ALL Marker
Beacons transmit on a frequency of 75 MHz.
The Carrier Wave is Amplitude Modulated with an audible identifying signal
which varies:
OUTER - 400 Hz O _ _ 2 x Dashes per second
MIDDLE - 1300 Hz C _ . _ . Alternating series of Dashes and Dots keyed at a
rate of 2 x Dashes and 6 x Dots per second
INNER - 3000 Hz I . . 6 x Dots per second