[Ground-station] Question for ORI:

[Douglas Quagliana]

Bruce writes:
> someone more skilled than me would be sitting down to make an open data
link implementation built on some cheap microprocessor

If I understand what you're saying, Phil has already written several
downlink schemes.  One of his implementations was used on AO-40, and the
AMSAT-UK team modified it for use on their FUNCube satellite.  Another
completely different version with a Viterbi decoder was used on ARISSat-1.
The Fox satellites use an implementation of this Reed-Solomon codes for
forward error correction on the downlink.  There's some other work he did
for ACE and other work for ICE.  He can probably tell you more....

Concatenated Reed-Solomon and Viterbi decoders have excellent performance
and are almost certainly patent free by now given their ages. NASA used
them for Voyager about thirty years ago or so.

For over the air signals, I would rather see us use a completely open
source implementation written in C (or some high level language) to
generate the bits, bytes, forward error correction and digital
samples-ready-for-a-D-to-A-converter and which can be run on a variety of
processors rather than get stuck with a particular custom hardware chip
that goes out of production long before the end-of-life of the satellite.
Remember, launches get delayed (sometimes for more than a year) and
satellites sometimes keep working in orbit for far longer than expected
(and/or come back to life after years, which has happened twice now).  It
wouldn't help us if the satellite is still operational but used a special
chip that nobody can get anymore.

73,
Douglas KA2UPW/5
"@Bruce:  or.... did I completely misunderstand what you said?"


On Wed, Mar 31, 2021 at 5:05 PM Bruce Perens via Ground-Station
<ground-station at lists.openresearch.institute> wrote:

> Pretty much all of the small satellite groups are interested in LORA and
> are telegraphing future missions, and we have the FossaSAT-1 mission, which
> although incorrectly implemented (and the firmware was not updatable) they
> claim to have received LORA packets.
>
> The sole advantage of LORA is that there are cheap chips available. As
> we've heard, it doesn't have the best data link performance. The problem
> for us is these two patents: US7791415
> <https://patents.google.com/patent/US7791415>, EP2763321
> <https://patents.google.com/patent/EP2763321A1>. They place all of our
> non-Semtech implementations in danger, and Pierros recently mentioned that
> Semtech doesn't respond when asked about them.
>
> If I had my 'druthers, someone more skilled than me would be sitting down
> to make an open data link implementation built on some cheap microprocessor
> and we would not have to deal with those folks and their patents.
>
> I suggest that this be an experimental pathfinder on some future
> satellite, not part of the main mission. Fly the Semtech chip and do a
> better implementation than the FossaSAT folks, and see what you can get out
> of it. After that, a greater effort might be justified.
>
>     Thanks
>
>     Bruce
>
>     Thanks
>
>     Bruce
>
> On Wed, Mar 31, 2021 at 1:13 PM Michelle Thompson via Ground-Station
> <ground-station at lists.openresearch.institute> wrote:
>
>> A question has been posed:
>>
>> "NASA wants to commercialize TDRS and the private sector is working on
>> making Ku and Ka band terrestrial links usable in space. This only works to
>> the advantage of big players that can close these links (NRO, NASA, etc)
>> and leaves it out of reach from hobby folks. The barrier to entry and
>> complexity are rather large (I'm working with SCaN and APL on some of this
>> at work).
>>
>> https://www.itu.int/dms_pub/itu-r/oth/0c/0a/R0C0A00000D0017PDFE.pdf
>>
>> Long story short, I think society needs to do this for LORA. Imagine,
>> having a cubesat that can ping Swarm with "I'm alive" and also get two way
>> messaging for TT&C/Health/Whatevs. Apparently, there is a regulatory
>> distinction between Earth-Space and Space-Space and folks are trying to be
>> sneaky in allowing dual use for only a few bands. Even if your satellite
>> lost attitude control, the nature of VHF/UHF would allow you to phone back
>> home from space via an in space LORA network and potentially help you
>> recover your satellite.
>>
>> My original work was for Iridium in terms of using Commercial networks on
>> cubesats and then expanded to broader networks but in terms of SWAP, LORA
>> and SWARM are better and I'm including them in a smallsat paper this year.
>>
>> https://ieeexplore.ieee.org/document/7500525
>> https://ieeexplore.ieee.org/document/4839583
>>
>> Do you think this is dumb? That would be question 1 :)
>>
>> And if not, does Open Research have anyone that knows how to navigate the
>> regulatory bits to make LORA usable as an inter satellite relay? I'm
>> willing to put in all the work needed but how to write a letter to the FCC
>> requires finesse and sneaking into these regulatory chats is rough. You can
>> probably accomplish using the network with an experimental license but
>> permanent regulatory authority would make things easier to proliferate."
>>
>> -Michelle W5NYV
>>
>>
>>
>
> --
> Bruce Perens - CEO at stealth startup. I'll tell you what it is eventually
> :-)
>
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