JP2002090441A - Gps receiving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a GPS receiving device capable of shortening initial positioning time and avoiding the WN roll-over problem of the GPS even in the case that time information can not be obtained from a RTC. SOLUTION: In the case that time information can not be obtained from the RTC (real-time clock) 23 inside the GPS receiving device 50, time information is acquired from a standard wave receiving part 11 for receiving standard waves. Visible satellites are listed through the use of the time information based on the standard waves, and priority for search is given to signals from the listed GPS satellites to execute positioning computations. In addition, in the case of WN rollover, the correct Western calendar is recognized through the use of information on the lower two digits of the Western calendar based on the standard waves.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a GPS (Global P
The present invention relates to a GPS receiver that performs positioning by receiving radio waves from a satellite.

[0002]

2. Description of the Related Art A GPS receiver obtains a distance between a GPS satellite and a receiver for a plurality of satellites by using a flight time of a radio wave (signal) arriving from the GPS satellite and information included in the signal, and obtains the distance. The position of the receiving device is measured based on the.

[0003] The GPS receiver has satellite information such as GPS satellite signal information and orbit information. When the GPS receiver is powered on, the GPS signals are sequentially output based on the satellite information. Is searched, and positioning is performed using signals from a plurality of captured GPS satellites. It takes a certain amount of time before a GPS signal can be searched to capture a predetermined number of satellites. At this time, if the GPS receiver can use the past orbit information of the satellite (at the time of the previous operation) and the elapsed time (time information) from that time, the GPS receiver
List GPS satellites (herein referred to as “visible satellites”) that are estimated to be able to receive waves,
By narrowing down the satellites to be searched, it is possible to reduce the time for searching for a GPS signal, that is, to reduce the time from when the power is turned on to when the first GPS positioning result is obtained (initial positioning time). In particular, the time information is important information for estimating the position of the satellite in the orbit, and greatly contributes to shortening the initial positioning time. Normally, a GPS receiver has an RTC (real-time clock)
The RTC is powered by a backup power supply. Therefore, when the GPS receiver is powered on,
Time information is obtained from the RTC, and by using the time information, visible satellites can be listed.

[0004]

SUMMARY OF THE INVENTION However, GPS
When the power is first turned on or the backup power is turned off, time information cannot be obtained from the RTC, so that it is difficult to shorten the initial positioning time.

On the other hand, the more the GPS is used for the time standard, the more accurate the time information is. However, the time management is performed in the form of a week number (WN; Week Number) and a Z count (Z-count). The time information obtained from the GPS satellites is also the WN and Z count. Note that WN is G
This indicates the week from January 6, 1980, when the PS started operation, and the Z count is the count number from midnight on Sunday of that week (one count in 1.5 seconds). WN is represented by 10-bit data, and 1024 weeks (about 20 weeks).
Every year), it rolls over (roll over) and counts up from 0 again. For this reason, when a rollover occurs, a GPS receiver that has not performed any processing always recognizes that the year is 1980-1999 based on the received WN, and cannot obtain a correct year, that is, correct time information. Then, the wrong satellite is listed up,
In the worst case, positioning cannot be performed.

The present invention has been made in view of such circumstances. That is, the present invention uses time information from an accurate time information source other than the GPS satellites and the RTC, and even if time information cannot be obtained from the RTC, the present invention is not limited thereto. A G that can reduce the positioning time and can recognize the correct year when the WN obtained from the GPS satellite rolls over.
An object is to provide a PS receiver.

[0007]

SUMMARY OF THE INVENTION Therefore, the GP of the present invention
The S receiving device is a GPS receiving device having an internal clock for providing first time information inside the GPS receiving device. The S receiving device receives a standard time signal, receives the standard time signal, and outputs the first time information and the standard time signal. Visible satellite list-up means for listing satellites (visible satellites) estimated to be capable of receiving GPS waves, using any one of the time information of the second time information based on the second time information; And a positioning operation means for performing a positioning operation by preferentially searching for an upgraded GPS satellite. Since the standard radio wave receiving means receives the standard radio wave and acquires the time information, the GPS
Even when information cannot be obtained from the internal clock of the receiving device, the visible satellite listing means can list visible satellites using time information based on the standard time signal. The positioning calculation means executes a positioning calculation by preferentially searching for the signals from the listed GPS satellites. Therefore, the waste of searching for invisible satellites can be eliminated,
Even when time information cannot be obtained from the internal clock of the GPS receiver, the initial positioning time can be reduced (claim 1).

