JP2013055588A - Time adjustment device and time adjustment method - Google Patents

Abstract

An object of the present invention is to provide a time control device and a time control method for reducing errors in RTCs possessed by a plurality of slave stations.
A first clock generation unit that receives information from a satellite and generates a first clock signal based on the received information, a second clock generation unit that generates a second clock signal, a first clock signal, and a first clock signal An error detection unit that detects an error from the two clock signal, and a control unit that adjusts the second clock signal generated by the second clock generation unit when the error detected by the error detection unit is greater than a predetermined value; .
[Selection] Figure 2

Description

  The present invention relates to a time control device and a time control method.

  In an environment monitoring system or the like, a telemeter system that transmits observation data observed by a master station and each of a plurality of slave stations installed at points away from the master station to the master station is used. These slave stations have time data based on the RTC (Real Time Clock) that each own station has.

  On the other hand, in the prior art described in Patent Document 1, the master station sequentially requests the slave stations to transmit observation data via the communication network. Each slave station transmits observation data in response to a transmission request from the parent station. Thereby, the master station has collected observation data of each slave station at a desired time. That is, the slave station transmits the observation data at a timing according to the transmission request from the master station.

JP 2003-308586 A

However, in the prior art described in Patent Document 1, an error occurs in the RTC due to the characteristics of the parts and the change in the ambient temperature where the slave station is installed. For this reason, when an error becomes large in the RTCs possessed by a plurality of slave stations, there is a problem that an administrator needs to manually adjust the error of the RTC of the slave station.
For this reason, in order to obtain observation data at a desired time, the master station needs to send a transmission request to each slave station to control the transmission timing of the slave station.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a time control device and a time control method that reduce errors in RTCs possessed by a plurality of slave stations.

  In order to achieve the above object, a time control apparatus according to the present invention receives information from a satellite, generates a first clock signal based on the received information, and generates a second clock signal. A second clock generation unit; an error detection unit that detects an error between the first clock signal and the second clock signal; and an error detected by the error detection unit that is greater than a predetermined value. And a control unit that adjusts a second clock signal generated by the two-clock generation unit.

  In the time control device of the present invention, the control unit controls the first clock generation unit to stop receiving information from the satellite after adjusting the second clock signal, and The unit may be controlled to sleep.

  In the time control device of the present invention, the second clock generation unit outputs an alarm signal that activates the control unit after a predetermined time has elapsed after adjusting the second clock signal. In response to the alarm signal output from the second clock generation unit, the control unit returns the control unit from a sleep state and starts receiving information from the satellite to the first clock generation unit. You may make it control so.

  In the time control device of the present invention, the control unit resets and adjusts the generation start timing of the second clock signal when the error detected by the error detection unit is larger than a predetermined value. Adjusting the internal clock frequency of the second clock generator by changing the count, and changing the count value for one second of the clock unit for measuring one second of the second clock generator by at least one of the adjustments The second clock signal may be adjusted.

  To achieve the above object, the present invention provides a time control method in a time control device, wherein a first clock generation unit receives information from a satellite and generates a first clock signal based on the received information. A 1 clock generation procedure, a second clock generation procedure in which a second clock generation unit generates a second clock signal, and an error in which an error detection unit detects an error between the first clock signal and the second clock signal A detection procedure; and a control unit that adjusts a second clock signal generated by the second clock generation unit when the error detected in the error detection procedure is greater than a predetermined value. It is characterized by.

  In the time control device of the present invention, the error detection unit detects an error between the first clock signal generated by the first clock generation unit from the information received from the satellite and the second clock signal generated by the second clock generation unit. The control unit determines whether the error is larger than a predetermined value. When it is determined that the error is larger than a predetermined value, the control unit adjusts the second clock signal generated by the second clock generation unit. As a result, errors in time information of such a time control device can be reduced. For this reason, since the time information of the slave station of the telemeter system provided with the time control device of the present invention is automatically within an error range within a predetermined range, the administrator needs to manually adjust the time information of the slave station. Disappears.

