JP2015068729A - Timing signal generation device, electronic apparatus, and mobile body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a timing signal generation device for quickly and accurately generating position information about a receiving point and improving accuracy of a timing signal, and further to provide a high-reliability electronic apparatus and mobile body equipped with the timing signal generation device.SOLUTION: A timing signal generation device 1 includes a GPS receiver 10 and a processing unit 20. The GPS receiver 10 and the processing unit 20 receive satellite signals transmitted from a plurality of GPS satellites, and generates position information about a receiving point on the basis of the received satellite signals. The GPS receiver 10 receives a satellite signal transmitted from at least one GPS satellite 2, determines whether or not an angle of elevation of a position information satellite pertaining to the received satellite signal is equal to or greater than the set value of an elevation angle mask, and generates 1 PPS on the basis of the satellite signal transmitted from the GPS satellite 2 at an angle of elevation equal to or greater than the set value of the elevation angle mask.

Description

  The present invention relates to a timing signal generation device, an electronic device, and a moving object.

Global navigation satellite system (GNSS) using artificial satellites
The GPS (Global Positioning System) which is one of e System) is widely known. G
The GPS satellite used for the PS is equipped with an extremely accurate atomic clock, and transmits a satellite signal on which the orbit information of the GPS satellite and the accurate time information are superimposed on the ground. A satellite signal transmitted from a GPS satellite is received by a GPS receiver. The GPS receiver then calculates the current position and time information of the GPS receiver based on orbit information and time information superimposed on the satellite signal, and an accurate timing signal that updates the time every second. Processing for generating (1PPS) is performed.
Such a GPS receiver is provided with a normal positioning (position estimation) mode that provides position and time based on positioning calculation and a position fixing mode that provides time by fixed position positioning at a known position. It is common.

In normal positioning mode, a predetermined number (minimum 3 if 2D positioning, 4 if 3D positioning)
Satellite signals from the above GPS satellites are required. Also, the greater the number of GPS satellites that can receive satellite signals, the more accurate the positioning calculation.
On the other hand, in the position fixing mode, if the position information of the GPS receiver is set, 1 PPS can be generated if the satellite signal from at least one GPS satellite can be received.

JP-A-9-178870

In the conventional GPS receiver, in the position fixing mode, 1 PPS is generated using the satellite signal of the GPS satellite captured in the same elevation angle range as that in the normal positioning mode. Therefore, if the range of the elevation angle of GPS satellites that can be captured in the normal positioning mode is increased in order to obtain accurate position information as soon as possible, it is easily affected by multipath, and as a result, accurate time information can be obtained from the GPS satellites. There is a problem that the accuracy of 1 PPS is reduced.
An object of the present invention is to provide a timing signal generation device capable of generating timing signal with high accuracy while enabling position information of a reception point to be generated quickly and with high accuracy, and to provide such a timing signal generation device. An object of the present invention is to provide an electronic device and a moving body with excellent reliability.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.
[Application Example 1]
The timing signal generation device of the present invention receives a satellite signal transmitted from a plurality of position information satellites, and based on the received satellite signal, a position information generation unit that generates position information of a reception point;
A timing signal generation unit that receives a satellite signal from a position information satellite at an elevation angle equal to or higher than a setting value of an elevation angle mask, and generates a timing signal based on the received satellite signal;
It is characterized by providing.

According to such a timing signal generation device, when generating a timing signal, since a satellite signal transmitted from a position information satellite at an elevation angle equal to or higher than the setting value of the elevation mask is used, it is difficult to be affected by multipath. The accuracy of the timing signal can be increased.
On the other hand, when generating the position information of the reception point, the position information of the reception point can be quickly and accurately used by using the satellite signal transmitted from the position information satellite at an elevation angle within a wider range than when generating the timing signal. It can be generated with high accuracy.

[Application Example 2]
In the timing signal generation device of the present invention, it is preferable that a set value of the elevation angle mask is 45 degrees or more.
Thereby, even in an environment where multipaths such as buildings, trees, and the like are likely to occur around the reception point, it is possible to reduce the influence of multipaths when generating timing signals.

[Application Example 3]
In the timing signal generation device of the present invention, it is preferable that the set value of the elevation mask can be changed.
Thereby, the set value of the elevation mask can be optimized according to the installation environment. Therefore, it is possible to make it less susceptible to multipath while avoiding errors as much as possible when generating timing signals.

[Application Example 4]
In the timing signal generation device of the present invention, the timing signal generation unit includes at least one of a received intensity of the received satellite signal and a difference between time information included in the satellite signal and time information of the reception point. It is preferable to change the setting value of the elevation mask based on information about one.

A satellite signal including a multipath error generally has a lower reception intensity than a regular satellite signal, and a time information shift occurs between the satellite signal and the regular satellite signal. Therefore, whether or not the received satellite signal includes a multipath error based on the reception intensity of the received satellite signal and at least one of the difference between the time information included in the satellite signal and the time information of the reception point. And the setting value of the elevation mask can be set so as not to use the satellite signal including the multipath error.

[Application Example 5]
In the timing signal generation device of the present invention, it is preferable that the timing signal generation unit changes a setting value of the elevation mask based on the information accumulated with time.
As a result, the setting value of the elevation angle mask can be optimized after accurately grasping the occurrence state of the multi-path in the installation place in one day.

[Application Example 6]
In the timing signal generation device of the present invention, the position information generation unit receives a reception point based on satellite signals transmitted from a plurality of position information satellites including position information satellites at an elevation angle smaller than a setting value of the elevation angle mask. It is preferable that position information can be generated.
As a result, the position information of the reception point can be generated quickly and with high accuracy using the satellite signal transmitted from the position information satellite at an elevation angle within a wider range than when the timing signal is generated.

[Application Example 7]
In the timing signal generation device of the present invention, the position information generation unit includes a positioning calculation unit that performs a positioning calculation based on a satellite signal, and a mode in a plurality of positioning calculation results by the positioning calculation unit over a predetermined time. It is preferable to generate the position information of the reception point based on the value or the median value.
As a result, even if the positioning calculation error increases due to the deterioration of the reception environment, it becomes difficult to be influenced by the positioning result having a large error, and as a result, the accuracy of the timing signal can be improved.

[Application Example 8]
In the timing signal generation device of the present invention, an oscillator that outputs a clock signal;
And a synchronization control unit that synchronizes the clock signal with the timing signal.
Thus, by synchronizing the clock signal output from the oscillator with the accurate timing signal, it is possible to generate a clock signal with higher accuracy than the accuracy of the oscillator. In addition, by using a high-accuracy oscillator such as an atomic oscillator or a thermostatic chamber crystal oscillator as the oscillator, a highly accurate timing signal can be generated even when there is no position information satellite at an elevation angle higher than the elevation mask set value. can do.

[Application Example 9]
An electronic apparatus according to the present invention includes the timing signal generation device according to the present invention.
Thereby, an electronic device having excellent reliability can be provided.
[Application Example 10]
The moving body of the present invention includes the timing signal generation device of the present invention.
Thereby, the mobile body which has the outstanding reliability can be provided.

1 is a diagram illustrating a schematic configuration of a timing signal generation device according to a first embodiment of the present invention. It is a figure which shows the structure of the navigation message transmitted from a GPS satellite. It is a block diagram which shows the structural example of the GPS receiver with which the timing signal generation apparatus shown in FIG. 1 is provided. It is a flowchart which shows an example of the process sequence in the normal positioning mode and position fixing mode in the GPS receiver shown in FIG. It is a flowchart which shows an example of the processing procedure of 1PPS output in the GPS receiver shown in FIG. It is a flowchart which shows an example of the process sequence of control of the GPS receiver by the process part of the timing signal generation apparatus shown in FIG. (A) is a table showing the positioning calculation results when the number of GPS satellites is large but the reception strength is low, and (B) is the positioning calculation results when the reception strength is high but the number of GPS satellites is small. It is a table. (A) is a schematic diagram for demonstrating the effect | action in normal positioning mode, (b) is a figure for demonstrating the effect | action in position fixing mode. It is a figure which shows schematic structure of the timing signal generator which concerns on 2nd Embodiment of this invention. It is a flowchart which shows an example of the process procedure of 1PPS selection in the GPS receiver with which the timing signal generation apparatus shown in FIG. 9 is provided. It is a figure which shows schematic structure of the timing signal generation apparatus which concerns on 3rd Embodiment of this invention. It is a flowchart which shows an example of the process procedure of 1PPS selection in the GPS receiver with which the timing signal generation apparatus shown in FIG. 11 is provided. It is a block diagram which shows embodiment of the electronic device of this invention. It is a figure which shows embodiment of the mobile body of this invention.

