Navigational signal tracking in low power mode
First Claim
1. A method of tracking navigational signals at a receiver, comprising:
- cycling between sleep and wakeup states;
monitoring a dynamic state of the receiver, including measuring an acceleration of the receiver during the wakeup state;
determining a duty cycle of the sleep and wakeup states based on the dynamic state of the receiver;
selecting a tracking mode from a plurality of tracking modes based on received signal strength during the wakeup state, wherein each tracking mode of the plurality of tracking modes respectively corresponds to a different signal power level; and
tracking a navigation signal by performing data aided long integration of the signal during the wakeup state, wherein tracking the navigation signal in certain of the selected tracking modes includes demodulating navigation data bits included in the navigation signal and coherently integrating samples of the signal using the demodulated navigation data bits.
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Abstract
The present invention provides systems and methods for navigational signal tracking in low power mode to conserve the power of handheld navigation receivers. In an embodiment, the receiver cycles between sleep and wakeup states. During the sleep state, most of the components of the receiver are powered off to conserve power, and during the wakeup state, the receiver tracks navigational signals. In an embodiment, the duty cycle of the sleep/wakeup states depends on the receiver dynamic state, e.g., whether the receiver is accelerating. In another embodiment, during the wakeup state, the receiver selects a tracking mode based on the signal strength. Under weak signal conditions, a tracking mode using a long integration to track the satellite signal is disclosed. In one embodiment, a tracking mode tracks the navigation signal by performing data aided integration using known or predicted data bits, such as the TLM and HOW words.
26 Citations
36 Claims
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1. A method of tracking navigational signals at a receiver, comprising:
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cycling between sleep and wakeup states; monitoring a dynamic state of the receiver, including measuring an acceleration of the receiver during the wakeup state; determining a duty cycle of the sleep and wakeup states based on the dynamic state of the receiver; selecting a tracking mode from a plurality of tracking modes based on received signal strength during the wakeup state, wherein each tracking mode of the plurality of tracking modes respectively corresponds to a different signal power level; and tracking a navigation signal by performing data aided long integration of the signal during the wakeup state, wherein tracking the navigation signal in certain of the selected tracking modes includes demodulating navigation data bits included in the navigation signal and coherently integrating samples of the signal using the demodulated navigation data bits. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 35)
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17. A navigational receiver, comprising:
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a radio frequency (RF) module for receiving a signal from a navigation satellite; a baseband section coupled to the RF module for correlating the received signal with a locally generated replica; and a processor, wherein the processor is configured to cycle the receiver between sleep and wakeup states, monitor a dynamic state of the receiver, including monitoring an acceleration of the receiver during the wakeup state, determine duty cycle of the sleep and wakeup state based on the dynamic state of the receiver, select a tracking mode from among a plurality of tracking modes based on the strength of the received signal during the wakeup state, wherein each tracking mode of the plurality of tracking modes respectively corresponds to a different signal power level, and track the received signal by performing data aided long integration on the correlated received signal during the wakeup state, wherein performing data aided long integration in certain of the selected tracking modes includes demodulating the correlated received signal and coherently integrating samples of the signal using the demodulated correlated received signal. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 36)
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Specification