Re: FW: Re: IO-117 status - we're back - AMSAT-BB

27 Oct 2023

      Hi Graham,
Thanks for reminding me of that one, I forgot about it!
73 de VE3SVF
On Fri, Oct 27, 2023 at 11:21 AM graham shirville via AMSAT-BB <
[email protected]> wrote:
...
Hi Sasha,
Thanks for the explanation…I had the same question my mind!
Just for the record, a 1U CubeSat, JY1SAT, also successfully used SSDV to
downlink a number of preloaded images from Jordan.
As you can see it worked really well! http://sv2hwm.ddns.net/JY1SAT.php
The User Dashboard, based upon the FUNcube system, enabled one to “hole
file” any missing blocks during subsequent orbits.
Sadly a failure in the onboard MCU some months ago means that it can no
longer provide these images.
73
Graham G3VZV
*From:* Sasha Tim via AMSAT-BB [email protected]
*Sent:* Friday, October 27, 2023 2:58 PM
*To:* Zach Metzinger [email protected]; Amsat - BBs <[email protected]
...
*Subject:* [AMSAT-BB] Re: IO-117 status - we're back
Hi Zach,
The reason against JPEG is primarily because of the corruption
capabilities. If the first packet is not received (which is often the
case), the entire image will be corrupt. If a single packet is missed, it
ruins the image for all of the packets after.
Multiple satellites use raw JPEG in space currently, and it is not working
well.'
A better format to use would be SSDV (https://github.com/fsphil/ssdv),
which has been tested on HAB flights for a long time, and was originally
implemented on an Atmega328!
It retains the JPEG compression capabilities, while simultaneously
protecting the imagery against potential packet loss.
There were only three satellites that I know of that used SSDV in space,
that is, GASPACS-1 and the Chinese Lunar Orbiter cubesats a while ago.
On Thu, Oct 26, 2023 at 3:46 PM Zach Metzinger via AMSAT-BB <
[email protected]> wrote:
On 10/26/23 14:13, Sasha Tim via AMSAT-BB wrote:
...
Any projects working on getting into MEO: PLEASE put in a camera (and
transmit in a format that is not JPEG)!
Hello Sasha,
Cameras do require a license, at least for the US. Not insurmountable,
but one has to consider this aspect.
What's wrong with JPEG? You'd prefer GIF? (or TIFF?) :-)
--- Zach
N0ZGO

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Re: FW: Re: IO-117 status - we're back

Sasha Tim

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