Hereinafter, a timing signal generation device, an electronic device, and a moving body of the present invention will be described in detail based on embodiments shown in the accompanying drawings.
1. Timing signal generator <First embodiment>
FIG. 1 is a diagram showing a schematic configuration of a timing signal generation device according to the first embodiment of the present invention.

A timing signal generator 1 shown in FIG. 1 includes a GPS receiver 10, a processing unit (CPU) 20,
An atomic oscillator 30, a temperature sensor 40, and a GPS antenna 50 are included.
Note that the timing signal generation device 1 may be partly or entirely physically separated from each other or may be integrated. For example, GPS receiver 10 and processing unit (CPU)
20 may be realized by separate ICs, or the GPS receiver 10 and the processing unit (CP
U) 20 may be realized as a one-chip IC.

The timing signal generator 1 receives a signal transmitted from a GPS satellite 2 (an example of a position information satellite) and generates a highly accurate 1PPS.
The GPS satellite 2 orbits a predetermined orbit above the earth and has a carrier wave of 1.575.
Navigation message and C / A code (Coarse / Acquisition) to 42 GHz radio wave (L1 wave)
Code) is superimposed (modulated carrier wave) and the satellite signal is transmitted to the ground.

The C / A code is for identifying satellite signals of about 30 GPS satellites 2 that are present, and each chip is either +1 or −1 1023 chips (1 ms period)
It is a unique pattern consisting of Therefore, by correlating the satellite signal and the pattern of each C / A code, the C / A code superimposed on the satellite signal can be detected.
The satellite signal (specifically, navigation message) transmitted by each GPS satellite 2 includes orbit information indicating the position of each GPS satellite 2 on the orbit. Each GPS satellite 2 has an atomic clock, and the satellite signal includes extremely accurate time information measured by the atomic clock. Accordingly, by receiving satellite signals from four or more GPS satellites 2 and performing positioning calculation using the orbit information and time information included in each satellite signal, the reception point (GPS antenna 5
It is possible to obtain accurate information on the position and time of (0 installation place). Specifically, the reception point 3
What is necessary is just to set up the 4-dimensional equation which makes a dimensional position (x, y, z) and time t four variables, and to obtain the solution.

When the position of the reception point is known, the satellite signal from one or more GPS satellites 2 can be received, and the time information of the reception point can be obtained using the time information included in each satellite signal. .
Also, information on the difference between the time of each GPS satellite 2 and the time of the reception point can be obtained using the orbit information included in each satellite signal. Each G is controlled by the ground control segment.
A slight time error of the atomic clock mounted on the PS satellite 2 is measured, and the satellite signal also includes a time correction parameter for correcting the time error, and reception is performed using this time correction parameter. By correcting the time of the points, extremely accurate time information can be obtained.

FIG. 2 is a diagram showing a configuration of a navigation message transmitted from a GPS satellite.
As shown in FIG. 2 (A), the navigation message is configured as data with a main frame having a total number of 1500 bits as one unit. The main frame is divided into five sub-frames 1 to 5 each having 300 bits. Data of one subframe is transmitted from each GPS satellite 2 in 6 seconds. Accordingly, data of one main frame is transmitted from each GPS satellite 2 in 30 seconds.

Subframe 1 includes satellite correction data such as week number data (WN). The week number data is information representing a week including the time of the GPS satellite 2. The starting time of the GPS satellite 2 is UTC (Universal Standard Time) on January 6, 1980, 00:00:00, and the week starting on this day has a week number 0. Week number data is updated on a weekly basis.
The subframes 2 and 3 include ephemeris parameters (detailed orbit information of each GPS satellite 2). The subframes 4 and 5 include almanac parameters (general orbit information of all GPS satellites 2).

Further, at the head of each of the subframes 1 to 5, a TLM (Telemetry) word storing 30-bit TLM (Telemetry word) data and a 30-bit HOW (hand over word)
) HOW word in which data is stored.
Accordingly, TLM words and HOW words are transmitted from the GPS device satellite 2 at intervals of 6 seconds, whereas satellite correction data such as week number data, ephemeris parameters, and almanac parameters are transmitted at intervals of 30 seconds.

As shown in FIG. 2B, the TLM word includes preamble data, a TLM message, a reserved bit, and parity data.
As shown in FIG. 2C, the HOW word includes time information called TOW (Time of Week) (hereinafter also referred to as “Z count”). Z count data is 0 every Sunday
The elapsed time from the time is displayed in seconds, and returns to 0 at 0 o'clock on the next Sunday. That is, the Z count data is information in seconds indicated every week from the beginning of the week, and the elapsed time is a number expressed in units of 1.5 seconds. Here, the Z count data indicates time information at which the first bit of the next subframe data is transmitted. For example, Z of subframe 1
The count data indicates time information at which the first bit of subframe 2 is transmitted. H
The OW word also includes 3-bit data (ID code) indicating the ID of the subframe. That is, each of the HOW words of subframes 1 to 5 shown in FIG.
ID codes “01”, “010”, “011”, “100”, and “101” are included.

By acquiring the week number data included in subframe 1 and the HOW word (Z count data) included in subframes 1 to 5, the time of GPS satellite 2 can be calculated.
If the week number data is acquired previously and the elapsed time from the time when the week number data was acquired is counted internally, the current week number data of the GPS satellite 2 can be obtained without acquiring the week number data every time. Can be obtained. Therefore, if only the Z count data is acquired, the current time of the GPS satellite 2 can be known roughly.
The satellite signal as described above is received by the GPS receiver 10 via the GPS antenna 50 shown in FIG.

The GPS antenna 50 is an antenna that receives various radio waves including satellite signals.
Connected to the receiver 10.
The GPS receiver 10 (an example of a satellite signal receiving unit) performs various processes based on the satellite signal received via the GPS antenna 50.
More specifically, the GPS receiver 10 has a normal positioning mode (an example of the first mode) and a position fixing mode (an example of the second mode), and a control command (CPU) ( Depending on the mode setting control command), either the normal positioning mode or the fixed position mode is set.

In the normal positioning mode, the GPS receiver 10 functions as a positioning calculation unit, receives satellite signals transmitted from a plurality (preferably four or more) of GPS satellites 2, and orbit information ( Specifically, positioning calculation is performed based on the above-described ephemeris data, almanac data, etc.) and time information (specifically, the above-described week number data, Z count data, etc.).

Further, the GPS receiver 10 functions as a timing signal generation unit in the position fixing mode, receives a satellite signal transmitted from at least one GPS satellite 2, and includes orbit information and time information included in the received satellite signal. 1PPS based on the position information of the set reception point
(1 Pulse Per Second) is generated. 1 PPS (an example of a timing signal synchronized with a reference time) is a pulse signal that is completely synchronized with UTC (Universal Standard Time), and includes one pulse per second.

Hereinafter, the configuration of the GPS receiver 10 will be described in detail.
FIG. 3 is a block diagram illustrating a configuration example of a GPS receiver included in the timing signal generation device illustrated in FIG. 1.
A GPS receiver 10 shown in FIG. 3 includes a SAW (Surface Acoustic Wave) filter 11, an RF processing unit 12, a baseband processing unit 13, and a temperature compensated crystal oscillator (T
CXO (Temperature Compensated Crystal Oscillator) 14 is included.

The SAW filter 11 performs a process of extracting a satellite signal from the radio wave received by the GPS antenna 50. The SAW filter 11 is configured as a bandpass filter that passes a 1.5 GHz band signal.
The RF processing unit 12 includes a PLL (Phase Locked Loop) 121, an LNA (Low Noise Amplifi).
er) 122, a mixer 123, an IF amplifier 124, an IF (Intermediate Frequency) filter 125, and an ADC (A / D converter) 126.

The PLL 121 generates a clock signal obtained by multiplying the oscillation signal of the TCXO 14 that oscillates at about several tens of MHz to a frequency of 1.5 GHz band.
The satellite signal extracted by the SAW filter 11 is amplified by the LNA 122. LNA12
The satellite signal amplified at 2 is mixed with the clock signal output from the PLL 121 by the mixer 123 and down-converted to an intermediate frequency band (for example, several MHz) signal (IF signal). The signal mixed by the mixer 123 is amplified by the IF amplifier 124.

