Re: VLF: 300 mA on 4470 Hz, 67 km band

[Paul Nicholson <vlf0403@abelian.org>]

Stefan wrote:

> f = 4470.100000 Hz
> Start time: 18.JAN.2018  16:00:00 UTC
> Symbol period: 60 s
> Characters: 2
> CRC bits: 16
> Coding 16K23A (NEW)
> Duration: 13h20min [hh:mm]
> Antenna current: 300 mA

Getting uplink now from Warsaw but it was a bit intermittent.
Unfortunately signal levels are down a few dB last night so
no decode at Warsaw.  Maybe Jacek can decode the 20/21 from
local storage?

 vtread -T2018-01-20_16:00,+48100 /raw |
   vtcat -p |
   vtfilter -a th=5,ul=6500 -h bp,f=4970,w=3000 |
   vtblank -a12 -d0 -t100 -v |
   vtmult -f 4470.1 |
   vtresample -r240 | vtresample -r1 > dk7fc-21.vt

and

 vtraw -oa dk7fc-21.vt |
    ebnaut -dp16K23A -r1 -S60 -k16 -N2 -PU -L100000 -v

This is likely to decode correctly for a new distance record.

Todmorden (881.2 km)
--------------------

 19/20 Eb/N0  +8.6 dB, S/N -27.7 dB/1Hz, phase 70.3 *Decoded*
 20/21 Eb/N0 +10.8 dB, S/N -25.4 dB/1Hz, phase 65.0 *Decoded*
 21/22 Eb/N0  +4.4 dB, S/N -31.8 dB/1Hz, phase 78.3 *Decoded*

Bielefeld (303.8 km DL4YHF)
---------------------------

 19/20 Eb/N0  -2.0 dB, S/N -38.3 dB/1Hz, phase -45.2;
 20/21 Eb/N0 +12.5 dB, S/N -23.8 dB/1Hz, phase -55.7 *Decoded*
 21/22 Eb/N0  +6.9 dB, S/N -29.4 dB/1Hz, phase -59.7 *Decoded*

Cumiana (504.6 km IK1QFK)
-------------------------

 19/20 Eb/N0  +8.9 dB, S/N -27.4 dB/1Hz, phase -116.3 *Decoded*
 20/21 Eb/N0 +11.3 dB, S/N -24.9 dB/1Hz, phase -105.0 *Decoded*
 21/22 Eb/N0  +7.4 dB, S/N -28.8 dB/1Hz, phase -107.5 *Decoded*

Warsaw (919.3 km SQ5BPF)
------------------------

 19/20 No uplink
 20/21 No uplink
 21/22 Eb/N0 -3.2 dB, S/N -39.4 dB/1Hz, phase 75.3;


--
Paul Nicholson
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