The visible satellite listing means uses the second time information based on the standard time signal when the power is turned on and the first time information from the internal clock of the GPS receiving device cannot be obtained. When the first time information is obtained from the clock, it is preferable to perform the listing using the first time information (claim 2).

Alternatively, if the second time information based on the standard time signal can be obtained when the power is turned on, the visible satellite listing means may list the visible satellites using the second time information. Good (claim 3).

[0010] The GPS receiver of the present invention further comprises time input means for the user to input time.
The visible satellite listing unit is configured to list using any one of the first time information from the internal clock, the second time information based on the standard time signal, and the third time information obtained from the input unit. Do the up. Even when the first time information, which is the time information from the internal clock of the GPS receiver, cannot be obtained, and the second time information based on the standard time signal cannot be obtained, the user manually inputs the time information. By inputting, it is possible to quickly list visible satellites estimated to be capable of receiving GPS waves and perform positioning. Therefore, the initial positioning time is reduced (claim 4).

The visible satellite listing means uses the third time information from the time input means only when neither the first time information from the internal clock nor the second time information based on the standard time signal can be obtained. It is preferable to make a list (claim 5).

Further, when the GPS receiver of the present invention obtains the second time information based on the standard time signal when the power is turned on, the GPS receiver internal clock is set using the second time information. The apparatus further includes time correction means for performing correction. Therefore, the internal clock of the GPS receiver is corrected with the correct standard time (claim 6).

[0013] The GPS receiving apparatus of the present invention is a GPS receiving apparatus.
When the difference between the first time information from the internal clock inside the receiving device and the second time information based on the standard time signal is larger than a predetermined value, the internal clock inside the GPS receiving device is set using the second time information. The apparatus further includes time correction means for performing correction. Therefore, when the internal clock inside the GPS receiving device falls below a predetermined accuracy, the time is corrected by the time correction means to an accurate time.

Further, the GPS receiving apparatus of the present invention has a GPS
When the WN (week number) information obtained from the satellite rolls over and becomes 0 again, there is further provided a means for recognizing the year using the last two digits of the year included in the time information based on the standard time signal. . Since the standard last two digits of the year can be obtained by the standard radio wave receiving means, at least GP
20 years after 100 years from 1980, the starting point of S operation
Until 1979, the WN rollover problem is avoided and the correct year is recognized (claim 8).

Further, the GPS receiving apparatus of the present invention has a GPS
A GPS receiving apparatus having an internal clock for providing first time information inside the receiving apparatus, wherein the FM multiplex receiving means receives an FM multiplex broadcast, the first time information, and a signal obtained by the FM multiplex receiving means. Visible satellite list-up means for listing satellites (visible satellites) presumed to be able to receive GPS waves using any of the time information of the second time information, and listing by visible satellite list-up means Positioning calculation means for performing a positioning calculation by preferentially searching for the selected GPS satellite. Since the FM multiplex receiving means acquires the time information, the visible satellite listing means can perform listing even when time information cannot be obtained from the internal clock of the GPS receiving apparatus. The positioning calculation means executes a positioning calculation by preferentially searching for the signals from the listed GPS satellites. Therefore, it is possible to reduce the waste of searching for an invisible satellite, and to shorten the initial positioning time even when time information cannot be obtained from the internal clock of the GPS receiver (claim 9).

The visible satellite list-up means uses the second time information obtained from the FM multiplex receiving means when the power is turned on and the first time information from the internal clock of the GPS receiving apparatus cannot be obtained. First from the internal clock of the device
When the time information is obtained, it is preferable to perform the listing using the first time information (claim 10).