1 is a schematic configuration diagram of a telemeter system 1 according to the present embodiment. It is a schematic block diagram of the time control part 11 in the sub_station | mobile_unit 10 which concerns on the embodiment. 6 is a timing chart of a time calibration operation performed for the first time after the slave station 10 according to the embodiment is activated. 6 is a timing chart of a time calibration operation performed after the second time of the slave station 10 according to the embodiment. It is a timing chart explaining the RTC calibration method concerning the embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a telemeter system 1 according to the present embodiment. As shown in FIG. 1, the telemeter system 1 includes n slave stations 10-1 to 10-n (n is a natural number of 1 or more), a master station 20, and a GPS satellite 30. The telemeter system is a slave station (also called an observation station) that transmits observation data observed at a remote location, and a master station (monitoring station) that receives the observation data transmitted from the slave station via a communication network. System). Hereinafter, the slave stations 10-1 to 10-n are collectively referred to as a slave station 10.

The slave station 10 includes a time control unit as will be described later. Other functions of each of the slave stations 10-1 to 10-n may be the same or different. The slave station 10 receives the navigation message s1 emitted from the GPS satellite 30, and calibrates the clock of the time control unit based on the received navigation message s1. The slave station 10-1 transmits transmission data s 3-1 to the master station 20 in response to a transmission request s 2-1 from the master station 20 or in accordance with a time set in advance for each slave station. Similarly, the slave station 10-n sends the transmission data s3-n to the master station 20 according to a transmission request s2-n from the master station 20 or according to a time set in advance for each slave station. Send. For example, the slave station 10 transmits observation data such as the temperature of the place where the slave station 10 is installed to the master station 20 as transmission data.
The master station 20 communicates with the slave station 10 via a communication satellite or a communication network (not shown). For example, the master station 20 transmits transmission requests s2-1 to s2-n to the respective slave stations 10, and transmission data s3-1 to s3-n that are responses to the transmitted transmission requests s2-1 to s2-n. Receive.

  A GPS (Global Positioning System) satellite 30 is an artificial satellite used in GPS, and is a quasi-synchronous satellite that moves in an orbit of about 200,000 km from the ground in about 12 hours. . The GPS satellite 30 emits a navigation message s1 toward outer space. The navigation message s1 includes time data from an atomic clock mounted on the GPS satellite 30, astronomical (orbital) calendar information of the own satellite, and the like.

Next, the configuration of the time control unit 11 of the slave station 10 will be described with reference to FIG.
FIG. 2 is a schematic configuration diagram of the time control unit 11 in the slave station 10 according to the present embodiment. As shown in FIG. 2, the time control unit 11 includes a GPS reception unit 101, an RTC 102, a control unit 103, an oscillator 104, a counter 105, a RAM 106, and a backup power supply unit 107. Further, the time control unit 11 is connected to the antenna 12. Note that power is supplied to the GPS receiving unit 101, the control unit 103, the oscillator 104, the counter 105, and the backup power supply unit 107 from a power supply unit (not shown) of the slave station 10.

  The GPS receiving unit 101 (first clock generating unit) receives the navigation message s1 emitted from the GPS satellite 30 via the antenna 12. The GPS receiving unit 101 generates a clock signal GPSPPS (first clock signal) based on the received navigation message s 1, and outputs the generated clock signal GPSPPS to the counter 105. Here, the clock signal GPSPPS (PPS is an abbreviation for pulse / second) is a clock signal based on GPS time information which is time data per second. The GPS time is a time managed by the GPS satellite 30 having a cycle of one week. In addition, the GPS receiving unit 101 extracts information related to leap seconds from the received navigation message s1, and stores the extracted information related to leap seconds in the RAM 106. In addition, the GPS receiving unit 101 calculates UTC (Coordinated Universal Time) based on information on GPS time and leap seconds, and outputs the calculated UTC information to the control unit 103. In addition, the information regarding leap seconds is information used for adjusting the difference from universal time based on the rotation of the earth in UTC.