Since the mixer 123 generates a high-frequency signal in the order of GHz along with the IF signal, the IF amplifier 124 amplifies the high-frequency signal together with the IF signal. I
The F filter 125 passes the IF signal and removes the high-frequency signal (precisely, it is attenuated below a predetermined level). The IF signal that has passed through the IF filter 125 is converted into a digital signal by an ADC (A / D converter) 126.

The baseband processing unit 13 includes a DSP (Digital Signal Processor) 131, a CPU (Ce
It includes a ntral processing unit (132) 132, a static random access memory (SRAM) 133, and an RTC (real time clock) 134, and performs various processes using the oscillation signal of the TCXO 14 as a clock signal.
The DSP 131 and the CPU 132 cooperate with each other to demodulate the baseband signal from the IF signal, acquire trajectory information and time information included in the navigation message, and perform processing in the normal positioning mode or position fixing mode.

The SRAM 133 stores time information and trajectory information acquired, position information of reception points set in accordance with predetermined control commands (position setting control commands), elevation angle masks used in the position fixing mode, and the like. It is. The RTC 134 generates timing for performing baseband processing. The RTC 134 is counted up by the clock signal from the TCXO 14.

Specifically, the baseband processing unit 13 generates a local code having the same pattern as each C / A code, and performs a process (satellite search) for correlating each C / A code included in the baseband signal with the local code. )I do. Then, the baseband processing unit 13 adjusts the local code generation timing so that the correlation value for each local code has a peak, and when the correlation value is equal to or greater than the threshold, the local code is set as the C / A code. It is determined that the GPS satellite 2 is synchronized (GPS satellite 2 is captured). In GPS, all GPS satellites 2
CDMA (Code Divisio) that transmits satellite signals of the same frequency using different C / A codes
n Multiple Access) method. Therefore, C included in the received satellite signal
By determining the / A code, the GPS satellites 2 that can be captured can be searched.

Further, the baseband processing unit 13 mixes a local code and a baseband signal having the same pattern as the C / A code of the GPS satellite 2 in order to acquire the orbit information and time information of the captured GPS satellite 2. I do. The mixed signal contains the captured GPS
The navigation message including the orbit information and time information of the satellite 2 is demodulated. Then, the baseband processing unit 13 acquires trajectory information and time information included in the navigation message, and the SRAM 133
The process to memorize is performed.

The baseband processing unit 13 receives a predetermined control command (specifically, a mode setting control command), and is set to either the normal positioning mode or the position fixing mode. In the normal positioning mode, the baseband processing unit 13 performs positioning calculation using orbit information and time information of four or more GPS satellites 2 stored in the SRAM 133.
Further, the baseband processing unit 13 uses the orbit information of one or more GPS satellites 2 stored in the SRAM 133 and the position information of the reception points stored in the SRAM 133 in the position fixing mode. 1PPS is output. Specifically, the baseband processing unit 13 includes a 1PPS counter that counts the generation timing of each 1PPS pulse in a part of the RTC 134, and uses the orbit information of the GPS satellite 2 and the position information of the reception point. , GPS
Calculate the propagation delay time required for the satellite signal transmitted from the satellite 2 to reach the reception point,
Based on this propagation delay time, the set value of the 1PPS counter is changed to an optimum value.

In particular, the baseband processing unit 13 uses the elevation mask stored in the SRAM 133 in the fixed position mode, and whether the elevation angle of the GPS satellite 2 related to the orbit information stored in the SRAM 133 is equal to or greater than the set value of the elevation mask. From the orbit information stored in the SRAM 133, at least one GPS satellite 2 orbit information at an elevation angle equal to or greater than the set value of the elevation mask is selected, and the selected orbit information and the SRAM 133 are stored. 1PPS with high accuracy is output using the position information of the receiving point. Specifically, the baseband processing unit 13 obtains the position coordinates of the GPS satellite 2 using the orbit information (ephemeris parameter) of the GPS satellite 2, and uses the position coordinates and the position information (position coordinates) of the reception point. After determining the elevation angle of the GPS satellite 2, it is determined whether or not the elevation angle is equal to or greater than the set value of the elevation mask, and the orbit information of the GPS satellite 2 at an elevation angle equal to or greater than the set value of the elevation mask is selected. The propagation delay time is calculated as described above, and the set value of the 1PPS counter is changed to the optimum value based on this propagation delay time.

Note that the baseband processing unit 13 may output 1 PPS based on the reception point time information obtained by the positioning calculation in the normal positioning mode. In the position fixing mode, the baseband processing unit 13 may output a plurality of GPs.
If the S satellite 2 can be captured, the positioning calculation may be performed.
In addition, the baseband processing unit 13 receives position information and time information as a result of positioning calculation, reception status (
NMEA data including various information such as the number of GPS satellites 2 captured and the intensity of the satellite signal is output.
The operation of the GPS receiver 10 configured as described above is performed by the processing unit (CPU shown in FIG.
) 20.

The processing unit 20 (an example of a satellite signal reception control device) transmits various control commands to the GPS receiver 10 to control the operation of the GPS receiver 10 and outputs 1P output from the GPS receiver 10.
Receives PS and NMEA data and performs various processes. The processing unit 20 may perform various processes according to a program stored in an arbitrary memory, for example.
The processing unit 20 includes a phase comparator 21, a loop filter 22, and a DSP (Digital Signal
Processor) 23, frequency divider 24, and GPS control unit 25. In addition,
The DSP 23 and the GPS control unit 25 may be composed of a single component.

The DSP 23 periodically acquires NMEA data from the GPS receiver 10 (for example, every second) and collects position information (results of positioning calculation in the normal positioning mode by the GPS receiver 10) included in the NMEA data. Statistical information for a predetermined time is created, and processing for generating position information of reception points is performed based on the statistical information (average value, mode value, or median value). here,
The configuration including the GPS receiver 10 and the DSP 23 constitutes a position information generation unit that receives satellite signals transmitted from a plurality of GPS satellites 2 and generates position information of reception points based on the received satellite signals. Note that the DSP 23 may use, for example, the average value, the mode value, or the median value of the positioning calculation result as it is as the position information of the reception point, or may use a value close to the average value, the mode value, or the median value. Alternatively, a value obtained by further calculation using an average value, a mode value, or a median value may be used.

The GPS control unit 25 (an example of a reception control unit) transmits various control commands to the GPS receiver 10 to control the operation of the GPS receiver 10. Specifically, the GPS control unit 25 is a GPS
A control command for mode setting is transmitted to the receiver 10, and the GPS receiver 10 is switched from the normal positioning mode to the position fixing mode. Further, the GPS control unit 25 transmits a position setting control command to the GPS receiver 10 before switching the GPS receiver 10 from the normal positioning mode to the position fixing mode, and receives the position information of the reception point generated by the DSP 23. GPS receiver 1
Processing to set to 0 is performed.

The frequency divider 24 divides the clock signal (frequency: f) output from the atomic oscillator 30 by f, and 1
Outputs a frequency-divided clock signal of Hz.
The phase comparator 21 includes 1PPS output from the GPS receiver 10 and 1H output from the frequency divider 24.
Phase comparison with z divided clock signal. The phase difference signal as a comparison result of the phase comparator 21 is input to the atomic oscillator 30 via the loop filter 22. The parameters of the loop filter 22 are set by the DSP 23.
The 1 Hz frequency-divided clock signal output from the frequency divider 24 is 1P output from the GPS receiver 10.
Synchronized with PS, the timing signal generator 1 outputs this divided clock signal to the outside as 1 PPS with extremely high frequency accuracy synchronized with UTC. In addition, the timing signal generation device 1 outputs the latest NMEA data to the outside every second in synchronization with 1 PPS.

The atomic oscillator 30 is an oscillator that can output a clock signal with high frequency accuracy using energy transition of atoms. For example, an atomic oscillator using rubidium atoms or cesium atoms is widely known. As the atomic oscillator 30, for example, EIT (Electromagnetically Indus
ced Transparency) phenomenon (also called CPT (Coherent Population Trapping) phenomenon)
And an atomic oscillator using the optical micro double resonance phenomenon can be used. The timing signal generator 1 also outputs a clock signal having a frequency f output from the atomic oscillator 30 to the outside.

