Process for the autonomous reduction of acquisition and tracking thresholds of carriers received in orbit

• US 6,147,641 A
• Filed: 11/12/1997
• Issued: 11/14/2000
• Est. Priority Date: 03/12/1996
• Status: Expired due to Term

• Current Assignee: Centre National D'Etudes Spatiales
• Original Assignee: Centre National D'Etudes Spatiales
• Inventors: Issler, Jean-Luc
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): PHAN, DAO LINDA
• Application Number:
  US08/945,808
• Time in Patent Office: 1,098 Days
• Field of Search: 342/352, 342/357.06, 342/418, 342/357.05, 342/402, 701/213
• US Class Current: 342/357.65
• CPC Class Codes: G01S 19/14 specially adapted for specific applications
• CPC Class Codes: G01S 19/26 involving a sensor measurement for aiding acquisition or tracking
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: H03L 7/07 using several loops, e.g. for redundant clock signal generation
• CPC Class Codes: H03L 7/10 for assuring initial synchronisation or for broadening the capture range
• CPC Class Codes: H03L 7/102 the additional signal being directly applied to the controlled loop oscillator
• CPC Class Codes: H03L 7/104 using an additional signal from outside the loop for setting or controlling a parameter in the loop H03L7/107, H03L7/12 take precedence

Abstract

The present invention relates to a process for the autonomous reduction of acquisition and tracking thresholds of carriers received in orbit by a receiver accessing an orbital navigator inside or outside said receiver, the latter having at least one phase loop. The phase loop, which is responsible for the acquisition and/or tracking of the carrier, is "pushed" by the fine speed aid and takes up the error between the real speed and the calculated speed. The search for the Doppler frequency of the carrier received takes place around a frequency prediction maintained by the fine speed aid coming from the orbital navigator.

Claims

1. A method for autonomously reducing at least one of an acquisition threshold and a tracking threshold of a carrier received in orbit by a receiver on a satellite accessing an on-board orbital navigator, comprising the steps of:

receiving the carrier by the receiver;

generating a fine speed aid on-board the satellite with a calculated speed from the on-board orbital navigator;

pushing a phase loop with the fine speed aid so as to reduce an error between a real speed and the calculated speed; and

performing a Doppler frequency search for the carrier around a frequency prediction provided by the fine speed aid.

2. The method of claim 1, further comprising the step of:

prior to the receiving step, providing the receiver with acquisition aids including (i) a date and a time of a receiver clock, (ii) a position/speed or orbital parameters of an emitter, and (iii) a position/speed or orbital parameters of the satellite, wherein,

the acquisition threshold is reduced to below a conventional aided acquisition threshold.

3. The method of claim 2, further comprising the steps of:

receiving a description of a maneuver that is dedicated to an orbit control of the satellite, wherein the description of the maneuver satisfies the equation ##EQU5## where δ

PV is a precision of the fine speed aid, δ

V is a precision of the description of the maneuver, B is an analysis band, f_i is a frequency of the carrier received, and C is a speed of light; and

updating the fine speed aid to account for the maneuver.

4. The method of claim 2, wherein:

the providing step comprises providing the receiver with acquisition aids through an external remote control.