio wave receiver of the present invention. In the flowchart of FIG. 11, the steps S1 to S3 and the demodulated waveform 21, pulse signal 22, pulse width 23, and actual measurement probability 24 are the same as those in steps S1 to S3 and the demodulated waveform 21, pulse signal in the flowchart of FIG. 22, the pulse width 23, and the actual measurement probability 24 are the same, and the description is omitted.

  The effective probability 27 is calculated in the effective probability calculation process (step S4) in the flowchart of FIG. The effective probability 27 is stored in the storage means 400 (step S6). In addition to the effective probability 27, the actual probability 24 and the determination result 28 obtained by the code determination process (step S5) in the flowchart of FIG. 5 may be stored together with the effective probability 27. Instead, the actual measurement probability 24 or the determination result 28 may be stored.

  Next, processing related to minute synchronization is performed (step S7), and effective probability 27 stored in the storage unit 400 is extracted (step S8). Minute synchronization refers to a process of searching for the beginning of one period of a time code because many time codes make one round in one minute. Specifically, the bit No. 59 “P” and bit No. By acquiring two consecutive “P” s of “P” s of 0, the head of one cycle can be searched.

When the time code period when the reception is started is the 0th period and the currently received time code period is the (n + 1) th period, there is a time code obtained from the 0th to the nth time code period. The bit effective probability 27 (or the actual measurement probability 24 or the determination result 28) may be expressed as R _j (j: 0... N). At this time, the effective probability 29 of the bit having the period of the time code being received is expressed by the following expression (3) obtained by extending the above expression (2).

Here, c _j (j: 0... N) is an arithmetic coefficient of R _j , and the index i of the code is a specific code, and “0”, “1”, One of “P” is common to all terms on the left and right sides. Equation (3) is limited when this bit is a bit that does not change in the 0th to (n + 1) th time code period. This is because, for example, when receiving from time 12:00 to time 12:10, the information of “hour” does not change, so all the bits of “hour” to be transmitted are fixed during reception. Is the case.

  On the other hand, if the bit to be determined is a bit that changes while receiving a plurality of time code periods, it must be taken into account. For example, since one period of a Japanese time code is one minute, information to be transmitted changes every time code period. As an example, the effective probability 29 of one-half bit (FIG. 8, bit 8) is obtained by Expression (4) obtained by modifying Expression (3).

Here, i and j are indices corresponding to codes, but different codes are assigned to i and j. When i is “0”, j is “1”. The third and subsequent R terms have i and j alternately so as to correspond to code changes. In the example of Expression (4), n is an even number and the index of the term R ₀ is i. However, when n is an odd number, the index of the term R ₀ is j, and the terms i and j after the term R ₁ are used. And alternately. In this way, the effective probability 29 is calculated (step S9). Then, the effective probability 29 calculated in step S9 is obtained for each code, and code determination processing is performed in which the determination result 30 is the code having the highest effective probability 29 (step S10).

Also, when using the above formulas (3) and (4), as in the case of formula (2), the calculation coefficients a, b, and c are changed according to the reception state 26 and the like to change the specific gravity of each term. It is also possible. FIG. 12 is a diagram for explaining a combination of the reception state 26 and the calculation coefficients a, b, and c. In Figure 12, similarly to FIG. 9, "good" reception status 26 for example, "normal", in three stages of "bad", respectively, coefficients _{a, b, c (c 0} ··· c n ) Is changed. When the reception state 26 is “good”, an accurate determination can be made with only the actual measurement probability 24. Therefore, the calculation coefficient b = 1.00 / (n + 2) and each of the n + 1 calculation coefficients c = 1.00 / (n + 2). The calculation coefficient a = 0.00, and the theoretical probability 25 is not used.

