Dear Andy and LF Group,
as expected, the 10 Hz Hell was superior to 20 Hz. The best image resulted
from a resolution bandwidth optimized to the short pixel duration and fast
scanning with no averaging (1.4 Hz, 250 ms). In the PaintShop
"postprocessing", I simply blanked the noise-only intervals before
compressing horizontally, so the maximum SNR for a given transmitted energy
should be recovered. A 29 kB gif file describing this procedure can be sent
directly.
Thank you Andy for this interesting experiment. Does the _BCN mean beacon?
vy 73 de Markus
DF6NM, JN59NK
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Markus Vester wrote:
Hi Andy,
just a quick response: yes, hell clearly is there, abt -5 dBuV/m now, but
hardly readable. I can easily see the vertical lines chirping downward, but
the horizontal dots are difficult. I tried several spectrogram settings, 0.7
Hz / 500 ms seemed best for SNR (see gif). Averaging would probaby be better
in connecting the parts of a character, but it smears out the dots so they
get lost in the noise. The signal can't be everywhere at the same time.
Theoretically, one would wish for a sliding bandpass synchronous to the
chirps, which would block the noise in between. I will experiment with more
settings on the recorded wav files later.
I'll try to call you in DFCW, and maybe you could also send narrower
bandwidth hell.
73 de Markus
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