JP2009198320A - Timepiece having time correction function and time correction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a timepiece having a time correction function and a time correction method, capable of improving the accuracy in time correction and reducing erroneous detection of a time signal. <P>SOLUTION: The detection signal of a forecast sound component and that of an exactly reporting sound component are outputted to a control section 6 from a sound signal included in FM broadcast waves by a tone decoder. An edge detecting section 21 in the control section 6 detects the termination (falling) edge of first to third forecast sound detection signals. A time signal discriminating section 22 measures the time interval between the falling edges and discriminates whether a prescribed criterion of the forecast sound signal has been met. When a prescribed criterion is met, an amount-of-time-correction calculating section 24 calculates the amount of time deviation between time indicated by the falling edge of the third forecast sound detection signal and current time by a real-time clock 7. The amount-of-time-correction calculating section 24 calculates the amount of time correction, based on the relation between the calculated amount of time deviation and the standard deviation, of up to the last amount of time deviation stored at a data storage section 25. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a clock device with a time correction function and a time correction method for detecting a time signal included in a broadcast wave transmitted from a broadcast station and correcting the current time.

  In a time measuring device for displaying time, a method using a time signal of FM (Frequency Modulation) broadcasting is known as a method for correcting the time. The time signal includes, for example, three predicted sound components and subsequent correct sound components. The time signal transmitted from the broadcasting station is demodulated into an audio signal after being received by the FM receiver.

  As a method for detecting a time signal from an audio signal, a method using a tone decoder is known. For example, the tone decoder is set to detect a signal having the same frequency as that of the forecast sound signal, and outputs a detection signal when it is detected. Such a tone decoder basically comprises a PLL (Phase Locked Loop) circuit.

  The PLL circuit detects a phase shift between the forecast sound signal input from the outside and the output of the in-loop oscillator, and oscillates by applying feedback to the in-loop oscillator so that the phase difference is constant. It is. In such a PLL circuit, it is necessary to loop a plurality of times until the phase difference becomes constant, and therefore a certain amount of time is required. That is, a certain amount of time lag occurs between the input signal and output signal of the tone decoder based on the principle of the PLL circuit.

  For example, Patent Documents 1 and 2 disclose time measuring devices that detect a time signal by using a PLL circuit and correct the time. The time measuring devices disclosed in Patent Documents 1 and 2 determine whether or not the received signal is a time signal, for example, by measuring the time of the forecast sound component or the time of the silent portion between the signals.

JP 2000-193768 A Japanese Patent No. 3329065

  The phase difference has a different value depending on the timing at which the forecast sound signal is input to the PLL circuit of the tone decoder. Therefore, the time until the phase difference becomes constant also differs depending on the timing when the forecast sound signal is input to the PLL circuit. That is, a certain amount of time lag occurs from when the forecast sound signal is input to the PLL circuit until the signal that detected the forecast sound signal is output from the PLL circuit, and the forecast sound signal is input to the PLL circuit. It varies depending on the timing. Note that the tone decoder needs to be provided separately for detecting the forecast sound and detecting the correct sound. Therefore, this problem similarly occurs for the correct sound.

  In the conventional time correction method, the timing for detecting the time signal is such that the rising edge of the detection signal of the tone decoder is detected for both the forecast sound and the correct sound. However, the signal from which the rising edge of the signal is detected is output with a certain time lag as described above.

  Therefore, if the time is corrected based on the rise of the detection signal of the tone decoder, the time is corrected in a state including a time lag. If the time lag is constant, this problem can be solved by correcting the time so that the time lag is anticipated and canceled, but the time lag is not constant and has some variation, so the time lag is completely eliminated. It cannot be canceled.

  That is, if the time is corrected by detecting the rising edge of the detection signal of the tone decoder, there is a problem that the accuracy of time correction is lowered.

  In addition, since an audio signal component having the same frequency as that of the time signal is present in the broadcast signal with a considerable probability, the sound signal component may be detected in the same pattern as the time signal. Therefore, conventionally, for example, an effective range is provided for the time from the rise of the signal of the forecast sound component to the rise of the signal of the next forecast sound component. Then, depending on whether or not a signal is detected within the effective range, it is determined whether the input signal is a time signal or a simple audio signal.

  However, in the conventional method, since the amount of time lag variation is large, the effective range has to be set large. For this reason, even if an effective range is provided, there is a problem that an audio signal that satisfies the condition is erroneously detected as a time signal.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a timing device with a time correction function and a time correction method capable of improving the accuracy of time correction and reducing erroneous detection of time signals. .

