GAPS
-
User Guide
5.1.5
P
ING
S
TACKING
5.1.5.1
Description
Ping stacking increases the positioning rate independently of the slant range between USBL
and transponder. The USBL pings at a faster rate than usual and does not wait for the
detection of the transponder before pinging again.
Application
Ping stacking mode is typically needed for tracking a tow fish with large slant ranges:
transponder in responder mode, USBL in external synchronization, up to 10 km slant range.
Discovery
period
Ping stacking starts by a
discovery period
run at the
main recurrence
during two
consecutive recurrences. During the discovery mode, the system opens a
tracking window
to validate the presence of the signal coming from the transponder. The objective of the
tracking window is to filter the detections and avoid detecting on echoes coming from previous
recurrences. The
main recurrence
must allow the interrogation / answer / detection cycle.
The switch between discovery mode and ping stacking mode occurs when all the
transponders "in use" are detected two times consecutively and when the second slant range
is inside the tracking window that was open in the last recurrence.
Ping stacking
Once the tracking window defined, the system pings at the
wished ping stacking
recurrence
. In fact a slightly different recurrence is used in order to take into account the
estimation of the arrival times of the signals and of the USBL deaf periods. This recurrence is
called
effective ping stacking recurrence
. During ping stacking, an algorithm associates the
detection to the actual ping to which it comes from, it also converts relative time travel into
absolute time travel. Ping stacking aborts after ten recurrences without detection.
Figure 36 - Ping stacking mode
78
MU-GAPS-AN-005-H - November 2019
Summary of Contents for GAPS
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