Alternatively, when the power is turned on, if the second time information can be obtained from the FM multiplex receiving means, the visible satellite list-up means may perform the list using the second time information. (Claim 11).

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a first embodiment when a GPS receiver according to the present invention is realized in a car navigation system. In FIG. 1, a standard radio wave receiving unit 11 has a function of receiving a standard radio wave. The received time information is sent to the CPU 13, and the CPU 13 sends the time information to the calculation unit 21. G
The PS receiving unit 20 has a function of receiving a GPS signal and executing a positioning operation, and sends a positioning result to the CPU 13. CPU
Reference numeral 13 denotes a CPU that executes all functions required as a car navigation system.

In FIG. 1, when the power of the car navigation system 50 is turned on, the arithmetic unit 21 obtains time information from an RTC (real-time clock) 23 which is a timer IC, and obtains the obtained time information and a non-volatile memory. The list of visible satellites is executed using the orbit information of the GPS satellites, the vehicle position information, and the like stored in a certain memory 24. When the listing is completed, the arithmetic unit 21 controls the signal processing unit 22 to preferentially capture a GPS satellite from the listed satellites. Note that the RTC 23
It is backed up by a backup battery (not shown).

The GPS wave received by the GPS antenna 17 is converted into an intermediate frequency signal by a down converter 25,
The signal is A / D converted and passed to the signal processing unit 22. The signal processing unit 22 is also called a channel, and has a plurality (for example, 8 to 12).
Channels), and these channels can receive signals from a plurality of GPS satellites. The signal processing unit 22 performs demodulation by correlating the pseudo-random code signal unique to the satellite under the control of the arithmetic unit 21 to measure the flight time of the GPS wave and various information such as satellite position information. Is taken out. The distance from the GPS satellite is calculated by multiplying the flight time of the GPS wave by the speed of light.

The arithmetic unit 21 calculates the distance from a predetermined number of GPS satellites and executes a positioning operation.
Send to The time from when the power is turned on to the car navigation system until the first positioning result is obtained is the initial positioning time. The CPU 13 executes functions necessary for a car navigation system, such as displaying a vehicle position, using map information (not shown) based on the obtained positioning result.

The standard radio wave receiving unit 11 receives the standard radio wave, acquires time information, and sends it to the CPU 13. Here, Japan's standard radio waves are time and frequency standards, as well as Coordinated Universal Time.
(UTC; Coordinated Universal Time) is a radio wave operated by the Communications Research Laboratory of the Ministry of Posts and Telecommunications to notify Japan Standard Time (JST), based on longwave (40KHz) and shortwave (5,8,10MHz). There is something. The time information of the standard time signal includes the year (last two digits of the year), the total date, the day of the week, the hour,
Information such as minute, leap second information, parity for hour and minute, etc. is included.

The user I / F 15 has a function of presenting information to the user or inputting information from the user. The user can input the current time into the car navigation system 50 via the user I / F 15. Therefore, in the car navigation system 50, the time information obtained from the GPS satellite, the time information obtained from the standard radio wave reception unit 11, or the user I / F 15
It is possible to list the visible satellites by using any of the time information input through the network and to correct the RTC time to a correct time.

FIG. 2 is a flowchart showing an example of a processing procedure in the car navigation system 50 of FIG. 1 from power-on to a transition to a positioning state. In FIG. 2, when the power of the car navigation system 50 is turned on (S1: YES), the CPU 13 causes the RTC 23 to operate.
It is determined whether or not there is time information _TRTC in (S)
2). That is, when the power is turned on for the first time after the manufacture of the car navigation system 50, or when the backup battery of the RTC 23 is exhausted, the time information of the RTC 23 is in an initial state (state before calibration). It can be determined that there is not. If the calculation unit 21 in FIG. 1 lists up the visible satellites using the wrong time information, an incorrect satellite list is created, so that the initial positioning time becomes longer or the positioning result cannot be obtained. .

