JP2006105606A - Radio-controlled timepiece, and standard radio wave receiving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio controlled timepiece and a standard radio wave receiving method capable of accurately determining the waveform, even when the difference between the modulation parts (or the nonmodulation parts) for the received standard radio wave is small. <P>SOLUTION: A clock signal different in oscillation timing from a specified clock signal is generated by a sampling addition circuit 10, based on the specified clock signal output from an oscillation circuit 5 for sampling. The generated clock signal is added to the specified clock signal output to a sampling circuit 4 and is output from the oscillation circuit 5. The sampling circuit 4 samples a demodulated waveform, in accordance with the clock signal added by this manner. A sampling frequency specified preliminarily by a microcomputer is increased thereby, and the sampling period in the sampling circuit 4 is substantially shortened to enhance the reliability for determining the waveform. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radio wave correction watch and a standard radio wave reception method.

  At present, in Japan, the United States, Germany, and the like, a so-called long wave standard radio wave that transmits time information using a frequency of several tens of kHz as a carrier wave is transmitted. Modified watches are becoming popular. (For example, see Patent Document 1)

  FIG. 4 is a diagram showing a pulse (demodulation) waveform of a standard radio wave in Japan, the United States, and Germany. Thus, the standard radio wave includes a carrier frequency, a transmission data format, data “0” and “1”, a marker. The pulse waveforms representing “P”, “M”, etc. vary from country to country.

  In the transmission data format, time data is transmitted at 1 bit / second. In Japan, the United States, and Germany, one minute is one frame. Within this frame, “minute”, “hour”, and January 1 Information such as “integrated date”, last two digits of “year”, “day of the week”, and the like is included.

  In order to extract the above information from the received standard radio wave, the transmitted data is sampled every second to determine the waveform. FIG. 5 is a block diagram showing a schematic configuration of a conventional radio-controlled timepiece, FIG. 6 is a diagram showing Japanese transmission data (demodulated waveform) and its sampling timing, and FIG. 7 is a waveform discrimination method based on the sampling result. It is a figure for doing. First, the standard radio wave received by the antenna 1 is amplified by the reception circuit 2 and output to the demodulation circuit 3. The demodulator circuit 3 demodulates the standard radio wave amplified by the receiver circuit 2 through a filter circuit, a rectifier circuit, a detector circuit, etc. (all not shown), and converts the modulation waveform of the standard radio wave into a demodulated waveform that is a square wave. Output to.

  The sampling circuit 4 samples the demodulated waveform output from the demodulating circuit 3 at the timing of two time points Ta and Tb as shown in FIG.

  The oscillation circuit 5 generates a clock signal having a predetermined oscillation period in hardware by a microcomputer and outputs the clock signal to the sampling circuit 4. The sampling circuit 4 generates a demodulated waveform according to the oscillation period of this clock signal, that is, the sampling period. Sampling is performed.

  Although FIG. 6 illustrates the case where sampling is performed at the timing of two time points Ta and Tb with respect to transmission data for one second, actually, it is several tens of times (for example, 32 for transmission data for one second). Sampling).

  The waveform discriminating unit 6 discriminates the "High" or "Low" state of the demodulated waveform at each sampling timing Ta and Tb according to the sampling of the sampling circuit 4, and based on the information, the demodulated waveform is converted into a digital signal. Convert.

  For example, as shown in FIG. 7, if Ta and Tb are “High” and “High”, respectively, they are recognized as “0” code waveforms, and if Ta and Tb are “High” and “Low”, respectively, It is recognized as a waveform of a “1” code. If Ta and Tb are “Low” and “Low”, respectively, it is recognized as a waveform of a “P” code.

  The digital signal output from the waveform discriminating unit 6 as described above is sent to the time specifying circuit 7 and read out as time information, and the result is output to the time measuring circuit 8. The time measuring circuit 8 corrects the time based on the time information output from the time specifying circuit 7 and displays it on the display unit 9.

Note that the shorter the sampling period, the greater the number of samplings and the more reliable the waveform discrimination. However, in the standard radio waves in Japan and the United States, as shown in FIG. Part) Since the difference between M0 and M1 (M0-M1 = 300 ms) is relatively large and the discrimination between the codes is easy, 31.25 ms is common, and a shorter sampling period is not required.
JP 2003-222687 A

  In a radio-controlled timepiece, the reception accuracy of a receiving circuit is greatly influenced by the electric field strength of a standard radio wave to be received and the ratio of signal components to noise components (hereinafter referred to as S / N). The receiving circuit can accurately receive the transmission waveform of the standard radio wave in a good S / N environment, but it is difficult to obtain an accurate reception result when the electric field strength of the standard radio wave becomes weak or the S / N value becomes small. Become.

  In particular, in the transmission waveform in Germany, as shown in FIG. 4, the modulation part M0 of the “0” code is 100 ms, the modulation part M1 of the “1” code is 200 ms, and the difference between the modulation parts (or non-modulation parts) M0 and M1 (M1-M0 = 100 ms) is smaller than the standard radio waves of other countries. In addition, as described above, when the electric field strength of the standard radio wave becomes weak or the S / N becomes small, the modulation units M0 and M1 become unnecessarily long or short.

  FIG. 8 shows a demodulated waveform of the German standard radio wave when the electric field strength becomes weak or the value of S / N becomes small. In this way, the modulation part (or non-modulation part) M0, M1 of the demodulated waveform is shown. If it becomes unnecessarily long or short, sampling with a sampling period of 31.25 ms may not be able to accurately determine the waveform because the sampling period is too long.

  For example, when a demodulated waveform representing a “0” code (positive) as shown in FIG. 8 is sampled at a sampling period of 31.25 ms, the maximum number of times the modulation unit M0 is sampled is 3 by 100 / 31.25. "Low" is output three times in succession.

  On the other hand, the maximum number of times the demodulated waveform (non-modulation part) other than the modulation part M0 is sampled is 29 times 900 / 31.25, and “High” is output 29 times continuously.

  The discrimination of the demodulated waveform is to count how many times "High" and "Low" of the demodulated waveform appear and how many times appear in the number of samplings per second (32 times according to 1000 / 31.25). Done in

  For example, as described above, after “Low” is output three times continuously and “High” is output 29 times continuously, it is recognized as a “0” code.

  Such a waveform recognition definition is arbitrarily determined in advance, but normally an error of about ± 1 or 2 is allowed in the number of continuous output of “High” or “Low”.

  For example, when a demodulated waveform of “0” code (positive) is sampled, if the allowable error is ± 1, the allowable range of “Low” continuous output is 2 to 4 times, and “High” is 28 to 30 times. It becomes.

  In other words, as long as the allowable error is ± 1 as described above, even if “Low” is output four times continuously instead of three times, it is within the error allowable range. Is recognized as normal.

  However, if the demodulated waveform unnecessarily extends from the normal value of 100 ms to the abnormal value of 160 ms, such as the “0” code (error) shown in FIG. 8, the number of times “Low” is continuously output is 160. /31.25, which is 5 times, which exceeds the allowable error range of 2 to 4 times of “Low” continuous output times.

  On the other hand, for the “1” code, as in the “0” code, for example, an allowable error of ± 1 is set. In this case, the error allowable range of the number of continuous outputs of “Low” in the modulation unit M1 is It becomes 5 to 7 times in ± 1 time in 6 times by 200 / 31.25.

  Then, the “Low” continuous output count (5 times) when the “0” code (error) modulation unit M0 is sampled falls within the error tolerance range (5 to 7 times) of the “1” code. Therefore, a demodulated waveform that should be recognized as a “0” code may be erroneously recognized as a “1” code. Even if erroneous recognition is not performed, it is recognized as NG when the number of continuous outputs of “Low” or “High” falls within an undefined range.

  That is, it becomes difficult to determine the waveform representing each code. If the waveform cannot be discriminated accurately, the time information included in the standard radio wave is mistakenly recognized, or the NG process is performed because it cannot be discriminated.

  Since the sampling period is predetermined in hardware by the microcomputer, it cannot be changed substantially.

  It is also possible to shorten the sampling period by simply changing the microcomputer to be used from one having a sampling period of 31.25 ms to one having a half sampling period of 15.625 ms, but a microcomputer having a short sampling period is generally used. Expensive.

  An object of the present invention is to provide a radio-controlled timepiece and a standard radio wave receiving method capable of accurately receiving a standard radio wave without causing an increase in cost.

at least,
A receiving means for receiving a standard radio wave including time information;
Demodulation means for demodulating the standard radio wave received by the receiving means and outputting a demodulated signal;
An oscillating means for outputting a first clock signal for sampling the demodulated signal;
A clock signal generating means for generating a second clock signal having a different oscillation timing from the first clock signal based on the first clock signal;
Sampling means for sampling the demodulated signal based on the first and second clock signals;
Waveform determining means for determining the waveform of the demodulated signal based on the sampling result of the sampling means;
A radio-controlled timepiece having time specifying means for reading time information included in the standard radio wave based on a waveform discrimination result of the waveform discrimination means.

  The second clock signal is a radio-controlled timepiece generated by delaying the first clock signal for a predetermined time.

  The oscillation timing of the second clock signal is a radio wave correction timepiece that is a timing located in the middle of the oscillation timing of the first clock signal.

