Another system which operated along the South African and Namibian coast was a series of Radio Transponder Beacons. There were five on the Namibian coast and fifteen on the South African coast.

The beacons operated in the 10 GHz (10cm) and 3 GHz (10 cm) radar bands. The beacons would emit a characteristic signal when activated by the emissions of a ship’s radar. This would provide a range and bearing of the beacon on the radar Planned Position Indicator (PPI). What you would observe on the PPI is a line of dots extending from slightly beyond the radar echo (if any) of the beacon outwards towards the circumference of the PPI. The range would be taken to the beginning of the line but, since there is a delay in the response of the beacon, the range obtained would be approximately 75 to 100 metres greater than the actual range from the ship. The beacons have an average nominal range of 12 nautical miles. In order to identify the beacon the transmission received on the PPI would be in the form of a morse code letter, ie C (-.-.).