  An RTC (real time clock) 102 (second clock generation unit) generates a clock signal RTCPPS (second clock signal) generated by a crystal oscillator, for example, and outputs the generated clock signal RTCPPS to the counter 105. The RTC 102 generates time information based on the generated clock signal RTCPPS, and outputs the generated time information to the control unit 103. In addition, the RTC 102 outputs an alarm signal to the control unit 103 after a predetermined time has elapsed after being reset by the control unit 103.

  The control unit 103 controls the on and off states of the GPS receiving unit 101 and the counter 105. The control unit 103 determines whether or not a deviation value (error) of the clock signal RTCPPS with respect to the clock signal GPSPPS output from the counter 105 is larger than a predetermined value. When determining that the error is larger than a predetermined value, the control unit 103 resets the clock generation timing to the RTC 102. Based on the alarm signal output from the RTC 102, the control unit 103 returns the self unit from the sleep state to the normal operation state. The sleep state is a state in which the control unit 103 is operated in the power saving mode. The control unit 103 outputs the UTC information output from the GPS receiving unit 101 and the timing information output from the RTC 102 to a transmission / reception control unit of the slave station 10 (not shown). The slave station 10 may transmit the transmission data s3-1 to s3-n including the UTC information and the timing information when transmitting the transmission data s3-1 to s3-n to the master station 20.

The oscillator 104 is a crystal oscillator, for example, and outputs the oscillated clock signal to the counter 105.
A clock signal GPSPPS output from the GPS receiving unit 101 and a clock signal RTCPPS output from the RTC 102 are input to the counter 105 (error detection unit). The counter 105 counts the timing difference of the clock signal RTCPPS output from the RTC 102 with respect to the input clock signal GPSPPS using the clock signal output from the oscillator 104. The counter 105 outputs the timing difference between the counted clock signals to the control unit 103.
A RAM (Random Access Memory) 106 stores information about leap seconds extracted from the navigation message s1.

  The backup power supply unit 107 is, for example, a secondary battery or a large capacity capacitor. The backup power supply unit 107 charges a secondary battery and a capacitor using power supplied from a power supply unit (not shown), and supplies the charged power to the RTC 102 and the RAM 106.

Next, the time calibration operation performed for the first time after the slave station 10 is activated will be described with reference to FIG.
FIG. 3 is a timing chart of the time calibration operation performed at the first time after the slave station 10 according to the present embodiment is activated. In FIG. 3, the horizontal axis represents time, and the vertical axis represents the signal level of each clock.
As shown in FIG. 3, at time t1, the time control unit 11 is turned on.
At time t2, the RTC 102 of the time control unit 11 starts generating the clock signal RTCPPS and outputs the generated clock signal RTCPPS to the counter 105.
During the period from time t3 to t5, the GPS receiver 101 waits for acquisition of the navigation message s1.
At time t <b> 4, the GPS reception unit 101 acquires GPS time information from the navigation message s <b> 1, starts generating the clock signal GPSPPS, and outputs the generated clock signal GPSPPS to the counter 105.

At time t5, the GPS receiving unit 101 extracts information about leap seconds from the navigation message s1. The GPS receiving unit 101 calculates UTC based on the GPS time information extracted at time t4 and the information regarding the leap second extracted at time t5.
At time t <b> 6, the counter 105 outputs, for example, a signal representing the rising timing of the signal to the control unit 103 in the clock signal GPSPPS. The control unit 103 resets the generation start timing of the clock signal of the RTC 102 at the timing indicated by the signal output from the counter 105. As a result, at time t6, there is no timing difference between the clock signal RTCPPS and the clock signal GPSPPS. After resetting the generation start timing of the clock signal, the control unit 103 controls the GPS receiving unit 101 so that the power is turned off.

  At time t7, the control unit 103 outputs alarm time information to the RTC 102. Note that the alarm time is the time from when the control unit 103 enters the sleep state until the control unit 103 returns by an alarm signal output by the RTC 102. Next, the RTC 102 sets a time for outputting an alarm signal to the control unit 103 based on the alarm time information output from the control unit 103 (also referred to as an RTC alarm set). Next, the control unit 103 controls the control unit 103 to enter a sleep state. Even when the control unit 103 is in the sleep state, the RTC 102 maintains the power-on state by the power supplied from the backup power supply unit 107 and continues to generate the clock signal RTCPPS. In addition, the control part 103 will be in a sleep state in the time t7 after progress of the predetermined time from the time t6.