In the determination of step S2, T_RTCIf there is
If it is determined (S2: YES), T _RTCVisible using
A list of satellites is created, and GPS satellites are listed based on the list.
Search is performed, and when the signal is received, the positioning calculation
It is executed (S3). On the other hand, time information is not stored in the RTC 23.
(S2: NO), the CPU 13
Determines whether the standard wave can be received by the wave receiving unit 11
Is performed (S4). When the standard time signal can be received
(S4: YES), the CPU 13 determines whether the
Time information T_JJY(S5), and the time information T
_JJYIs sent to the calculation unit 21. Then in step S6
And T_JJYTo list visible satellites
The search for GPS satellites is performed based on the list, and the signal is
The positioning calculation is executed at the time of reception.

Time information T from RTC 23_RTCAlso
Time information T from the quasi-wave receiver 11 _JJYCan not get
In this case (S4: NO), the CPU 13 sets the user I / F
15 to input the time information to the user.
Time information T by manual input from the user_USRTake
Obtain (S7). Then, T_USRUsing visible satellites
A list is created, and GPS satellite services are based on the list.
And the positioning calculation is executed when the signal is received.
(S8).

FIG. 3 is a flowchart showing another example of the processing procedure from power-on to the positioning state in the car navigation system 50 of FIG. In the processing procedure of FIG. 2, the time information T
_{When the RTC} is obtained, the positioning calculation is performed using the time information. However, in the procedure of FIG. 3, if the time information _TJJY from the standard radio wave receiving unit 11 is obtained, the time information is always used. That is, when the power is turned on to the car navigation system 50 (S11: YES), the CPU 23 determines whether or not the standard radio wave can be received. If the standard radio wave can be received (S12: YES), C
PU13 acquires time information _{T JJY} standard radio wave receiving unit 11 (S13), and sends the time information _{T JJY} the arithmetic unit 21. Then, in step S14, a list of visible satellites is made using _TJJY , and GPS is listed based on the list.
A search for a satellite is performed, and a positioning operation is performed when a signal is received.

In step 12, the standard radio wave is received.
If it is determined that there is no connection (S12: NO), the CPU
13, the time information T of the RTC 23_RTCWhether there is
Is determined. T_RTC(S1)
5: YES), T_RTCList of visible satellites using
GPS satellite search based on the list
And when the signal is received, the positioning calculation is executed (S
16). Time information T from the standard radio wave receiving unit 11
_JJYAlso, the time information T from the RTC 23_RTCAlso obtained
If not (S15: NO), the CPU 13
-Require user to input time information via I / F15
And time information T manually input from the user.
_USRIs acquired (S17). Then, T_USRUsing
List of visible satellites is made, and GPs are created based on the list.
When the search for the S satellite is performed and the signal is received, positioning is performed.
An operation is performed (S18).

Note that, in the processing procedures of FIGS.
Time information T from the quasi-wave receiver 11 _JJYAlso RTC2
Time information T from 3_RTCIf not available
Time information T from_USR, But T_JJYAlso
T_RTCIf no time information is available,
List of visible satellites using only both position information
May be. Further, vehicle position information is also obtained from the memory 24.
If not, assume a certain position for the vehicle.
The visible satellites may be listed. Or car
If both location information is not available, all GPS orbiting
When satellites are searched one after another and one satellite is captured,
Restore visible satellites, assuming you are directly under the satellite
It is also possible to perform a backup.

If time information can be obtained from the standard radio wave receiving unit 11 but vehicle position information cannot be obtained from the memory 24, if the standard radio wave received by the standard radio wave receiving unit 11 is a Japanese standard radio wave, For example, the vehicle position may be limited to Japan (for example, Akashi City, Hyogo Prefecture), and a list of visible satellites may be made. Since standard radio waves are also used in countries other than Japan (different frequencies, etc.), similar to the above, when standard radio waves from countries other than Japan are received, the vehicle position is limited in that country. It is also possible.

Further, the CPU 13 executes step S5 in FIG.
Alternatively, in step S13 of FIG.
When the time information T _JJY is acquired, or when the time information T _JJY based on the standard radio wave is acquired during the operation of the car navigation system 50, T _JJY and RT
Compares the time information _{T RTC} of C23, the difference may be corrected in _{T JJY} time of RTC23 is greater than a predetermined value.

