Gps Module - Globalstar ST150 User Manual

9150-0125-01 R-4
9.1.14.5 Previous Track Point
Previous Track Point is a feature that helps compensate for any missed tracks by sending the delta latitude/longitude of
the last two positions at preset intervals. This makes it possible to re-construct a track up to two reporting intervals
beyond the initial reported location.
9.1.14.6 OTA Messages
OTA messages can include legacy standard and speed/heading messages, or Modular GPS Position messages.
Up to 64 bytes of user-defined payload can accompany OTA messages when utilizing the Mod Msg GPS Position Track
OTA profile (See Messages section).
9.1.14.7 Track Events
Track events can be sent via URCs to indicate asynchronous events that are occurring, and can be very useful for
debugging.
9.1.14.8 Non Maskable Track Mode
Non Maskable Track Mode is similar to regular Track Mode, except it is intended to be used like an SOS track mode,
where a priority 4 OTA message will pre-empt any and all messages in the transmit queue (See Transmit Queue section).
Non Maskable Track Mode contains its own modular message profile, or can be used with legacy standard and
speed/heading messages (see Messages section).

9.1.15 GPS Module

The GPS module can use the internal GPS chipset or leverage an external GPS via the set GPS position AT commands. The
GPS generates events that are used by the application's track mode.
9.1.15.1 Stale Time
GPS stale time is the amount of elapsed time allowed to occur while utilizing the current GPS fix in OTA messages that
send GPS positions.
If the stale time has elapsed, a new fix will be attempted. Requesting new GPS fixes consumes considerable power, so the
stale time can provide a balance for optimizing this tradeoff.
9.1.15.2 Fix Timeout
The GPS fix timeout refers to the maximum amount of time the GPS module will wait to obtain a position before giving up
and putting the GPS back into a low-power state.
9.1.15.3 Fix Settle Time
The GPS fix settle time refers to the maximum amount of time the GP9S module will allow to try to meet the minimum
accuracy requirements before giving up. The fix settle time begins once a fix is obtained or the fix timeout occurs.
9.1.15.4 GPS Accuracy
The GPS accuracy refers to the minimum estimated horizontal accuracy that should be met in order to declare the current
fix position. The GPS fix settle time will wait for this condition to be met or timeout.
9.1.15.5 Geofence Position
The Geofence position is a configuration setting that can store the root of the current geofence. GPS events can notify
the application when the device has transitioned in or out of the geofence, when a gps fix occurs.
The geofence can be set to a circle or square with configurable radius/half-width.
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