FIG. 4 is a timing chart of the time calibration operation performed after the second time of the slave station 10 according to the present embodiment. In FIG. 4, the horizontal axis represents time, and the vertical axis represents the signal level of each clock.
At time t11, the RTC 102 determines whether or not the set alarm time has been reached, and outputs an alarm signal to the control unit 103 when determining that the set alarm time has been reached. Based on the alarm signal output by the RTC 102, the control unit 103 controls the control unit 103 to return from the sleep state.

During the period from time t12 to t17, the GPS receiver 101 waits for acquisition of the navigation message s1.
At time t <b> 13, after receiving GPS time information from the navigation message s <b> 1, the GPS receiving unit 101 starts generating the clock signal GPSPPS and outputs the generated clock signal GPSPPS to the counter 105.
At time t14, the counter 105 counts the time (time t13) from the rising edge of the previous clock signal RTCPPS to the rising edge of the clock signal GPSPPS using the clock signal generated by the oscillator 104, as will be described later. The counter 105 counts the time (t14) from the rising edge of the previous clock signal RTCPPS to the rising edge of the clock signal RTCPPS. The counter 105 calculates a timing difference (= t14−t13) of the clock signal RTCPPS with respect to the clock signal GPSPPS. The counter 105 outputs the calculated timing difference to the control unit 103.
Similarly, at time t <b> 16, the counter 105 calculates a timing difference (= t <b> 16 − t <b> 15) of the clock signal RTCPPS with respect to the clock signal GPSPPS, and outputs the calculated timing difference to the control unit 103.
At time t <b> 17, the GPS receiving unit 101 reads information regarding leap seconds stored in the RAM 106, calculates UTC based on the GPS time information and information regarding leap seconds, and outputs the calculated UTC to the control unit 103.
Similarly, at time t19, the counter 105 calculates a timing difference (= t19−t18) of the clock signal RTCPPS with respect to the clock signal GPSPPS, and outputs the calculated timing difference to the control unit 103.
Next, the control unit 103 calculates the error of the clock signal RTCPPS by dividing the timing difference output from the counter 105 at times t14, t16, and t19 by the elapsed time from the previous calibration time to the present time. Next, the control unit 103 determines whether or not the calculated error is a value larger than a predetermined value.

  When determining that the error is larger than a predetermined value at time t20, the control unit 103 calibrates the timing of the clock signal RTCPPS by resetting the generation start timing of the clock signal of the RTC 102. After the calibration is completed, the control unit 103 controls the GPS receiving unit 101 to be turned off.

  At time t <b> 21, the control unit 103 outputs alarm time information to the RTC 102. The RTC 102 sets the time for outputting the alarm signal to the control unit 103 based on the alarm time information output from the control unit 103. The alarm time information is, for example, 30 minutes later, 1 hour later. Next, the control unit 103 controls the control unit 103 to enter a sleep state.

Next, an example of the RTC calibration method will be described with reference to FIG.
FIG. 5 is a timing chart for explaining the RTC calibration method according to the present embodiment. FIG. 5A is a timing chart for explaining an example in which the timing is shifted in the positive direction, and FIG. 5B is a timing chart for explaining an example in which the timing is shifted in the negative direction. 5A and 5B, the horizontal axis represents time, the vertical axis represents the signal level in the waveforms g101, g101 ′, g102, and g102 ′, and the count value in the waveforms g103 and g103 ′. Represents. 5A and 5B, waveforms g101 and g101 ′ are the clock signal GPSPPS, waveforms g102 and g102 ′ are the clock signal RTCPPS, and waveforms g103 and g103 ′ are the counter 105. It is a count value.