In order to achieve the above object, the time measuring device with a time correction function of the present invention is:
A time measuring means for measuring the current time;
Receiving means for receiving a broadcast signal including a time signal including a plurality of forecast sound signals and correct sound signals, and demodulating the predicted sound signal and the correct sound signals;
A forecast sound signal end detection means for detecting the end of the forecast sound signal;
Correction means for correcting the time measured by the time measuring means based on the time on the time signal corresponding to the terminal portion of the forecast sound signal and the time measured by the time measuring means,
It is characterized by that.

A correct sound signal front end detecting means for detecting a front end of the correct sound signal;
It is good as well.

The receiving means includes a filter circuit that extracts an audio signal of a predetermined frequency that constitutes the forecast sound signal, and a PLL (Phase Locked Loop) circuit that phase-locks to a signal that has passed through the filter circuit,
The forecast sound signal termination part detection means detects the termination part of the forecast sound signal from the output signal of the PLL circuit.
It is good as well.

The correcting means is
A time correction amount calculating means for calculating a time correction amount for the time of the time measuring means based on a difference between the time on the time signal corresponding to the terminal portion of the forecast sound signal and the time of the time measuring means;
A time correction unit for correcting the time of the time measuring means based on the calculated time correction amount;
It is good as well.

Whether or not the forecast sound signal received by the receiving means is authentic is determined based on the end of the forecast sound signal detected by the forecast sound signal end detection means, and the forecast sound Further comprising a time signal determining means for determining that the time signal is genuine based on a combination of a terminal portion of the signal and a front end portion of the correct sound signal;
The correcting means corrects the time measured by the time measuring means when it is determined that the time signal is genuine;
It is good as well.

The time signal determination means measures a time interval between terminal portions of the plurality of forecast sound signals corresponding to the number of the forecast sound signals for the forecast sound signal, and based on the time intervals, the forecast sound Determining whether the signal meets a predetermined criterion,
It is good as well.

Data storage means for storing data referred to by the time correction amount calculation means;
The data storage means includes a standard deviation up to the previous time correction with respect to a time lag between a time on a time signal corresponding to a terminal portion of one of the plurality of forecast sound signals and a time of the time measuring means. Remember
When it is determined that the predicted sound signal satisfies a predetermined determination criterion, the time correction amount calculation means calculates the current time lag amount and stores the calculated current time lag amount. Calculating the time correction amount based on the relationship with the standard deviation of the time lag amount up to the previous time correction amount;
It is good as well.

The data storage means further stores an arithmetic average value up to the previous time correction for the time lag amount,
The time signal determining means further determines whether or not the time signal is detected within a predetermined time range,
When it is determined that the time signal has not been detected within the predetermined time range, the time correction amount calculation means is based on the stored arithmetic mean value of the time lag amount up to the previous time correction amount. Calculating the time correction amount;
It is good as well.

When the time signal is detected within the predetermined time range, the time correction amount calculating means calculates an arithmetic mean value and a standard deviation of the time lag amount up to the current time correction amount, and Updating the arithmetic mean value and standard deviation data of the amount of time lag up to the previous time correction stored in the data storage means,
It is good as well.

In order to achieve the above object, the time correction method of the present invention includes:
A broadcast signal including a time signal including a plurality of forecast sound signals and a correct sound signal is received,
Demodulating the forecast sound signal and the correct sound signal from the broadcast signal,
Detecting the end of the demodulated forecast sound signal;
Correct the time based on the time on the time signal corresponding to the terminal portion,
It is characterized by that.

  According to the present invention, since the time is corrected using the terminal portion of the time signal as a trigger, the time correction accuracy can be improved.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. First, a first embodiment of the present invention will be described. FIG. 1 is a block diagram illustrating a configuration of a time measuring device with a time correction function (hereinafter simply referred to as a time measuring device) according to the first embodiment.

  As shown in FIG. 1, the timing device 1 of the present embodiment includes an antenna 2, a broadcast wave receiving unit 3, tone decoders 4 and 5, a control unit 6, and a real time clock (RTC) 7.

  The broadcast wave receiver 3 receives broadcast waves via the antenna 2. The broadcast wave receiving unit 3 in this embodiment is a kind of radio receiver that receives FM broadcast waves transmitted from a broadcast station. Then, the broadcast wave receiving unit 3 detects the received FM signal, extracts the audio signal, and outputs it to the tone decoders 4 and 5.

