Hello Stefan, Michel and all,
In fact the 'EbNaut recorder' configuration doesn't use the FFT for
decimation. But it uses the same class of pre-processing to decimate
the sampling rate for the recorder, by means of I/Q multiplication
(with the center frequency of the later decimated band), and a long
chain of decimators. Each decimator can divide by either 2 or 3,
that's how (and why) we arrive at the strange-looking sampling rate
in the saved file.
But there is another configuration developed and used by Markus,
DF6NM, which indeed uses the complex spectra from SL's FFT for the
spectrum analyser, to extract a narrow band of frequencies which are
then transformed back into a complex signal for the wave file.
Theoretially, the result should be the same in both cases, but I
never checked this myself.
Cheers,
Wolf DL4YHF .
Am 04.06.2016 um 16:15 schrieb IZ7SLZ:
Hello
Domenico,
When recording EbNaut samples, do you have to compensate for
the lag due to the huge decimation factor ?
In other words is it ok or not, to start recording your H:00
transmission at H-1:00 and stop recording at H:15 ?
Another question: how do you achieve the sr=111.118706906 of
your WAV files ?
Thanks,
Michel - f5wk
Le samedi 4 juin 2016 à 12:06:15, IZ7SLZ écrivait :
> Good day LF,
> I have activated a beacon on 137.485 kHz sending an
EbNaut message every
> 30 minutes starting at .00 and .30.
> Message lenght is 13 characters at 1 s/symbol. Coding
= 8K19A
> Duration is 14'56"
> Carrier is on 1 minute before each transmissions and
off at .45 and .15
> My receiver is also tuned around 137.500 kHz and it
is programmed to
> record EbNaut.
> Recording audio from the receiver, prearranged for
EbNaut-rx direct
> usage, is available at this DropBox folder
>
https://www.dropbox.com/sh/9c3nnw40nyb5pqc/AABZ6oPxpAY4IwuWFmebMSfba?dl=0
> Each (15 minutes) audio file is named with
the date and time of its start.
> I will try to keep active the beacon for the week end.
> Report are welcome.
> 73 and good WE all,
> Domenico, iz7slz
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