The atomic oscillator 30 is configured such that the frequency can be finely adjusted according to the output voltage (control voltage) of the loop filter 22, and as described above, the phase comparator 21, the loop filter 22, and D
The clock signal output from the atomic oscillator 30 is completely synchronized with 1 PPS output from the GPS receiver 10 by the SP 23 and the frequency divider 24. That is, the configuration of the phase comparator 21, the loop filter 22, the DSP 23, and the frequency divider 24 functions as a synchronization control unit that synchronizes the clock signal output from the atomic oscillator 30 with 1 PPS. In addition, since the frequency temperature characteristic of the atomic oscillator 30 is not flat by itself, the temperature sensor 40 is disposed in the vicinity of the atomic oscillator 30, and the DSP 23 has a phase corresponding to the detection value (detection temperature) of the temperature sensor 40. By adjusting the output voltage of the comparator 21, the temperature temperature characteristic of the atomic oscillator 30 is subjected to temperature compensation.

When a situation (holdover) occurs in which the GPS receiver 10 cannot receive a satellite signal, the accuracy of 1 PPS output from the GPS receiver 10 deteriorates, or the GPS receiver 10 stops outputting 1 PPS. . In such a case, the processing unit 20 may stop the process of synchronizing the clock signal output from the atomic oscillator 30 with 1 PPS output from the GPS receiver 10 and cause the atomic oscillator 30 to self-oscillate. In this way, the timing signal generation device 1 can output 1 PPS with high frequency accuracy due to free-running oscillation of the atomic oscillator 30 even when the accuracy of 1 PPS output from the GPS receiver 10 deteriorates. In particular,
In the fixed position mode, an elevation mask is used, so that holdover is likely to occur. However, by using the high-accuracy atomic oscillator 30, the G at an elevation angle equal to or higher than the set value of the elevation mask is used.
Even in the state where the PS satellite 2 does not exist, a highly accurate timing signal can be generated. Note that even if a double oven or single oven thermostat crystal oscillator (OCXO) is used in place of the atomic oscillator 30, 1 PPS with high frequency accuracy due to free-running oscillation can be output.

Hereinafter, the normal positioning mode and the position fixing mode will be described in detail.
FIG. 4 is a flowchart showing an example of a processing procedure in the normal positioning mode and the position fixing mode in the GPS receiver shown in FIG.
As shown in FIG. 4, first, when the power is turned on (Y in S10), the baseband processing unit 1
3 is initialized to the normal positioning mode, starts a satellite search for searching for a GPS satellite 2 that can be captured (S12), and determines whether the GPS satellite 2 has been captured (S14).

Specifically, the baseband processing unit 13 demodulates the baseband signal from the IF signal generated by the RF processing unit 12 receiving the satellite signal, and the local pattern having the same pattern as the C / A code of each satellite number. A code is generated, and a correlation value between the C / A code included in the baseband signal and each local code is calculated. If the C / A code and the local code included in the baseband signal are the same code, the correlation value has a peak at a predetermined timing, but if the code is different, the correlation value does not have a peak and is always almost zero. The baseband processing unit 13 adjusts the local code generation timing so that the correlation value between the C / A code and the local code included in the baseband signal is maximized. If the correlation value is equal to or greater than a predetermined threshold, the GPS satellite 2
Is determined to have been captured. Then, the baseband processing unit 13 stores the captured information (satellite number and the like) of each GPS satellite 2 in the SRAM 133.

When the baseband processing unit 13 captures at least one GPS satellite 2, the baseband processing unit 13 demodulates the navigation message transmitted from the captured GPS satellite 2, and starts acquiring various information included in the navigation message (S16).
Specifically, the baseband processing unit 13 demodulates each captured navigation message from each GPS satellite 2 to acquire various types of information such as time information and orbit information, and the acquired information is SRA.
Store in M133.

Next, the baseband processing unit 13 determines whether or not information of four or more GPS satellites 2 has been acquired (S18). If acquired, the baseband processing unit 13 uses orbit information, time information, and the like included in the navigation message. Then, the position of the reception point is calculated (positioning calculation) (S20).
Specifically, the baseband processing unit 13 selects four or more GPS satellites 2 from all the captured GPS satellites 2, and stores the orbit information and time information of the selected GPS satellites 2 in the SRAM.
Read from 133 and perform positioning calculation. Then, the baseband processing unit 13 stores various information such as the positioning calculation result (reception point position information) and the reception status in the SRAM 133.

The baseband processing unit 13 determines whether or not the mode is the position fixing mode (S22), and repeats the processes of steps S18 and S20 until the mode is changed to the position fixing mode.
When the mode is changed to the fixed position mode, the baseband processing unit 13 determines whether or not information on one or more GPS satellites 2 has been acquired (S24).
It is determined whether or not the elevation angle of the satellite 2 is greater than or equal to the set value of the elevation mask (S26).

Specifically, the baseband processing unit 13 reads the orbit information (ephemeris parameter) of the GPS satellite 2 from the SRAM 133 and calculates the position coordinates of the GPS satellite 2. Further, the baseband processing unit 13 reads out the position information (position coordinates) of the reception point from the SRAM 133, and uses the position coordinates of the GPS satellite 2 and the position information (position coordinates) of the reception point obtained by the calculation to obtain a GPS satellite. 2. Calculate the elevation angle of 2. The baseband processing unit 13 includes an SRAM 13
The elevation angle mask is read out from 3, and it is determined whether or not the elevation angle obtained by calculation is equal to or greater than the set value of the elevation angle mask.

As a result of such determination, when there is no GPS satellite 2 at an elevation angle equal to or higher than the set value of the elevation mask, the process proceeds to step 24, and information on the GPS satellite 2 is acquired again. On the other hand, when there is at least one GPS satellite 2 at an elevation angle equal to or greater than the set value of the elevation angle mask, orbit information of the GPS satellite 2 at an elevation angle equal to or greater than the set value of the elevation mask is selected (S28). Using the position information of the set reception point and the orbit information and time information included in the navigation message, the time of the reception point and the propagation delay time of the satellite signal are calculated (S30).

Specifically, the baseband processing unit 13 selects one or more GPS satellites 2 having an elevation angle equal to or higher than the set value of the elevation mask from all the captured GPS satellites 2, and selects the selected GPS satellite 2.
Time information (Z count data, etc.) is read from the SRAM 133, and the time of the reception point (for example, the beginning time of the next subframe) is calculated. In addition, the baseband processing unit 13 reads the orbit information of the selected GPS satellite 2 from the SRAM 133 and calculates the position of the GPS satellite 2. Furthermore, the baseband processing unit 13 reads out the position information of the reception point set by the processing unit 20 from the SRAM 133, and uses the GPS satellite 2 position calculation result and the position information of the reception point to determine the position of the GPS satellite 2 and the reception point. The distance between them is calculated, and the propagation delay time of the satellite signal is calculated from the radio wave velocity.

Next, the baseband processing unit 13 updates the set value of the 1PPS counter using the propagation delay time of the satellite signal (calculation result of step S26) (S32).
Specifically, the 1PPS counter is a counter that generates a 1PPS pulse when it counts up to a set value, and the baseband processing unit 13 is, for example, the latest reception timing of 1PPS with respect to the reception timing of the head of the next subframe. The set value of the 1PPS counter is updated so that the pulse is generated before the propagation delay time of the satellite signal.

Then, the baseband processing unit 13 determines whether or not the normal positioning mode is set (S34).
The process of steps S24 to S32 is repeated until the normal positioning mode is changed. When the normal positioning mode is changed, the process proceeds to step S18.
FIG. 5 is a flowchart showing an example of a processing procedure of 1PPS output in the GPS receiver shown in FIG.

As shown in FIG. 5, the baseband processing unit 13 is turned on (Y in S50),
The set value of the 1PPS counter provided in the RTC 134 is initialized (S52).
Next, the baseband processing unit 13 determines whether or not it is the timing of the clock edge of the 1PPS counter (S54), and determines whether or not the count value of the 1PPS counter matches the set value at that timing. (S56) If they match, one pulse and NMEA data are output (S58).

Specifically, the baseband processing unit 13 reads the latest various information stored in the SRAM 133, converts the data into NMEA format data, and outputs the data. Note that the set value of the 1PP counter is sequentially updated in step S32 of FIG. 4 described above.
Then, the baseband processing unit 13 counts up the 1PPS counter (S60
Then, the process proceeds to step S54.
On the other hand, if the count value of the 1PPS counter does not coincide with the set value at the timing of the clock edge of the 1PPS counter, the baseband processing unit 13 does not perform the process of step 58, proceeds to step S60, and sets the 1PPS counter. Count up (S60
Then, the process proceeds to step S54.

