BACKGROUND EPHEMERIS DOWNLOAD IN NAVIGATIONAL RECEIVERS
First Claim
1. A method of maintaining current ephemeris in a navigation receiver, comprising:
- alternating between a sleep mode and a wake up mode; and
downloading current ephemeris if a last downloaded ephemeris is no longer current.
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Abstract
The present invention provides methods and systems for keeping the ephemeris in a navigational receiver current to achieve fast TTFF without the need for connecting to an aiding network or remote server. In an embodiment, the receiver keeps the ephemeris current by downloading the ephemeris in the background. In the preferred embodiment, the receiver uses a background sleep/wake up process to download current ephemeris with minimal power drain. In this embodiment, the receiver alternates between a sleep mode and a wake up mode. During the wake up mode, the receiver attempts to download current ephemeris. The receiver then goes back to the sleep mode until the next wake up to conserve power. The receiver may wake up from the sleep mode to download the ephemeris when the stored ephemeris is no longer current or the ephemeris broadcasted from a satellite has been updated or based on receiver usage patterns.
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Citations
41 Claims
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1. A method of maintaining current ephemeris in a navigation receiver, comprising:
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alternating between a sleep mode and a wake up mode; and downloading current ephemeris if a last downloaded ephemeris is no longer current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A navigation signal receiver, comprising:
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a radio frequency (RF) front-end for receiving satellite signals; a baseband section for processing received signals into correlation values; a processor coupled to the baseband section, wherein the processor downloads ephemeris if a last ephemeris is no longer current; and a sleep/wake up module coupled to a power system of the receiver, wherein the sleep/wake up module alternately switches the receiver between a sleep mode and a wake up mode. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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41. The receiver of 21, wherein the processor stores the downloaded ephemeris to predict the satellite orbit and using the predicted satellite orbit to compute satellite position when current ephemeris can not be downloaded.
Specification