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SiRFstarIV GPS Chip Sips Power, Improves Sensitivity, Accuracy

A new GPS chip for smartphones and other battery-powered portables


SiRFstarIV GPS chip

SiRFstarIV GPS chip

SiRF Technologies

Frequent use of a smartphone's GPS feature tends to burn through battery power quickly, and users have simply learned to live with it, either by charging once or even twice daily, or using pricey, supplemental battery packs. Top GPS chip maker SiRF Technologies recently announced SiRFstarIV, a new chip to begin appearing on devices next year that will use only [em]five percent[/em] as much power as most chips available today. SiRFstarIV will dramatically reduce power needs with more efficient ways of acquiring and calculating satellite almanac data, and Energy Manager software to throttle the chip back to the minimum power required in various situations. SiRF also promises increased GPS signal sensitivity and accuracy, as well as improved software for creating A-GPS. I'll be checking out these claims on new products as they are introduced.

More details from SiRF:

"Continuous location awareness unlocks a world of possibilities for portable consumer electronics products. The current generation of GPS-enabled products may not always be location aware because their GPS receivers are often turned off to conserve power, resulting in long start-up times.

A new level of continuous location awareness is needed to enable instant geo-tagging, LBS (Location Based Services), and location based games. But to achieve continuous location awareness in mass market devices, a location engine must deal with several design constraints:

-Mixed indoor and outdoor use
-Location with or without network aiding
-Limited power budget
-Internal noise sources
-Limited board real estate
-Fast, easy design cycle

Mixed Indoor and Outdoor Use
The old operating model would switch the GPS receiver on only when necessary to get a position fix, but this compromised performance to save power, and getting a position fix indoors was often not possible.

The SiRFstarIV architecture is optimized for how people really use location-aware products: often indoors with periods of unobstructed sky view when moving from place to place. This new architecture can detect changes in context, temperature, and satellite signals to achieve a state of near continuous availability by maintaining and opportunistically updating its internal fine time, frequency, and ephemeris data while consuming mere microwatts of battery power.

Lack of Network Aiding
Most portable consumer electronics products don't have continuous wireless connectivity, and are typically constrained by a small battery, limited sky view, and no assistance data. Aside from handsets and smartphones in certain operator networks, even most handsets don't have network aiding available everywhere.

The new SiRFaware self-assisted GPS mode opportunistically captures satellite fine time, frequency, and ephemeris whenever visibility improves.

Limited Power Budget
The typical design choice for powering a GPS receiver is to either turn it off until a location fix is needed—to save power, compromising location performance, or to leave the receiver on for an extended period of time, draining battery power. SiRFstarIV architecture eliminates this trade-off via SiRFaware advanced technology features: Opportunistic ephemeris decode and advanced power management, allowing the GPS receiver to stay in a hot-start condition nearly continuously while consuming very little power Local ephemeris prediction, capturing ephemerides, and predicting them for up to three days in advance, boosting sensitivity and performance Dynamic contextual awareness, monitoring temperature change and available sensors to detect movement and predict sky view availability to conserve power and boost performance."

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