FIG. 6 is a flowchart illustrating an example of a processing procedure for controlling the GPS receiver by the processing unit of the timing signal generation device illustrated in FIG. 1.
As shown in FIG. 6, when the power is turned on (Y in S100), the processing unit 20 first resets statistical information of the positioning calculation result (S102).
Next, the processing unit 20 determines whether or not a predetermined time has elapsed (S104), and determines whether or not it is the timing of 1PPS pulse output of the GPS receiver 10 until the predetermined time has elapsed (S104). (S106) At each timing, NMEA data output from the GPS receiver 10 is acquired, and the positioning calculation result in the normal positioning mode by the GPS receiver 10 is added to the statistical information (S106).
S108).

And when predetermined time passes, the process part 20 will calculate an average value from the statistical information of a positioning calculation result,
The mode value or the median value is selected and set in the GPS receiver 10 as reception point position information (S1).
10) Further, the GPS receiver 10 is set to the position fixing mode (S112).
Since the accuracy of the position information of the reception point is improved as the predetermined time in step S108 is longer, the predetermined time in step S108 is preferably set to about one day (24 hours), for example.

As described above, the GPS receiver 10 can set the average value, the mode value, or the median value of the statistical information of the positioning calculation result as the position information of the reception point in the fixed position mode.
It is preferable to set the mode value or the median value. That is, GPS receiver 10 and GP
It is preferable that the S control unit 25 generates the position information of the reception point based on the mode value or the median value in the results of a plurality of positioning calculations by the baseband processing unit 13 over a predetermined time. As a result, even if the positioning calculation error increases due to the deterioration of the reception environment, it becomes difficult to be affected by the positioning result having a large error, and as a result, the accuracy of 1PPS can be improved.

In order to clarify the effect of setting the mode or median as the position information of such a reception point, an experiment was conducted using a GPS simulator and a GPS receiver (actual machine). In this experiment, the simulation is performed by setting the receiving position (latitude, longitude, altitude), the number of captured satellites, and the intensity of the satellite signal in the GPS simulator, and the signal output from the GPS simulator is input to the GPS receiver. The position information (latitude, longitude, altitude) output by the GPS receiver in the normal positioning mode is acquired every second, and the average value, median value, mode value, and each of these and the true position (GPS simulator) The distance to the receiving position set in (1) was calculated.

FIG. 7A is a table showing a positioning calculation result when the number of GPS satellites captured is large but the reception strength is low, and FIG. 7B is a positioning when the reception strength is large but the number of GPS satellites captured is small. It is a table | surface which shows a calculation result.
In addition, the positioning calculation result shown in FIG. 7 (A) is obtained under the conditions that the number of GPS satellites captured is 7 to 8, the intensity of the satellite signal is −145 dBm, and the positioning time is 16 hours. Although a sufficient number of GPS satellites are acquired for positioning calculation, a reception environment where the intensity of the satellite signal is small is assumed. On the other hand, the positioning calculation result shown in FIG.
The satellite signal strength is -130 dBm and the positioning time is 17 hours. Under such conditions, the satellite signal strength is high, but a sufficient number of GPS satellites are captured for the positioning calculation. This assumes an unlimited reception environment.

The positioning calculation results shown in FIGS. 7A and 7B were the mode value, median value, and average value in ascending order of distance from the true position. From such results, select the mode value or median value of the position obtained by positioning calculation, and set it in the GPS receiver as the position information of the receiving point in the fixed position mode, compared with the case of selecting the average value It can be seen that the accuracy of 1 PPS is improved.

In other words, if the satellite signal reception environment deteriorates, positioning calculation errors due to multipath and the like increase. Therefore, if the average value of positioning results is set as position information in the fixed position mode, the error may increase. Although it is high, setting the mode value and the median value makes it difficult to be affected by the positioning result having a large error, so that the accuracy of 1 PPS in the position fixing mode can be increased.

In addition, by calculating the position information to be set in the position fixing mode using the positioning result in the normal positioning mode, it is possible to reduce the cost without being limited by the receiving location.
In such a normal positioning mode, even if the elevation mask is not used or the elevation mask is used, the setting value of the elevation mask is set smaller than the setting value of the elevation mask used in the position fixing mode.

That is, in the normal positioning mode, the baseband processing unit 13 and the GPS control unit 25
Can generate position information of reception points based on satellite signals transmitted from a plurality of GPS satellites 2 including GPS satellites 2 having an elevation angle smaller than the setting value of the elevation mask used in the position fixing mode. As a result, the position information of the reception point can be generated quickly and with high accuracy using the satellite signal transmitted from the GPS satellite 2 at an elevation angle within a wider range than when 1PPS is generated in the position fixing mode. .

On the other hand, in the position fixing mode, as described above, the baseband processing unit 13 determines whether the elevation angle of the GPS satellite 2 related to the orbit information is greater than or equal to the set value of the elevation angle mask, and the SRAM 13
3 is selected from the orbit information stored in the GPS mask 2 at an elevation angle equal to or greater than the set value of the elevation mask, the selected orbit information, and the position information of the reception point stored in the SRAM 133, Is used to output 1PPS with high accuracy.

FIG. 8A is a schematic diagram for explaining the operation in the normal positioning mode, and FIG.
It is a figure for demonstrating the effect | action in position fixing mode.
In the normal positioning mode, as shown in FIG. 8A, the elevation angle of the GPS satellite 2 that can be captured or that can use satellite signals for positioning is θ1 or more, whereas in the position fixing mode, the elevation angle of FIG.
), The elevation angle of a GPS satellite that can be used to generate 1PPS is θ greater than θ1.
2.

When generating the position information of the reception point in the normal positioning mode, θ1 is set to be relatively small. Therefore, when the elevation angle range of the GPS satellite 2 that can be captured is increased, and 1PPS is generated in the position fixing mode. A satellite signal transmitted from the GPS satellite 2 at an elevation angle within a wider range can be used. Therefore, the number of GPS satellites 2 necessary for generating the position information of the reception point can be quickly acquired. Further, as many GPS satellites 2 as possible can be captured. As a result, the position information of the reception point can be generated quickly and with high accuracy.

Here, in the normal positioning mode, a multipath satellite signal reflected by an obstacle O such as a building among satellite signals transmitted from a plurality of captured GPS satellites 2 (two-dot chain arrows shown in FIG. 8A). However, as described above, by using the mode value or median value of the statistical information of the positioning calculation result, the accuracy of the position information of the reception point can be improved. Note that a parameter having a correlation with the multipath can be set in the baseband processing unit 13 or the GPS control unit 25, and the positioning error can be reduced using the parameter.
Moreover, (theta) 1 should just be smaller than (theta) 2, and although it does not specifically limit, It is preferable that it is less than 45 degree | times, and it is more preferable that it is 5-30 degree | times. Thereby, even when there are many obstacles around the reception point, the number of GPS satellites 2 necessary for generating the position information of the reception point can be captured relatively quickly.

On the other hand, when 1PPS is generated in the fixed position mode, since θ2 is set to be relatively large, the range of the elevation angle of the GPS satellite 2 that can be captured is reduced, and the GPS satellite 2 that is not affected by the multipath is used. Only the transmitted satellite information can be used. Therefore, it is difficult to be affected by multipath, and 1PPS can be highly accurate.
Here, in the fixed position mode, a multipath satellite signal reflected by an obstacle O such as a building (a two-dot chain arrow shown in FIG. 8B) is not captured or is captured.
Not used to generate 1PPS.

Also, θ2, that is, the set value of the elevation mask is preferably 45 degrees or more, and 6
It is more preferably 0 ° or more, and further preferably 70 ° or more. As a result, even in an environment where multipath is likely to occur such as buildings, trees, etc. around the reception point, it is difficult to be affected by multipath when 1PPS is generated.
Moreover, it is preferable that the set value of the elevation mask can be changed. Thereby, the set value of the elevation mask can be optimized according to the installation environment. Therefore, it is possible to make it less susceptible to multipath while avoiding errors as much as possible when generating 1PPS. For example, the setting value of the elevation mask may be changed by rewriting the setting value of the elevation mask stored in the SRAM 133 of the baseband processing unit 13 by a control command from the GPS control unit 25. A program for changing the setting value of the elevation angle mask may be stored in the SRAM 133, and the CPU 132 of the baseband processing unit 13 may rewrite the setting value of the elevation angle mask stored in the SRAM 133 according to the program. . Moreover, the setting value of the elevation angle mask may be changed only once after the GPS receiver 10 is installed, or may be periodically performed a plurality of times (for example, once every several hours to several years). .