The first clock signal has an oscillation period of 31.25 ms.

at least,
A receiving step for receiving a standard radio wave including time information;
A demodulation step of demodulating the standard radio wave received by the receiving means and outputting a demodulated signal;
An oscillation step of outputting a first clock signal for sampling the demodulated signal;
A clock signal generating step for generating a second clock signal having a different oscillation timing from the first clock signal based on the first clock signal;
A sampling step of sampling the demodulated signal based on the first and second clock signals;
A waveform determining step for determining a waveform of the demodulated signal based on a sampling result of the sampling step;
A standard radio wave receiving method comprising: a time specifying step of reading time information included in the standard radio wave based on a waveform discrimination result of the waveform discrimination step.

  The second clock signal is a standard radio wave receiving method generated by delaying the first clock signal for a predetermined time.

  The standard radio wave reception method is used in which the oscillation timing of the second clock signal is a timing located in the middle of the oscillation timing of the first clock signal.

  The oscillation frequency of the first clock signal is a standard radio wave receiving method of 31.25 ms.

  In the present invention, the sampling frequency of the microcomputer is substantially shortened by increasing the number of sampling times in software for sampling whose number is defined (limited) in advance by hardware. Reliability in determining the waveform is improved. Further, since it is sufficient to use the same low-frequency microcomputer as the conventional one as it is, it is not necessary to replace it with an expensive high-frequency microcomputer, and the cost is not increased.

  FIG. 1 is a block diagram showing a schematic configuration of a radio-controlled timepiece according to the present invention, FIG. 2 is a diagram showing Japanese transmission data (demodulated waveform) and its sampling timing, and FIG. 3 is a waveform discrimination method based on the sampling result. It is a figure for demonstrating. However, FIG. 2 is schematically shown for easy viewing, and the line spacing and the like are not proportional. Hereinafter, an embodiment of the present invention will be described with reference to FIGS. First, the standard radio wave received by the antenna 1 is amplified by the reception circuit 2 and output to the demodulation circuit 3. The demodulator circuit 3 demodulates the standard radio wave amplified by the receiver circuit 2 through a filter circuit, a rectifier circuit, a detector circuit, etc. (all not shown), and converts the modulation waveform of the standard radio wave into a demodulated waveform that is a square wave. Output to.

  The sampling circuit 4 samples the demodulated waveform output from the demodulating circuit 3 in accordance with a specified sampling period (31.25 ms in this embodiment) generated by the oscillation circuit 5. At this time, the sampling basically proceeds in accordance with the above-mentioned prescribed sampling period of 31.25 ms. In this embodiment, the sampling number adding circuit 10 is provided to increase the number of samplings, thereby substantially shortening the sampling period. . Details are as follows.

  First, a clock signal with an oscillation period of 31.25 ms is output from the oscillation circuit 5 to the sampling circuit 4, and simultaneously, a clock signal with an oscillation period of 31.25 ms is also output from the oscillation circuit 5 to the sampling adder circuit 10.

  The sampling number adding circuit 10 uses a clock signal outputted from the oscillation circuit 5 with a clock frequency of 31.25 ms as a reference timing to apply a timer in software, generates a clock signal with a timing delayed by a certain time, and generates the sampling circuit 4 Output to. Although the delay time can be set arbitrarily, in this embodiment, the delay period is set to 15.625 ms, which is half of 31.25 ms.

  The delay timing clock signal output to the sampling circuit 4 is added to the specified clock signal (oscillation period 31.25 ms) output from the oscillation circuit 5 to generate a clock signal with a substantially short oscillation period. .

  These series of operations are repeated each time a sampling clock signal is output from the oscillation circuit 5 to the sampling number adding circuit 10. That is, if the sampling clock signal output from the oscillation circuit 5 represents a sampling (oscillation) cycle of 31.25 ms as in this embodiment, the sampling cycle is reduced from 31.25 ms to 15.625 ms, which is a half. The number of sampling increases from 32 times / second to 64 times / second.

  In this embodiment, the number of times of sampling performed by the sampling circuit 4 is approximately doubled, but it is possible to arbitrarily increase the number of times by setting a plurality of delay times by a timer.

  The sampling circuit 4 samples the demodulated waveform output from the double tone circuit 3 in accordance with the clock signal having a substantially short oscillation period generated as described above, that is, according to the increased number of samplings. That is, the sampling circuit 4 performs sampling at timings Ta ′ and Tb ′ delayed by 15.625 ms from the sampling timings Ta and Tb based on the clock signal having an oscillation period of 31.25 ms as shown in FIG. Do.

  The waveform discriminating unit 6 discriminates the “High” or “Low” state of the demodulated waveform at each sampling timing Ta, Ta ′, Tb, Tb ′ according to the sampling of the sampling circuit 4 and demodulates based on the information. The waveform is converted as a digital signal.