Since highly accurate time information can be obtained from a GPS satellite, RTC is performed using time information from the GPS satellite.
The time of the RTC 23 can be maintained with high accuracy by correcting the time of the RTC 23. However, the time information of the GPS satellite is a week number (WN) and a Z count. Since the WN is 10-bit data, the time information is 1024.
The value will be the same every week. This is said to be a WN roll over problem. For example, 1024 from January 6, 1980, when GPS began operation
A week later (about 20 years), WN returns to 0 again on August 22, 1999. Then, for example, even if a signal indicating that WN is 1 is received on August 29, 1999, there is a possibility that the signal is erroneously recognized as January 13, 1980. Assuming that the GPS receiver had orbit data of a satellite at a certain time in 1998, when trying to create a list of visible satellites, when the time is advanced by about one year by the approximate formula of the satellite orbit, and when it goes back 18 years Then the list of inferred visible satellites will be completely different. Since the GPS receiver performs a search based on this list, positioning becomes impossible unless a similar list is created by accident.
Once in a different 20-year period, it is impossible for the GPS receiver to return on its own. To avoid this problem, the CPU 13 recognizes the correct year using the last two digits of the year in the time information from the standard radio wave receiving unit 11, and uses the recognized correct year to determine the RTC.
23 time information can be corrected. By using the last two digits of the Christian era from the standard radio wave receiving unit 11, at least 100 years after the start of operation of GPS,
Until 079, it is possible to recognize the correct year.

Also, WN returns to 0 every 1024 weeks,
Since 1024 weeks are not exactly 20 years, WNZ
Count and date of birth (the day from January 1 of that year)
By monitoring the relationship of the days of the week, the WN rollover problem can be avoided even after 2079. Also,
By storing the date of manufacture in the memory 24 and using the last two digits of the year from the standard radio wave receiving unit 11, it is possible to recognize the correct year for 100 years from the date of manufacture. For example, when the date of manufacture is 2010, if the last two digits of the year from the standard radio wave receiving unit 11 is 11, it is 2011; if the last two digits of the year is 09, it is 2109. It can be recognized that there is.

FIG. 4 is a block diagram showing a second embodiment when the GPS receiver of the present invention is realized in a car navigation system. 4, the same reference numerals are used for the portions having the same functions as those shown in FIG. 1, and description thereof will be omitted.
The car navigation system 60 of FIG. 4 is substantially the same as the car navigation system 50 of FIG. 1 except for the function of acquiring time information from FM multiplex broadcasting instead of receiving time information from a standard radio wave. That is, when a processing procedure corresponding to the processing procedure of FIG. 2 or FIG. 3 is executed in the car navigation system 60, the time information from the standard radio wave reception unit 11 is used instead of the time information from the FM multiplex tuner 9. Time information is used. The FM multiplex tuner 9 converts the FM multiplex broadcast received by the FM antenna 8 into VICS (Vehicle information).
and Communication System) information and DGPS (Differential
Not only GPS) information but also time information is obtained and the CPU 1
Send to 3a. The CPU 13a sends the time information obtained from the FM multiplex tuner 9 to the arithmetic unit 21, and the arithmetic unit 21 executes listing of visible satellites using the time information. Also, the WN rollover problem can be avoided based on the time information from the FM multiplex broadcast, as in the case of using the standard radio wave described above.

In the embodiment shown in FIG. 1, the user I / F 15 is connected to the CPU 13. However, the user I / F 15 is connected to the operation unit 21, and the operation unit 21 is connected to the user I / F 15. It is also possible to provide a function of transmitting / receiving information to / from the server. Similarly,
In the embodiment shown in FIG. 4, the user I / F 15 can be connected to the arithmetic unit 21.

[0036]

As described above, according to the present invention, G
Even if the RTC inside the PS receiving apparatus is in a state before calibration and time information cannot be obtained, time information based on standard radio waves or time information based on FM multiplex broadcasting is used,
It is possible to reduce the initial positioning time until the GPS receiving device outputs the first positioning result. At the same time, by using the last two digits of the year of the time information based on the standard radio wave, G
Even when the phenomenon that the WN (week number), which is a problem unique to the PS, rolls over and returns to 0, occurs, the correct year is recognized.

