One of the systems which were used along the Namibian and South African coasts was a series of marine radio beacons situated along the coastline and which provided vessels navigating in our waters with a means of obtaining radio bearings. Six of these stations were situated in Namibia and twenty four in South Africa.
The system operated in the MF (medium frequency) band (280 – 315 KHz) and had a range of between 25 and 100 nautical miles. Since the bearings obtained were great circle bearings, they had to be corrected for convergency before they could be plotted on a Mercator chart. The systems two main shortcomings were:
- The signal was prone to distortion when it passed over the coastline. Radio waves travel more slowly over land than over the sea.
- At night the sky waves interfere with the ground waves, causing fading when the two signals are received simultaneously. The sky waves also cause bearing errors.