KR102173654B1 - Asf compensating apparatus for precise time synchronization using long-wave korea standard time and asf compensating method thereof - Google Patents

Abstract

According to an embodiment, disclosed are an ASF compensation apparatus for high-precision visual synchronization using a long-wave standard time and a method thereof. The ASF compensation apparatus includes: a GPS receiver receiving a GPS reference signal, and outputting a GPS 1 pulse per second (PPS) signal and position information based on the received GPS reference signal; a long-wave receiver receiving a long-wave reference signal, and outputting a long-wave 1PPS signal based on the received long-wave reference signal; a first compensation part primarily compensating a primary factor (PF) and a secondary factor (SF) of the long-wave reference signal based on the position information; a second compensation part secondarily compensating an additional secondary factor (ASF) of the primarily compensated long-wave reference signal based on the long-wave 1PPS signal and the GPS 1PPS signal; and a processor outputting the received GPS reference signal or the secondarily compensated long-wave reference signal depending on whether the GPS receiver is normally operated.

Description

ASF compensation device and its method for high-precision time synchronization using long-wave standard time {ASF COMPENSATING APPARATUS FOR PRECISE TIME SYNCHRONIZATION USING LONG-WAVE KOREA STANDARD TIME AND ASF COMPENSATING METHOD THEREOF}

The embodiment relates to a time synchronization technique, and more particularly, to an ASF (Additional Secondary Factor) compensation apparatus and method for high-precision time synchronization using long-wave standard time.

Since the long-wave standard time broadcast signal contains time information about Korean Standard Time, the receiver demodulates it to obtain time information and synchronizes the receiver's signal to obtain a result synchronized with Korea Standard Time.

1 is a diagram for explaining a time synchronization method in a general long-wave receiver.

Referring to FIG. 1, a general long-wave receiver merely demodulates time information of a received signal and uses a time synchronized thereto. The accuracy of time synchronization by this method becomes more than a few microseconds, and this method cannot be used in places requiring time synchronization of less than microseconds.

The biggest limitation in performing high-precision time synchronization of less than microseconds using long-wave standard time is the method of measuring and compensating for ASF (Additional Secondary Factor). The ASF value can range from tens to hundreds of microseconds depending on the position of the long-wave receiver, and therefore, high-precision time synchronization can be achieved only by compensating for this.

Since the paths through which radio waves are transmitted are different depending on the location of the long-wave receiver, the only way to compensate for such ASF value is by continuously measuring and compensating the long-wave receiver.

Registered Patent Publication No. 10-1654739 Unexamined Patent Publication No. 10-2013-0024300

The embodiment may provide an ASF compensation apparatus and method for high-precision time synchronization using long-wave standard time.

An ASF compensation apparatus according to an embodiment of the present invention includes a GPS receiver that receives a GPS reference signal and outputs a GPS Pulse Per Second (1PPS) signal and location information based on the received GPS reference signal; A long-wave receiver for receiving a long-wave reference signal and outputting a long-wave 1PPS signal based on the received long-wave reference signal; A first compensating unit for primary compensation of a primary factor (PF) and a secondary factor (SF) of the long-wave reference signal based on the location information; A second compensating unit for secondary compensation for an additional secondary factor (ASF) of the first compensated long-wave reference signal based on the long-wave 1PPS signal and the GPS 1PPS signal; And a processor that outputs the received GPS reference signal or the second compensated longwave reference signal according to whether the GPS receiver operates normally.

The first compensation unit calculates a distance between the long wave transmitter and the long wave receiver using the location information, calculates a PF value and an SF value using the calculated distance, and uses the calculated PF value and SF value. Thus, by compensating for the received long-wave reference signal, the PF and the SF may first compensate for the long-wave reference signal.

The second compensation unit calculates an ASF value using the difference between the long-wave reference signal and the GPS 1PPS signal, in which the PF and SF are first compensated, and the RF and SF are first compensated using the calculated ASF value. By compensating for the long-wave reference signal, the ASF may output the second-corrected long-wave reference signal.

The second compensation unit calculates an ASF average value based on the ASF value calculated at a predetermined time interval, and continuously updates the calculated ASF average value at the predetermined time interval, and when the GPS receiver does not operate normally, the most The ASF of the long-wave reference signal may be compensated by using the recently updated ASF average value as a reference ASF value.

