[Aavso-sid-list] Software longwave receiver

[ChrisAtUpw at aol.com]

In a message dated 29/03/2007, pws at rechtsmedizin.uni-kiel.de writes:

Playing  around with a new sound card (M-Audio, Audiophile 192)
I'm testing the  autonomous creation of "waterfall spectra" from
4.0 KHz up to 96.0 KHz over  time. The signal strengths are coded
as colours. Examples:  http://home.arcor.de/df3lp/spec/
updated in 30 min. intervals. Resolution:  1000x1200 pixels.

Some technical details:
-Antenna: ferrite coil  l=20cm, nulls at 240/60 deg.
-Preamp: OP27 low noise operational  amplifiers.
 
Hi Peter,
 
    You might do better with one of the VLF radio  chips? Maybe an audio 
preamplifier? Or a few transistor pairs connected in  series? Alternatively, an 
OP37 has bandwidth to 200kHz. OP27s are not great  over 30 kHz.
 
    There seems to be something wrong with the spectrum  at 
_http://home.arcor.de/df3lp/spec/2007-03-29_one_spec.png_ 
(http://home.arcor.de/df3lp/spec/2007-03-29_one_spec.png) 
 
    The 60.0 kHz Rugby time signal seems to be  recording at 60.5 kHz. There 
is no FM/AM modulation on this signal - it is  on/off modulation. It is strong 
over your area. DCF77 seems to be coming  through strongly and is correctly 
indicated. 
 
    Regards,
 
    Chris Chapman



   
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