NEO-M9N - Integration manual
If the EXTINT pin is configured for on/off switching of the receiver, the internal pull-up
becomes disabled. Thus make sure the EXTINT input is always driven within the defined
voltage level by the host.
3.9 Multiple GNSS assistance (MGA)
The u-blox AssistNow services provide a proprietary implementation of an A-GNSS protocol
compatible with u-blox GNSS receivers.
The MGA services consist of AssistNow Online and Offline variants delivered by HTTP or HTTPS
protocol. AssistNow Online optionally provides immediate satellite ephemerides, health information
and time aiding data suitable for GNSS receiver systems with direct internet access.
When a client device makes an AssistNow request, the service responds with the requested data
using standard UBX protocol MGA messages. These messages are ready for direct transmission
from the client to the receiver port without requiring any modification.
The AssistNow Offline service benefits u-blox GNSS receivers that only have occasional internet
access. Users request data from the service by specifying the time period for which they want
coverage (1 to 5 weeks).
The data downloaded from the service is organized by date and encoded into a sequence of UBX
MGA messages.
In addition there is an MGA service called AssistNow Autonomous which does not need an internet
connection and runs entirely on the receiver.
below contains an overview of the different MGA services u-blox provides.
Requirements
AssistNow Online
AssistNow Offline
AssistNow Autonomous
Requires external flash memory
No
Optional
Optional
Requires internet connection
Permanently
Sporadically
No
Amount of internet data
Medium
High
None
Ephemeris in data
Yes
No
No
Almanac in data
Yes
Yes
Yes
Table 17: AssistNow service overview
3.9.1 Authorization
To use the AssistNow services, customers will need to obtain an authorization token from u-
blox. Contact your local technical support or go to https://www.u-blox.com/en/solution/services/
assistnow to get more information and to request access to the service.
3.9.2 Preserving MGA and operational data during power-off
The time-to-fix after a receiver power interruption is dependent on the amount of operational data
available at start-up. Satellite broadcast information plus an estimate of accurate time can be
fetched form the AssistNow service. In addition, the following techniques can restore previously
stored data prior to power down.
•
Battery-backed RAM:
The receiver operational state stored in this RAM can be maintained
during power outages by connecting the V_BCKP pin to an independant supply, e.g a battery.
This is a recommended method as it will maintain all MGA related information plus any user
configuration, calibration data and an estimate of time via the Real Time Clock. See section
UBX-19014286 - R07
3 Receiver functionality
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