The second compensation unit calculates a daily ASF average value by obtaining the average or moving average of the ASF values calculated during the day, calculates the time-based ASF average value by obtaining the average of the ASF values at predetermined time intervals, and the calculated time reference By calculating the difference value between the ASF average value and the daily reference ASF average value, the calculated difference value may be calculated as a reference ASF value for each time slot.

The second compensation unit may estimate a correlation according to a temperature and an ASF change amount using the sensed temperature information, and compensate the daily reference ASF value based on the estimated correlation.

The processor may output the received GPS reference signal when the GPS receiver operates normally, and output the second compensated longwave reference signal when the GPS receiver does not operate normally.

Further comprising a time information demodulator for demodulating the received long-wave standard time reference signal to obtain long-wave time information, and extracting long-wave reference time information to be used as a reference from the obtained long-wave time information, wherein the processor is the time information demodulator The secondly compensated long-wave reference signal may be output according to a timing based on the long-wave reference time information extracted from.

ASF compensation method according to another embodiment of the present invention includes the steps of: receiving a GPS reference signal by a GPS receiver, and outputting a GPS Pulse Per Second (1PPS) signal and location information based on the received GPS reference signal; Receiving, by a long wave receiver, a long wave reference signal and outputting a long wave 1PPS signal based on the received long wave reference signal; First compensating, by a first compensator, for a primary factor (PF) and a secondary factor (SF) of the long-wave reference signal based on the location information; Performing secondary compensation for an additional secondary factor (ASF) of the first compensated long-wave reference signal based on the long-wave 1PPS signal and the GPS 1PPS signal; And outputting, by the processor, the received GPS reference signal or the secondly compensated longwave reference signal according to whether the GPS receiver operates normally.

In the primary compensating step, a distance between the long-wave transmitter and the long-wave receiver is calculated using the location information, a PF value and an SF value are calculated using the calculated distance, and the calculated PF value and SF value The PF and the SF may be compensated for the received long-wave reference signal by using and may output a long-wave reference signal in which the first compensation is performed.

In the second compensating step, an ASF value is calculated using the difference between the long-wave reference signal and the GPS 1PPS signal for which the PF and SF are first compensated, and the RF and SF are first ordered by using the calculated ASF value. By compensating the compensated long wave reference signal, the ASF may output the secondly compensated long wave reference signal.

In the second compensating step, an ASF average value is calculated based on the ASF value calculated at a predetermined time interval, and the calculated ASF average value is continuously updated at the predetermined time interval, and the GPS receiver does not operate normally. , The ASF of the long-wave reference signal may be compensated by using the most recently updated ASF average value as a reference ASF value.

In the secondary compensation step, the average or moving average of the ASF values calculated during the day is calculated to calculate the daily ASF average value, the average of the ASF values is calculated at predetermined time intervals to calculate the time based ASF average value, and the calculated By calculating a difference value between the time-based ASF average value and the daily reference ASF average value, the calculated difference value may be calculated as a time-based reference ASF value.

In the second compensating step, the daily reference ASF value may be compensated based on the estimated correlation by estimating a correlation according to the temperature and ASF change amount using the sensed temperature information.

In the outputting step, when the GPS receiver operates normally, the received GPS reference signal may be output, and when the GPS receiver does not operate normally, the secondly compensated longwave reference signal may be output.

A time information demodulation unit demodulates the received long-wave standard time reference signal to obtain long-wave time information, and extracting long-wave reference time information to be used as a reference from the obtained long-wave time information, wherein the processor includes the time information The secondly compensated long-wave reference signal may be output according to a timing based on the long-wave reference time information extracted from the demodulator.

According to an embodiment, when the GPS reference signal for time synchronization cannot be received by compensating for ASF as well as PF and SF of the long-wave reference signal by using the location information of the long-wave reference signal, the GPS receiver, and the super-pulse signal, the long-wave reference Can be replaced with a signal.

According to the embodiment, since it is possible to use a long-wave collimating signal, performance required in a high-precision time synchronization system can be satisfied even in the absence of a GPS reference signal.

1 is a diagram for explaining a time synchronization method in a general long-wave receiver.
2 is a diagram showing an ASF compensation apparatus according to an embodiment of the present invention.
3 is a diagram illustrating an ASF compensation method according to an embodiment of the present invention.
4 is a diagram for describing a process of calculating an ASF value according to the first embodiment of the present invention.
5 is a diagram for explaining a process of calculating an ASF value according to a second embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

However, the technical idea of the present invention is not limited to some embodiments to be described, but may be implemented in various different forms, and within the scope of the technical idea of the present invention, one or more of the constituent elements may be selectively selected between the embodiments. It can be combined with and substituted for use.

