JP3422827B2 - Satellite receiver - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite receiver for periodically receiving signals from a plurality of artificial satellites to obtain data, and more particularly to NAVSTAR / GPS (NAVigation System).
with TimeAnd Ranging / Global Positioning System)
The present invention relates to a satellite receiver used for such purposes.

[0002]

2. Description of the Related Art As is well known, GPS finds the position of each of a plurality of (three or more) artificial satellites and the respective distances between the user and these artificial satellites, and performs positioning calculation. Performs seeking the user's current location. Of these, the distance can be calculated relatively easily by multiplying the difference between the time when the satellite transmits a signal and the time when the signal is received from the satellite by the speed of light, but the satellite position is calculated using the orbital elements transmitted from the satellite. It is calculated by using the information in a method uniquely specified by the positioning system. Since this calculation needs to use, for example, the Kepler's equation or the satellite's equation of motion, it is complicated and time-consuming. A conventional satellite receiving apparatus of this type is a system using three or four artificial satellites, and is said to be once every second, for example, every time when calculation processing is possible using a high-speed computing unit. Positioning calculation is performed by calculating the position and distance of each satellite described above.

[0003]

As described above, the conventional satellite receiving apparatus of this type performs a complicated and time-consuming calculation of the position of each satellite, for example, for each positioning calculation once per second. Therefore, the processing capacity is limited, and the system uses a high-speed arithmetic unit and uses three or four artificial satellites. For this reason, there is a drawback in that positioning cannot be performed when information from one or two satellites cannot be received, and in order to eliminate such a drawback, all satellites existing on the horizon (this is tentatively called a visible satellite). However, even if an attempt is made to construct a system that uses a large number of visible satellites, the amount of computation becomes too large, and the computation processing cannot be performed at every prescribed positioning calculation interval, making it difficult to construct the system.

Further, in order to realize a low power consumption device in consideration of portability, a method of slowing the operation clock may be adopted. In such a case, three to four artificial satellites are used. Even in the system using individually, the above-mentioned arithmetic processing cannot be performed in time, and the specified positioning calculation interval cannot be satisfied. Furthermore, when a high-speed arithmetic unit is used, there is a problem that the device becomes large and expensive.

The present invention has been made to solve the above problems, and reduces the calculation amount required for positioning calculation.
It is an object of the present invention to provide a satellite receiving device capable of performing positioning calculation at a specified positioning calculation interval even in a system using many visible satellites or a device with low power consumption.

[0006]

A satellite receiving apparatus according to the present invention periodically calculates a satellite by using orbital element information transmitted from the artificial satellite at a time interval longer than a time interval for executing positioning calculation. While obtaining the position of the satellite, obtain a predicted orbit that predicts the orbit of the artificial satellite, and update the sequence of the predicted orbit and the distance between the receiver and the artificial satellite at each time interval for executing positioning calculation. The position of the artificial satellite at the time when the positioning calculation is executed is sequentially calculated using the predicted orbits obtained by the above means, and the positioning calculation is executed for a plurality of artificial satellites based on this position and the distance. And a positioning calculation executing means for performing the positioning calculation.

[0007]

With the satellite receiving apparatus according to the present invention having the above-mentioned configuration, even if the number of times of calculating the position of the satellite using the orbital element information with a large amount of calculation is reduced, the positioning calculation for each specified positioning calculation is performed. It may be an executable device.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of the satellite receiver according to the present invention. In the figure, 1 is the position of the first satellite.
The velocity calculator calculates the satellite position Pj and velocity Vj at time tj using the orbital element information received and recorded from the satellite (where j is a suffix for distinguishing the time). Reference numeral 2 is a second satellite position / velocity calculation unit, which uses the same orbital element information collected from the above-mentioned satellites to generate a time t.
Position Pm of the satellite at time tm which is td away from j
And the velocity Vm is calculated (where m is also a subscript for differentiating the time, for example, if j is the current time, m means a future point in time td apart, which is a trajectory element. Calculate time as a parameter for information).
Reference numeral 3 is an approximate curve calculation unit, which is position Pj / speed Vj / time tj.
And position Pm, speed Vm, and time tm, Pj and P
An approximate curve (an approximate orbital curve) of the satellite between m and m is obtained.
Although it is defined as an approximate curve here, it is a satellite orbit of a short time, and may be an approximation straight line by simplifying the calculation, as long as the predicted orbit of the satellite can be obtained as information.

Reference numeral 4 denotes an approximate curve storage unit, which is an approximate curve calculation unit 3
The approximate curve output from is stored, and when the next approximate curve is calculated and a new approximate curve is output, the stored contents are updated. A third satellite position / velocity calculation unit 5 uses the approximate curve stored in the approximate curve storage unit 4 to calculate the satellite position Pi and velocity V at time ti at which positioning calculation is performed.
Calculate i. These first satellite position / velocity calculator 1,
The second satellite position / velocity calculation unit 2, the approximate curve calculation unit 3, the approximate curve storage unit 4, and the third satellite position / speed calculation unit 5 are provided by the number of satellites used by the system, that is, the satellites used by the system. If n is set to n, then n reception channels are provided.

