VLF,
After more than 2 weeks, the 5 characer message has been transmitted
nearly each night! Tonite will be the last night.
W1VD and K3SIW are collecting files since the 26th. There is a stack of
15 nights available now!
So far there has been no decode, neither by weighting the stack based
on informations known by the RX side nor by by weighting/aligning the
stack based on informations known by the TX side.
However, the reconstructed spectrum peak reaches > 10 dB on both RX
stations. The final optimum SNR will be reported tomorrow.
5 characters should have been made in a much shorter time, based on
what we saw from the 2 character decode by W1VD. But the QRN insreased
significantly since then. Another reason is the quickly shorter getting
nighttime. The beginning and the end of the message is already in
daylight now and so the terminator messes up the phase in the stack,
reducing the stacking gain.
For Eb/N0 = 0 dB we need 14.5 dB SNR, so there is no hope, except i
would use a kite again and add 10 dB ERP!!!! :-)
We will see how things go on 17.47 kHz on the same paths. I will be on
air there in 2 days, starting attempts to be detected in VK7.
73, Stefan
Am 25.02.2018 23:17, schrieb DK7FC:
Hi Jay, VLF,
A great success again! Thanks for your efforts on the RX side. And
congrats to that result!
It was exciting and interesting to follow the rising Eb/N0 and the
daily variations when using the -f16 function in the Linux decoder.
It can be quite an effort to tweak out the last 0.05 dB in the hope to
find the correct message then, by varying time offsets and weighting. I
am learning a bit more each time i follow the decode process here on
the TX side by analysing the wav files you kindly provided.
We are now leaving the winter season. The QRN has been clearly stronger
during the last nights. There are regular thunderstorms in south Italy
and Greece now.
A longer message is realistic. Let us try 5 characters now:
f = 8270.1000 Hz
Start time: 25.FEB.2018 22:30:00 UTC (daily)
Symbol period: 24 s
Characters: 5
CRC bits: 18
Coding 16K21A
Duration: 07:15:12 [hh:mm:ss]
Antenna current: 700 mA
I bet you will get the result after 4 days of stacking! Let's see! Good
luck!
73, Stefan
Am 25.02.2018 19:23, schrieb [email protected]:
Stefans transmission:
f = 8270.1000 Hz
Start time: 19.FEB.2018 22:30:00 UTC (daily)
Symbol period: 30 s
Characters: 2
CRC bits: 22
Coding 16K21A
Duration: 07:12 [hh:mm]
Antenna current: 700 mA
After a successful one character reception earlier in the
week,
we can now report the successful reception of a 2 character
message. Stacking of 3 transmissions was required (0221, 0222 and
0223). There is also a 0224 file but it has timing issues and may or
may not be usable.
ebnaut-rx V0.8
input file C:\EbNaut\DK7FC\sum212223.wav
sample rate 0.457240 per second
rx frequency 8270
file start time 2018-02-22 22:21:17.790
polynomial 16K21A
crc size 22
number of chars 2
block size 34
symbol period 30.000
number of symbols 864
start offset 537.000
freq offset 0.100000
cores 2
list length 500000
skipped 538.011261 seconds to start
initial reference phase 30.6
---------------------------------------------
found DX
list rank 48426
reference phase 150,150,150,150
carrier S/N 11.04 dB in 38.6 uHz, -33.10 dB in 1Hz, -67.08 dB in 2.5kHz
carrier Es/N0 -18.33 dB
carrier Eb/N0 0.47 dB
info bit period 2273.68 seconds
symbol error rate 373/864 = 43.171 %
Es/N0 from symbol errors -18.2 dB
Eb/N0 from symbol errors 0.6 dB
Shannon capacity 2.5 bits/hour
Shannon efficiency 62.7 %
symbols file C:\EbNaut\DK7FC\sum212223-symbols.csv
elapsed 52 seconds
---------------------------------------------
found DX
list rank 17074
reference phase 120,150,120,150
carrier S/N 11.19 dB in 38.6 uHz, -32.94 dB in 1Hz, -66.92 dB in 2.5kHz
carrier Es/N0 -18.17 dB
carrier Eb/N0 0.62 dB
info bit period 2273.68 seconds
symbol error rate 374/864 = 43.287 %
Es/N0 from symbol errors -18.4 dB
Eb/N0 from symbol errors 0.4 dB
Shannon capacity 2.6 bits/hour
Shannon efficiency 60.5 %
symbols file C:\EbNaut\DK7FC\sum212223-symbols.csv
elapsed 383 seconds
Jay W1VD WD2XNS WE2XGR/2
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