  The tone decoders 4 and 5 detect signals of predetermined set frequencies from the audio signals input from the broadcast wave receiving unit 3 and output the detected signals to the control unit 6 as detection signals. In the present embodiment, the tone decoder 4 is set to detect a 440 Hz audio signal, and the tone decoder 5 is set to detect an 880 Hz audio signal.

  The control unit 6 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and controls the timing device 1 as a whole. Further, the control unit 6 receives detection signals of 440 Hz and 880 Hz from the tone decoders 4 and 5, and determines whether or not the received signal indicates a time signal. When it is determined that the time signal is indicated, the control unit 6 corrects the current time of a real time clock (RTC) 7 based on the time signal.

  The real time clock 7 is a clock that is built in the time measuring device 1 and keeps the current time. The real-time clock 7 operates independently except when the time is adjusted by the control unit 6 and provides time data to the control unit 6 and external devices.

  FIG. 2 shows a configuration of a main part of the tone decoders 4 and 5. The tone decoders 4 and 5 each include a PLL circuit unit 10 and an output filter 15.

  Hereinafter, the case of the tone decoder 4 will be described with reference to FIG. The PLL circuit unit 10 includes a capacitor 11, a phase detector (PD) 12, a low-pass filter (LPF) 13, and an oscillator (OSC) 14. The oscillator 14 may be a voltage controlled oscillator (VCO) or a current controlled oscillator (CCO). Moreover, a frequency divider etc. may be included.

  The phase detector 12 is a level of a signal input from the outside to the phase detector 12 via the capacitor 11 and an output signal from the oscillator 14 in a loop composed of the phase detector 12, the low-pass filter 13 and the oscillator 14. Detect phase difference. The PLL circuit unit 10 oscillates by applying feedback control to the oscillator 14 so that the phase difference becomes constant. In the example of the tone decoder 4 in FIG. 1, the PLL circuit unit 10 loops a plurality of times so that the phase difference between the 440 Hz component of the audio signal from the broadcast wave receiving unit 3 and the output signal of the oscillator 14 is constant. Control.

  When the phase difference between the 440 Hz component and the output signal of the oscillator 14 becomes constant, the 440 Hz detection signal is output to the control unit 6 from the PLL circuit unit 10 via the output filter 15. Similarly, in the case of the tone decoder 5, an 880 Hz detection signal is output to the control unit 6. The relationship between the hourly audio signal, the 440 Hz detection signal, and the 880 Hz detection signal will be described later.

  FIG. 3 is a block diagram showing a functional configuration of the control unit 6 in the timing device 1 shown in FIG. As shown in FIG. 3, the control unit 6 includes an edge detection unit 21, a time signal determination unit 22, a time correction amount calculation unit 24, a data storage unit 25, and a time correction unit 26.

  The edge detector 21 detects the falling edge of the 440 Hz detection signal (hereinafter also simply referred to as “falling”) and the 880 Hz detection signal as shown in FIG. 4 from the detection signals (440 Hz / 880 Hz) from the tone decoders 4 and 5. A rising edge (hereinafter also simply referred to as rising) is detected. In the present embodiment, the 440 Hz detection signal output from the tone decoder 4 is a positive pulse signal having a value of, for example, 1 when 440 Hz is detected and 0 in other cases. Similarly, the 880 Hz detection signal output from the tone decoder 5 is also a positive pulse signal that is, for example, 1 when 880 Hz is detected and 0 in other cases.

  The time signal determination unit 22 activates a built-in timer, the time from the fall of the 440 Hz detection signal detected by the edge detection unit 21 to the fall of the next 440 Hz detection signal, and the last 440 Hz detection signal. The time from the fall to the rise of the 880 Hz detection signal is measured. Moreover, the time signal determination part 22 determines whether the combination of detection signals shows a time signal from the measured time.

  The time correction amount calculation unit 24 calculates the amount of time lag between the time based on the 440 Hz detection signal determined to indicate three forecast sound signals and the current time of the real-time clock 7. The time correction amount calculation unit 24 calculates a time correction amount for the real-time clock 7 based on the calculated time shift amount and data related to the time shift amount up to the previous time correction. Data relating to past time lag amounts is stored in the data storage unit 25.

  The time correction unit 26 determines the real time clock based on the time correction amount calculated by the time correction amount calculation unit 24 when the time signal determination unit 22 determines that the combination of the 440 Hz detection signal and the 880 Hz detection signal is a time signal. 7 corrects the current time.

  FIG. 4 is a timing chart showing the relationship between the audio signal input to the tone decoders 4 and 5 and the detection signal output from the tone decoders 4 and 5.

  In this specification, time correction is performed using a time signal included in an FM broadcast wave transmitted from a broadcasting station. FIG. 4 shows the waveform of a time signal among audio signals obtained by demodulating this broadcast wave. The time signal audio signal shown in FIG. 4 is a combination of three forecast sounds and one correct sound. In each forecast sound, a 440 Hz sine wave having a constant volume oscillates for 100 ms. There is a silent state of 900 ms between the predicted sound and the next predicted sound, and between the third predicted sound and the correct sound. In the correct sound, a 880 Hz sine wave having a constant volume oscillates for 1000 ms and then attenuates in 2000 ms. As shown in FIG. 4, the time correction in the present embodiment is performed on the basis of time 0:00:00 as an example. Further, in the audio signal of FIG. 4, waveforms of three forecast sounds (440 Hz) and one correct report sound (880 Hz) are simplified and displayed.

  Also, the 440 Hz detection signal shown in FIG. 4 is a signal output by the tone decoder 4 shown in FIG. 1 detecting and outputting a forecast sound component (440 Hz) from the audio signal. Further, the 880 Hz detection signal is a signal that the tone decoder 5 detects and outputs a correct sound component (880 Hz) from the audio signal. As described above, the tone decoders 4 and 5 output the forecast sound component and the correct sound component as rectangular waves, respectively.

  As described in the description of the background art, for example, a tone decoder is used to detect the predicted sound component and the correct sound component from the audio signal. Since the tone decoder uses the PLL circuit, there is a certain time lag between the input signal and the output signal of the tone decoder due to the characteristics of the PLL circuit.

  Conventionally, the time (signal width) of the forecast sound component and the time of the silent part have been measured. Further, for example, the time between the rising of the predicted sound component and the rising of the next predicted sound component is measured. And based on the measured time, it was judged whether the combination of an audio | voice signal was a time signal.

  However, all of these methods measure time from the leading edge of the signal. Since the phase difference between the signal input to the PLL circuit and the signal generated from the oscillator in the PLL circuit varies depending on the timing at which the audio signal is input to the PLL circuit, the time until the phase difference becomes constant is not uniform. Accordingly, if the leading edge of the signal is used as a trigger for time signal detection, variations in time (time lag) until the phase difference becomes constant are likely to occur. Thus, the large variation in the time lag has caused a decrease in time correction accuracy and erroneous detection of a time signal.

  On the other hand, if the trailing edge of the audio signal, that is, the falling edge in this embodiment is used as a trigger for time signal detection, the phase difference is already in a constant state, so that the rising edge is used as a trigger for time signal detection. There is no time lag. Similarly, there is no problem of time lag variations caused by the difference in phase difference between the signal input to the PLL circuit and the signal generated from the oscillator in the PLL circuit depending on the timing at which the audio signal is input to the PLL circuit.

  Although there are time lags and variations due to the characteristics of the PLL circuit, the magnitudes are smaller than when the rising edge is used as a trigger for time signal detection.

  For the above reasons, by detecting the time signal using the end edge of the audio signal as a trigger, it is possible to correct the time so that the variation in the time lag can be accurately estimated and canceled. Therefore, the accuracy of time correction can be improved.

  Next, the time adjustment operation in the timing device 1 of the present embodiment will be described with reference to FIGS. 5 and 6 are flowcharts showing the time correction method in the present embodiment. In the following description, FIGS. 1 to 4 are also referred to as appropriate.

  First, as shown in FIG. 1, the broadcast wave receiving unit 3 receives FM broadcast waves via the antenna 2. The received FM broadcast wave is demodulated into an audio signal and output to the tone decoder 4 and the tone decoder 5.

  When the tone decoder 4 detects a 440 Hz signal from the audio signal input from the broadcast wave receiving unit 3, the tone decoder 4 outputs it as a 440 Hz detection signal as shown in FIG. 4. This 440 Hz detection signal corresponds to a signal of a forecast sound component of a time signal in this specification, and is shown as forecast sound (1) to forecast sound (3) in order of time in FIG.

  When the 440 Hz detection signal is input from the tone decoder 4, the edge detection unit 21 of the control unit 6 detects the falling edge of the input 440 Hz detection signal (step S11).

  The time signal determination unit 22 recognizes this signal as the forecast sound (1) and starts a built-in timer (step S12). Then, the time signal determination unit 22 measures the time from the fall of the forecast sound (1).

  After that, when the 440 Hz detection signal is input again from the tone decoder 4 to the edge detection unit 21, the edge detection unit 21 detects the falling edge of the input 440 Hz detection signal (step S13).