Reference numeral 6 denotes a positioning calculation unit, which is a third unit for each channel.
Positions Pi1 to Pin and speeds Vi1 to Vi of each satellite at time (i) obtained by the satellite position / velocity calculator 5.
The position of the user is calculated from n and the pseudo distance of each satellite obtained at the time (i) by actually receiving the signal from each satellite. Reference numeral 7 denotes a positioning calculation timing control unit, which controls the control signal i at regular time intervals (for example, once a second).
Is output, and the third satellite position / velocity calculation unit and the positioning calculation unit 6 of each channel are activated, and the positioning calculation is executed at the specified positioning calculation interval. An approximate curve calculation timing control unit 8 outputs control signals j1 to jn to each of the n reception channels at fixed time intervals, and calculates the first satellite position / speed calculation unit 1 and the second satellite position / speed calculation for each channel. The unit 2 and the approximate curve calculation unit 3 are activated to calculate and output the approximate curve.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. Now, when the device is powered on, the arithmetic processing is started from the start step 100,
Proceed to the start element collection step 200 to receive signals from all satellites used in the system, for example, all visible satellites, and collect orbit element information data of those satellites transmitted from each satellite for each channel. To do. And
When the collection of the orbital element information is completed, the process proceeds to the control signal i output monitoring routine 300 that monitors the control signal i output from the positioning calculation timing control unit 7, and at the time ti when the control signal i is output, the approximate curve calculation / Memory routine 4
Go to 00.

The approximate curve calculation / storing routine 400 uses n
Each reception channel operates independently. The approximate curve calculation / storing routine 400 for each reception channel uses the control signal j output from the approximate curve calculation timing control unit 8.
Of 1 to jn, the control signal j for its own reception channel is monitored. Then, at the time tj when the control signal j for its own reception channel is output, the first satellite position / velocity calculation unit calculates the satellite position Pj and the satellite position Pj at the time tj based on the orbital element information collected from the satellites in step 200. The speed Vj is calculated, and the calculation result is output to the approximate curve calculation unit 3. Further, the second satellite position / velocity calculation unit 2 also uses the same orbital elements collected from the satellites in step 200, based on the future time tm (= tj + t).
The satellite position Pm and velocity Vm in d) are calculated, and the calculation results are sent to the approximate curve calculation unit 3.

In the next approximation curve calculation unit 3, as shown in FIG. 3, an approximation curve is obtained by assuming the movement (orbit) of the satellite between Pj and Pm as a quadratic curve, and stored in the approximation curve storage unit 4. To do. This approximated curve is based on the calculated positions Pj and Pm and the velocity V.
It can be determined by j and Vm. Then, by setting the time interval for outputting the control signal j longer than the time interval for outputting the control signal i for activating the positioning calculation,
It is possible to reduce the calculation frequency of the satellite position having a long calculation time and reduce the calculation time per unit time. That is, in this embodiment, the position P of the satellite at time tj
j, velocity Vm and the position Pm and velocity Vm of the satellite at time tm in the future, the predicted orbit of the satellite up to time tm in the future is calculated as an approximate curve, while
For each prescribed positioning calculation, only the pseudo distance to the satellite is obtained, and the positioning calculation is performed using the obtained pseudo distance and the position of the satellite at the time of the positioning calculation obtained by the approximate curve.
In the conventional device, the satellite position calculation, which is performed for each positioning calculation, is performed at a predetermined interval to reduce the calculation amount and the calculation time.

That is, in the next satellite position approximate calculation routine 500, the approximate curve stored in the approximate curve storage unit 4 is used to cause the third satellite position / speed calculation unit 5 to calculate the time ti.
Calculate the satellite position Pi and the velocity Vi at.
Since the output interval of the control signal j is longer than the output interval of the control signal i, the approximate curve is not calculated every time, but since it is sequentially stored and updated in the approximate curve storage unit 4, the control signal is Each time i is output, the stored approximate curve can be used to calculate the position and velocity of the satellite. In the next pseudorange measurement routine 600, the pseudorange of the satellite being received is measured at the time ti when the control signal i is output. In the next positioning calculation routine 700, the positions Pi1 to Pin and the speeds Vi1 to Vin of the respective satellites at the time ti calculated by the satellite position approximation calculation routine 500 and the respective satellites at the time ti calculated by the pseudo distance measurement routine 600 are calculated. The position of the user is calculated from the pseudo distance. This calculation is similar to the conventional device. After that, the steps from the control signal i output monitoring routine 300 to the positioning calculation routine 700 are repeatedly executed each time the positioning calculation timing control section 7 outputs the control signal i.

In the above embodiment, the satellite orbit is approximated by a quadratic curve as shown in FIG. 3, but it may be a straight line instead of a curve, and a cubic curve may be used.
It goes without saying that the next curve may be used.

