SARA-G450 - System integration manual
UBX-18046432 - R08
System description
Page 43 of 143
C1-Public
SARA-G450 modules feature embedded GNSS aiding, which is a set of specific features developed by
u-blox to enhance GNSS performance and decrease the Time-To-First-Fix (TTFF), thus making it
possible to calculate the position in a shorter time with higher accuracy.
SARA-G450 modules support these GNSS aiding types:
Local aiding
AssistNow Online
AssistNow Offline
AssistNow Autonomous
The embedded GNSS aiding features can be used only if the DDC (I2C) interface of the cellular module
is connected to the u-blox GNSS receiver.
SARA-G450 modules provide an additional custom function over GPIOs pins to improve the
integration with u-blox positioning chips and modules:
GNSS receiver power-on/off: “GNSS supply enable” function provided by GPIO1, GPIO2 (default),
GPIO3 or GPIO4 improves the positioning receiver power consumption. When the GNSS
functionality is not required, the positioning receiver can be completely switched off by the cellular
module that is controlled by AT commands.
☞
For more details regarding the handling of the DDC (I2C) interface, the GNSS aiding features and
the GNSS related function over GPIOs, see section
, the u-blox AT commands manual
(+UGPS, +UGPRF, +UGPIOC AT commands) and the GNSS implementation application note
As additional improvement for the GNSS receiver performance, the V_BCKP supply output of
SARA-G450 modules can be connected to the V_BCKP supply input pin of u-blox positioning chips
and modules to provide the supply for the GNSS real time clock and backup RAM when the VCC supply
of the cellular module is within its operating range and the VCC supply of the GNSS receiver is
disabled.
This enables the u-blox positioning receiver to recover from a power breakdown with either a hot start
or a warm start (depending on the duration of the GNSS receiver VCC outage) and to maintain the
configuration settings saved in the backup RAM.