  The hourly signal determination unit 22 recognizes this signal as the forecast sound (2). Then, the time signal determination unit 22 determines whether or not the measurement time from the fall of the forecast sound (1) to the fall of the forecast sound (2) is within a range of 1000 ± 10 ms (step S14).

  If it is determined that the measurement time is not within the range of 1000 ± 10 ms (step S14: NO), it means that the combination of the signals of the forecast sound (1) and the forecast sound (2) does not indicate a time signal. In this case, the process returns to step S11. Since the 440 Hz detection signal recognized as the forecast sound (2) in the above process may actually be the first forecast sound, this 440 Hz detection signal is used as the forecast sound (1) and after step S12. Processing may be continued.

  If it is determined that the measurement time is within the range of 1000 ± 10 ms (step S14: YES), the hourly signal determination unit 22 restarts the timer (step S15). Note that the restart of the timer is not a problem even after the determination in step S14 as shown in FIG. 5 if the processing is performed at high speed. In addition to the above, the timer may be restarted in synchronization with the fall detection in step S13. Further, the time from the fall of the forecast sound (1) to the fall of the forecast sound (2) may be calculated based on a series of times from the start of the timer in step S12.

  Thereafter, when the 440 Hz detection signal is input again from the tone decoder 4 to the edge detection unit 21, the edge detection unit 21 detects the falling edge of the input 440 Hz detection signal (step S16).

  The hourly signal determination unit 22 recognizes this signal as the forecast sound (3). Then, the time signal determination unit 22 determines whether or not the measurement time from the fall of the forecast sound (2) to the fall of the forecast sound (3) is within a range of 1000 ± 10 ms (step S17).

  If it is determined that the measurement time is not within the range of 1000 ± 10 ms (step S17: NO), it means that the combination of signals of the forecast sound (1) to the forecast sound (3) does not indicate a time signal. In this case, the process returns to step S11. Since the 440 Hz detection signal recognized as the forecast sound (3) in the above process may actually be the first forecast sound, this 440 Hz detection signal is used as the forecast sound (1) and subsequent steps. Processing may be continued.

  When it is determined that the measurement time is within the range of 1000 ± 10 ms (step S17: YES), the hourly signal determination unit 22 restarts the timer (step S18). This means that it is determined that the combination of the forecast sound (1) to the forecast sound (3) indicates the forecast sound of the time signal.

  When it is determined that the signals of the forecast sound (1) to the forecast sound (3) are time signal signals, the time correction amount calculation unit 24 determines the difference between the current time of the real time clock 7 and the time based on the time signal (hereinafter, Time deviation). Then, the time correction amount calculation unit 24 calculates a time correction amount with respect to the current time of the real-time clock 7 based on the calculated time deviation amount (step S19).

The time correction amount calculation process shown in step S19 of FIG. 5 will be described with reference to the flowchart shown in FIG. If it is determined in the process up to step S18 in FIG. 5 that the forecast sound (3) is a time signal, as described above, the time correction amount calculation unit 24 calculates the time shift amount xN _{+ 1} (step S31). Note that (N) indicates the number of time corrections up to the previous time.

For example, it is assumed that the time indicated by the falling edge of the forecast sound (3) is 23: 59: 59.1 seconds. On the other hand, it is assumed that the current time of the real-time clock 7 is 23: 59: 59.2 seconds. In this case, the current time of the real-time clock 7 is advanced by 0.1 second (x _{N + 1} = 0.1 second). The time correction amount calculation unit 24 stores the time shift amount xN _{+ 1} in the data storage unit 25.

Subsequently, the time correction amount calculation unit 24 compares the time shift amount xN _{+ 1} with the standard deviation (σ) of the N time shift amounts. At that time, the time correction amount calculation unit 24 refers to the data of the standard deviation stored in the data storage unit 25.

When xN _{+ 1} satisfies the relationship of −σ ≦ x _{N + 1} ≦ + σ with respect to the average value (arithmetic mean) of the time lag (step S32: YES), the time lag for this time (N + 1) is the arithmetic mean. On the other hand, the variation is small. In this case, the time correction amount calculation unit 24 sets xN _{+ 1} as the time correction amount. (Step S33). In the above example, x _{N + 1} = 0.1 seconds is the time correction amount, and the current time of the real-time clock 7 is corrected so as to cancel this.

When xN _{+ 1} does not satisfy the relationship of −σ ≦ x _{N + 1} ≦ + σ with respect to the average value (arithmetic mean) of the time lag (step S32: NO), −2σ ≦ x _{N + 1} <−σ or + σ <x _{N + 1} It is determined whether or not the relationship of ≦ + 2σ is satisfied (step S34).