  On the other hand, when the reception state 26 is “bad”, it is determined that an accurate determination cannot be made only with the actual measurement probability 24, and the calculation coefficient b = 0.90 / (n + 2) and each of the n + 1 calculation coefficients c = 0. .90 / (n + 2), the calculation coefficient a is set to 0.10, the ratio using the theoretical probability 25 is increased, and an indeterminate state can be avoided as much as possible. When the reception state 26 is “normal”, the numerical values of the calculation coefficients a, c, and b are set so that the ratio is between the “good” case and the “bad” case. Further, as described in the flowchart of FIG. 5 described above, the reception state 26 may include conditions of the transmitting station.

[Control of AD conversion means]
Next, control of the AD conversion means 200 using the theoretical probability 25 will be described. FIG. 13 is a diagram for explaining the relationship between the output waveform of the receiving means of the standard radio wave receiving apparatus of the present invention and the output signal of the AD converting means.

  Using the theoretical probability 25, or the theoretical probability 25 and the data of the time code period prior to the time code period being received stored in the storage means 400 during reception, one of the bits preceding the bit being received is used. Alternatively, the accuracy of code determination is increased by predicting a plurality of previous bits and changing the characteristics of the constituent elements of the standard radio wave receiver 10 in accordance therewith to increase or decrease the probability that a specific code is determined. be able to.

As an example of the control of the AD conversion unit 200, a method of controlling the characteristics when the AD conversion unit 200 performs binarization of HIGH and LOW will be described. While receiving a bit, use the stored data of the theoretical probability 25 of the bit before that bit, or the theoretical probability 25 and the period of the time code prior to the period of the time code being received, Find the prediction probability of each code in bits. In general, the prediction probability P ⁱ _p is obtained by deleting the actual measurement probability P _m from the equation (3), and can be expressed by the following equation (5).

If the data accumulated during reception is not used, the right side is only the first term, so if the calculation coefficient is standardized, a = 1. Therefore, P ⁱ _p = P ⁱ _t and the prediction probability is the same as the theoretical probability 25. In the control example of the AD conversion unit 200, for example, when the prediction probability of “1” for the next bit is higher than the prediction probability of other codes, the threshold for binarization of the AD conversion unit 200 is changed. Control is performed so that “1” is easily detected.

  This will be specifically described with reference to the waveform of FIG. 13 (a) schematically shows a demodulated waveform (analog signal), and FIGS. 13 (b) and 13 (c) schematically show pulse signals output from the AD conversion means, with the horizontal axis representing time and the vertical axis representing signal. Is the value of

  The broken horizontal line in FIG. 13A is a threshold for binarization in the AD conversion means 200. The AD conversion means 200 outputs HIGH when the demodulated waveform exceeds this threshold value, and outputs LOW when the demodulated waveform falls below the threshold value. The output of the AD conversion means 200 becomes a pulse signal as shown in FIGS.

  In a situation where the reception state 26 is very good, the demodulated waveform is close to a rectangular wave reflecting the original time code, but when the reception state 26 deteriorates, the waveform becomes dull as shown in FIG. In such a case, the pulse width tends to be narrowed. Therefore, by lowering the threshold value, the output pulse width becomes wider, and “0” is more easily determined than “1”.

  The threshold value can be changed by switching the resistance value, the capacitor capacity, or the like with a switch so that other components of the standard radio wave receiver 10 such as the tuning circuit 102 and the AGC control circuit 106 can be controlled based on the prediction probability. As a result, similar to the control of the AD conversion means 200, it is possible to increase the probability that a specific code is detected and to increase the accuracy of code determination.

  As described above, when the standard radio wave receiving apparatus 10 is controlled using the prediction probability of each code of bits prior to reception, the code is calculated using any one of the equations (2), (3), and (4). Although the determination can be made, the optimum combination is selected for the standard radio wave receiver 10 required by the calculation capability, power consumption, etc. of the code determination means.

