Re: VLF: tonite on the 36km band...

[DK7FC <selberdenken@posteo.de>]

Hello Alex,

Many thanks for your results! This is very interesting. A very good result for May over that 1990 km landpath! It was not really a quiet night :-) I can see the QRN situation on the RC4HAA VLF grabber (http://136.su/grabber/).
I did not expect a decode from you because because i had to restart the transmission later, 3 hours after the optimal time.
No false decodes despite the low CRC value, must be due to the lower list length. Paul seems to be right ;-) I will continue with tests of low CRC values.
We are impressingly close to the limit!

Let me try tonite:

f = 8270.100000 Hz
Start time: 05.May.2017   18:00:00 UTC
Symbol period: 40 s
Characters: 4
CRC bits: 6
Coding 16K21A
Duration: 8h, 53m, 20s
Antenna current: 670 mA
(Set list length to: 74 in the first run)

With 4 characters, it becomes easier to filter out false decodes by the human decoder stage.

73, Stefan



Am 05.05.2017 16:52, schrieb Alex K:

Hello Stefan, VLF!
The 3-char transmission was decoded here in nr Moscow without false decodes!

ebnaut-rx V0.5
input file C:\EbNaut\VLF_EBNAUT\EbNaut\ebnaut04_MAY_2336_8270-1pps.wav
sample rate 0.342935 per second
rx frequency 8270.1
file start time 2017-05-04 16:58:49.600
polynomial 16K21A
crc size 8
number of chars 3
block size 26
symbol period 40.000
number of symbols 736
list length 250
start offset 14482.364
freq offset 0.000000
cores 1
skipped 14483.790082 seconds to start
initial reference phase 10.6
---------------------------------------------
found VLF
list rank 104
reference phase    0    0    0    0
carrier RMS 5.045e-005 noise RMS 1.340e-005
carrier S/N 11.52 dB in 34.0 uHz
carrier Es/N0 -17.15 dB
carrier Eb/N0 -0.81 dB
info bit period 1721.64 seconds
symbol error rate 315/736 = 42.799 %
Es/N0 from symbol errors -17.8 dB
Eb/N0 from symbol errors -1.5 dB
Shannon capacity 2.5 bits/hour
Shannon efficiency 84.4 %
symbols file C:\EbNaut\VLF_EBNAUT\EbNaut\ebnaut04_MAY_2336_8270-1pps-symbols.csv
elapsed 10 seconds
---------------------------------------------
found VLF
list rank 43
reference phase    0    0  -30  -30
carrier RMS 5.402e-005 noise RMS 1.340e-005
carrier S/N 12.11 dB in 34.0 uHz
carrier Es/N0 -16.56 dB
carrier Eb/N0 -0.22 dB
info bit period 1721.64 seconds
symbol error rate 322/736 = 43.750 %
Es/N0 from symbol errors -19.0 dB
Eb/N0 from symbol errors -2.7 dB
Shannon capacity 2.8 bits/hour
Shannon efficiency 73.7 %
symbols file C:\EbNaut\VLF_EBNAUT\EbNaut\ebnaut04_MAY_2336_8270-1pps-symbols.csv
elapsed 170 seconds


Files for reprocessing:
http://rn3aus.narod.ru/ebnaut-04may2017-2100-8270.zip

73 de rn3aus/Alex

Пятница, 5 мая 2017, 0:12 +03:00 от DK7FC <selberdenken@posteo.de>:

Am 04.05.2017 22:54, schrieb Markus Vester:

> The 3 char transmission for tonite failed.

Pity. Do you want to try again later tonight? That would probably imply rescheduling the following daytime sequence as well.

Exactly!
Update:

f = 8270.100000 Hz
Start time: 04.May.2017   21:00:00 UTC
Symbol period: 40 s
Characters: 3
CRC bits: 8
Coding 16K21A
Duration: 8h, 10m, 40s
Antenna current: 670 mA
(Set list length to: 239 in the first run)
This is an experiment using a low CRC value which gives a lower optimum list length. Let's see if it produces to many false decodes.


Probably that's a transmission for Paul only:

f = 8270.100000 Hz
Start time: 05.May.2017   05:30:00 UTC
Symbol period: 10 s
Characters: 100
CRC bits: 0
Coding 8K19A
Duration: 13h, 44min
Antenna current: 670 mA

> The fan has blown itselfe from the table

Wow, you might end up using that fan as a helicopter to raise the antenna ;-)

Again, exactly! Because that may become necessary in the future. They are planning a safety inpection for July this year! In the worst case it will be the end of this setup here. So i'm pallning for any eventualities: http://www.xxl-modellbau.de/Multicopter_2
A good new project anyway...

73, Stefan