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AssistNow

Free A-GPS Services



Fast Time To First Fix

Assisted GPS helps you find your position quickly

  No more waiting for GPS acquisition!

AssistNow is a free of charge service that gives you instant positioning upon request.

Under stand-alone GPS operation, a GPS receiver needs at least 30 seconds to receive the satellite position data ('Ephemeris') and other satellite information it requires in order to compute a position. In weak signal areas such as urban canyons and building interiors, where the receiver has limited or no direct access to the sky, determining a positioning can take much longer, or may be altogether impossible!

For users who cannot afford to wait, or simply wish to benefit from instant positioning regardless of GPS signal conditions, Assisted GPS (A-GPS) is the solution. The service works by instantly providing the GPS receiver with the data it needs to compute a position, thus shortening Time To First Fix (TTFF) down to as little as 1 second!

AssistNow Online

AssistNow Online is u-blox' A-GPS data provisioning service for conventional MS-based applications. Using standard user-plane communication links and protocols like GPRS, AssistNow Online works on all mobile networks. At start-up, the GPS receiver requests Ephemeris and Almanac satellite position data, as well as accurate time and other satellite information over a mobile network. This data, transfered from an assistance server at system start-up, boosts the receiver's TTFF, enabling it to compute a position within seconds. The assistance data file is 3 KB or smaller and is transmitted over wireless networks to mobile end-products like mobile phones, PDAs and any other handheld Personal Navigation Devices (PND) with mobile connectivity.
 

AssistNow Offline

AssistNow Offline is u-blox' A-GPS data provisioning service that does not require an application to have mobile connectivity at start-up. Under AssistNow Offline, u-blox' assistance server provides the GPS receiver with AlmanacPlus differential almanac correction data that is valid for up to 14 days. The data can be updated via a simple Internet download at the user's convenience any time within the time period that the data is valid for. This enables the receiver to benefit from fast TTFF and accurate navigation for extended time periods, anywhere in the world!


  AssistNow Online AssistNow Offline
Data download frequency At every startup Once every 14 days
Data retrieval at startup Data downloaded from server Pre-downloaded data retrieved from local memory
Downloaded Aiding data types Ephemeris
Almanac
Time
Satellite health / status
AlmanacPlus differential almanac correction data
Data validity period 2-4 hours 14 days
Size of downloaded data 1 - 3 KB 10 KB (1 day) ... 90 KB (14 days)
Acquisition (TTFF) performance As low as 1 second As low as 5 seconds



 
 
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last modified: 20.12.2007

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