Dear VLF,
In Spectrum Lab there are different methods for noise reduction (e.g. of
lightnings). Those were discussed here in the last weeks. While
Jim/M0BMU preferes the clipper (using 0 dB above AVG if i remember
correctly), Markus/DF6NM prefers the noise blanker.
Since i do a lot of experiments with the second grabber page, checking
the optimal software and hardware for this
antenna/location/band/mode..., i have now added a 7th window that shows
the DFCW-600 window with a noise blanker instead of the clipper (i am
also using the clipper so far). So there are 7 windows running now on
this site:
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html
1: DFCW-600 with clipper (3dB above AVG)
2: DFCW-600 with noise blanker (ramp 0,002s, trigger 9dB, pulse 0,05s)
3: DFCW-60 (all others with the clipper as well)
4: DFCW-3
5: ALPHA (RSDN-20, F1) in 424µHz (currently OFF)
6: DFCW-6000
7: wide band window 0...24 kHz
I still have to reduce the IM in the first stage (2nd order low pass
filter at the output of the first stage does not better the situation),
either by reducing the wire length or adding a series resistor or...hm,
will see (any ideas?). When the IM is reduced, i want agn to transmit
DFCW-600 out of 1,1 km using the TV transformer. Then, one will see
which noise reduction method makes the best readability :-)
73, Stefan/DK7FC
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