Hi Luis,
A good idea, very basic.
Am 18.03.2018 18:22, schrieb VIGILANT Luis Fernández:
There is a text file "sr.txt" you need
to configure according to your SpectrumLab settings this way
In the sr.txt file you also need to write the FFT center frequency, like
95998.34 104976 32768 17470.00
Select the file in the EbNaut decoder and press Run. You will
get the real File start at 23:22:41.040
Then you need to calculate and set the exact Start offset in
EbNaut decoder
Anyway you will need to convert the result to seconds. Easy,
even for a dummy
Don't forget to increase the CPU number if you are using a multi
core processor. Press Run again
and let the force be with you while the decoder work digging for
a signal in that file
Sure I'm missing something here. I think have read there is a 4
sample delay to be added to the offset
time.
There is also a 0.3 second delay if the TX stations uses SL to transmit
the VLF signal, like i do.
For the above file start i'm calculating the offset as:
0.3 +4/SR +18.96+7*60
List lenght is also important, but as a dummy I prefer not to
place a finger there at this moment
Please elaborate and describe how one (dummy) can translate that
to seconds.
The list length depends on these transmit parameters, CRC bits,
polynomial, message length.
There is an optimum list length that can be calculated on Pauls site:
http://abelian.org/ebnaut/calc.php?
The default list length of 20000 is ok for typical messages in typical
modes and typical list lengths :-)
But e.g. for messages with a very high CRC, messages beeing very close
to the limit, or messages as long as 'garden fence' may need a longer
list length.
On the other side, a 1 character message with CRC0 and list length
20000 will produce several decodes. So sometimes it is worth to have a
look for the optimum list length.
For my transmission, the optimum list length is 6485439, much more than
the default value, due to my very high CRC level.
There is also a lack of lower level explanations about SL here.
You must be running sample rate compensation
from 1pps GPS signal, and the system timing must be accurately
set. There is also a relation between FFT
configuration and file lenght which determines how much
transmission time you get in a single file. Depending
on announced transmission duration it should be modified to fit
a complete transmission window
Yes, the important information is the FFT window time. It should cover
at least the transmission length + the scroll intervall.
So, please go ahead and feel free to complete this basic
instructions. And specially ... CORRECT it !
But always keeping it simple, for us, dummies ;-)
Hope it is simple enough so far :-)
73, Stefan
|
|
