Determining Ping Position Status

Echoview assigns a position status to each ping in an echogram based on the status of nearby GPS fixes. This ensures precise spatial positioning for echosounder data points (samples).

Algorithm for determining ping position status

Once GPS fix statuses are assigned, the algorithm evaluates the position of each ping using the following rules:

1. Unknown:
   1. If a ping occurs before the first GPS fix or after the last GPS fix, it is assigned a status of unknown.
2. Good or Good (Uncertain):
   1. If the ping occurs between valid GPS fixes, its status is determined by the next non-bad GPS fix in time.
   2. For example, if a ping occurs between a good fix and a bad fix, and the next non-bad (valid) fix is "good (uncertain)", the ping will inherit this status.

Example Clarification

Consider a cruise track with the following sequence of GPS fixes along its timeline:

1. Fix 1: Good
2. Fix 2: Bad
3. Fix 3: Good (Uncertain)

If a ping occurs between Fix 1 (Good) and Fix 2 (Bad), and Fix 3 is the next non-bad fix in time, the ping will be assigned the status of Fix 3, which is "Good (Uncertain)."

Notes on ping position status:

1. Good (Uncertain): Reflects partial compliance with gap criteria for the associated GPS fix.
2. Unknown: Assigned when there is insufficient GPS data to determine the ping's position.
3. Echoview uses Ping position status to display cruise track quality between GPS fixes. For details on GPS fix status, see Determining GPS fix status and About GPS fix status.

See also

About GPS fix status
About Ping Position Status
Position status area on Echograms
Processing and smoothing cruise tracks