Technology
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02 Jun 2025
Boost positioning performance across the board with faster GNSS satellite data downloads.
Signal acquisition is one of the main bottlenecks of satellite-based positioning technologies. It is a power-hungry process that involves detecting signals from orbiting GNSS satellites, downloading the almanac of their constellation, and each individual satellite’s ephemeris data, which are transmitted via the GNSS signal.
A cold start (in which the GNSS receiver does not have valid ephemeris data stored in memory) typically takes around 30 seconds in perfect conditions. In more challenging conditions, it can take considerably longer or fail altogether.
Assisted GNSS (A-GNSS) speeds up the signal acquisition process and shortens the time needed to achieve a first position fix. It does so by retrieving satellite data, accurate time, and satellite status using a faster data connection – typically wireless networks or the internet. With A-GNSS, GNSS receivers can determine their position in seconds, even under poor signal conditions.
A-GNSS improves the performance of GNSS receivers beyond shorting the time required to determine their position when switched on, their time to first fix (TTFF). Eliminating lengthy or repeated data download attempts reduces the duration of the signal acquisition phase, increasing the battery life of GNSS devices.
A-GNSS increases satellite availability, particularly in challenging scenarios such as urban canyons and when exiting buildings or tunnels. By providing the ephemerides and signals for all satellites, even those beyond line of sight or when signal levels are low (below -148 dBm), GNSS receivers can immediately track new satellites that enter their field of view. By tracking more satellites, this can substantially improve the accuracy of the position output.
u-blox offers two types of A-GNSS services:
Both service variants are compatible with u-blox Gen9 and Gen10 standard precision GNSS hardware.
AssistNow Live Orbits is the only real-time, globally available GNSS assistance service that is backed by a full warranty and support. It is network operator independent and works on all standard mobile communication networks that support internet access, including 2G, 3G, 4G, and wireless LAN.
AssistNow is available in all Gen9 and Gen10 u-blox positioning solutions and can be easily integrated into third-party GNSS receivers. It requires no additional hardware, generates negligible CPU load, and can be installed and operational within a day. It is the only A-GNSS service that extends to modems that are not SUPL (secure user plane location) compliant.
AssistNow is delivered through the Thingstream IoT service delivery platform, a cloud-based administration interface for enterprise IoT services. Pressure tested and proven to support the delivery of billions of messages, the platform provides a self-service user interface for users to manage IoT device fleets, optimize service plans, manage billing, monitor events, and control functionality.
Automotive. With AssistNow Live Orbits, automotive solutions such as in-vehicle navigation systems precisely determine their location within seconds when they are switched on and immediately reestablish an accurate position fix when they regain GNSS coverage, for example, upon exiting a parking garage.
Logistic Trackers. AssistNow extends the battery life of power constrained industrial tracking solutions such as logistics trackers that spend most of their time in power save mode or asleep. With access to real-time satellite data, the logistics trackers shorten the signal acquisition phase and minimize wake time.
Wearables. By storing ephemeris predictions transferred from a paired smartphone in their device memory with AssistNow Predictive Orbits, smart watches, medical wearables, pet and people trackers, and other connected consumer wearables and ehealth solutions considerably reduce the time they need to acquire a first position fix, prolonging battery life and improving end-user experience.
