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New GPS platform aims to save batteries

Cambridge Silicon Radio's new architecture, designed for mobile phones and other portable devices, can run in an 'aware' state that uses very little power
Written by David Meyer, Contributor

Cambridge Silicon Radio has unveiled a new GPS architecture that it says will let portable devices be constantly location-aware without draining their batteries.

The architecture, SiRFstarIV, was announced on Tuesday along with the first product to use it, CSR's GSD4t receiver for mobile phones and other portable devices.

Mobile phones increasingly have GPS as a feature, for navigation and other location-based services. However, current GPS architecture is a major contributor to battery drain — a situation CSR is hoping to fix.

The UK-based company, which has generally concentrated more on Bluetooth chip design, bought GPS architecture firm SiRF in February. As part of the deal, SiRF's founder, Kanwar Chadha, joined CSR as chief marketing officer.

Chadha told ZDNet UK on Tuesday that smartphones using current GPS platforms deliver a worse experience than dedicated personal navigation devices with the same technology. He attributed this lag in smartphones to three factors: battery consumption, the time it takes to get a fix on GPS satellites (as the GPS has to turn on and off to save power), and interference from other electronics inside the devices.

"GPS was not designed to be navigation-centric," Chadha said. "If you try to make location available all the time, you drain the battery very quickly. Other radios, the LCD display and the processor also interfere with the GPS signal."

This situation was a driver for the creation of SiRFstarIV, which is "not on all the time, and not off all the time", Chadha said.

The platform instead uses an 'aware' state, which "keeps the necessary information to do a very fast calculation from the satellite [and is] alive all the time but in a very low micropower mode", he explained. This approach means the device's GPS does not need to be continually turned on and off to conserve power — hence the speed with which it can get a satellite fix.

Chadha said the SiRFstarIV platform uses between 50-500 microamps. That power consumption level is substantially lower than that found in existing GPS platforms, which burn up power in the milliamps.

The company also looked at the other drags on GPS performance in smartphones for the new architecture.

"The second thing we did is [to] put in a new technology which scans for all the noisy signals that interfere with GPS, and eliminates interferers before they can hit the GPS signal," Chadha said.

The GSD4t receiver is now available in sample quantities to manufacturers of mobile phones and other portable devices, with full-scale production scheduled for October. According to Chadha, the first handsets using SiRFstarIV should become available to end-users in early 2010.

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