Electronic Marking System

The Retriever System is the well proven radio-detection system for invisibly marking locations on the ground, such as archaeological sites and vegetation quadrats. A small transponder is buried at the location and is activated and detected by the “Retriever Unit”. The Transponders have indefinite life. The system is now widely used throughout the country for long-term monitoring. The Retriever Unit has a Pinpoint mode and we are offering to update existing units to add this feature. The system can also be used for monitoring path erosion or marking archaeological sites.


The transponders are low frequency radio receiver/transmitters. They are buried below the surface and are therefore safe from vandals and grazing animals. The transponders have the following features:

  • Unlimited life (no batteries)
  • Invisible from the surface
  • Small in size and therefore easy to bury
  • Waterproof, can be used underwater
  • Robust
  • Economical


The Retriever is a lightweight unit which consists of a control box and hand-held antenna. The unit is very easy to use and the search area can be rapidly scanned. The proximity of the marker is indicated by an increase in frequency of the audible output, and a maximum is obtained when the antenna is directly above it. The Retriever has the following features:

  • Responds only to the markers
  • Gives precise and rapid location
  • Very easy to use
  • All-weather operation
  • NEW pinpoint mode