[Ground-station] Question for ORI:

Thu Apr 1 07:50:48 PST 2021

I think we have the discussion for LoRa's apparent emerging
proliferation in satellites, a bit in reverse.
I would argue that the main reasons future teams turn to it are the
following two:
1. They think that TTN (or any other LoRa Network) would be their
ground segment.
2. They are learning for RF through googling "Arduino+LoRa pinout"
(/sarcasm-off.. I am alluring to the vast amounts of "learning" and
"how-to-get-started" materials you can find about LoRa and LoRaWAN)

The following are reasons we think people are looking for LoRa (but
are not really the actual reasons imho - look above):
a. "It is cheaper" - Assuming you are getting your launch for free,
have you seen your solar panel costs? And you think 5 vs 20$ on a chip
would make a difference?
b. "It is free frequency" - ISM does not exist in space as a service,
and using LoRa in radio amateur bands is actually not compliant with
radio amateur service (I know.. debatable, but in SatNOGS we choose to
take the hard line on proprietary protocols"

It all boils down to education, materials and available
implementations that can be easy to manufacture and/or buy. On the
cheap spectrum of open hardware radios for space right now we have the
following (to my knowledge):

LSF PQ9ISH-COMMS
AX5043 based
https://gitlab.com/librespacefoundation/pq9ish/pq9ish-comms-vu-hw/

UBNanosat Lab LFR
Si446x based
https://github.com/UBNanosatLab/lfr-hardware

Planet Labs OpenLST
CC1110 based
https://github.com/OpenLST/openlst

Are any of those 3 (and possibly others) in the NASA Cubesat 101 handbook?
Are they on the NASA SST SoA report (yes they are SoA from a
price-point perspective)?
Are they in IARUs page references?

Nope they are not. We have a long way to go to educate people and make
those things more available widely.
I plan to make a comprehensive write-up on our (LSF) views for LoRa in
Space and the possible way forward (and share it here too)

~pierros

On Thu, Apr 1, 2021 at 6:33 AM Bruce Perens via Ground-Station
<ground-station at lists.openresearch.institute> wrote:
>
> The second issue about LORA is that it's a garbage band, and destined to become a really big garbage band. On the ground that's OK, you have the square law and obstacles hiding most of those transmitters from each other. From space, maybe even from a balloon, I would imagine you would be hearing a lot of chips on top of each other, or the noise floor would be high with no intelligible signal. They might all be able to hear you, but not the other way around.
>
> So, maybe what we want to do from a satellite is downlink or even broadcast using LORA or some other Part 15 mode. It uses the strengths of a satellite, not the weaknesses.
>
> Perhaps this is undemocratic :-) But I think it might be better if it took a little more effort to put together a station that we would be likely to hear from a satellite, and more difficult for stations intended to be terrestrial to be heard accidentally. Maybe you should have a ham license, too.
>
>     Thanks
>
>     Bruce
>
> On Wed, Mar 31, 2021 at 4:40 PM Howie DeFelice <howied231 at hotmail.com> wrote:
>>
>> I’m not a patent expert but it appears the first one listed covers the generation of spread spectrum “chirps” using a fractional N synthesizer. The other patent covers the  data formatting and modulation scheme. Assuming we have to stay away from those two aspects, we could still use chirp spread spectrum, just not generated the same way. The biggest advantage to chirped spread spectrum from a satellite operations perspective is that it’s inherently resistant to doppler issues. As long as the signal is in the receiver bandwidth and you can detect the direction of the chirp you can decode the signal.  Using a chirp spread spectrum physical layer into a an adapted 802.16 mesh network configuration could provide a way to have satellite augmented ground networks (or vice versa) without having to have a planned constellation of satellites. If every new LEO carried the transponder, the network would automatically form and grow.  When satellites are visible to each other traffic would also be repeated satellite to satellite. If the frequency plan was compatible to QO-100 transatlantic relays could be possible into the QO-100 footprint.
>>
>>
>>
>> Howie AB2S
>>
>>
>>
>>
>>
>> From: Bruce Perens via Ground-Station
>> Sent: Wednesday, March 31, 2021 7:13 PM
>> To: Douglas Quagliana
>> Cc: Michelle Thompson via Ground-Station
>> Subject: Re: [Ground-station] Question for ORI:
>>
>>
>>
>>
>>
>>
>>
>> On Wed, Mar 31, 2021 at 3:43 PM Douglas Quagliana <dquagliana at gmail.com> wrote:
>>
>> 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.
>>
>>
>>
>> Yes, but I am not aware of Phil addressing this particular application, which is dirt-cheap SS data links between so-far-terrestrial embedded microprocessors with a link budget to go miles at the lowest data rate and long life on small batteries. I hold out some hope that the functionality of their chip can be duplicated with a relatively small number of discrete components and a cheap microprocessor. Certainly we have ones that can do significant DSP in the $4 range these days, and they idle at microamps drain.
>>
>>
>>
>>     Thanks
>>
>>
>>
>>     Bruce
>>
>>
>
>
>
> --
> Bruce Perens - CEO at stealth startup. I'll tell you what it is eventually :-)

-- 
Papadeas Pierros
Executive Director
Libre Space Foundation
https://libre.space