GPS Filter

This operator creates a position variable containing only those GPS fixes from the operand that match the user specified Fix Specification and Fix Retention settings on the GPS filter page of the Variable Properties dialog box.

Echoview accepts operands with the following data types:

  • Position

For more information on the use of this operator see Processing and smoothing cruise tracks.


The GPS Filter Variable Properties dialog box pages include (common) Variable Properties pages and these operator pages:

Operands page

GPS filter page



Fix Specification

Enter an expression, for a filter, containing zero or more groups of GPS-fix letters.

  1. A space is used to separate each letter group.
  2. The ? symbol represents any letter.
  3. The groups of letters can include: "undefined" and NMEA GPS-fix letter groups identified by Echoview in the Fix Availability list on the GPS filter page.
  4. Restore Default will create a virtual variable that contains GPS fixes matching the default filter expression. The default filter expression produces a pre-Echoview 4.20 GPS variable.

Fix Retention

This setting specifies what to do with GPS fixes in the operand that match the filter expression set in Fix Specification.

You can choose to Retain matching fixes or Discard matching fixes.

Fix Availability

Lists the available GPS-fix letter groups in the operand.

Fix Selection

Lists the GPS-fix letter groups selected for the virtual variable. This list updates when OK or Apply is used.

See also

About virtual variables
Operator licensing in Echoview