Further, it is preferable that the set value of the elevation mask is set so that as many satellite signals as possible can be used while eliminating the influence of multipath as much as possible. Specifically, GPS
The receiver 10 receives information on at least one of the reception intensity of the received satellite signal and the difference between the time information included in the satellite signal and the time information of the reception point (hereinafter referred to as “multipath information”). Based on this, it is preferable to change the setting value of the elevation angle mask.

A satellite signal including a multipath error generally has a lower reception intensity than a regular satellite signal, and a time information shift occurs between the satellite signal and the regular satellite signal. Therefore, whether or not the received satellite signal includes a multipath error based on the reception intensity of the received satellite signal and at least one of the difference between the time information included in the satellite signal and the time information of the reception point. And the setting value of the elevation mask can be set so as not to use the satellite signal including the multipath error.

When changing the setting value of such an elevation mask, the GPS receiver 10 determines the elevation mask based on the multipath information accumulated over time (that is, a plurality of multipath information accumulated over a predetermined period). It is preferable to change the set value. As a result, the setting value of the elevation angle mask can be optimized after accurately grasping the occurrence state of the multi-path in the installation place in one day. Here, the period for accumulating the multipath (the predetermined period) is preferably, for example, one day or more from the viewpoint of accurately grasping the occurrence status of the multipath for one day at the installation location,
More preferably, it is 1-2 days.
According to the timing signal generation device 1 as described above, 1P in the position fixing mode.
Since the satellite signal transmitted from the GPS satellite 2 at an elevation angle equal to or higher than the set value of the elevation mask is used when generating the PS, the timing signal can be highly accurate without being affected by the multipath.

On the other hand, when generating the position information of the reception point in the normal positioning mode, the reception is performed using the satellite signal transmitted from the GPS satellite 2 at an elevation angle within a wider range than when generating the 1PPS in the position fixing mode. Point position information can be generated quickly and with high accuracy.
In addition, by synchronizing the clock signal output from the atomic oscillator 30 with accurate 1PPS,
A clock signal with higher accuracy than that of the atomic oscillator 30 can be generated. further,
The accuracy of 1PPS output from the GPS receiver 10 is degraded, or the GPS receiver 10 is 1
When the output of the PPS is stopped (that is, when the holdover enters), the process of synchronizing the clock signal output from the atomic oscillator 30 with 1 PPS is stopped and the atomic oscillator 30 is caused to self-run, thereby at least the atomic oscillator 30 1 PPS with frequency accuracy can be output.
Since 1PPS output from such a timing signal generator 1 is extremely accurate,
For example, it can be used as a clock input signal of a time server that manages computer time.

Second Embodiment
FIG. 9 is a diagram showing a schematic configuration of a timing signal generation device according to the second embodiment of the present invention.
This embodiment is the same as the first embodiment described above except that the number of GPS antennas and GPS receivers and the configuration of the processing unit are different.

In the following description, the second embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted. In FIG. 9, the same reference numerals are given to the same configurations as those in the above-described embodiment.
The timing signal generator 1A shown in FIG. 9 includes two GPS receivers 10A and 10B, a processing unit (CPU) 20A, an atomic oscillator 30, a temperature sensor 40, and two GPS antennas 50A.
, 50B.

As shown in FIG. 9, the GPS antenna 50A is connected to the GPS receiver 10A.
The GPS receiver 10A receives the satellite signal transmitted from each GPS satellite 2 via the GPS antenna 50A, and performs various processes similar to those of the GPS receiver 10 of the first embodiment described above.
Similarly, the GPS antenna 50B is connected to the GPS receiver 10B, and the GPS receiver 10B receives the satellite signal transmitted from each GPS satellite 2 via the GPS antenna 50B, and the first embodiment described above. Various processes similar to those of the GPS receiver 10 of the embodiment are performed.

Here, the two GPS antennas 50A and 50B are installed at the same place (precisely, substantially the same place which can be said to be substantially the same). Therefore, the two GPS receivers 10A and 10B
Output the same or almost the same position information.
Similar to the processing unit 20 of the first embodiment, the processing unit 20A includes a phase comparator 21, a loop filter 22, a DSP 23, a frequency divider 24, and a GPS control unit 25, and further includes a selection switch 26 and a failure determination unit 27. It is configured to include.

Failure determination unit 27 includes a set of GPS antenna 50A and GPS receiver 10A, and G
Processing for determining whether or not each of the set of the PS antenna 50B and the GPS receiver 10B has failed is performed. For example, the failure determination unit 27 detects the failure of the GPS antennas 50A and 50B by monitoring the output currents of the GPS antennas 50A and 50B, and the GPS receiver 10A,
By monitoring the output signal (1PPS and NMEA data) of 10B, the GPS receiver 10A,
A failure of 10B can be detected.

The selection switch 26 selects and outputs either 1PPS output from the GPS receiver 10A or 1PPS output from the GPS receiver 10B based on the determination result of the failure determination unit. 1 PPS output from the selection switch 26 is input to the phase comparator 21.
The DSP 23 periodically acquires (for example, every second) NMEA data from the GPS receivers 10A and 10B, and the position information (GPS receiver 10A included in each NMEA data).
10B) (positioning calculation results in the normal positioning mode) are collected to create two pieces of statistical information for a predetermined time, and based on the average value, mode value, or median value of each, the position information of the two receiving points Process to generate.

The GPS control unit 25 transmits various control commands to the GPS receivers 10A and 10B.
The operation of the PS receivers 10A and 10B is controlled. Specifically, the GPS control unit 25 is a GPS
A control command for mode setting is transmitted to the receivers 10A and 10B, and the GPS receivers 10A and 1B are transmitted.
A process of switching 0B from the normal positioning mode to the position fixing mode is performed. The GPS control unit 25 transmits a position setting control command to the GPS receivers 10A and 10B before switching the GPS receivers 10A and 10B from the normal positioning mode to the position fixing mode. Processing for setting the position information of the reception point in the GPS receivers 10A and 10B is performed.

FIG. 10 shows 1 PPS in the GPS receiver included in the timing signal generator shown in FIG.
It is a flowchart which shows an example of the process sequence of selection.
As shown in FIG. 10, when the processing unit 20A is turned on (Y in S200), first,
1 PPS output from the GPS receiver 10A is selected as 1 PPS for oscillation control of the atomic oscillator 30 (1 PPS input to the phase comparator 21) (S202).

Next, the processing unit 20A determines the failure of the GPS receivers 10A and 10B (S204).
It is determined whether only the PS receiver 10A is out of order (S206).
If it is determined in step S206 that only the GPS receiver 10A has failed, 1 PPS for controlling the oscillation of the atomic oscillator 30 is switched to 1 PPS output by the GPS receiver 10B (S208). Thereafter, the processing unit 20A determines a failure of the GPS receiver 10B (S
212).

Then, it is determined whether or not the GPS receiver 10B has failed (S214). If the GPS receiver 10B has not failed, the process proceeds to step S212, and steps 212 and 214 are performed until the GPS receiver 10B fails. On the other hand, if the GPS receiver 10B fails, the atomic oscillator 30 is switched to free-running oscillation (S216).
On the other hand, when it is determined in step S206 that the GPS receiver 10A is in a state other than the failure, the processing unit 20A determines whether both the GPS receivers 10A and 10B are defective (S210). ), If both of the GPS receivers 10A and 10B are out of order, the process proceeds to step S214, and steps 204, S206, and S210 are repeated until both of the GPS receivers 10A and 10B fail, GPS receiver 10A, 10
If both B fail, the atomic oscillator 30 is switched to free-running oscillation (S216).

Note that, when one or both of the GPS receivers 10A and 10B fail, the processing unit 20A may output a failure notification signal for notifying the failure to the outside. For example, if information corresponding to the failure notification signal is displayed on an external monitor, the user recognizes the failure,
The failed part can be replaced.
As described above, the timing signal generation device 1A according to the second embodiment replaces the GPS receiver 10B with G.
When the GPS antenna 50A or the GPS receiver 10A breaks down, 1 PPS input to the phase comparator 21 is operated as the PS receiver 10A.
The 1PPS output from A is quickly switched to 1PPS output from the GPS receiver 10B. In this embodiment, there are two sets of GPS receivers and GPS antennas, but three or more sets may be used.

As described above, according to the timing signal generation device 1A of the second embodiment, the plurality of GPS antennas 50A and 50B installed in the same place, and the GPS antennas 50A and 50B.
A plurality of GPS receivers 10A and 10B that respectively process satellite signals received by B are provided, and a set of other GPS antennas and GPS receivers is detected by detecting a failure of the selected GPS antenna and GPS receiver set. Switch to. Therefore, the selected GPS antenna and GPS
Even when a failure occurs in the set of receivers, high-precision 1PPS output can be continued.
In addition, the timing signal generation device 1 </ b> A of the second embodiment can exhibit the same effects as the effects of the timing signal generation device 1 of the first embodiment described above.

<Third Embodiment>
FIG. 11 is a diagram showing a schematic configuration of a timing signal generation device according to the third embodiment of the present invention.
This embodiment is the same as the first embodiment described above except that the number of GPS antennas and GPS receivers and the configuration of the processing unit are different.

In the following description, the third embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted. In FIG. 11, the same reference numerals are given to the same configurations as those in the above-described embodiment.
The timing signal generator 1B shown in FIG. 11 includes three GPS receivers 10A, 10B,
It includes 0C, a processing unit (CPU) 20B, an atomic oscillator 30, a temperature sensor 40, and three GPS antennas 50A, 50B, and 50C.

As shown in FIG. 11, the GPS antenna 50A is connected to the GPS receiver 10A, and the GPS receiver 10A receives the satellite signal transmitted from each GPS satellite 2 via the GPS antenna 50A, and Various processes similar to those of the GPS receiver 10 of the embodiment are performed.
Similarly, the GPS antenna 50B is connected to the GPS receiver 10B. The GPS receiver 10B receives the satellite signal transmitted from each GPS satellite 2 via the GPS antenna 50B, and the GPS antenna 50B of the first embodiment. Various processes similar to those performed by the GPS receiver 10 are performed.
Similarly, the GPS antenna 50C is connected to the GPS receiver 10C. The GPS receiver 10C receives the satellite signal transmitted from each GPS satellite 2 via the GPS antenna 50C, and the GPS antenna 50C of the first embodiment. Various processes similar to those performed by the GPS receiver 10 are performed.

Unlike the second embodiment, this embodiment has three GPS antennas 50A, 50B, and 50C.
Are installed in different places. Therefore, the three GPS receivers 10A, 10B,
10C outputs mutually different positional information. For example, three GPS antennas 50A, 5
If 0B and 50C are installed on the north side, the south side, the east side, etc. of the building, respectively, the reception status of the satellite signal is different, and the one that is most likely to receive the satellite signal changes depending on the time zone.
Therefore, as time passes, the superiority or inferiority order of accuracy of 1 PPS output by the GPS receivers 10A, 10B, and 10C also changes.

The processing unit 20B includes a phase comparator 21, a loop filter 22, a DS, as in the first embodiment.
P23, the frequency divider 24, and the GPS control part 25 are included, and also the selection switch 26 is included.
The DSP 23 periodically (for example, from the GPS receivers 10A, 10B, 10C)
NMEA data is acquired every second), and the location information (results of positioning calculation in the normal positioning mode by the GPS receivers 10A, 10B, 10C) included in each NMEA data is collected, and three statistical information at a predetermined time is collected. A process of generating the position information of the three reception points is performed based on the mode value or the median value.

In addition, the DSP 23 acquires the NM acquired from the GPS receivers 10A, 10B, and 10C, respectively.
The GPS receivers 10A, 10B, and 10C output 1 based on predetermined parameter information included in the EA data (for example, the number of captured GPS satellites and the reception intensity of satellite signals).
Compare the accuracy of PPS (UTC (Universal Standard Time) synchronization accuracy with 1 second). For example, DSP
If the number of GPS satellites captured is the same, 23 indicates 1 as the satellite signal reception intensity increases.
If the accuracy of PPS is high and the reception strength is similar, it can be determined that the accuracy of 1PPS is higher as the number of GPS satellites captured is larger.

According to the comparison result of the DSP 23, the selection switch 26 is 1PPS output from the GPS receiver 10A, 1PPS output from the GPS receiver 10B, and 1P output from the GPS receiver 10C.
Select one of PS and output. 1 PPS output from the selection switch 26 is input to the phase comparator 21.
In the present embodiment, after the DSP 23 controls the selection switch 26 to select 1PPS, the DSP 23 monitors the NMEA data output from the GPS receiver that outputs the selected 1PPS.
When the difference with the last time is larger than a threshold value, the process which compares the precision of 1PPS which GPS receiver 10A, 10B, 10C outputs is performed again.

The GPS control unit 25 transmits various control commands to the GPS receivers 10A, 10B, and 10C, and controls the operations of the GPS receivers 10A, 10B, and 10C. In this embodiment, GPS
The control unit 25 transmits a mode setting control command to the GPS receivers 10A, 10B, and 10C, and performs a process of switching the GPS receivers 10A, 10B, and 10C from the normal positioning mode to the position fixing mode. In addition, the GPS control unit 25 sets the GPS receivers 10A, 10B, and 1C before switching the GPS receivers 10A, 10B, and 10C from the normal positioning mode to the position fixing mode.
A position setting control command is transmitted to 0C, and the position information of the three reception points generated by the DSP 23 is set in the GPS receivers 10A, 10B, and 10C, respectively.

FIG. 12 shows 1PP in the GPS receiver included in the timing signal generator shown in FIG.
It is a flowchart which shows an example of the process sequence of S selection.
As shown in FIG. 12, when the power is turned on (Y in S300), the processing unit 20B determines whether or not the predetermined time has elapsed until the predetermined time has elapsed (S302), and the predetermined time has elapsed. In this case, first, the accuracy of 1 PPS output from the GPS receivers 10A, 10B, and 10C is compared based on the NMEA data output from the GPS receivers 10A, 10B, and 10C, respectively (S304).

Next, the processing unit 20B selects the most accurate 1PPS as the 1PPS for controlling the oscillation of the atomic oscillator 30 (1PPS input to the phase comparator 21) (S306).
Next, the processing unit 20B outputs a new N output from the GPS receiver that outputs the selected 1PPS.
The difference between the MEA data and the previous NMEA data is calculated (S308).
Then, the processing unit 20B determines whether or not the difference calculated in step S308 is greater than a threshold (S310). If the difference is equal to or less than the threshold, the processing unit 20B proceeds to step S308.
Until the difference becomes larger than the threshold value, the process of step S308 and step S31 are performed.
On the other hand, if the difference is greater than the threshold value, the process proceeds to step S304, and the processes after step S304 described above are performed again.

As described above, the timing signal generation device 1B of the third embodiment includes three GPS antennas connected to the three GPS antennas 50A, 50B, and 50C installed at different locations.
When the receivers 10A, 10B, and 10C are operated in the same manner, 1PPS having the highest accuracy is selected as 1PPS input to the phase comparator 21, and it is determined that the accuracy of the currently selected 1PPS has deteriorated again. Reselect 1PPS with high accuracy. In the present embodiment, G
The set of PS receivers and GPS antennas is three, but may be two or four or more.

As described above, according to the timing signal generation device 1B of the third embodiment, a plurality of GPS antennas 50A, 50B, and 50C installed at different locations and the GPS antennas 50A, 50B, and 50B are received. A plurality of GPS receivers 10A, 10B, and 10C for processing satellite signals are provided, and a plurality of 1PPS output by the plurality of GPS receivers are provided.
1PPS with the highest accuracy is selected from the above and output. Therefore, even if the reception environment such as the reception intensity, the number of visible satellites, and the multipath changes with the passage of time, the highly accurate 1PPS output can be continued.
In addition, the timing signal generation device 1B of the third embodiment can achieve the same effects as the effects exhibited by the timing signal generation device 1 of the first embodiment described above.

2. Next, an embodiment of an electronic device of the present invention will be described.
FIG. 13 is a block diagram showing an embodiment of the electronic apparatus of the present invention.
13 includes a timing signal generation device 310, a CPU (Central Pr
ocessing Unit) 320, operation unit 330, ROM (Read Only Memory) 340, RAM (R
andom Access Memory) 350, a communication unit 360, and a display unit 370.

