SARA-R4/N4 series - AT Commands Manual
UBX-17003787 - R09
22 GNSS
Page 224 of 307
22 GNSS
22.1 NMEA
u-blox cellular modules support reading NMEA strings from the GNSS receiver through AT commands.
Before being able to read a specific NMEA string, it is necessary to activate the storage of the last value of
that particular NMEA string. If storing a particular NMEA string was not activated, the response to the query
will be "0,NULL". The last value of a specific NMEA string is saved in RAM and is made available even after the
GNSS receiver switch off.
The NMEA standard differentiates between GPS, GLONASS and Multi-GNSS receivers using a different 'Talker
ID'. Depending upon device model and system configuration, the u-blox receiver could output messages using
any one of these Talker IDs.
By default, the receivers configured to support GPS, SBAS and QZSS use the 'GP' Talker ID, receivers configured
to support GLONASS use the 'GL' Talker ID, receivers configured to support BeiDou use the 'GB' Talker ID and
receivers configured for any combinations of multiple GNSS use the 'GN' Talker ID.
Even if the NMEA specification indicates that the GGA message is GPS specific, u-blox receivers support the
output of a GGA message for each of the Talker IDs.
As a factory-programmed setting, the cellular modules configure the GNSS receiver tUGPS AT
command to not provide the NMEA sentences.
When reading an NMEA message, if the response value is "1,Not available" then the storing of the NMEA
string is activated but this information has not been still sent to the user, if this persist check that the
relative NMEA message is enabled. To enable it use the +UGUBX command (for further information see
the UBX-CFG-MSG message in the u-blox GNSS Protocol Specification).
22.2 GNSS power manaUGPS
+UGPS
SARA-R410M-02B SARA-R410M-52B
Modules
SARA-N4
Syntax
PIN required
Settings saved Can be aborted
Response time Error reference
Attributes
full
No
No
No
22.2.1 Description
Switches on or off a u-blox GNSS receiver connected to the cellular module via a dedicated DDC (I
2
C) interface.
For more details about the connection between cellular module and u-blox GNSS receiver see the corresponding
module system integration manual.
Furthermore the command sets the aiding type to be used to enhance GNSS performance, e.g. decreasing
Time To First Fix (TTFF), thus allowing to calculate the position in a shorter time with higher accuracy. The
following aiding types are supported:
• Local aiding: the cellular module automatically uploads data such as ephemeris, almanac, last position,
time, etc. from the GNSS receiver into its local memory, and restores back the GNSS receiver at the next
power up of the GNSS module (if the data are still valid, otherwise it uses GSM information such as country
code for a rough position estimation)
• AssistNow Online: a connection profile (either PSD or CSD) must be defined and activated before selecting
the AssistNow Online; see the
+UGAOP
command descriptions. If CellLocate
®
is used, the first
HTTP profile will be properly configured
• AssistNow Offline: a connection profile (either PSD or CSD) must be defined and activated before selecting
the AssistNow Offline if the almanac file must be downloaded; see the
+UGAOF
and
command
descriptions.
• AssistNow Autonomous: based on a broadcast ephemeris downloaded from the satellite (or obtained
by AssistNow Online) the receiver can autonomously generate an accurate satellite orbit representation
(«AssistNow Autonomous data») that is usable for navigation much longer than the underlying broadcast