NAUTA scientific

instruments for science


software for the position estimation of a towed sensor

This software allows a real-time estimation of the postition of a tow body, whether at surface or underwater.
This software was developed to add geotags (a numeric coordinates overlay) over the footage taken by a towed videocamera.
Its features allow to estimate the position of a towed sensor (or net) along a direction opposite to the course or the drifting.


How it works

The software receives current position data from a standard GPS string (RMC string). From these positions it averages a direction vector.
Knowing the lenght of the tow cable, and the sensor depth, the sensor position is estimated and output in both kiometric and geographic formats.
Suitable coefficients help keeping this estimation precise, considering, for example, the cable not as a straight line but as a parabole arch.


The software runs under MSwindows and uses two independent serial ports.
Input port receives the standard position data from the NMEA bus, while the output port gives the sensor position back in both geographic and kilometric format. Two strings are broadcast on the second serial port: $TLRMC (that sticks to the NMEA standard for the RMC specifications including the checksum), and $TLUTM (that contains the kilometric format and the checksum).


With a suitable hardware this software delivers a video image coming from a towed videocamera, with the position numeric overlay.
It will also return the position of any towed sensor, including hydrophones, airguns, sonars or even nets.
With minor modifications it could be used to estimate the position of objects on the ground during survey flights.

License & download

A limited test license is available for free, while the unlimited license is distributed upon payment.
To download the limited test version please send an email to, and you will receive a link for installer download.
For general infos about the program please write to