The timing signal generation device 310 is, for example, the timing signal generation device (1, 1A, or 1B) of any of the first to third embodiments described above, and receives a satellite signal as described above. A highly accurate timing signal (1PPS) is generated and output to the outside. Thereby, the electronic device 300 with higher reliability at a lower cost can be realized.
The CPU 320 performs various calculation processes and control processes in accordance with programs stored in the ROM 340 and the like. Specifically, the CPU 320 synchronizes with the timing signal (1PPS) and the clock signal output from the timing signal generation device 310, performs various processes according to the operation signal from the operation unit 330, data communication with the outside In order to perform the process, a process of controlling the communication unit 360, a process of transmitting a display signal for displaying various information on the display unit 370, and the like are performed.

The operation unit 330 is an input device including operation keys, button switches, and the like, and outputs an operation signal corresponding to an operation by the user to the CPU 320.
The ROM 340 stores programs, data, and the like for the CPU 320 to perform various calculation processes and control processes.
The RAM 350 is used as a work area of the CPU 320, and temporarily stores programs and data read from the ROM 340, data input from the operation unit 330, calculation results executed by the CPU 320 according to various programs, and the like.

The communication unit 360 performs various controls for establishing data communication between the CPU 320 and an external device.
The display unit 370 is a display device configured by an LCD (Liquid Crystal Display) or the like, and displays various types of information based on a display signal input from the CPU 320. Display unit 37
0 may be provided with a touch panel that functions as the operation unit 330.
As such an electronic device 300, various electronic devices are conceivable and not particularly limited.
For example, a time management server (time server) that realizes synchronization with the standard time, a time management device (time stamp server) that issues time stamps, a frequency reference device such as a base station, and the like can be given.

3. FIG. 14 is a diagram showing an embodiment of the moving body of the present invention.
14 includes a timing signal generation device 410, a car navigation device 420, controllers 430, 440, 450, a battery 460, and a backup battery 470.

As the timing signal generation device 410, the timing signal generation device 1 of each of the above-described embodiments can be applied. For example, when the moving body 400 is moving, the timing signal generation device 410 performs a positioning calculation in real time in the normal positioning mode and outputs 1 PPS, a clock signal, and NMEA data. In addition, for example, when the moving body 400 is stopped, the timing signal generation device 410 performs the positioning calculation a plurality of times in the normal positioning mode, and then obtains the mode value or the median value of the plurality of positioning calculation results as the current position. Set as information, 1PPS in fixed position mode,
A clock signal and NMEA data are output.

The car navigation device 420 is a 1PPS output from the timing signal generator 410.
In synchronism with the clock signal, the NMEA data output from the timing signal generator 410 is used to display the position, time, and other various information on the display.
The controllers 430, 440, and 450 perform various controls such as an engine system, a brake system, and a keyless entry system. Controller 430, 440, 45
0 may perform various controls in synchronization with the clock signal output from the timing signal generator 410.

Since the moving body 400 of the present embodiment includes the timing signal generation device 410, high reliability can be ensured both during movement and during stoppage.
As such a moving body 400, various moving bodies can be considered, and examples thereof include automobiles (including electric automobiles), aircraft such as jets and helicopters, ships, rockets, and artificial satellites.
As described above, the timing signal generation device, the electronic apparatus, and the moving body of the present invention have been described based on the illustrated embodiments, but the present invention is not limited to these.

In addition, the present invention can be replaced with an arbitrary configuration that exhibits the same function as that of the above-described embodiment, and an arbitrary configuration can be added.
Moreover, you may make it this invention combine suitably the arbitrary structures of each embodiment mentioned above.
Further, in the above-described embodiment, the case where the atomic oscillator is used as the oscillator included in the timing signal generation device has been described as an example. However, the present invention is not limited to this, and is, for example, a relatively high-precision crystal oscillator. A thermostatic crystal oscillator (for example, DOCXO) can also be used. Further, as the oscillator, other crystal oscillators, MEMS (Micro Electro Mechanical Systems) oscillators, or the like may be used.

Further, for example, in the timing signal generation device of the third embodiment described above, a backup set may be provided for each set of the GPS antenna and the GPS receiver, as in the second embodiment.
Further, in each of the above-described embodiments, a timing signal generation device using GPS is taken as an example, but a global navigation satellite system (GNSS) other than GPS, for example, Galileo, GLO
NASS or the like may be used.

DESCRIPTION OF SYMBOLS 1 ... Timing signal generator 1A ... Timing signal generator 1B ... Timing signal generator 2 ... GPS satellite 10 ... GPS receiver 10A ... GPS receiver 1
0B ... GPS receiver 10C ... GPS receiver 11 ... SAW filter 12 ...
RF processing unit 13 Baseband processing unit 14 Temperature compensated crystal oscillator 20 Processing unit 20A Processing unit 20B Processing unit 21 Phase comparator 22 Loop filter 23 DSP 24 Frequency divider 25 GPS control unit 26 Selection switch 27 Failure determination unit 30 Atomic oscillator 40 Temperature sensor 50 GPS
Antenna 50A ... GPS antenna 50B ... GPS antenna 50C ... GPS antenna 121 ... PLL 122 ... LNA 123 ... Mixer 124 ... IF amplifier 125 ... IF filter 126 ... ADC 131 ... DSP 132 ... C
PU 133 ... SRAM 134 ... RTC 300 ... Electronic equipment 310 ... Timing signal generator 320 ... CPU 330 ... Operation unit 340 ... ROM 350 ...
... RAM 360 ... Communication unit 370 ... Display unit 400 ... Moving body 410 ... Timing signal generator 420 ... Car navigation device 430, 440, 450 ... Controller 460 ... Battery 470 ... Backup battery O ... ‥Obstacle

FIG. 7A is a table showing a positioning calculation result when the number of GPS satellites captured is large but the reception strength is low, and FIG. 7B is a positioning when the reception strength is large but the number of GPS satellites captured is small. It is a table | surface which shows a calculation result.
In addition, the positioning calculation result shown in FIG. 7 (A) is obtained under the conditions that the number of GPS satellites captured is 7 to 8, the intensity of the satellite signal is −145 dBm, and the positioning time is 16 hours. Although the strength of the satellite signal is less is obtained by assuming the receiving environment where a sufficient number of GPS satellites to the positioning computation Ru is captured. On the other hand, the positioning calculation results shown in FIG. 7B were obtained under the conditions that the number of GPS satellites captured was 3 to 5, the satellite signal intensity was −145 dBm , and the positioning time was 17 hours. This assumes a reception environment in which the intensity of the satellite signal is small and a sufficient number of GPS satellites are not captured for positioning calculation.

Claims (10)

Receive satellite signals transmitted from multiple location information satellites, and based on the received satellite signals,
A position information generation unit that generates position information of a reception point;
A timing signal generation unit that receives a satellite signal from a position information satellite at an elevation angle equal to or higher than a setting value of an elevation angle mask, and generates a timing signal based on the received satellite signal;
A timing signal generating device comprising: The timing signal generation device according to claim 1, wherein a set value of the elevation mask is 45 degrees or more. The timing signal generation device according to claim 1, wherein a setting value of the elevation mask is changeable. The timing signal generation unit is based on information on at least one of the received intensity of the received satellite signal and the time information included in the satellite signal and the time information of the reception point. The timing signal generation device according to claim 3, wherein the setting value of the elevation angle mask is changed. The timing signal generation device according to claim 4, wherein the timing signal generation unit changes a setting value of the elevation angle mask based on the information accumulated over time. The position information generation unit can generate position information of a reception point based on satellite signals transmitted from a plurality of position information satellites including position information satellites at an elevation angle smaller than a set value of the elevation angle mask. Item 6. The timing signal generation device according to any one of Items 1 to 5. The position information generation unit includes a positioning calculation unit that performs positioning calculation based on a satellite signal, and receives based on a mode value or a median value in a plurality of positioning calculation results by the positioning calculation unit over a predetermined time. The timing signal generating device according to claim 1, wherein the timing signal generating device generates point position information. An oscillator that outputs a clock signal;
The timing signal generation device according to claim 1, further comprising: a synchronization control unit that synchronizes the clock signal with the timing signal. An electronic apparatus comprising the timing signal generation device according to claim 1. A moving body comprising the timing signal generation device according to claim 1.

Images