In addition, terms (including technical and scientific terms) used in the embodiments of the present invention are generally understood by those of ordinary skill in the art, unless explicitly defined and described. It can be interpreted as a meaning, and terms generally used, such as terms defined in a dictionary, may be interpreted in consideration of the meaning in the context of the related technology.

In addition, terms used in the embodiments of the present invention are for describing the embodiments and are not intended to limit the present invention.

In the present specification, the singular form may include the plural form unless specifically stated in the phrase, and when described as “at least one (or more than one) of A and (and) B and C”, it is combined with A, B, and C. It may contain one or more of all possible combinations.

In addition, terms such as first, second, A, B, (a), and (b) may be used in describing the constituent elements of the embodiment of the present invention.

These terms are only for distinguishing the component from other components, and are not limited to the nature, order, or order of the component by the term.

And, when a component is described as being'connected','coupled' or'connected' to another component, the component is not only directly connected, coupled or connected to the other component, but also the component and It may also include the case of being'connected','coupled' or'connected' due to another component between the other components.

In addition, when it is described as being formed or disposed on the “top (top) or bottom (bottom)” of each component, the top (top) or bottom (bottom) is one as well as when the two components are in direct contact with each other. It also includes a case in which the above other component is formed or disposed between the two components. In addition, when expressed as "upper (upper) or lower (lower)", the meaning of not only an upward direction but also a downward direction based on one component may be included.

In an embodiment, time synchronization is achieved by compensating not only the PF (primary factor) and SF (secondary factor) of the long-wave reference signal, but also the ASF (Additional Secondary Factor) by using the location information and the superpulse signal from the long-wave reference signal and the GPS receiver A new scheme is proposed that can be replaced with a long-wave reference signal when the GPS reference signal cannot be received.

At this time, the delay errors generated during radio wave propagation are divided into PF by radio wave transmission in the atmosphere, SF by radio wave transmission on the surface, and ASF by radio wave transmission on land. The relationship between the propagation delay errors PF, SF, and ASF and the time synchronization error is as follows. That is, when time synchronization is performed using a long-wave standard time broadcast signal, the time synchronization error is as shown in [Equation 1] below.

[Equation 1]

T _err = T _Tx + T _path + T _Rx

Here, T _err is the total time synchronization error at the receiver for _KST , T _Tx is the transmission time error at the transmitter, T _path is the propagation delay, and T _Rx is the reception time error at the receiver.

At this time, T _Tx and T _Rx can be ignored because they have values within a few nanoseconds to tens of nanoseconds.

In addition, the propagation delay T _path can be expressed as the following [Equation 2].

[Equation 2]

T _path = PF + SF + ASF

Here, PF=d/c, d is the distance between the transmitter and the receiver, and c=3*10 ⁸ m/s represents the speed of light. SF represents the propagation delay value in seawater. The value of SF can be calculated as a constant using 5 as a conductivity value commonly used for seawater and 80 as a conductivity value. ASF represents an additional propagation delay over land rather than sea. Since the path through which the radio waves are transmitted differs depending on the location of the receiver, the ASF value is the only method of continuously measuring and compensating the receiver.

As such, PF and SF can be easily modeled and compensated for because they have constant characteristics according to distance, whereas ASF is not easy to model because it is affected by the characteristics of terrain and medium.

Explaining these ASF characteristics, ASF is an additional delay factor that occurs when a signal propagates through the ground, and is a variable error factor that is affected by the altitude, permittivity, conductivity, and weather of the terrain. In this case, propagation delay occurs due to the influence of the uneven conductivity of the terrain, various elevation angles, and weather. At this time, weather components such as humidity and temperature affect the reflection coefficient and the impedance of the zone during radio wave propagation. Due to this environmental factor, ASF can introduce delay errors of hundreds of meters.

2 is a diagram showing an ASF compensation apparatus according to an embodiment of the present invention.

2, the ASF compensation apparatus according to an embodiment of the present invention includes a long wave receiver 100, a GPS receiver 200, a time information demodulation unit 300, a first compensation unit 400, and a second compensation unit. 500, may include a processor 600.

The long-wave receiver 100 may receive a long-wave standard time broadcast signal or a long-wave reference signal for time synchronization. These long-wave reference signals contain visual information about Korean Standard Time.

The GPS receiver 200 may receive a GPS reference signal. The GPS receiver 200 may output not only the received GPS reference signal, but also location information and a GPS Pulse Per Second (1PPS) signal.

The time information demodulation unit 300 may obtain long-wave time information by demodulating the received long-wave standard time reference signal.

In this case, the visual information demodulation unit 300 may detect abnormal information among the long-wave visual information obtained using a predetermined algorithm. Here, the abnormal information includes information in which a predetermined error has occurred, not normal information. When the abnormal information is detected, the visual information demodulator 300 may replace the abnormal information with an average value or an intermediate value of normal information.

The visual information demodulator 300 may extract long-wave reference time information to be used as a reference from the long-wave time information by using a method such as moving average or linear fitting.

The first compensator 400 may calculate a distance between the long-wave transmitter and the long-wave receiver by using location information of the long-wave receiver using a GPS reference signal or location information of the long-wave receiver previously input.

The first compensation unit 400 calculates the PF value and the SF value using the calculated distance, and subtracts the calculated PF value and SF value from the long wave reference signal received from the long wave receiver 100, thereby subtracting the PF and SF. By compensating, it is possible to output a long-wave reference signal with RF and SF compensation.

The second compensating unit 500 may calculate a reference ASF value by using a difference between the long-wave reference signal and the GPS 1PPS signal for which PF and SF are compensated. The second compensating unit 500 may calculate an ASF average value using a method such as a moving average based on the ASF value calculated at a predetermined time interval, and continuously update the ASF average value at the predetermined time interval.

When receiving an interrupt signal indicating that the GPS receiver does not operate normally, the second compensation unit 500 compensates the ASF using the most recently updated ASF average value as the reference ASF value, thereby compensating the PF, SF, and ASF. It is possible to output a long-wave reference signal compensated for all.

The processor 600 continuously monitors the normal operation of the GPS receiver, generates an interrupt signal for notifying that a hold over has occurred because the GPS receiver does not operate normally, and converts the generated interrupt signal to the second compensation unit 500 ) Can be provided.

The processor 600 may output a reference signal for time synchronization. That is, when the GPS receiver operates normally, the processor 600 may output a GPS reference signal that is a reference signal of the GPS receiver, and when the GPS receiver does not operate normally, the processor 600 may output a long-wave reference signal compensated for by PF, SF, and ASF.

In this case, when the long-wave reference signal is to be output because the GPS reference signal cannot be used, the processor 600 may output the long-wave reference signal according to a timing based on the long-wave reference time information.

That is, the processor 600 may output a long-wave reference signal instead of the GPS reference signal when a holdover occurs in a state in which the GPS reference signal is not received while outputting the GPS reference signal.

As described above, according to this embodiment, in the industrial field requiring high-precision time synchronization of less than microseconds, such as mobile communication base stations, sensor networks, power networks, etc., by compensating for ASF ranging from several μs to several hundreds μs in time synchronization using a long-wave reference signal. Can be utilized.

3 is a diagram illustrating an ASF compensation method according to an embodiment of the present invention.

Referring to FIG. 3, the ASF compensation apparatus according to an embodiment of the present invention may receive a GPS reference signal for time synchronization through a GPS receiver (S301), and may receive a longwave reference signal through a longwave receiver (S302). ).

Next, the ASF compensation apparatus may collect long-wave time information by demodulating the received long-wave reference signal (S303).

Next, the ASF compensation apparatus may detect abnormal information among the collected long-wave time information using a predetermined algorithm (S304).

Next, when abnormal information is detected among the long-wave time information, the ASF compensation device may replace the detected abnormal information with normal information, in which case, the abnormal information may be replaced with an average value or an intermediate value of the normal information ( S305).

On the other hand, the ASF compensation apparatus may extract long-wave reference time information to be used as a reference from the long-wave time information when the abnormal information is not detected or if the abnormal information is replaced with normal data (S306). In this case, the ASF compensation apparatus may extract long-wave reference time information to be used as a reference from the long-wave time information using a method such as a moving average or linear fitting.

Thereafter, the ASF compensation apparatus may calculate a distance between the long wave transmitter and the long wave receiver by using the location information from the GPS receiver. Here, the location information may be location information of a long wave receiver using a GPS receiver or location information of a long wave receiver input in advance.

Next, the ASF compensation apparatus may compensate for PF and SF by calculating the PF value and the SF value using the calculated distance, and subtracting the calculated PF value and the SF value from the received long-wave standard time reference signal (S307. ).

Next, the ASF compensation device calculates the ASF value by using the difference between the PF and SF-compensated long-wave reference signal and the GPS 1PPS signal, and subtracts the PF and SF-compensated long-wave reference signal by using the calculated ASF value. , ASF can be compensated (S308).

Next, the ASF compensation apparatus may monitor whether or not the GPS receiver operates normally (S309).

Next, the ASF compensation apparatus may output a GPS reference signal when the GPS receiver operates normally (S310).

On the other hand, the ASF compensation apparatus may output a long-wave reference signal compensated by the previously generated PF, SF, and ASF when holdover occurs because the GPS receiver does not operate normally (S311).

In this case, when the ASF compensating device cannot use the GPS reference signal and thus needs to output the long-wave reference signal, it may output the long-wave reference signal according to the timing based on the long-wave reference time information.

4 is a diagram for describing a process of calculating an ASF value according to the first embodiment of the present invention.

Referring to FIG. 4, the ASF compensation apparatus according to the first embodiment of the present invention may obtain an average or moving average of ASF values for a day and calculate the average ASF value on a daily basis (S410).

Next, the ASF compensation apparatus may calculate the average of the ASF values at each predetermined time interval and calculate the average of the time-based ASF (S420).

Next, the ASF compensation apparatus may calculate a difference value between the calculated time-based ASF average value and the daily reference ASF average value, and calculate the calculated difference value as a time-based reference ASF value (S430). The calculated reference ASF value for each time slot is used to compensate for the ASF of the long-wave reference signal.

5 is a diagram for explaining a process of calculating an ASF value according to a second embodiment of the present invention.

Referring to FIG. 5, the ASF compensation apparatus according to the second embodiment of the present invention may obtain an average or moving average of ASF values for a day and calculate a daily reference ASF value (S510).

At this time, the ASF compensation apparatus may estimate a correlation according to the temperature and ASF change amount using the temperature information sensed through the temperature sensor (S511), and compensate the daily reference ASF value based on the estimated correlation (S512). . Here, a case of compensating the ASF value by estimating the correlation between the temperature and the ASF change amount is described as an example, but the present invention is not limited thereto, and various factors such as humidity that may affect the ASF value may be used.

Next, the ASF compensation apparatus may calculate the average of the ASF values at each predetermined time interval and calculate the time-based ASF value (S520).

Next, the ASF compensation apparatus may calculate a difference value between the calculated time-based ASF value and the daily reference ASF value, and finally calculate the calculated difference value as a time-based reference ASF value (S530).

The term'~ unit' used in this embodiment refers to software or hardware components such as field-programmable gate array (FPGA) or ASIC, and'~ unit' performs certain roles. However,'~ part' is not limited to software or hardware. The'~ unit' may be configured to be in an addressable storage medium, or may be configured to reproduce one or more processors. Thus, as an example,'~ unit' refers to components such as software components, object-oriented software components, class components and task components, processes, functions, properties, and procedures. , Subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, database, data structures, tables, arrays, and variables. The components and functions provided in the'~ units' may be combined into a smaller number of elements and'~ units', or may be further divided into additional elements and'~ units'. In addition, components and'~ units' may be implemented to play one or more CPUs in a device or a security multimedia card.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention within the scope not departing from the spirit and scope of the present invention described in the following claims. You will understand that you can do it.

100: longwave receiver
200: GPS receiver
300: visual information demodulation unit
400: first compensation unit
500: second compensation unit
600: processor

Claims (16)

