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The challenge of stand-alone GPS
GPS users expect instant position information. With standard GPS this is sometimes not possible because at least four satellites must be identified, and their complete orbital position data, called Ephemeris, received. Under adverse signal conditions, data downloads from the satellites to the receiver can be unacceptably long, hours or even fail altogether. Assisted GPS (A-GPS) accelerates calculation of position by delivering satellite data such as Ephemeris, Almanac, accurate time and satellite status to the GPS receiver via wireless networks or the Internet. This aiding data enables a GPS receiver to compute a position within seconds, even under poor signal conditions.
AssistNow A-GPS services
AssistNow Online and AssistNow Offline are u-blox’ end-to-end A‑GPS services for OEM customers and their end users. These services boost GPS acquisition performance for devices with or without network connectivity. AssistNow Online and AssistNow Offline can either be used alone or in combination. AssistNow A‑GPS services require no additional hardware and generate virtually no CPU load. The system is very easy to implement and can be installed and operational within a day.
u-blox wireless modules feature an embedded AssistNow client making integration simple.
With AssistNow Online, an internet-connected GPS device downloads assistance data from u-blox’ AssistNow Online Service at system start-up. The service works on all standard mobile communication networks that support Internet access, including GPRS, UMTS and Wireless LAN. No special arrangements with mobile network operators are needed to enable AssistNow Online, making this solution network operator independent and globally available. u-blox only sends ephemeris data for those satellites currently visible to the mobile device requesting the data, thus minimizing the amount of data transferred.
With AssistNow Offline, users download u-blox’ Differential Almanac Correction Data from the Internet at their convenience. The correction data is then transferred to the mobile terminal via TCP/IP, serial port, memory card, etc, and can either be stored in the GPS receiver’s memory or in the memory of the application processor. Therefore, the service requires no connectivity at system start-up and enables a position fix within seconds, even when no network is available.
AssistNow Autonomous is an embedded feature available free-of-charge that accelerates GPS positioning by capitalizing on the periodic nature of GPS satellite orbits. GPS orbit predictions are directly calculated by the GPS receiver and no external aiding data or connectivity is required. AssistNow Autonomous can be used alone, or together with AssistNow Online or AssistNow Offline for increased positioning speed and accuracy.
Click here to download the AssistNow product summary.
Benefits of AssistNow
AssistNow data is collected by u-blox’ global array of satellite receivers, and maintained in real-time on u-blox AssistNow servers accessible via the Internet. For best effort applications, u-blox provides AssistNow free-of-charge to its customers. For applications requiring a guaranteed minimum Quality of Service (QoS), u-blox provides AssistNow Premium which provides guaranteed availability based on a service level agreement and 24/7 support.
u-blox products compatible with AssistNow: