ZED-F9K - Integration manual
AssistNow Online optionally provides satellite ephemerides, health information and time aiding data
suitable for GNSS receiver systems with direct internet access.
3.7.1 Authorization
The AssistNow Online Service is only available to u-blox customers. To use the services, customers
will need to obtain an authorization token from u-blox. This token must be supplied as a parameter
whenever a request is made to either service. Contact your local technical support or go to
https://www.u-blox.com/en/solution/services/assistnow to get more information and to request an
authorization token.
3.7.2 Multiple servers
To protect customers against the impact of outages that might be caused by, for example,
maintenance activity, u-blox runs at least two instances of the AssistNow Online Service on
independent servers. u-blox recommends implementing a fallback mechanism of using another
server in case one fails. All servers provide the same information, which means that assistance data
can be requested from any of these servers.
3.7.3 Preserving information during power-off
The performance of u-blox receivers immediately after they are turned on is enhanced by providing
them with as much information as possible. The information can be fetched from the AssistNow
service, or it can be retained from the previous use of the receiver. The information from the previous
use improves the receiver's ability to calculate the current position even if the satellite signal level or
signal quality is poor. The retained information can also significantly improve time to first fix (TTFF).
There are several ways in which a u-blox receiver can retain useful data while it is powered down,
including:
•
Battery-backed RAM:
The receiver can be supplied with sufficient power to maintain a small
portion of internal storage, while it is otherwise turned off. This is the best mechanism,
provided that the small amount of electrical power required can be supplied continuously.
V_BCKP is the pin sustaining battery-backed RAM.
•
Save-on-shutdown:
The receiver can be instructed to dump its current state to the flash
memory as part of the shutdown procedure; this data is then automatically retrieved when the
receiver is restarted. For more information, see the description of the UBX-UPD-SOS messages
in the ZED-F9K Interface description [
3.7.4 AssistNow Online
AssistNow Online is u-blox's end-to-end Assisted GNSS (A-GNSS) solution for receivers that have
access to the internet. Data supplied by the AssistNow Online Service can be directly uploaded
to the receiver in order to substantially reduce time to first fix (TTFF), even under poor signal
conditions (typically around 2 seconds; see ZED-F9K Data sheet [
] "Aided start"). The system
works by collecting data such as ephemeris and almanac from the satellites through u-blox's "Global
Reference Network" of receivers and providing this data to customers in a convenient form that can
be forwarded directly to u-blox receivers.
The AssistNow Online Service uses an HTTP interface. Therefore, it works on all standard mobile
communication networks that support internet access, including GPRS, UMTS and Wireless LAN.
No special arrangements are needed with mobile network operators to enable AssistNow Online.
UBX-20046189 - R01
3 Receiver functionality
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C1-Public
Early production information