When xN _{+ 1} is within the range shown in step S34 (step S34: YES), it means that the variation of xN _{+ 1} is slightly large. This may be because, for example, the time is shifted due to an additional factor in addition to that caused by the PLL circuit. In this case, the arithmetic mean value of the N time shift amounts is set as the time correction amount by the time correction amount calculation unit 24 (step S35). The data of the arithmetic average value for N times is stored in the data storage unit 25. According to such a time correction method, the current time of the real-time clock 7 can be corrected so that a large error does not occur even when the time is shifted due to an additional factor.

If x _{N + 1} is not within the range shown in the step S34 (step S34: NO), _i.e., if _{x N + 1} is in the _{x N} + 1 _<-2σ or ₊ 2σ _{<x N} + ₁ relationship to the arithmetic mean of the time shift amount, The time correction amount calculation unit 24 does not correct the time (step S36). The reason why the time deviation amount has a large variation as described above may be because, for example, the time signal has not been acquired correctly or the radio wave environment is very poor. Therefore, in this case, time correction is not performed.

  As described above, when the time correction amount is calculated in step S19 of FIG. 5, when the 880 Hz detection signal is input from the tone decoder 4 to the edge detection unit 21, the edge detection unit 21 detects the input 880 Hz detection. The rising edge of the signal is detected (step S20).

  The hourly signal determination unit 22 recognizes this signal as a correct sound. Then, the time signal determination unit 22 determines whether or not the measurement time from the fall of the forecast sound (3) to the rise of the correct sound is within a range of 900 ± 20 ms (step S21).

  When it is determined that the measurement time is not within the range of 900 ± 20 ms (step S21: NO), the combination of the signals of the forecast sound (1) to the forecast sound (3) and the correct sound does not indicate a correct time signal. Means that. Therefore, in this case, the process returns to step S11.

  When it is determined that the measurement time is in the range of 900 ± 20 ms (step S21: YES), the combination of the signals of the forecast sound (1) to the forecast sound (3) and the correct sound indicates a real time signal It means that. In this case, the time correction unit 26 corrects the time of the real-time clock 7 based on the time correction amount calculated in step S19 (step S22). Although the rising edge of the detection signal is used to determine the correct alarm sound, the amount of time lag and the amount of time correction are calculated based on the falling edge of the forecast sound (3). Can be small.

  The timing for correcting the current time of the real-time clock 7 may be any time as long as it is determined to be a time signal by the process of step S21. In the present embodiment, it is assumed that the current time of the real-time clock 7 is corrected at a timing that changes to 0:00:01 when the correct sound indicates 0:00:00. In the example of the time lag amount described above, the time correction unit 26 corrects the current time of the real-time clock 7 so as to be a time obtained by subtracting 0.1 seconds from the time of the real-time clock 7 before correction.

When the time is corrected as described above, the time correction amount calculation unit 24 calculates the time deviation amount x _{N + 1} calculated in step S31 of FIG. 6 and the previous time stored in the data storage unit 25 (N times). The arithmetic mean and standard deviation of the (N + 1) time lags including the current correction are calculated from the arithmetic mean and standard deviation of the time lags (step S23). The arithmetic mean and standard deviation of (N + 1) times can be obtained from the following mathematical formulas (1) and (2).

The number of times of time correction including the current time (N + 1) and the arithmetic mean and standard deviation of the amount of time deviation calculated in step S23 (N + 1) are stored in the data storage unit 25 (step S24). Here, as shown in the above formulas (1) and (2), only the latest data may be stored in the data storage unit 25 for the time correction count and the arithmetic mean and standard deviation of the time lag. At the time of the next time correction, the time deviation amount shown in FIG. 6 is evaluated with the value of the standard deviation 求 め_{N + 1} obtained by the above equation (2) as σ.

  Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a flowchart showing a time correction method in the second embodiment. In the first embodiment, the process is repeated until the time signal acquisition is successful, but in actuality, the time signal is on the hour (0:00:00, 1:00:00, ..., 23:00 It may be acquired within a certain range based on (00:00). The present embodiment is characterized in that if the time signal acquisition is not successful, it is determined whether or not the current time is within a predetermined range based on the hour. Note that the configuration of the timing device and the time signal of the broadcast wave in this embodiment are the same as those in the first embodiment.

