Unassisted indoor GPS receiver
First Claim
1. A method for operating a satellite-based navigational receiver under weak signal conditions, comprising:
- switching the receiver between a sleep state with a portion of the satellite-based navigation receiver powered down and a wake-up state where the receiver has access to first ephemeris data;
predicting first position information for an at least one satellite using polynomial extrapolation based upon at least the first ephemeris data;
acquiring at least one satellite signal during the wake-up state using at least the predicted first position information, if the receiver is unable to acquire the at least one satellite signal during the wake up state, switching the receiver to the sleep state and reattempting to reacquire the at least one satellite signal after a predetermined period using at least the predicted first position information; and
attempting to collect second ephemeris data from the at least one satellite signal acquired during the wake-up state.
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Accused Products
Abstract
The present invention provides GPS receivers capable of tracking very weak GPS signals particularly in an indoor environment without assistance from an external server or a network. In a preferred embodiment, a GPS receiver initially acquires and locks onto GPS satellite signals to compute receiver position outdoors. The GPS receiver then tracks at least one satellite signal indoors to maintain acquisition parameters for quick acquisition of GPS signals. To save power, the receiver automatically goes to the sleep state and periodically wakes up, i.e., powers up, to maintain the at least one satellite signal tracking. During the wakeup state, the receiver collects ephemeris data from the at least one satellite signal when the ephemeris data needs to be updated for quick acquisition of GPS signals.
43 Citations
48 Claims
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1. A method for operating a satellite-based navigational receiver under weak signal conditions, comprising:
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switching the receiver between a sleep state with a portion of the satellite-based navigation receiver powered down and a wake-up state where the receiver has access to first ephemeris data; predicting first position information for an at least one satellite using polynomial extrapolation based upon at least the first ephemeris data; acquiring at least one satellite signal during the wake-up state using at least the predicted first position information, if the receiver is unable to acquire the at least one satellite signal during the wake up state, switching the receiver to the sleep state and reattempting to reacquire the at least one satellite signal after a predetermined period using at least the predicted first position information; and attempting to collect second ephemeris data from the at least one satellite signal acquired during the wake-up state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A navigational receiver, comprising:
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a radio frequency front-end for receiving satellite signals; a baseband section for processing the received satellite signals into correlated values; and a processor adapted to; switch the receiver between a sleep state with a portion of the satellite-based navigation receiver powered down and a wakeup state, where the receiver has access to first ephemeris data; predict first position information for an at least one satellite using polynomial extrapolation based upon at least the first ephemeris data; acquire at least one satellite signal during the wake-up state using at least the predicted first position information, if the processor is unable to acquire the at least one satellite signal during the wake up state, switch the radio frequency front-end to the sleep state and reattempt to reacquire the at least one satellite signal after a predetermined period using at least the predicted first position information; attempt to collect second ephemeris data from the at least one satellite signal during the wake-up state. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48)
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Specification