[Brief description of the drawings]

FIG. 1 is a block diagram of a car navigation system according to a first embodiment of the present invention.

FIG. 2 illustrates a car navigation system of FIG.
It is an example of a flowchart showing a processing procedure from power-on to entering a positioning state.

FIG. 3 illustrates a car navigation system of FIG.
It is another example of the flowchart which shows the processing procedure from power-on until it enters into a positioning state.

FIG. 4 is a block diagram of a car navigation system according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 8 FM antenna 9 FM multiplex tuner 11 Standard radio wave receiving unit 13 CPU 15 User I / F 17 GPS antenna 20 GPS receiving unit 21 Operation unit 22 Signal processing unit 23 RTC 24 Memory 25 Down converter

Claims (11)

[Claims] 1. GPS (Global Positioning System)
A GPS receiving device having an internal clock for providing first time information inside the receiving device, wherein the standard time signal receiving unit receives a standard time signal, the first time information, and the standard time signal received by the standard time signal receiving unit. Using any of the time information of the second time information
Satellites that are estimated to be able to receive PS waves (visible satellites)
GPS receiving means for listing the GPS satellites listed by the visible satellite listing means, and positioning calculation means for performing positioning calculation by preferentially searching for the GPS satellites listed by the visible satellite listing means. apparatus. 2. The visible satellite list-up means uses second time information based on the standard time signal when power is turned on and the first time information from the internal clock cannot be obtained.
The GPS receiving device according to claim 1, wherein when the first time information is obtained from the internal clock, the listing is performed using the first time information. 3. The visible satellite list-up means uses the second time information when the power is turned on and the second time information based on the standard time signal can be obtained. The GPS receiving device according to 1. 4. A time input means for inputting a time by a user, wherein the visible satellite list-up means includes first time information from the internal clock, second time information based on the standard time signal, 4. The listing is performed by using any one of the third time information obtained from the input unit.
The GPS receiver according to any one of the above. 5. The visible satellite list-up means uses the third time information only when neither the first time information from the internal clock nor the second time information based on the standard time signal can be obtained. 5. The method according to claim 4, wherein
The GPS receiving device according to 1. 6. When power is turned on, a second signal based on the standard radio wave
6. The apparatus according to claim 1, further comprising: a time correction unit configured to correct the internal clock using the second time information when the time information is obtained. 7. GPS receiver. 7. When the difference between the first time information from the internal clock and the second time information based on the standard time signal is larger than a predetermined value, the internal clock is corrected using the second time information. The GPS receiver according to any one of claims 1 to 5, further comprising a time correction unit that performs time correction. 8. A WN (week n) acquired from a GPS satellite
umber) Information rolls over and rolls back to 0
The system according to claim 1, further comprising a unit for recognizing the Christian era using the last two digits of the Christian era included in the second time information based on the standard time signal in the case where The GPS receiver according to any one of the above. 9. A GPS receiving apparatus having an internal clock for providing first time information inside the GPS receiving apparatus, comprising: an FM multiplex receiving unit for receiving an FM multiplex broadcast; the first time information; Using any time information of the second time information acquired by the FM multiplex receiving means,
Satellites that are assumed to be able to receive PS waves (visible satellites)
GPS receiving means for listing the GPS satellites listed by the visible satellite listing means, and positioning calculation means for performing positioning calculation by preferentially searching for the GPS satellites listed by the visible satellite listing means. apparatus. 10. The visible satellite list-up means uses, when power is turned on, second time information based on the FM multiplex broadcast when first time information cannot be obtained from the internal clock, 10. The GPS receiving apparatus according to claim 9, wherein when the first time information is obtained, the listing is performed using the first time information. 11. The visible satellite list-up means, when power is turned on, if the second time information based on the FM multiplex broadcast can be obtained, performs the list using the second time information. The GPS receiver according to claim 9, wherein: