[Ground-station] Question for ORI:

Thu Apr 1 15:30:09 PST 2021

Hey Jay,

We have been following tinygs and related developments, yes.

We have also been testing some of those semtech chips and they are not
*at all* suited for a ground station. Do not get confused by opportunistic
results, cause those are happening around the TCA of a pass since the
doppler effect is close to zero then. None of those chips can do
doppler shifting so they are not really good for our use cases (and
that's for LoRa.. don't get me started on support for other
modulations doppler shifted on those chips).

(for your reference, the equivalent satnogs baseline setup only
differs on the cost of a RPi+rtlsdr so less than 50 USD of difference)

And while I am at it, let me try to bring the point back home:
LoRa is currently used in space only because IARU and ITU tolerates
its usage (wrongfully imho) within the Amateur Radio Satellite service
(EA). If it wasn't for this then I would love to see those missions
take their chances on other services and ITU being happy with it (i.e.
not-gonna-happen)

We, as radio amateurs, need to seriously take a strong stance against
LoRa unless Semtech is willing to lawfully allow an open SDR-based
complete implementation of LoRa PHY.

Best,

~pierros

On Thu, Apr 1, 2021 at 1:56 PM Jay Francis <jayfrancis at aol.com> wrote:
>
> I'm sure some of you are aware of this effort but I haven't seen it
> mentioned in this discussion yet. https://tinygs.com
>
>  From the History:
>
> "We are passionate about space and created this project to be able to
> track and use the satellites and to learn and experiment about radio.
> Currently the network is open to any LoRa satellite and we also support
> other flying objects that have a compatible radio modulation with our
> hardware such as FSK, GFSK, MSK, GMSK, LoRa and OOK"
>
> There certainly is a proliferation of LoRa devices being used as ground
> stations.  The Semtech chips can receive modes other than LoRa.  The
> 433MHz device configuration, while designed for one of the "junk" ISM
> bands, also tunes the rest of the 70cm ham band.
>
> Being able to set up a ground station that feeds into a network of
> ground stations for less than $30 USD seems like a valuable effort.  I
> think we should be careful not to throw the baby (inexpensive ground
> stations, lots of enthusiastic people interested in satellite radio) out
> with the bathwater (proprietary LoRa).
>
> --Jay, KA1PQK
>
>
> Pierros Papadeas via Ground-Station wrote on 4/1/21 3:50 AM:
> > I think we have the discussion for LoRa's apparent emerging
> > proliferation in satellites, a bit in reverse.
> > I would argue that the main reasons future teams turn to it are the
> > following two:
> > 1. They think that TTN (or any other LoRa Network) would be their
> > ground segment.
> > 2. They are learning for RF through googling "Arduino+LoRa pinout"
> > (/sarcasm-off.. I am alluring to the vast amounts of "learning" and
> > "how-to-get-started" materials you can find about LoRa and LoRaWAN)
> >
> > The following are reasons we think people are looking for LoRa (but
> > are not really the actual reasons imho - look above):
> > a. "It is cheaper" - Assuming you are getting your launch for free,
> > have you seen your solar panel costs? And you think 5 vs 20$ 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