Clocks were used to time radio beacon
broadcasts at Point Sur. As the minute
hand passed through each red area on
the face of the clock, the radio beacon
would transmit a Morse code signal for
one minute. The letter "S" (dot-dot-dot)
was the unique radio signal for Point Sur.
Navigators on ships and aircraft used
this signal to help determine their loca-
tion. Two clocks were used for safety, in
case one failed. Radio beacons were the
first form of electronic navigation devel-
oped, and they were put to use on a
large scale in the 1920s. Point Sur's
radio beacon was deactivated in 1994,
made obsolete by new satellite naviga-
tion systems.