LF: Re[2]: LF: my results on VLF 05-08 May 2017

[Alex K <rn3aus@gmail.com>]

Hello VLF, Stefan, Paul
I have made many attempts of reprocessing of the file "ebnaut07_MAY_0037_6470-1pps.wav" with little variations of time and frequency offset and it seems I have interesting result:

ebnaut-rx V0.7a
input file C:\EbNaut\ebnaut07_MAY_0037_6470-1pps.wav
sample rate 0.342935 per second
rx frequency 6470.1
file start time 2017-05-06 17:59:34.790
polynomial 16K21A
crc size 2
number of chars 2
block size 14
symbol period 60.000
number of symbols 544
list length 20
start offset 636.174
freq offset 0.000009
cores 4
skipped 635.688979 seconds to start
initial reference phase 67.8
---------------------------------------------
.......
---------------------------------------------
found 73
list rank 1
reference phase   30   30    0    0
carrier S/N 9.70 dB in 30.6 uHz, -35.44 dB in 1Hz, -69.42 dB in 2.5kHz
carrier Es/N0 -17.66 dB
carrier Eb/N0 -0.87 dB
info bit period 2863.16 seconds
symbol error rate 238/544 = 43.750 %
Es/N0 from symbol errors -19.0 dB
Eb/N0 from symbol errors -2.2 dB
Shannon capacity 1.5 bits/hour
Shannon efficiency 85.4 %
symbols file C:\EbNaut\ebnaut07_MAY_0037_6470-1pps-symbols.csv
elapsed 11 seconds

73!  (?)
:)
rn3aus/Alex

Четверг, 11 мая 2017, 10:55 +03:00 от Paul Nicholson <vlf0403@abelian.org>:

Alex wrote:

 > {06 May 18:10 6470.1 2-char} transmissions.

 > http://rn3aus.narod.ru/ebnaut-6470-06may2017-1810z.zip

Sorry this one did not decode. The message is there, at
offset +636 seconds but the Eb/N0 is only -1.6 dB.

Incidentally, the command I use on Linux to decode from these WAV
files is (for the 4-char message)

  dd if=ebnaut06_MAY_0136_8270-1pps.wav bs=1 skip=124 |
    od -v -An -w8 -tfF |
    ebnaut -dp16K21A -N4 -S40 -r0.342935 -PS -c8 -k6 -L100 -v -T1001

'dd' strips off the header by skipping 124 bytes and 'od' converts
the 32 bit IEEE floats to two columns of ASCII numbers for input
to ebnaut.

The 4-char WAV header contained timestamp

   1494010730.79 = 2017-05-05_18:58:50.79

and the message started at

   2017-05-05_19:15 = 1494011700.00

so the start offset for EbNaut should be

   1494011700.00 - 1494010730.79 = 969.21

but the message was found at offset 1001.

For the 2-char

  WAV 1494093574.79 2017-05-06_17:59:34.79
  Msg 1494094200.00 2017-05-06_18:10:00.00

Offset should be: +625.21
Message found at: +636.00

Eb/N0 with the +625.21 drops to -3.7 dB due to the symbol
misalignment.

--
Paul Nicholson
--

/DK7FC-06May17-6470-73.png
Description: PNG image