[Explanation of station switching]
As described above, the definition of the time code varies depending on the transmitting station, but by storing the theoretical probability 25 for each transmitting station in the storage unit 400 in advance, it is possible to correspond to a plurality of transmitting stations. In addition, since the carrier frequency and AM modulation degree differ depending on the transmitting station, the output characteristics of the receiving means 100 corresponding to the carrier frequency also vary. However, by setting the mathematical expression and calculation coefficient used for code determination for each transmitting station, It can respond to changes.

  As described above, according to the embodiment of the present invention, even if the reception environment is deteriorated and the reliability of the output of the standard radio wave receiving means is reduced, and it becomes difficult to separate each code, the theoretical probability 25 is set. By using it, accurate code determination can be performed and accurate time information can be provided. In addition, when receiving a plurality of time codes in order to improve the reliability of acquired information, comparison and correction with a small amount of data can be performed based on an accurate code determination result, and reception time can be shortened.

  Since the reception time can be shortened, power consumption can be reduced, and problems caused by the time not being displayed during time correction can be reduced.

  In the embodiment described above, the standard radio wave receiver of the present invention is an example of a radio wave correction watch. Since the standard radio wave receiver of the present invention can provide time information accurately even if the reception state 26 deteriorates, it can be used from a small radio wave correction watch such as a wrist watch having many physical restrictions on the antenna and the receiving circuit, and from an indoor window. It is suitable for a radio wave correction watch at a remote location.

  The standard radio wave receiver of the present invention is not limited to this, and is a mobile phone or PDA (Personal Digital Assistant), personal computer, measuring device, communication device, electronic device manufacturer, etc., which incorporates a device that receives a standard radio wave. It may be a portable information terminal device (such as a game machine or a digital camera) such as a standard device, a standard oscillator for terrestrial digital broadcasting, or a portable music player. In addition, the present invention can be applied to an item that requires accurate time information, such as an electronic advertisement using a display.

  The standard radio wave receiving apparatus of the present invention includes a standard radio wave receiving apparatus that receives a standard radio wave including time information, and in particular, a radio wave correction clock and a radio wave correction clock that correct time based on time information included in the received standard radio wave. It is suitable for a time correction method for correcting the time based on the built-in electronic device and the time information included in the received standard radio wave.

It is a block diagram which shows the structure of the radio wave correction timepiece (or electronic device) of this invention. It is explanatory drawing which shows an example of the hardware constitutions of the standard radio wave receiver of this invention. It is a block diagram which shows the functional structure of the standard radio wave receiver of this invention. It is a block diagram explaining the circuit structure of the receiving means of the standard wave receiver of this invention. It is a flowchart explaining the procedure of the code | cord | chord determination of the standard radio wave receiver of this invention. It is a figure explaining the pulse width of "0", "1", and "P" code in the time code of Japanese standard radio waves. It is a figure explaining the time code of Japanese standard radio waves. It is a chart showing theoretical probabilities of “0”, “1”, and “P” in Japanese standard radio time code. It is a figure explaining the combination of a receiving state and the calculation coefficients a and b. It is a figure explaining the difference between the code determination when only the actual measurement probability is used and the code determination when the actual measurement probability and the theoretical probability are used. It is a flowchart explaining another procedure of the code | cord | chord determination of the standard radio wave receiver of this invention. It is a figure explaining the combination of a receiving state and the calculation coefficients a, b, and c. It is a figure explaining the relationship between the output waveform of the receiving means of the standard wave receiver of this invention, and the output signal of AD conversion means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Standard radio wave receiver 100 Reception means 101 Antenna 102 Tuning circuit 103 Amplification circuit 104 Filter circuit 105 Demodulation circuit 106 AGC control circuit 200 AD conversion means 300 Code determination means 400 Storage means 500 Reception state determination means 600 Transmission station selection means 700 Transmission station Switching control means

Claims (10)