As shown in FIGS. 5A and 5B, at time t101, the control unit 103 resets and calibrates the RTC 102 at the rising edge of the clock signal RTCPPS (g102). Thereafter, the counter 105 receives the clock signal generated by the oscillator 104 during the period from the rising edge of the clock signal RTCPPS to the rising edge of the next clock signal RTCPPS (time t101 to t102, t102 to t103, t103 to t104,...). Use to count.
After time t103 after the RTC calibration, the control unit 103 controls the GPS receiving unit 101 to be turned off. Then, after the control unit 103 returns from the sleep state by the alarm signal, that is, after a certain time has elapsed, the counter 105 resets and restarts the count from the rising edge of the clock signal RTCPPS at time t105. The control unit 103 controls the GPS receiving unit 101 to be turned on.

Next, the case where the timing is shifted in the positive direction will be described with reference to FIG.
At time t106, the GPS receiving unit 101 extracts GPS time information from the navigation message s1, and restarts generation of the clock signal GPSPPS (g101). In this case, since a certain time has elapsed after the calibration of the clock signal RTCPPS, a positive timing difference occurs between the rising edge of the clock signal RTCPPS (time t107) and the rising edge of the clock signal RTCPPS (time t107). ing.
At time t108, the counter 105 stores the first counter value (count value from time t107 to time t108) when the clock signal GPSPPS is input.
At time t109, the counter 105 stores the second count value (count value from time t107 to time t109) when the clock signal RTCPPS is input.
The counter 105 subtracts the first counter value from the second counter value to calculate a timing difference, and outputs a value indicating the calculated timing difference to the control unit 103.

Next, the case where the timing is shifted in the negative direction will be described with reference to FIG.
At time t106 ′, the counter 105 resets the count value at the input timing of RTCPPS. At time t107 ′, the GPS receiver 101 resumes generating the clock signal GPSPPS (g101 ′). In this case, since a certain time has elapsed after the calibration of the clock signal RTCPPS, the rising edge of the clock signal RTCPPS (time t106 ′) is different from the rising edge of the clock signal GPSPPS (time t106 ′). Has occurred.
At time t108 ′, the counter 105 resets the count value at the input timing of RTCPPS. Next, the counter 105 starts counting from time t108 ′.
At time t109 ′, the counter 105 outputs the counter value (count value from time t108 ′ to time t109 ′) when the clock signal GPSPPS is input to the control unit 103 as a value indicating a timing difference.

The control unit 103 calculates the error of the clock signal RTCPPS by dividing the timing difference output from the counter 105 by the elapsed time from the previous calibration time to the present time.
As shown in FIGS. 5A and 5B, at time t110, the control unit 103 determines that the error is larger than a predetermined value, and thus resets the generation start timing of the clock signal of the RTC 102. Thus, the clock signal RTCPPS is calibrated. Alternatively, the control unit 103 may change the frequency of the clock signal generated for the RTC 102 in a direction that reduces the error. Alternatively, the control unit 103 may change the count value for one second of a counter (not shown) that counts one second in the RTC 102.
At time t111, the counter 105 and the control unit 103 calculate a timing difference of the clock signal RTCPPS with respect to the clock signal GPSPPS, and determine whether or not an error calculated from the timing difference is larger than a predetermined value. In this case, the control unit 103 determines that the error is not larger than a predetermined value after the RTC calibration.

As described above, the time control unit 11 extracts the GPS time information from the navigation message s1 and calibrates the clock signal RTCPPS. After calibration, the time control unit 11 uses the clock signal RTCPPS as time information instead of the clock signal GPSPPS. In order to periodically calibrate the timekeeping information, the controller 103 sets alarm time information for the RTC 102 after the calibration is completed. Based on this alarm signal, the control unit 103 starts an RTC calibration processing operation, and controls the sleep state after the calibration is completed. In this way, the control unit 103 is controlled so that the power supply is periodically turned on only during the calibration period of the clock signal RTCPPS, so that power consumption can be reduced. Further, since the GPS receiving unit 101 is controlled so that the power is turned on only during the reception period of the navigation message s1, power consumption can be reduced. In this case, the GPS receiving unit 101 acquires the information about the leap second once in the first time and several days when the time control unit 11 is activated, stores the information in the RAM 106, and stores the information in the RAM 106 after returning from the sleep state. Added information about leap seconds. For this reason, the GPS receiving unit 101 does not need to receive all the navigation message s1 after returning from sleep, and only receives GPS time information. Therefore, the navigation message acquisition standby periods t12 to t17 in FIG. 4 are shorter than the navigation message acquisition standby periods t3 to t5 in FIG.
In addition, since the calibration is performed as described above, the accuracy of the time recorded in the operation log stored in each slave station 10 is high. As a result, the master station 20 can utilize this operation log when confirming the operation of the telemeter system 1 or the like. For example, when the transmission data is not transmitted from each slave station 10 or when the transmission data is not appropriate, the master station 20 investigates the operation of the slave station 10 by acquiring and verifying the operation log of the slave station 10. be able to.

  In this embodiment, the timing difference is divided by the elapsed time from the previous calibration time to the present time to calculate the error of the clock signal RTCPPS. However, the timing difference between the clock signal RTCPPS and the clock signal GPSPPS is calculated. Then, calibration may be performed depending on whether or not the calculated value is larger than a predetermined value.

In this embodiment, the control unit 103 receives the navigation message s1 from the GPS reception unit 101 (FIG. 3, time t5), and after the clock signal RTCPPS several clocks (FIG. 3, time t6), the clock of the RTC 102. Although an example in which the signal generation start timing is reset and calibrated has been described, the present invention is not limited to this. For example, in FIG. 3, the clock signal generation start timing of the RTC 102 may be reset at the rising edge of the clock signal GPSPPS between times t5 and t6. Further, the control unit 103 may reset the clock signal GPSPPS not at the rising edge but at the falling edge.
In this embodiment, the counter 105 counts the number of clocks of the clock signal RTCPPS and the clock signal GPSPPS. However, the counter 105 includes a counter for the clock signal RTCPPS and a counter for the clock signal GPSPPS. The unit 103 may calculate the error of these count numbers.

10, 10-1 to 10-n ... Slave station, 20 ... Master station, 30 ... GPS satellite, 11 ... Time controller, 101 ... GPS receiver, 102 ... RTC , 103 ... Control unit, 104 ... Oscillator, 105 ... Counter, 106 ... RAM, 107 ... Backup power supply unit

Claims (5)

A first clock generator for receiving information from a satellite and generating a first clock signal based on the received information;
A second clock generator for generating a second clock signal;
An error detector for detecting an error between the first clock signal and the second clock signal;
A control unit that adjusts a second clock signal generated by the second clock generation unit when the error detected by the error detection unit is larger than a predetermined value;
A time control device comprising: The controller is
2. After adjusting the second clock signal, the first clock generation unit is controlled to stop receiving information from a satellite, and the control unit is controlled to be in a sleep state. The time control device described in 1. The second clock generator is
After adjusting the second clock signal, after a predetermined time has elapsed, an alarm signal for starting the control unit is output,
The controller is
In response to the alarm signal output from the second clock generation unit, the control unit is returned from the sleep state, and the first clock generation unit is controlled to start receiving information from a satellite. The time control apparatus according to claim 1 or 2, characterized in that The controller is
When the error detected by the error detection unit is larger than a predetermined value,
Resetting and adjusting the generation start timing of the second clock signal; adjusting by changing the internal clock frequency of the second clock generation unit; and a timing unit for timing one second of the second clock generation unit 4. The time control device according to claim 1, wherein the second clock signal is adjusted by at least one of adjustments by changing a count value for one second. 5. A time control method in a time control device,
A first clock generation unit that receives information from a satellite and generates a first clock signal based on the received information;
A second clock generation procedure in which a second clock generation unit generates a second clock signal;
An error detection procedure in which an error detection unit detects an error between the first clock signal and the second clock signal;
A procedure for the controller to adjust the second clock signal generated by the second clock generator when the error detected in the error detection procedure is greater than a predetermined value;
The time control method characterized by including.

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