Datatrak reverse-engineering

Datatrak was a land-based radio navigation system which used the phase difference between several long-wave radio signals to pinpoint the location of a receiver.

I acquired a few of Datatrak location-only “Trakbak” receivers from eBay, and have been slowly reverse-engineering them.

I'm currently trying to build a desktop Datatrak LF signal simulator, and reverse-engineer the receiver to the point where they could be used to receive signals in the 136kHz (2200 metre) UK LF amateur radio band.

You may also find the presentation I gave at CampGND 2020 interesting: (slides) (recording).

I presented an updated version of my talk at EMF Camp 2022, but mostly covered the hardware reverse-engineering side of things. Sadly EMF's camera broke (or something) and my talk was one of several which weren't recorded.

• Introduction to Datatrak and hyperbolic navigation
• The Datatrak signal – technical details
• The Datatrak transmitter network (LF and UHF)
• Datatrak receivers (Locators)
• Locator Mk.II pinouts
• Locator Mk.II hardware
• Locator Mk.II firmware notes
• Locator Mk.II EPROM cartridge emulator – a replacement EPROM cartridge which allows fast-turnaround firmware patching and debugging.
• Network Simulator – generates signals which simulate a network of Datatrak transmitters.
• Software tools – for analysing the network based on data obtained from Locators
• Signal recordings
• References – other sources of information

Datatrak was featured on TV several times during its development.

Thanks to Alasdair for finding these and sending the links. Both videos are on Youtube.

• BBC Tomorrow's World, 28 May 1987 – featuring either a prototype or Mk.1 Locator being demonstrated in the London area, using the initial three transmitters.
  • Shows early demonstration software and either a prototype or Mk.1 Locator receiver.
• Top Gear, 1990 season, 5th episode – Jeremy Clarkson tries to steal a Vauxhall Cavalier (!) which was fitted with Datatrak.
  • This episode also features the Autotag immobiliser, which allows the car to be remotely disabled using a radio paging signal.
  • Shows what is believed to be the later 'base station' software used by the Datatrak call centre at the time
• The Cook Report, "Car Sharks", 1993 season (season 6, episode 4)
  • Shows the Datatrak software running on a PC at Datatrak HQ, as part of a segment on car theft and “cut-and-shut” crime.