EXPLORER 1 - Recording of signals


Recorded by Roy Welch, W5SLL (now W0SL) at Dallas, TX on Februrary 11, 1958
at 0100Z using a home made VHF converter in front of a National NC-300
Amateur Band receiver.

Explorer 1 was America's first orbiting satellite, launched on an Army
Redstone rocket after several failures to launch the Vanguard Satellite
with the Navy's Vanguard rocket.  The telemetry heard in this recording
consists a combination of three or more relatively stable audio tones
and two alternating audio tones.  The alternating tones were indications
of cosmic particle collisions detected by an on board counter.  The tones
shift from one to the other when the detector has counted sixteen particles.
It shifts back again with the detection of the next sixteen particles and
so on.

The satellite had two RF frequencies, 108.0Mhz and 108.03Mhz.  This
recording is from the 108.0Mhz frequency.  The 108.03Mhz frequency had a
similar sounding telemetry, but without the alternating tones.

At W5SLL, there was no tracking antenna available.  The antenna was cut for
108Mhz for listening to the new USA satellites.  It was a six element
colinear array constructed on a 13X13 foot wooden frame and suspended above
a "chicken wire" reflector.  The whole array was placed on the roof of the
house looking up at about 75 degrees above the southern horizon.  Satellites
were captured as they flew through the main lobe of the antenna.


Enjoy a bit of history.

73, Roy -- W0SL