Conclusions:
The closer to the equator you are the higher the
frequency required because of atmospheric noise.
The closer to the
pole, the lower the noise level, the lower the frequency.
Because
the sun strikes the ionosphere at the pole obliquely not straight on,
ionoization is thinner requiring lower frequencies.
Notice that
there is very little difference in frequency day or night at any
location, except at the pole.
* Lt - Local time.
FOT - Optimum working frequency.
Depending on location, frequencies between 2-3 MHz can expect severe
interference, especially at night, from ship-to-shore stations,
therefore these frequencies should be avoided. Tactical transmitting
equipment has little chance of maintaining communication.
See page
121 for other frequency bands to avoid depending on location and time
of day. Anytime interference is experienced submit a M1J1 report and
request another frequency.
Comparisons (on following page) of MUF, FOT and LUF for various
antennas during a low sunspot (SSN10) using the AN/GRC-142 (400
watts), RATT in Europe, for a range of 100 miles. Unlettered LUF is
90 percent, B 80-90 percent, C 60-80 percent, D 40-60 percent, E 20-
40 percent, and F 0-20 percent reliability.
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