Re: VLF: Carrier on 3675.005 Hz / EbNaut - YES

[Markus Vester <markusvester@aol.com>]

It looks like we got a valid decode of Stefan's 16 hour transmission from the DL0AO cardioid antenna. 

I had also attempted an early decode from a file ending 18:12 UT. This one appeared to be even better (rank 0, +2.2 dB carrier EbN0), perhaps because it ended before the QRN increased.

We had no success with the earlier 24 h transmissions on Aug 10th and 11th, neither single days nor both stacked - surely due to much higher QRN levels than today.

BTW Each decode attempt also produced several false hits with relatively good ranking, so a longer CRC might be preferable.

All the best,
Markus (DF6NM)
 


-----Ursprüngliche Mitteilung-----
Von: DK7FC <selberdenken@posteo.de>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Fr, 11. Aug 2017 15:32
Betreff: Re: VLF: Carrier on 3675.005 Hz / EbNaut

...looks like there was no decode from DL0AO from that transmission. It was one of the noisiest days again. I already expected that result and repeated the same message again, running today (24 hours, ending 0 UTC). With Markus' tool to stack the resulting files, they could gain 3 dB by stacking these two transmissions.
Today the noise is much lower. Attached is a RDF spectrogram showing the BPSK as recveived on the tree.

I'm announcing another test, again trying 3 characters, even in a shorter time, avoiding the night time where the SNR is much lower:

f = 3675.005000 Hz
Start time: 12.August.2017  04:00:00 UTC
Symbol period: 80 s
Characters: 3
CRC bits: 7
Coding 16K21A
Duration: 16h
Antenna current: 160 mA


73, Stefan



Am 09.08.2017 16:48, schrieb DK7FC:

Hi VLF,

An attempt for a first message transfer between radio amateurs in the range 3...4 kHz for an expected distance of 226 km, or 2.77 wavelengths:

f = 3675.005000 Hz
Start time: 10.August.2017  00:00:00 UTC
Symbol period: 120 s
Characters: 3
CRC bits: 7
Coding 16K21A
Duration: 24h
Antenna current: 160 mA

73, Stefan

W08120516_result.png
Description: PNG image