Re: LRPT Laboratory Bandwidth testing


Patrick Lindecker
 

Hello David and Fred,

Yes, internally small Jpg images (8x8) are transmitted (it's perhaps why it's a Low rate Picture Transmission and not a High rate).
I was wondering if it would not be possible to fill these lines of 8 pixels width with a set of "most probable pixels", taken into account the pixels at the frontier of these lines and the different derivative in the border zones of these lines. It would be an interesting mathematical game.

73
Patrick

-----Message d'origine-----
De : multipsk@groups.io [mailto:multipsk@groups.io] De la part de David J Taylor via groups.io
Envoyé : mardi 22 décembre 2020 15:21
À : multipsk@groups.io
Objet : Re: [multipsk] LRPT Laboratory Bandwidth testing

On 22/12/2020 13:25, Fred Albertson wrote:
Hi David,

I don't think so, because they decode ad BMP's from AMIGOS. I convert
them to JPG's for the e-mail. I have noticed no difference.

Thanks and great day,

Fred
Thanks, Fred.

At least one references suggests it's JPEG data:

http://jmfriedt.free.fr/glmf_meteor_eng.pdf
https://www.rtl-sdr.com/forum/viewtopic.php?t=343

If so, it might be better to work in the JPEG space rather than go JPEG=>BMP=>JPEG. BMP is much more convenient for subsequent processing, of course.

I'm uncertain whether or not JPEG=>BMP decoding always produces the same results or whether some assumptions are made (beyond the tables included with the JPEG data) which affect the results.

73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
Twitter: @gm8arv

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