A continuous wave, medium frequency (300 kHz region) long range directional radio beacon producing a number of radial equi-signal zones which shift in azimuth at a fixed rate and are separated by zones of dot and dash signals.
The bearing of a mobile station with respect to the beacon is determined by a count of the dot and dash signals within each respective zone.
The ambiguity can be resolved by the use of a D.F. receiver.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
diameter at the waterline (m)
change in the value of a term
Solar declination angle (in degrees)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM