Some spectrogram and
spectrum plots of anomalous propagation
Rain Scatter and Tropospheric
Enhancement on 10 GHz (Summer 2005):
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All the following images are of OH3SHF (10368.800 MHz) as seen
backscattering off a local GSM site mast about 1 km away. This means
that in the cases of Tropospheric Enhancement and Forward Rain Scatter,
the signals are received via at least two reflections. None of the
recordings contain Rain Backscatter, although these signals are
exremely strong. My QTH simply does not allow reception of the beacon
from the correct direction due to terrain obtacles and local high hills
with Pine and Douglas trees bearing heavy canopy + some Birchtree
with thick summer foliage. The only way I can locate the beacon at
reception system noise floor level is by using my 120 cm prime focues
dish trained on the peak of a local 70 m mast...
Also, please note:
- the beacon itself has a well know feature of jumping frequency
occanionally, evident also especially in the spectrogram plots
- the CW ID of the beacon causes the receiver AGC to pump accordingly
(for these recordings it was not possible to defeat the receiver AGC)
- there is some ambient temperature dependency of the receiver LO as
this is only thermall stabilized in a coarse manner, hence the evident
drift
Rain Forward Scatter, including mobile phone mast backscatter:
- clear sky
conditions for reference
- clear sky reference, temperature drift
of receiver on 29.08.2005
- rain forward scatter
on 27.08.2005 (light rain)
- rain forward scatter
on 28.08.2005 (light rain)
- rain forward scatter
on 28.08.2005 (ligh rain)
- rain forward scatter
on 28.08.2005 (light rain)
- rain forward scatter
on 28.08.2005 (light rain, single front)
- rain forward scatter
on 28.08.2005 (light rain, three fronts)
- rain forward scatter
on 28.08.2005 (light rain, two fronts)
- rain forward scatter
on 28.08.2005 (medium rain, single front)
- rain forward scatter
on 29.08.2005 (light rain, single front, high headwind)
- rain forward scatter
on 29.08.2005 (light rain, single front, high headwind)
- rain forward scatter
on 30.08.2005 (sporadic rain showers)
- an audio example (approx. 3 Mb) of the rain signal forward scatter +
mast scatter
Tropospheric Enhancement, including mobile phone mast backscatter:
- evening Tropospheric Enhancement
on 01.09.2005, plot ending 2324
Local Time
- evening Tropospheric Enhancement
on 01.09.2005, plot ending 0112 Local Time
- morning Tropospheric Enhancement
on 01.09.2005, plot ending shortly after Sunrise
- Enhanced Tropospheric Scatter
signal at approx. 43 dB C/N on
02.09.2005, 0835 Local Time
- morning Tropospheric Enhancement
on 02.09.2005, plot ending 0902 Local Time
- normal commonplace
Tropospheric Scatter signal on 02.09.2005, plot ending 1119 Local Time
- normal commonplace
Tropospheric Scatter signal on 02.09.2005, plot ending 1345 Local Time
- slightly
Enhanced Tropospheric Scatter signal at approx. 6 dB C/N on 02.09.2005
at 1345 Local Time
- Enhanced Tropospheric Scatter
signal at approx. 21 dB C/N on 02.09.2005 after Sunset
- Enhanced Tropospheric Scatter
signal at approx. 32 dB C/N on 02.09.2005 after Sunset
- Enhanced Tropospheric Scatter
signal at approx. 55 dB C/N on 02.09.2005 after Sunset
- Enhanced Tropospheric Scatter
signal at approx. 57 dB C/N on 02.09.2005 after Sunset
Rain Scatter recordings of the OH3SHF beacon:
- an audio example (approx. 3 Mb) of
regular propagation after being backscattered from the Mobile Comms
mast (25.08.2005, 2122 Local Time)
- an audio example (approx. 3 Mb) of about 30 dB Rain Backscatter enhancement
(25.08.2005, 2310 Local Time)
- and finally an audio file (approx. 3 Mb) yielding simultaneous
Rain Backscatter and Tropospheric Forward Scatter Enhancement
(25.08.2005, 2233 Local Time)
Updated 05.09.2005