[Ground-station] Question for ORI:

[Leffke, Zachary]

I hope I don’t sound too stupid here, but whatever I’ll go for it (Bob N4HY used to tell me there are no stupid questions, only stupid people hihi ☺ )…….. I have a question on this one.  Bruce specifically mentions the FunCube Dongle, but I think this would apply to RTL-SDRs……and my question is specifically related to Bruce’s response below.

I’ve wanted to do my own custom layouts with integrated RTL-SDRs for various projects (like multi-sdr coherent projects, custom single chain receivers with my own RF front ends, hats for things like RPis, etc.) and have run into multiple barriers, some related to (I think) proprietary ICs, lack of documentation, and lack of the ability to purchase the chips in small quantities.  Not an expert on any of this…point is, you can’t buy the chips on digikey/mouser for whatever reason and documentation of them is hard to come by (some stuff was leaked….but that doesn’t seem legit either).  Seems like if you want to build RTL-SDR flavored hardware, you have to go direct to the manufacturer, sign NDAs, and order in bulk.

So my question is, given that RTL-SDRs are so prolific (same for funcube dongles, though maybe to a lesser extent), does it REALLY matter if the ICs are proprietary?  Isn’t what actually matters is that the drivers needed to use them are open source?  https://github.com/dl1ksv/gr-fcdproplus and https://github.com/osmocom/rtl-sdr (and there are multiple forks of the rtl-sdr drivers and various other open source wrappers for things like GNU Radio or even direct IQ sample access in Python).  We don’t need to fabricate RTL-SDRs or FunCube dongles from scratch, but offering reference system designs that include those devices with all open source software and with well defined and published protocols (such as Douglas’s list, and concepts related to spread spectrum) that don’t step on any patent toes seems acceptable to me……

I guess everything above really only helps you with ground station implementation as you aren’t likely to fly an RTL-SDR ‘as-is’.  If ORI is going for all open source / open hardware, including the satellite side, then implementing the protocols (either on a chip or in an SDR) including an open hardware design might be where things start to get sticky (like the proprietary nature of most space rated SDRs out there today, or IP cores, etc.)…….

…..I also realize this distracts a little from the original post and the question posed by Michelle, so feel free to ignore…..I have some thoughts there as well…but will save for a separate email.

-Zach, KJ4QLP
--
Research Associate
Aerospace & Ocean Systems Lab
Ted & Karyn Hume Center for National Security & Technology
Virginia Polytechnic Institute & State University
Work Phone: 540-231-4174
Cell Phone: 540-808-6305

From: Ground-Station <ground-station-bounces at lists.openresearch.institute> On Behalf Of Bruce Perens via Ground-Station
Sent: Thursday, April 1, 2021 2:23 PM
To: Douglas Quagliana <dquagliana at gmail.com>
Cc: Michelle Thompson via Ground-Station <ground-station at lists.openresearch.institute>
Subject: Re: [Ground-station] Question for ORI:



On Thu, Apr 1, 2021 at 11:06 AM Douglas Quagliana <dquagliana at gmail.com<mailto:dquagliana at gmail.com>> wrote:
We have.  ARISSat.  FUNCube.  Fox's DUV (coarse FM tuning is fine for DUV as long as you are receiving the FM signal).

FunCube might not be a great example, since the dongle (and presumably the satellite) are based upon ICs with NDA documentation - or that was the case when I spoke with the FunCube developer, years ago.

    Thanks

    Bruce
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