NEO-M9N-Integration manual
Externally controlled power management operations override the internally controlled power
management operations.
3.11.1 Continuous mode
u-blox receivers make use of dedicated signal processing engines optimized for signal acquisition
and tracking. The acquisition engine delivers rapid signal searches during cold starts or when
insufficient signals are available for navigation. The tracking engine delivers signal measurements
for navigation and acquires new satellites as they become available during navigation. The resources
of both engines are deployed adaptively to minimize overall power consumption.
Note that even if the acquisition engine is powered off, satellites continue to be acquired.
3.11.2 Power save mode
Power save mode (PSM) allows a reduction in system power consumption by selectively switching
parts of the receiver on and off. It is selected with CFG-PM-OPERATEMODE and configured with
items in the CFG-PM group.
PSM is designed to only support the operation of GPS, GLONASS, BeiDou, Galileo and QZSS.
Enabling SBAS is possible only if at least one of the other systems is enabled. The PSM state
machine behavior will not be altered by enabling SBAS and it will not take them into account in
operation. Therefore, it is recommended to disable SBAS when operating in power save mode. They
can be disabled in the CFG-SIGNAL group.
The logic within power save mode is designed so that time pulse operation is not
compromised. This means that entering all power saving states is delayed until the
conditions necessary to produce a time pulse have been met. Therefore, in order to obtain
good power save mode operation, it is essential that any time pulse is correctly configured
with an appropriate time base, or that time pulses are turned off if not needed (by disabling
the TPX_ENA item in the CFG-TP group).
3.11.2.1 Operation
Power save mode has two modes of operation:
•
Power save mode cyclic tracking (PSMCT) operation is used when position fixes are required in
short periods of 0.5 to 10 s.
•
Power save mode on/off (PSMOO) operation is used for periods longer than 10 s, and can be in
the order of minutes, hours or days.
The mode of operation can be configured, and depending on the setting, the receiver demonstrates
different behavior: In on/off operation the receiver switches between phases of start-up/navigation
and phases with low or almost no system activity (backup/sleep). In cyclic tracking the receiver does
not shut down completely between fixes, but uses low-power tracking instead.
Currently PSMCT is restricted to an update period between 0.5 and 10 seconds and PSMOO is
restricted to an update period over 10 seconds. However, this may change in future firmware
releases.
PSM is based on a state machine with five different states: (Inactive) awaiting next fix and (Inactive)
awaiting next search states, Acquisition state, Tracking state and power optimized tracking (POT)
state.
•
Inactive states: Most parts of the receiver are switched off.
•
Acquisition state: The receiver actively searches for and acquires signals. Maximum power
consumption.
UBX-19014286 - R07
3 Receiver functionality Page 43 of 95
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