Method for calculating instanteneous characteristic of a satellite in orbit equipped with a gnss receiver

• US 20040064222A1
• Filed: 03/12/2003
• Published: 04/01/2004
• Est. Priority Date: 09/15/2000
• Status: Active Grant

• Current Assignee: Centre National D'Etudes Spatiales
• Original Assignee: Centre National D'Etudes Spatiales
• Inventors: Laurichesse, Denis
• Granted Patent: US 6,882,908 B2
• Time in Patent Office: Days
• US Class Current: 701/13
• CPC Class Codes: G01S 19/40 Correcting position, velocity or attitude
• CPC Class Codes: G01S 19/50 whereby the position solution is constrained to lie upon a particular curve or surface, e.g. for locomotives on railway tracks

Abstract

The present invention relates to a method for calculating the instantaneous characteristics of a satellite in orbit equipped with a GNSS receiver, capable of performing measurements of pseudo-distance, when fewer than four transmitters are simultaneously in visibility. This method comprises the following stages:

a first stage (20) of pre-processing of quantities measured by the receiver to deliver measurements of pseudo-distance, pseudo-speed and instantaneous pseudo-accelerations;

a second stage (21) of mathematically processing these measurements, enhanced by the knowledge of complementary data concerning the orbit of the receiver satellite and the receiver, delivering several solutions,

a third stage (22) of physically filtering these solutions delivering the position and the speed of the receiver satellite as well as the clock bias and drift of the receiver.

Claims

1. A method for calculating instantaneous characteristics of a satellite in orbit, equipped with a GNSS receiver, capable of performing measurements of pseudo-distance, when fewer than four transmitters are in simultaneous visibility, characterised in that it comprises the following stages:

a first stage (20) of pre-processing of quantities measured by the receiver to deliver measurements of pseudo-distance, pseudo-speed and instantaneous pseudo-accelerations;

a second stage (21) of mathematically processing these measurements, enhanced by the knowledge of complementary data concerning the orbit of the receiver satellite and the receiver, delivering several solutions,

a third stage (22) of physically filtering these solutions delivering the position and the speed of the receiver satellite as well as the clock bias and drift of the receiver.

2. The method as claimed in claim 1, wherein, during the first stage (20), measurement of instantaneous pseudo-speed is calculated either by differentiation of two measurements of pseudo-distances close in time:

3. The method as claimed in claim 1, wherein, during the first stage (20), measurement of instantaneous pseudo-acceleration is calculated either by differentiation of two instantaneous measurements of pseudo-speeds close in time:

4. The method as claimed in claim 1, wherein, during the second stage (21), the desired solutions are the following:

position of the receiver satellite {right arrow over (P)}

speed of the receiver satellite {right arrow over (V)}

clock bias of the receiver b

clock frequency shift of the receiver

$\frac{\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>f}{f}.$

5. The method as claimed in claim 1, wherein, during the third stage (22), for a receiver satellite in low orbit the meniscal axis a of the desired solution is considered limited:

6400 Km<

a<

8400 Km.

6. The method as claimed in claim 1, wherein, during the third stage (22), the absolute value of the clock frequency shift of the receiver is considered limited:

for a low-quality oscillator (low orbit);

$<br><br>\frac{\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>f}{f}<br><br><<br><br>300<br><br>\text{\hspace{1em}<br><br>}<br><br>m/s$

for a good-quality oscillator, (geostationary orbit);

$<br><br>\frac{\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>f}{f}<br><br><<br><br>10<br><br>\text{\hspace{1em}<br><br>}<br><br>m/s.$

7. The method as claimed in claim 1, wherein, during the third stage (22), a reference inclination of the receiver satellite (10) is considered.

8. The method as claimed in claim 7, wherein the inclination of the satellite is the nearest to this reference inclination.

9. The method as claimed in claim 1, wherein, during the third stage, the satellite is in radio-electric visibility of each transmitter.

10. The method as claimed in claim 1, wherein at least one transmitter is a satellite.

11. The method as claimed in claim 1, wherein at least one transmitter is a terrestrial station.