  For example, as shown in FIG. 3, if Ta, Ta ′, Tb, and Tb ′ are “High”, “High”, “High”, and “High”, they are recognized as “0” code waveforms, and Ta, Ta If ', Tb, and Tb' are “High”, “High”, “Low”, and “Low”, respectively, the waveform is recognized as a “1” code, and Ta, Ta ′, Tb, and Tb ′ are “Low”. , “Low”, “Low”, and “Low” are recognized as “P” code waveforms.

  The digital signal output from the waveform discriminating unit 6 as described above is output to the time specifying circuit 7 and read as time information, and the result is output to the time measuring circuit 8. The time measuring circuit 8 corrects the time based on the time information output from the time specifying circuit 7 and displays it on the display unit 9.

  The sampling cycle of the sampling circuit 4 is basically impossible to change because it is defined by the microcomputer in terms of hardware. However, as described above, the sampling circuit 4 has a sampling timing specified by software. By additionally performing sampling at different timings, it becomes possible to substantially change the sampling period (number of times of sampling) which cannot be changed originally, and the reliability of waveform discrimination is improved.

  Further, if the sampling timing generated by the sampling number adding circuit 10 as in this embodiment is set to an intermediate position of the sampling period 31.25 ms defined by the microcomputer, that is, the timing of 15.625 ms, the sampling period is substantially increased. Is fixed to 15.625 ms, which is preferable because the reliability of waveform discrimination is improved.

  The gist of the present invention is to increase the number of samplings defined in advance by hardware in terms of software, that is, to substantially shorten the sampling period, and the embodiment is limited to the above examples. It can take other various forms.

Block diagram showing a schematic configuration of a radio-controlled timepiece according to the present invention (Example) Example of transmission data (demodulation waveform) and sampling timing in Japan (Example) Diagram for explaining waveform discrimination method based on sampling result (example) Diagram showing pulse (demodulation) waveform of standard radio wave in Japan, USA, Germany Block diagram showing the schematic configuration of a conventional radio-controlled timepiece Japanese transmission data (demodulated waveform) and its sampling timing (conventional) Diagram for explaining waveform discrimination method based on sampling result (conventional) The figure which shows the demodulation waveform of the German standard radio wave when electric field strength becomes weak or the value of S / N becomes small

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna 2 Reception circuit 3 Demodulation circuit 4 Sampling circuit 5 Oscillation circuit 6 Waveform discrimination part 7 Time specification circuit 8 Timekeeping circuit 9 Display part 10 Sampling frequency addition circuit

Claims (8)

at least,
A receiving means for receiving a standard radio wave including time information;
Demodulation means for demodulating the standard radio wave received by the receiving means and outputting a demodulated signal;
An oscillating means for outputting a first clock signal for sampling the demodulated signal;
Clock signal generation means for generating a second clock signal having a different oscillation timing from the first clock signal based on the first clock signal;
Sampling means for sampling the demodulated signal based on the first and second clock signals;
Waveform determining means for determining the waveform of the demodulated signal based on the sampling result of the sampling means;
A radio-controlled timepiece comprising: time specifying means for reading time information included in the standard radio wave based on a waveform discrimination result of the waveform discrimination means.   The radio-controlled timepiece according to claim 1, wherein the second clock signal is generated by delaying the first clock signal for a predetermined time.   The radio-controlled timepiece according to claim 1 or 2, wherein the oscillation timing of the second clock signal is a timing located in the middle of the oscillation timing of the first clock signal.   The radio-controlled timepiece according to any one of claims 1 to 3, wherein the oscillation period of the first clock signal is 31.25 ms. at least,
A receiving step for receiving a standard radio wave including time information;
A demodulation step of demodulating the standard radio wave received by the receiving means and outputting a demodulated signal;
An oscillation step of outputting a first clock signal for sampling the demodulated signal;
A clock signal generating step for generating a second clock signal having a different oscillation timing from the first clock signal based on the first clock signal;
A sampling step of sampling the demodulated signal based on the first and second clock signals;
A waveform determining step for determining a waveform of the demodulated signal based on a sampling result of the sampling step;
And a time identifying step of reading time information included in the standard radio wave based on a waveform discrimination result of the waveform discrimination step.   6. The standard radio wave receiving method according to claim 5, wherein the second clock signal is generated by delaying the first clock signal for a predetermined time.   7. The standard radio wave receiving method according to claim 5, wherein the oscillation timing of the second clock signal is a timing located in the middle of the oscillation timing of the first clock signal. 8. The standard radio wave receiving method according to claim 5, wherein an oscillation period of the first clock signal is 31.25 ms.

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