JPH08327718A - Apparatus and method for position measurement - Google Patents

Abstract

PURPOSE: To shorten the time period from time when a power supply is turned on to the initial obtaining of the position of a receiving point by using the effective orbit information already collected when the operation is started when the power supply is turned and the like, and computing the position of the receiving point. CONSTITUTION: A control part 13 has a CPU, a ROM and a RAM. The CPU executes the ROM-stored program, performs the specified loop filter operation and obtained a pseudo distance. Furthermore, the CPU extracts the orbit information from navigation message data and computes the position of a receiving point from the position information and the pseudo-distance information of each satellite at the time when the pseudo distance is obtained. The orbit information of each satellite updates the orbit information data of each satellite at every one hour during the on-period of the power supply. Thereafter, when the power supply is turned off, the power supply is turned on only for the short time during the period from the update time of the previous orbit information data to be effective time, and the reception from each satellite is performed. Thus, the update of the data and the position measuring operation are performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning device and a positioning method for receiving a radio wave transmitted from a positioning satellite for positioning.

[0002]

2. Description of the Related Art Conventionally, in a positioning system such as GPS, information for observing the distance from each positioning satellite to a receiving point and information for calculating the position of each positioning satellite are provided for each positioning. The distance from each positioning satellite to the receiving point and the position of each positioning satellite are obtained by extracting from the positioning signal transmitted from the satellite, and the position of the receiving point is obtained from this information. Specifically, the positioning device receives orbit information called ephemeris from each positioning satellite, collects and stores it, and calculates the position of each satellite at a desired time from these orbit information. The position of the reception point is calculated based on the observation distance (pseudo distance) to the reception point. The ephemeris is usually updated every hour, and its effective time is set to 4 hours. Therefore, the ephemeris data of each satellite of the positioning device is usually updated every time the ephemeris is updated.

Further, the radio waves transmitted from such positioning satellites are made less susceptible to noise, and even if all satellites transmit signals using the same carrier, they can be transmitted from desired satellites. In order to identify and receive only radio waves, spread spectrum modulation is performed using a pseudo noise code (C / A code) during transmission from a satellite. Therefore, a signal from a desired satellite is searched by generating a C / A code corresponding to the number of the satellite to be received and changing its phase and Doppler frequency.
I am trying to receive it.

[0004]

As described above, since the effective time of the ephemeris of each satellite is 4 hours, if the signal from that satellite cannot be continuously received for more than this time, the positioning device will not be able to receive it. The collected satellite ephemeris data is not used, and the positioning calculation is performed after collecting new ephemeris. Therefore, for example, when a car equipped with a positioning device returns home at about 9:00 pm and leaves at about 7:00 the next morning, the positioning device stops operating for more than 4 hours, so immediately after the power is turned on at 7:00 the next morning. Ephemeris of each satellite is newly collected. Since the time required to collect the ephemeris of each satellite is at least 30 seconds, in this case, it takes an extra 30 seconds until the first positioning result is obtained, as compared with the case where a valid ephemeris is held.

Here, taking a general 8-channel GPS receiver as an example, the state at power-on and the time until the first positioning result is obtained after power-on (generally TTFF: Ti
Called me To First Fix. The relationship with the value of () is shown in FIG. The deviation from the actual position at power-on from the final positioning position is within 1 degree in latitude and longitude, the deviation of the positioning device clock with respect to the GPS time is within 10 minutes, and the almanac data one month ago and 4 hours ago If the ephemeris data is backed up, TTFF will be about 20 seconds. If valid ephemeris data does not exist (because the effective time of the ephemeris data is 4 hours in the GPS system, even if past ephemeris data exceeding 4 hours is backed up, it will not be used), new ephemeris data will be used. About 3 to collect
Since 0 second is required, TTFF is about 50 seconds.

Further, as described above, since the signals from the respective satellites are subjected to the spread spectrum modulation by the pseudo noise code (C / A code), the positioning signals from the desired positioning satellites can be received. Requires a certain search time for each satellite. When searching for signals from each of these satellites, the satellites are selected so as to search for the signals from the satellites predicted to exist within the field of view, but whether each satellite is in view or out of view , Orbit information of each satellite (Almanac)
And the estimated position of the receiving point and the current time. Therefore, when the positioning device largely moves while the power is off and then is powered on, a large error is included in the estimated position of the reception point, and the estimation of the inside and outside of the field of view of each satellite is erroneous. For example, if the satellite estimated to be in the field of view is actually out of the field of view such as under the horizon, the search will fail, and the search time will be wasted.
Therefore, it takes a long time to complete the search for all the required number of satellites.

