About Echocalc GPS

Overview of Echocalc GPS

Echocalc GPS is a stand-alone utility designed to generate GPS data in Echoview’s text encoded GPS file format. GPS data can be produced based on a number of parameters and initial conditions. The resulting .gps.csv file can be added to an Echoview as a data file; a position variable will be derived from this data file.

Echocalc GPS can be installed by running the Echoview installer, choosing the "Custom" installation option, and selecting Echocalc GPS from the list of utilities. The Echoview installer is available for download from the Echoview website, or on an Echoview USB drive.

Using Echocalc GPS

Creating GPS Data:

Open Echocalc GPS from the Windows Start menu.
In the CSV file name box, enter a file name for the GPS data file.
Specify the parameters, initial conditions and end conditions (see below).
Click Make.
Note: A progress bar will be displayed while the program is working and will disappear when the file creation is complete.

Initial and End Conditions

Echocalc GPS creates GPS data based on several initial and end conditions.

Setting	Description
Start date	Date the first GPS fix
Start time	Time the first GPS fix
End date	Date the last GPS fix
End time	Time the first GPS fix
Start longitude	Longitude of the first GPS fix
Start latitude	Latitude of the first GPS fix
Start direction	Direction taken by the vessel after the first fix (relative to North)

Parameters

A set of parameters - in combination with the initial and end conditions – determines the form taken by the created GPS data.

Setting	Description
Vessel speed	Speed of the vessel between the first and last GPS fixes. Note: The vessel speed is assumed to be constant - Echocalc GPS cannot reproduce the effects of varying vessel speed.
Time gap	Number of seconds between each GPS fix. Note: This affects both the total number of GPS fixes generated and the spatial resolution of the resulting GPS data.
Mode	Defines the modes of GPS creation (described below).
Transect length	Length of each transect segment in the initial direction of vessel travel. Note: Available in Transects mode only.
Transect spacing	Length of each transect segment in the direction orthogonal to the initial direction of travel. Note: Available in Transects mode only.

GPS creation modes

The three GPS creation modes are:

Mode	Description
Straight Line	Generates GPS fixes with positions that define a straight line between the positions of the first and last GPS fixes.
Random wander	Generates GPS fixes initially (for the GPS fix that follows the first) in the direction specified and after that in a direction chosen randomly within +/- five degrees relative to the previous fix.
Transects	Generates GPS fixes with positions that define a transect pattern based on the parameters Transect length and Transect spacing. The pattern is generated by creating fixes that define a straight line of the length defined by Transect length in the direction specified by Start direction. The direction then changes ninety degrees to starboard, and fixes are created that define a line of the length specified by Transect spacing. The direction then changes ninety degrees to port and fixes are created that define a line of the length specified by Transect length and so on until the GPS fix time reaches or exceeds that of the final GPS fix.

Example

A cruise track created by Echocalc GPS and the initial conditions and parameters that were used to create it are shown below.