A military, centimetre level, remote platform, real-time tracking solution...

Back in 2000 I was designing, building and commissioning a secure GPS tracking system - Nav-Trax - for, rather ironically,  the Royal Navy.


The system comprised a static, Base station that calculated real-time GPS errors and was in constant two-way communication with its remote units on board various naval vessels (to whom it sent differential correction data) and with its control centre (that received the corrected, now highly accurate, vessel position data).

Each base station comprised :

  • a Leica System 500 GPS operating in differential Tx mode

  • multiple Satel 3as UHF modems transmitting differential and configuration data TO the mobile units and receiving corrected position and status/health data FROM them

  • a suitable NiMh battery back-up (10 hours autonomous operation)

  • a Win XP workstation (DELL) running the Nav-Trax (base) GUI.

Each mobile station comprised :

  • a Leica System 500 GPS operating in differential Rx mode

  • multiple Satel 3as UHF modems receiving differential and configuration data FROM the base station and transmitting corrected position and status/health data FROM the platform

  • a suitable NiMh battery back-up (10 hours autonomous operation)

  • a Win XP laptop (IBM Thinkpad) onboard each mobile platform running the Nav-Trax (mobile) GUI

The first solution was delivered in 2002 and, after various trials, it was accepted into service. An order for the second system was quick to follow... but with some modifications and improvements. This second system was installed, trialled, accepted into service and handed over in 2003.

Nav-Trax converted (or, more technically correct, 'transformed') standard GPS WGS84 (Lat/Lon) datum positional data into OSGB36 grid ref (Northing/Easting) data and displayed all information on proprietary (EireTech) vector maps within the Nav-Trax GUI to a repeatable accuracy of better than 1metre..

During the second system installation the Nav-Trax (V1) system was upgraded for the impending future roll-out around the UK.

Unfortunately (for me) the UK government decided it better to privatise DERA which became Qinetiq and Dstl with MoD maintaining a holding. The really bad news for me though was that the Carlyle group (American) became financially involved and decided they had, or could modify, or build, a better / cheaper solution in-house, with existing contractors. In 2005 QinetiQ demanded the project IPR, source-code and design specs of the Nav-Trax project. This was denied. It was agreed, however, that annual licence fees would continue to be paid for up to two years whereupon the in-house replacement solution would come on-line and that further Nav-Trax development and roll-out would be cancelled.


In theory, that should have been the end of the matter, however, some 4 years later, late in 2009, I was approached due to certain technical challenges having been encountered with the replacement solution; the end result was that a life-time licence was procured but not the IPR, the tech. specs. or the source-code. The Nav-Trax solution had worked flawlessly, without failure for almost 10 years.

The major benefits of the V2 system over the original V1 system are best seen by comparing images. The V1 (red) case (above) with Leica System500 GPS and 4x Satel Modems (in simplex mode) had a footprint of some 55cm x 40cm x 18cm and weighed in at @ 5Kg).

It was replaced by a single, sealed, IP67 tracker with integrated battery (11hours autonomy @ full-power) and GPS antenna, with the UHF encrypted / secure comms antenna on the outside as shown below.

This 'upgrade' was made possible by switching out the Leica System500 unit for a CSI Sx-2 GPS, a Microhard MHx2400 modem and latest tech Li-ion batteries - all on an in-house developed SMT motherboard powered by an Atmel 2561 LoVoltage micro-processor. The V2 tracker was named ERDALL : Eiretech's Remote Data Acquisition, Logging & Look-up module.

An ERDALL tracker weighs in at 395gm.

Each tracker has a footprint of 16cm x 8cm. Each is 5cm high.

This 'V2' (ERDALL) tracker became the basis for the Race-Trax yacht tracking / OCS (premature start detection) system.


© 2017 Ian Watts