Representing a plurality of codes by a plurality of rectangular pulse widths included in a predetermined period, receiving and demodulating a standard radio wave including a time code in which time information assigned to a predetermined bit is defined by the plurality of codes, Receiving means for outputting an analog signal;
AD conversion means for converting the analog signal output by the receiving means into a digital signal and outputting the digital signal;
Appearance of each code of each bit constituting the time code obtained in advance from the actual measurement probability of each code obtained by arithmetic processing of the digital signal output by the AD conversion means and the regularity of the time code Code determination means for performing code determination using a theoretical probability obtained from the probability, and decoding the time code based on the result of the code determination;
A standard radio wave receiver characterized by comprising: A reception state determining means for determining the strength of the standard radio wave received by the receiving means;
The code determination unit performs code determination by changing the calculation coefficient of the actual probability and the calculation coefficient of the theoretical probability based on a determination result of the reception state determination unit. The standard radio wave receiver according to 1.   3. The code determination unit according to claim 1, wherein the code determination unit calculates an effective probability of each code using the actual measurement probability and the theoretical probability, and performs code determination based on the calculated effective probability. Standard radio wave receiver. Storage means for storing at least one of the actual measurement probability, the effective probability, and the code determination result;
The code determination means, for the predetermined bit of the time code, the theoretical probability, the measured probability of the period of the time code being received, and the time code being received stored in the storage means The standard radio wave receiver according to claim 3, wherein the code is determined using at least one of the actual measurement probability, the effective probability, and the code determination result of the period of the time code before the period. A reception state determining means for determining the strength of the standard radio wave received by the receiving means;
The code determination means is stored in the storage means based on the determination result of the reception state determination means, the calculation coefficient of the actual probability of the period of the time code being received, the calculation coefficient of the theoretical probability. Code determination by changing at least one of the actual measurement probability, the effective probability, and the code determination result of the same bit of the time code period prior to the time code period being received The standard radio wave receiver according to claim 4, wherein: Storage means for storing at least one of the actual measurement probability, the effective probability, and the code determination result;
The code determination means, for the predetermined bit of the time code, the theoretical probability and the measured probability of the period of the time code prior to the period of the time code being received stored in the storage means, Calculating the probability of each code of a predetermined bit after the next bit using at least one of the effective probability and the result of code determination, and controlling the AD conversion means based on the calculation result The standard radio wave receiver according to claim 3. A reception state determining means for determining the strength of the standard radio wave received by the receiving means;
The code determination means, based on the determination result of the reception state determination means, the calculation coefficient of the theoretical probability and the time code before the time code period being received stored in the storage means. 7. The standard radio wave receiving apparatus according to claim 6, wherein code determination is performed by changing at least one of the actual measurement probability, the effective probability, and the code determination result of the bits having the same period. . A transmitting station selecting means for selecting an arbitrary transmitting station from a plurality of transmitting stations transmitting the standard radio wave;
A transmission station switching control means for controlling the reception means so as to switch to the transmission station selected by the transmission station selection means and receive the standard radio wave;
With
The storage means stores the theoretical probability for each of the plurality of transmitting stations to be received;
The code determination means extracts the theoretical probability corresponding to the selected transmission station from the storage means, the measured probability of the standard radio wave transmitted from the selected transmission station, and the extracted theoretical The standard radio wave receiver according to any one of claims 1 to 7, wherein the code determination is performed using a general probability.   A radio-controlled timepiece comprising the standard radio wave receiver according to any one of claims 1 to 8. Representing a plurality of codes by a plurality of rectangular pulse widths included in a predetermined period, receiving and demodulating a standard radio wave including a time code in which time information assigned to a predetermined bit is defined by the plurality of codes, A receiving step of outputting an analog signal;
An AD conversion step of converting the analog signal output by the reception step into a digital signal and outputting the digital signal;
Appearance of each code of each bit constituting the time code obtained in advance from the actual measurement probability of each code obtained by arithmetic processing of the digital signal output by the AD conversion step and the regularity of the time code A code determination step of performing code determination using a theoretical probability obtained from a probability, and decoding the time code based on a result of the code determination;
The time correction method characterized by including.

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