Image may be NSFW.
Clik here to view.
© Public Domain
popular cellular, WiFi and emergency services. Perhaps lesser known is
the widespread use across so called amateur radio. The use for these,
so called amateurs, is divided across many, typically narrow (100s of KHz),
bands. With popular ones being around 160, 80, 40 and 20 meters in
wavelength.
One of the uses of these amateur bands is for competitions in which as
many possible contacts between stations all across the world have to be
established. This is possible due to the influence of the ionosphere
which can act as reflective surface for radio waves, particularly
at frequencies below 30 MHz (although higher is possible due to a
phenomena known as sporadic E).
LOFAR LBA antennas are capable of receiving many of the bands used in
these world wide amateur radio competitions, including the ARRL
international DX competition that happened last weekend (2nd and 3rd of
March). Cees Bassa and I (Corne Lukken PD3SU) used this opportunity to
test the new AZELGEO support in our Telescope Manager Specification System
(TMSS) to point in several directions (East, West, North etc) and retrieve
the raw IQ data. This data was processed using the excellent program, GNU
Radio, and imported in to popular Software Defined Radio (SDR) programs
such as GQRX and SDRPP.
Part of these amateur radio competitions is identifying yourself using
a call sign and providing your location (maidenhead locator). Cees used
this property to correlate station locations to signal strength on the
all-sky images as well as plotting out their location on a world map.
The results speak for itself, not only are the received stations cleanly
audible but they strongly correlate with the direction of intense
signals in the all-sky image as well as align with the AZELGEO
direction used for beamforming.
73,
Corne Lukken & Cees Bassa
