AGO LF HF Reciever Instructions Manual

AGO Field Manual
Dartmouth College LF-HF Receiver
May 10, 1996 

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1  Introduction
Many studies of radiowave propagation have been performed in the LF/MF/HF radio
bands, but relatively few systematic surveys have been made of natural emissions in this
part of the spectrum.  The predominance of man-made signals in this frequency range
requires a remote location and a radio receiver of specialized capabilities in order to
search for natural emissions.  For instance, a receiving system must be capable of both
detecting very weak signals, and be able to step around or...

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3  Antenna and Preamplifier
The AGO LF/MF/HF receiver employs a magnetic loop antenna which is less susceptible
to locally generated noise than an electric dipole, especially when oriented to null out the
strongest local signal.  The loop consists of a single turn of wire arranged in a square
between two vertical 12-foot-long 4 x4  posts placed 3 m apart.  One horizontal wire
runs along the snow, and the other connects the tops of the posts, so that the area of the
loop antenna is 10 square meters....

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Figure 1: The 10 m2 loop antenna installed at AGO-P2, Antarctica.  The AGO facility,
along with two Scott tents, can be seen in the background.  The preamplifier is buried
several feet under the checkered flag in order to keep it at a constant temperature. 

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If a calibration resistor Rcal is placed in series with the antenna such that cal calR V I=, the
calibration voltage (voltage at the antenna terminals) becomes
E
cL AR
Vcal
cal=(4)
For our 10
2 loop antenna, the electric field strength (V/m) and Vcal are related through the
following equation,
calV E01 . 0 =(5)
which was obtained by substituting the appropriate measured quantities into the above
equations.
The least detectable signal of this receiving system corresponds to 
V Vcalµ50 ≈.
Therefore, the...

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The receiver as currently configured measures 116 frequencies from 30 kHz to
4.5 MHz. The frequencies are not spaced linearly but are arranged to optimize reception
of known natural signals such as auroral hiss and auroral roar. Furthermore, the
frequencies are arranged in two sets of 58 frequencies with each of these subsweeps
ranging from the low end of the frequency range to the high end but consisting of
frequencies slightly offset. Using sub subsweeps provides higher effective time resolution
for...

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The output of the receiver is available as an analog signal on the front of the
receiver box, and instructions in this manual tell how a two-channel oscilloscope can be
used to produce an image on the screen of power versus frequency.  Furthermore, a
computer program has been written for DOS, which decodes the digital output of the
receiver and produces a power-versus-frequency plot on the computer screen, which
updates in real time. To use this program, the digital output of the receiver must be...

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