Re: VLF: Carrier on 8270.0025 Hz

[Paul Nicholson <vlf0403@abelian.org>]

Stefan wrote:

> Since 22:45 UTC i'm running a plain and stable carrier
> Carrier stopped 00:05 UTC.

A strong signal!  About 0.35 fT,  18.0 dB in 208uHz.

Could have sent 11 chars with the 80 minute signal.

 vtread -T 2017-01-15_22:45,+80m /raw |  # Extract signal, 3 chans
   vtmix -c 0.866/-20,-0.5/-35,-0.85 |   # Antenna mix and phase EQ
   vtfilter -h bp,f=8270,w=3000 |        # 3kHz bandpass
   vtblank -a2.2 -d0 -t1 |               # Blanking
   vtmult -f8270.0025 |        # Mix down to baseband I/Q
   vtresample -r240 |          # Drop to 240 samples/sec
   vtraw -oa |                 # Convert to 3 column ASCII
   ebnaut -r240 -dp16K25A -N11 -S2.8 -PS -c8 -L350000 -v

found rank 399 ber 4.0035e-01 Eb/N0 -0.6
M -2.546543181e-01 [***********] ps [  2   30   30   30   30]

> but the BEEEEP is very loud!

Audible at 8270, not 16450.  Can anyone explain why the sound
is at the signal frequency and not the 2nd harmonic?

--
Paul Nicholson
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