As described above, in the conventional positioning apparatus, if the orbit information of each satellite held by the receiver or the estimated position of the reception point is uncertain, the TTFF tends to be long.

It is an object of the present invention to eliminate the need to newly collect satellite orbit information even when the power is turned on after a long power off period, and the position of the receiving point is first obtained after the power is turned on. It is to provide a positioning device and a positioning method in which the time (TTFF) is shortened.

Another object of the present invention is to shorten the time required for the search by enabling proper selection of the satellite to be searched immediately after the power is turned on even if the positioning device moves largely during the power off period. It is to provide a positioning device and a positioning method in which TTFF is shortened.

[0010]

The positioning device of the present invention comprises:
In order to obtain a state in which valid orbit information has already been collected at the time of the first positioning immediately after the power is turned on, as described in claim 1, signals from a plurality of positioning satellites are received and each positioning satellite is received. In a positioning device comprising orbit information collecting means for collecting, storing and updating orbit information of, and positioning calculation means for calculating the position of a receiving point using the orbit information of each positioning satellite,
During an operation stop period such as a power-off period, a short-time starting means for starting the orbit information collecting means for a short time until the valid time of the orbit information of each positioning satellite collected by the orbit information collecting means elapses. Is provided, the positioning calculation means calculates the position of the reception point by using the orbit information already collected by the orbit information collection means when the operation is started such as when the power is turned on.

Further, in order to enable the satellite to be searched appropriately to be selected immediately after the power is turned on, the positioning device of the present invention provides the estimated position of the receiving point and the orbit information of each satellite as described in claim 2. Satellite signal receiving means for searching and receiving signals of each positioning satellite by using the orbit information collecting means for collecting and storing and updating orbit information of each positioning satellite from the signals received by the satellite signal receiving means; A positioning device that calculates the position of the reception point using the orbit information of each positioning satellite, the orbit information for a short time at regular intervals during an operation suspension period such as a power-off period. By providing the collecting means and the short-time start-up means for starting the positioning calculation means, the position information of the final reception point obtained by the positioning calculation means at the start of operation such as power-on is received. The satellite signal receiving means as an estimated position of which is characterized in that search for the positioning satellites.

Further, according to the positioning method of the present invention, the effective orbit information is already collected at the time of the first positioning immediately after the power is turned on. During the operation period of, the signals from a plurality of positioning satellites are received, the orbit information of each positioning satellite is collected, stored and updated, and the position of the reception point is calculated using the orbit information of each positioning satellite. However, during operation stop such as power off period, the orbit information of each positioning satellite is collected and updated for a short time until the valid time of the orbit information of each satellite already collected passes, and the power is turned on. It is characterized in that the position of the reception point is calculated using the orbit information that has already been collected when the operation such as time starts.

Further, according to the positioning method of the present invention, a plurality of satellites to be searched can be properly selected immediately after the power is turned on. Searches and receives signals from positioning satellites, collects orbital information of each positioning satellite, calculates the position of the receiving point using these orbital information, and during operation stop periods such as power off periods. , Orbit information of each positioning satellite is obtained by searching and receiving the signal of each positioning satellite using the estimated position of the receiving point and the orbit information of each positioning satellite that has already been collected for a short period of time at fixed intervals. Calculate the position of the receiving point using
The position information of the final reception point is set as the estimated position of the reception point when searching the signals of each positioning satellite at the start of operation such as when the power is turned on, and the estimated position of the reception point and the orbit information of each satellite are set. It is characterized in that a signal of each satellite is searched for and received using the orbit information of each positioning satellite and the position of the receiving point is calculated.

[0014]

With the positioning device according to claim 1 and the positioning method according to claim 3 of the present invention, signals from a plurality of positioning satellites are received during an operation period such as a power-on period, and orbit information of each satellite is obtained. The position of the receiving point is calculated by using the orbit information of each satellite.However, during the operation stop period such as the power off period, it takes a short time until the valid time of the already collected orbit information elapses. Only, the reception of signals from positioning satellites and the collection of orbital information of each satellite are periodically repeated. As a result, since the orbit information within the valid time is always collected, the position of the receiving point should be immediately calculated using the valid orbit information that has already been collected when the operation is started such as when the power is turned on. Is enabled and TTFF is shortened.

In the positioning device according to the second aspect and the positioning method according to the fourth aspect, the signals of the respective satellites are searched using the estimated position of the reception point and the orbit information of the respective satellites, and the respective signals are searched from the received signals. The satellite orbit information is collected, and the position of the receiving point is calculated using the orbit information of each satellite.However, during a period of operation suspension such as power off period, the When the search and positioning calculations are performed and the operation starts when the power is turned on, the position information of the final reception point that has been obtained up to that point is used as the estimated position information of the reception point when searching the signals of each satellite. To be Even if the positioning device moves during the power-off period, this estimated position information of the receiving point is updated at regular intervals, so when searching for satellite signals immediately after the power is turned on, such as immediately after the power is turned on, The inconvenience of searching for satellites is avoided. As a result, the desired satellite can be searched promptly immediately after the operation is started, and the TTFF can be prevented from being prolonged.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of a positioning device according to an embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram showing the configuration of the positioning device. In the figure, a GPS board 10 is a main part relating to positioning control for receiving signals from GPS satellites and performing positioning of a reception point, and a warm box 1 is a main part relating to power supply control. In this embodiment, a vehicle-mounted GPS positioning device is taken as an example. In the warm box 1, the charging circuit 2 inputs a power supply voltage from a power supply line of a cigarette lighter of an automobile, for example, to charge the secondary battery 3. This secondary battery 3
Is supplied to the control unit of the GPS board 10 as the power supply voltage for the RTC (clock circuit) and the backup power supply voltage for the memory as V _BATT . Switch 4
Is a switch that is turned on / off by a warm box start switch control signal, and when the function of the warm box 1 is used, this switch 4 remains on. The switch 5 is a switch that is turned on / off by an output signal of the control unit in the GPS board 10 described later.
The voltage of the secondary battery 3 via the switches 4 and 5 or the input power supply voltage from the automobile is supplied to the GPS board 10 as the power supply voltage Vcc via the diodes 6 and 7.
The main power supply monitoring circuit 7 is a circuit for monitoring whether or not the input power supply voltage from the vehicle has reached a specified value, and gives a logic signal according to the presence / absence of power supply input to the control unit in the GPS board 10.

In the GPS board 10, the battery 14 is a lithium battery or the like, is connected to the V _BATT line through the diodes 8 and 9, and supplies a backup voltage for the RTC and the memory. Analog signal processing circuit 1
1a performs intermediate frequency conversion of a signal from the GPS satellite received by the antenna, and the AD converter 11b converts the signal into digital data. The signal processing circuit 12 receives the digital data from the AD converter 11b, the C / A code pattern data, the C / A code phase data and the carrier phase data from the control unit 13, and generates the C / A code pattern and C. / Correlate with A code. The signal processing circuit 12 also measures GPS time. The RTC in the control unit 13 includes a reference oscillator and divides the reference oscillation signal to measure the current time.
The control unit 13 is composed of a microprocessor including a CPU, a ROM and a RAM, and the CPU executes a program written in the ROM in advance to execute the signal processing circuit 12.
C / A code phase data and carrier phase data are given to the signal processing circuit 12 by reading the correlation data from the data, performing a predetermined loop filter operation, and providing the signal processing circuit 12 with the C / A code phase data and the carrier phase data. Synchronize with and obtain the pseudo distance. Also C
The PU extracts the navigation message data, extracts the ephemeris from the navigation message data, and calculates the position of the receiving point from the position information of each satellite at the time when the pseudo distance is obtained and the pseudo distance information.

FIG. 2 is a diagram showing an example of the update timing of the ephemeris data when the positioning device is powered on and off. The ephemeris of each satellite is usually updated at the same time every hour, so 1 during the power-on period.
Ephemeris data of each satellite is updated every hour.
After that, when the power is turned off at a certain point, during the power-off period, the power is turned on only for a short time until 4 hours have elapsed since the last time the ephemeris data was updated, and reception from each satellite is started. To update the ephemeris data and perform positioning calculation. After that, when the power is turned on at some point, the ephemeris data already collected will be 4
Since it is within the time, positioning is performed using the ephemeris data as it is.