  In the second embodiment, the time adjustment process is started when the time is within a predetermined range with reference to the hour. It should be noted that within a predetermined range with reference to the hour is the time interval between the front and the rear when an appropriate time margin is provided around the time at which the time difference of the timing device is expected. That means. For example, if there is a margin of 5 minutes around 0:00:00, 10 minutes is the predetermined range, and if time correction is performed during that time, even if there is a time lag It is possible to receive a time signal. As shown in FIG. 7, when the time adjustment process is started, a time signal acquisition process is first performed (step S41). This process corresponds to the process of steps S11 to S21 shown in FIG. 5, and includes the calculation of the time correction amount (step S19). However, if it is determined that the signal is not a time signal in the measurement time determination process corresponding to steps S14, S17, and S21, the process directly proceeds to step S42 in FIG.

  Subsequently, it is determined whether or not the time signal acquisition is successful (step S42). Here, when it is determined that the acquisition of the time signal has been successful (step S42: YES), the same processing as in the first embodiment is performed. That is, the processes of time correction (step S43), arithmetic mean and standard deviation of time lag (step S44), and data storage (step S45) are performed in the same manner as in the first embodiment. Ends.

  The case where the time signal acquisition is not successful in step S42 (step S42: NO) is a case where it is determined that the signal is not a time signal in the measurement time determination process as described above. In this case, the time signal determination unit 22 determines whether or not the current time is still within a predetermined range with reference to the hour (step S46). Here, it is determined whether or not the current time obtained from the real-time clock 7 is within a predetermined time reference range including the time on the assumption that the time signal is acquired in advance.

  If it is determined in step S46 that the current time is within the hourly reference range (step S46: YES), the process returns to step S41, and the time signal is acquired again.

  If it is determined in step S46 that the current time is not within the hourly reference range (step S46: NO), the time signal acquisition is stopped and stored in the data storage unit 25 by the time correction amount calculation unit 24. The arithmetic mean value of the amount of time lag until the previous time (N times) is set as the time correction amount (step S47). This process is the same as step S35 shown in FIG. Then, the time correction unit 26 corrects the time of the real-time clock 7 based on the calculated time correction amount (step S48). As a result, when the time signal to be acquired at noon cannot be acquired, the time is corrected based on the arithmetic mean value of the time lag amount, so that accumulation of errors can be effectively suppressed. Thereafter, the process corresponding to step S44 and step S45 is not performed, and the current time correction process is terminated. That is, the amount of time difference data stored in the data storage unit 25 remains N times.

  As described above, in the time measuring device of the present invention, the time signal is detected using the terminal edge (the falling edge in the above embodiment) of the signal of the forecast sound component as a trigger, and the time is corrected. As a result, the delay and variation in detection timing can be reduced as compared with the case where the leading edge (rising edge in the above-described embodiment) of the signal of the forecast sound component is used as a trigger, so that the accuracy of time correction can be improved. it can.

  Further, when the time between the time signal signals is measured using the end edge of the time signal as a trigger, there is little variation in the measurement result, and therefore the effective range of time for detecting the time signal can be narrowed. Thereby, it is possible to reduce the probability that an audio signal other than a time signal is erroneously detected as being a time signal.

  In addition, the timing device of the present invention holds the standard deviation and the arithmetic mean value calculated from the time lag amount acquired in the N time correction processes. Thus, the reliability of the time signal can be verified based on the standard deviation, the time can be corrected based on the time signal information if the reliability is high, and the time can be corrected based on the arithmetic average value if the reliability is low. it can. Furthermore, even when the time signal cannot be received, the time can be corrected based on the arithmetic mean value, so that accumulation of time lag can be effectively suppressed.

  As mentioned above, although embodiment of this invention was described, in implementing this invention, a deformation | transformation and application by a various form are possible, and it is not restricted to said embodiment.

  For example, in the above-described embodiment, it is determined whether or not the sound signal is a time signal by using the fall of the forecast sound as a trigger. Thereby, erroneous detection of the time signal can be reduced, but detection of the signal width of the forecast sound may be combined.

  In the above-described embodiment, the control unit corrects the time of the real-time clock built in the time measuring device. In addition, the control unit may directly correct the time of an external timing device or the like.

  In the above embodiment, the forecast sound signal is a positive pulse and the end of the forecast sound signal is detected by a falling edge. However, if the forecast sound signal is a negative pulse, for example, the end of the forecast sound signal is It is also possible to detect at the rising edge. Thus, the specific circuit configuration can be changed as appropriate.

  Further, the frequency of the time signal, the time of the signal width, etc. may be other than those shown in this specification.

It is a block diagram which shows the structure of the time measuring device which concerns on the 1st Embodiment of this invention. It is a figure which shows the structure of the principal part of a tone decoder. It is a block diagram which shows the functional structure of a control part. It is a timing chart which shows the relationship between the audio | voice signal input into a tone decoder, and the time signal detection signal output from a tone decoder. It is a flowchart which shows the time correction method in the 1st Embodiment of this invention. It is a flowchart which shows a time correction amount calculation process among the time correction methods in the 1st Embodiment of this invention. It is a flowchart which shows the time correction method in the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Time measuring device 2; Antenna 3; Broadcast wave receiving parts 4 and 5; Tone decoder 6; Control part 7; Real time clock 10; PLL circuit part 15; Output filter 21; Edge detection part 22; Correction amount calculation unit 25; data storage unit 26; time correction unit

Claims (10)

A time measuring means for measuring the current time;
Receiving means for receiving a broadcast signal including a time signal including a plurality of forecast sound signals and correct sound signals, and demodulating the predicted sound signal and the correct sound signals;
A forecast sound signal end detection means for detecting the end of the forecast sound signal;
Correction means for correcting the time measured by the time measuring means based on the time on the time signal corresponding to the terminal portion of the forecast sound signal and the time measured by the time measuring means,
A time measuring device with a time correction function. A correct sound signal front end detecting means for detecting a front end of the correct sound signal;
The time measuring device with a time correction function according to claim 1. The receiving means includes a filter circuit that extracts an audio signal of a predetermined frequency that constitutes the forecast sound signal, and a PLL (Phase Locked Loop) circuit that phase-locks to a signal that has passed through the filter circuit,
The forecast sound signal termination part detection means detects the termination part of the forecast sound signal from the output signal of the PLL circuit.
The time measuring device with a time correction function according to claim 1 or 2. The correcting means is
A time correction amount calculating means for calculating a time correction amount for the time of the time measuring means based on a difference between the time on the time signal corresponding to the terminal portion of the forecast sound signal and the time of the time measuring means;
A time correction unit for correcting the time of the time measuring means based on the calculated time correction amount;
The timekeeping device with a time correction function according to any one of claims 1 to 3. Whether or not the forecast sound signal received by the receiving means is authentic is determined based on the end of the forecast sound signal detected by the forecast sound signal end detection means, and the forecast sound Further comprising a time signal determining means for determining that the time signal is genuine based on a combination of a terminal portion of the signal and a front end portion of the correct sound signal;
The correcting means corrects the time measured by the time measuring means when it is determined that the time signal is genuine;
The time measuring device with a time correction function according to any one of claims 1 to 4. The time signal determination means measures a time interval between terminal portions of the plurality of forecast sound signals corresponding to the number of the forecast sound signals for the forecast sound signal, and based on the time intervals, the forecast sound Determining whether the signal meets a predetermined criterion,
The time measuring device with a time correction function according to claim 5. Data storage means for storing data referred to by the time correction amount calculation means;
The data storage means includes a standard deviation up to the previous time correction with respect to a time lag between a time on a time signal corresponding to a terminal portion of one of the plurality of forecast sound signals and a time of the time measuring means. Remember
When it is determined that the predicted sound signal satisfies a predetermined determination criterion, the time correction amount calculation means calculates the current time lag amount and stores the calculated current time lag amount. Calculating the time correction amount based on the relationship with the standard deviation of the time lag amount up to the previous time correction amount;
The time measuring device with a time correction function according to any one of claims 1 to 6. The data storage means further stores an arithmetic average value up to the previous time correction for the time lag amount,
The time signal determining means further determines whether or not the time signal is detected within a predetermined time range,
When it is determined that the time signal has not been detected within the predetermined time range, the time correction amount calculation means is based on the stored arithmetic mean value of the time lag amount up to the previous time correction amount. Calculating the time correction amount;
The time measuring device with a time correction function according to claim 7. When the time signal is detected within the predetermined time range, the time correction amount calculating means calculates an arithmetic mean value and a standard deviation of the time lag amount up to the current time correction amount, and Updating the arithmetic mean value and standard deviation data of the amount of time lag up to the previous time correction stored in the data storage means,
The time measuring device with a time correction function according to claim 8. A broadcast signal including a time signal including a plurality of forecast sound signals and a correct sound signal is received,
Demodulating the forecast sound signal and the correct sound signal from the broadcast signal,
Detecting the end of the demodulated forecast sound signal;
Correct the time based on the time on the time signal corresponding to the terminal portion,
The time correction method characterized by the above-mentioned.

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