[0016]

As described above, the satellite receiving apparatus of the present invention calculates the satellite position based on the orbital element information, which has been conventionally performed for each positioning calculation, from the predicted orbit predicting the satellite orbit. Since the satellite position calculation based on the element information is intermittently performed in order to obtain the predicted orbit, the amount of calculation required for positioning calculation can be significantly reduced, and therefore many (all) visible satellites are used. Even when constructing such a system, it is possible to obtain a device capable of executing positioning calculation at a prescribed time interval.

Further, even if the basic clock of the arithmetic processing is slowed down in order to reduce the power consumption, a device capable of executing positioning calculation at a prescribed time interval can be provided, and the amount of calculation performed by the arithmetic unit can be further reduced. There is an effect that an inexpensive arithmetic unit can be used as a low-cost device, or a device that can simultaneously perform other navigation calculations and calculations such as displaying various information.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a flow chart for explaining the operation of the present invention.

FIG. 3 is a diagram for explaining an approximated curve in the present invention.

[Explanation of symbols]

1 First satellite position and velocity calculator 2 Second satellite position / speed calculator 3 Approximate curve calculation section 4 Approximate curve storage 5 3rd satellite position / speed calculator 6 Positioning calculation section 7 Positioning calculation timing control unit 8 Approximate curve calculation timing control unit

Front Page Continuation (56) References JP-A-4-324383 (JP, A) JP-A-3-18716 (JP, A) JP-A-6-201812 (JP, A) POPESCU M, ON THE CRITICAL STABILITY CASE OF MOTION AR OUND THE EQUILATOR AL LIBRATION POINTS OF THE EARTH-MOON S, Rev. Room. Sci. Techn. -Mec. Appl. , ED ITURA ACADEMIEI RE PUBLICII SOCIALIST E ROMANIA, 1982, Vol. 27, No. 1, pp. 3-14 S. S. RUSSEL; J. H. SC HAIBY, Control Segment and User Perfance, Navigaten, USA, The Institute of Navigation, 1978, Vol. 25, No. 2, pp. 166-172 (58) Fields investigated (Int.Cl. ⁷ , DB name) G01S 5/00-5/14 G01C 21/00-21/24 G01C 23/00-25/00

Claims (4)

(57) [Claims] 1. GPS (Global Positioning System)
For satellite receivers that are used for, for example, positioning of a plurality of artificial satellites and distances from the receiver to perform positioning calculation, artificial satellites are used at a time interval longer than the time interval for executing positioning calculation. while position calculation of the satellite by calculation using the orbital element information transmitted from a total of the position calculation
Orbit information prediction means that predicts the orbit of the artificial satellite based on the calculation result, accumulates this as information, and sequentially updates it, and the distance between the receiving device and the artificial satellite at each time interval for executing positioning calculation. Is calculated sequentially, and the position of the artificial satellite at the time when the positioning calculation is executed is calculated using the predicted orbit of the artificial satellite obtained by the orbit information prediction means, and the positioning calculation is performed based on this position and the distance. A satellite receiving apparatus comprising: a positioning calculation executing unit that executes the plurality of artificial satellites. 2. GPS (Global Positioning System)
For satellite receivers that are used for, for example, positioning of a plurality of artificial satellites and distances from the receiver to perform positioning calculation, artificial satellites are used at a time interval longer than the time interval for executing positioning calculation. while position calculation of the satellite by calculation using the orbital element information transmitted from a total of the position calculation
An approximate straight line that predicts the orbit of the artificial satellite based on the calculation result is obtained, and an approximate straight line calculating means that sequentially updates the straight line, and the distance between the receiving device and the artificial satellite is calculated at each time interval for executing positioning calculation. The position of the artificial satellite at the time when the positioning calculation is executed is calculated using the approximate straight line that is sequentially obtained and obtained by the approximate straight line calculating means, and the positioning calculation is performed based on this position and the distance. A satellite receiving device, comprising: positioning calculation executing means for executing the following. 3. GPS (Global Positioning System)
For satellite receivers that are used for, for example, positioning of a plurality of artificial satellites and distances from the receiver to perform positioning calculation, artificial satellites are used at a time interval longer than the time interval for executing positioning calculation. while position calculation of the satellite by calculation using the orbital element information transmitted from a total of the position calculation
An approximate curve for predicting the orbit of the artificial satellite based on the calculation result is obtained, and an approximate curve calculation means for sequentially updating the curve is calculated, and the distance between the receiving device and the artificial satellite is calculated at each time interval for executing positioning calculation. The position of the artificial satellite at the time when the positioning calculation is executed is calculated using the approximate curve that is sequentially obtained and obtained by the approximate curve calculation means, and the positioning calculation is performed based on this position and the distance. A satellite receiving device, comprising: positioning calculation executing means for executing the following. 4. The satellite receiver according to claim 1.
The orbit information predicting means is provided to each of the plurality of artificial satellites.
Correspondingly provided, the orbit information prediction means is used to calculate the position of the artificial satellite.
It also has a timing controller to control the timing.
And a satellite receiver.