FIG. 3 is a flowchart showing a processing procedure for collecting ephemeris data and setting an alarm during the power-on period. First, the signals from the satellites within the field of view are searched to determine whether the ephemeris of each satellite has been updated (n1 → n2). If the ephemeris has been updated, the new ephemeris is collected and the ephemeris data stored in the memory is updated (n3). Then, the RTC error is corrected by adjusting the contents (current time) of the RTC to the second digit of the GPS time obtained by receiving the signal from the satellite (n4). Further, the alarm time is set to the RTC so that the RTC will activate the CPU after 3 hours and 59 minutes (n5). At that time, RTC 3 hours 59 minutes or about 4
The alarm time is set in consideration of the accumulated error in time in advance. As a result, the CPU is activated within 1 second after 3 hours and 59 minutes from the time when the ephemeris is updated. If the power is off at that time, the CPU is activated to collect ephemeris data of each satellite as described later.

FIG. 4 shows the contents of the processing for measuring the RTC deviation performed every 15 minutes during the power-on period. The difference between the RTC time and GPS time at that time is the amount of RTC deviation in 15 minutes. Calculate as Eq. This information is used in the alarm setting for the RTC shown in step n5 of FIG. That is, since the amount of RTC deviation after about 4 hours is 4 × 4 × Eq, the current time by RTC + 3 hours 59 minutes−4 × 4 × Eq, which is an accurate 3 hours 59.
Set an alarm after minutes.

FIG. 5 is a flowchart showing the procedure of the positioning process performed during the power-on period. First, it is determined whether or not pseudoranges of four or more satellites within the field of view are obtained, and if so, the position of the receiving point is determined from each pseudorange, the time when these pseudoranges were observed, and the start information of each satellite. Is calculated and updated (n21 → n22 → n23).

FIG. 6 is a flow chart showing the procedure of power supply monitoring and wakeup processing. First, the on / off state of the power supply is determined based on the main power supply monitoring signal from the main power supply monitoring circuit 7 (see FIG. 1) (n11). When it is detected that the input of the main power supply is cut off, for example, when the engine key of the automobile is turned off, the CPU of the control unit 13 executes the low power stop command (n11 → n12). This puts the CPU in a power save mode. Then output the backup power on / off signal for scheduled operation,
By turning off the switch 5 shown in FIG. 1, the power consumption in the GPS board of the secondary battery 3 is stopped. As a result, only the RTC continues to operate with the voltage V _BATT from the secondary battery 3 shown in FIG. 1 (n13).

After that, by the processing of step n5 in FIG. 3, 3 hours 5 from the time when the last ephemeris was collected.
When the switch 5 is turned on by the backup power supply on / off signal for scheduled operation output from the RTC after 9 minutes,
The power supply voltage Vcc is applied to the CPU from the secondary battery 3,
The CPU restarts (n14). As a result, the processing shown in FIGS. 3 and 5 is started, the signals from the satellites within the field of view are searched, the ephemeris of each satellite is collected, and the ephemeris data on the memory is updated. Further, the position of the reception point is calculated. When the number of satellites within the field of view or the ephemeris data for eight satellites is updated, the process returns to step n11 (n15 → n11). It takes about 10 seconds from the restart to the reception of the satellite signal within the field of view. However, ephemeris data cannot be updated when the car is parked in a place where the field of view is not open, such as in the garage. If ephemeris cannot be updated within 1 minute after CPU restart, R
Set the alarm setting after 3 hours and 59 minutes in TC and forcibly return to step n11 (n16 → n17 → n1
1). After returning to step n11, the power is still off at this time, so the low power stop command is executed again to turn off the backup power (n12 → n1).
3). However, since the alarm after 3 hours and 59 minutes is set again in the RTC by the processing in step n5 of FIG. 3 or step n17 of FIG. 6, the backup power supply is turned on again by the signal from the RTC after 3 hours and 59 minutes. ,
The CPU will restart (n14). By repeating the same processing thereafter, during the power-off period, ephemeris collection / update and positioning are performed at time intervals that do not exceed 4 hours, which is the effective time of ephemeris.

The above-mentioned alarm setting for 3 hours and 59 minutes and the limitation of the operation time within 1 minute after the restart are set by the secondary battery 3
This is to minimize the consumption of
If a secondary battery is used, for example, it is possible to set an alarm every two hours or set a sufficient time (for example, 3 minutes) to collect the ephemeris of all satellites within the field of view after restart.

Normally, since the ephemeris is updated on every hour, as described above, after the ephemeris is updated, every 2 hours or every 4 hours, the CP immediately before every hour.
By restarting U to collect ephemeris and updating the ephemeris data in the memory, it is possible to keep the latest ephemeris while minimizing battery consumption.

In this way, since the ephemeris data within the valid time is always held, it is not necessary to collect the ephemeris immediately after the power is turned on. Therefore, at the earliest, after the power is turned on, the first positioning result can be obtained in about 15 seconds including about 10 seconds required to receive the signals of the four satellites within the field of view and about 5 seconds required for the positioning calculation.

[0028]

According to the positioning device and the positioning method of the third aspect of the present invention, the orbit information within the valid time is always collected even during the operation stop period such as the power-off period. Therefore, when the operation is started such as when the power is turned on, the position of the reception point can be immediately calculated using the valid orbit information that has already been collected, and the TTFF can be shortened.

According to the positioning device of the second aspect and the positioning method of the fourth aspect, the estimated position information of the reception point is updated at regular intervals even if the positioning device moves during the power-off period. The inconvenience of searching for a satellite outside the field of view is avoided when searching for a satellite signal immediately after the power is turned on, such as immediately after the power is turned on. As a result, the desired satellite can be searched promptly immediately after the operation is started, and the TTFF can be prevented from being prolonged.

[0030]

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a positioning device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of ephemeris update timing in a power-on period and a power-off period.

FIG. 3 is a flowchart showing a processing procedure of the positioning device.

FIG. 4 is a flowchart showing a processing procedure of the positioning device.

FIG. 5 is a flowchart showing a processing procedure of the positioning device.

FIG. 6 is a flowchart showing a processing procedure of the positioning device.

FIG. 7 is a diagram showing the relationship between the start state and TTFF when the power is turned on.

Claims (4)

[Claims] 1. Receiving signals from a plurality of positioning satellites,
A positioning device comprising orbit information collecting means for collecting and storing and updating orbit information of each positioning satellite, and positioning calculation means for calculating the position of a receiving point by using the orbit information of each positioning satellite. A short-time starting means for starting the orbit information collecting means for a short time until the valid time of the orbit information of each positioning satellite collected by the orbit information collecting means elapses during an operation stop period such as a period As a result, the positioning calculation means calculates the position of the reception point using the orbit information already collected by the orbit information collection means at the start of operation such as power-on. 2. A satellite signal receiving means for searching and receiving a signal of each positioning satellite using the estimated position of the reception point and orbit information of each satellite, and each positioning from the signal received by the satellite signal receiving means. In a positioning device including an orbit information collecting unit that collects and stores and updates the orbit information of the satellite for use, and a positioning calculation unit that calculates the position of the receiving point using the orbit information of each positioning satellite, a power-off period, etc. By providing a short-time starting means for starting the orbit information collecting means and the positioning calculating means for a short time every fixed time during the operation stop period, the positioning calculating means at the start of operation such as power-on A positioning device, wherein the satellite signal receiving means searches each positioning satellite by using the obtained positional information of the final receiving point as an estimated position of the receiving point. 3. Orbit information of each positioning satellite is received by receiving signals from a plurality of positioning satellites during operation period such as power-on period, collecting orbit information of each positioning satellite, and storing and updating. The position of the receiving point is calculated by using the orbit information of each positioning satellite for a short time until the valid time of the orbit information of each satellite that has already been collected elapses during operation stop such as power off period. A positioning method, which collects and updates the memory, and calculates the position of the receiving point using the orbit information that has already been collected when the operation starts such as when the power is turned on. 4. A signal from a plurality of positioning satellites is searched and received during an operation period such as a power-on period, orbit information of each positioning satellite is collected, and received using these orbit information. The position of the point is calculated, and during the operation stop period such as the power off period, the estimated position of the receiving point and the orbit information of each positioning satellite that has already been collected are used for each positioning for a short period of time. The satellite signal is searched and received, the position of the receiving point is calculated using the orbit information of each positioning satellite, and the final position information of the receiving point is calculated when the operation starts, such as when the power is turned on. Is used as the estimated position of the receiving point when searching, and the signal of each satellite is searched and received using the estimated position of the receiving point and the orbit information of each satellite, and the orbit information of each positioning satellite is used. A positioning method characterized in that the position of the receiving point is calculated by