A GPS receiver that receives a GPS reference signal and outputs a GPS Pulse Per Second (1PPS) signal and location information based on the received GPS reference signal;
A long-wave receiver for receiving a long-wave reference signal and outputting a long-wave 1PPS signal based on the received long-wave reference signal;
A first compensating unit for primary compensation of a primary factor (PF) and a secondary factor (SF) of the long-wave reference signal based on the location information;
A second compensating unit for secondary compensation for an additional secondary factor (ASF) of the first compensated long-wave reference signal based on the long-wave 1PPS signal and the GPS 1PPS signal; And
A processor for outputting the received GPS reference signal or the second compensated long-wave reference signal according to whether the GPS receiver operates normally, and
The second compensation unit,
ASF value is calculated using the difference between the first compensated long-wave reference signal and the GPS 1PPS signal,
An ASF average value is calculated based on the ASF value calculated at a predetermined time interval, and the calculated ASF average value is continuously updated at the predetermined time interval,
When the GPS receiver does not operate normally, the ASF compensation apparatus for compensating the ASF of the first compensated long-wave reference signal by using the most recently updated ASF average value as a reference ASF value. The method of claim 1,
The first compensation unit,
The distance between the long wave transmitter and the long wave receiver is calculated using the location information,
Calculating the PF value and the SF value using the calculated distance,
Compensating the received long-wave reference signal using the calculated PF value and SF value, and outputting a long-wave reference signal in which the PF and the SF are first compensated. delete delete The method of claim 1,
The second compensation unit,
The average or moving average of the ASF values calculated during the day is calculated to calculate the daily ASF average value,
By calculating the average of the ASF values at each predetermined time interval, the time-based ASF average value is calculated,
ASF compensation apparatus for calculating a difference value between the calculated time-based ASF average value and a daily-based ASF average value to calculate the calculated difference value as a time-based reference ASF value. The method of claim 5,
The second compensation unit,
ASF compensation device for compensating the daily reference ASF value based on the estimated correlation by estimating a correlation according to a temperature and ASF change amount using the sensed temperature information. The method of claim 1,
The processor,
When the GPS receiver operates normally, outputs the received GPS reference signal,
When the GPS receiver does not operate normally, outputs the second-compensated long-wave reference signal. The method of claim 1,
A time information demodulator for demodulating the received long-wave standard time reference signal to obtain long-wave time information, and extracting long-wave reference time information to be used as a reference from the obtained long-wave time information,
The processor outputs the secondly compensated long-wave reference signal according to a timing based on the long-wave reference time information extracted from the time information demodulator. Receiving, by a GPS receiver, a GPS reference signal, and outputting a GPS Pulse Per Second (1PPS) signal and location information based on the received GPS reference signal;
Receiving, by a long wave receiver, a long wave reference signal and outputting a long wave 1PPS signal based on the received long wave reference signal;
First compensating, by a first compensator, for a primary factor (PF) and a secondary factor (SF) of the long-wave reference signal based on the location information;
Performing secondary compensation for an additional secondary factor (ASF) of the first compensated long-wave reference signal based on the long-wave 1PPS signal and the GPS 1PPS signal; And
And outputting, by a processor, the received GPS reference signal or the secondly compensated longwave reference signal according to whether the GPS receiver operates normally,
In the step of secondary compensation,
ASF value is calculated using the difference between the first compensated long-wave reference signal and the GPS 1PPS signal,
An ASF average value is calculated based on the ASF value calculated at a predetermined time interval, and the calculated ASF average value is continuously updated at the predetermined time interval,
When the GPS receiver does not operate normally, the ASF of the first compensated long-wave reference signal is compensated by using the most recently updated ASF average value as a reference ASF value. The method of claim 9,
In the step of primary compensation,
The distance between the long wave transmitter and the long wave receiver is calculated using the location information,
Calculating the PF value and the SF value using the calculated distance,
Compensating the received long-wave reference signal using the calculated PF value and SF value to output a long-wave reference signal in which the PF and the SF are first compensated. delete delete The method of claim 9,
In the step of secondary compensation,
The average or moving average of the ASF values calculated during the day is calculated to calculate the daily ASF average value,
By calculating the average of the ASF values at each predetermined time interval, the time-based ASF average value is calculated,
ASF compensation method for calculating a difference value between the calculated time-based ASF average value and a daily-based ASF average value to calculate the calculated difference value as a time-based reference ASF value. The method of claim 13,
In the step of secondary compensation,
ASF compensation method for compensating the daily reference ASF value based on the estimated correlation by estimating a correlation according to a temperature and ASF change amount using the sensed temperature information. The method of claim 9,
In the outputting step,
When the GPS receiver operates normally, outputs the received GPS reference signal,
If the GPS receiver does not operate normally, outputting the second-compensated long-wave reference signal, ASF compensation method. The method of claim 9,
A time information demodulation unit demodulates the received long-wave standard time reference signal to obtain long-wave time information, and extracting long-wave reference time information to be used as a reference from the obtained long-wave time information,
The processor outputs the second-compensated long-wave reference signal according to a timing based on the long-wave reference time information extracted from the time information demodulator.

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