OBB does not work against CMU200 BTS simulator

craig craig at unreasonablefarm.org
Sun Mar 10 21:15:07 UTC 2019


Oops, I accidentally replied to Mychaela directly, here's our conversation so far, please others join in
with thoughts.

On Sun, Mar 10, 2019 at 09:09:31AM -0800, Mychaela Falconia wrote:
> Hi Craig,
> 
> > Thanks again for your details Mychaela. I will read this very carefully
> > and keep it in mind as I try to port osmocom-bb to fernvale/mediatek.
> > I already expect a good dose of refactoring in layer1 so maybe I will touch
> > on fixing the issue.
> 
> Have you got yourself a CMU200 instrument or not yet?  A CMU200 is
> absolutely required if you wish to have any chance of success at your
> idea of OBB on MTK.

I do have a Racal Instruments 6103E GSM Digital Radio Test Set which seems to 
work well so far. I have tested some SIM800 modules (mtk6261) with the internal
BTS. Not sure if that will fall short or not but I'll take things one step at
a time. When I need a CMU200 I'll probably get one. :)

> Another question: is there any way to run any official MTK-based
> firmware, however non-free and blob-laden it may be, on Fernvale hw?

Probably. I know from reading that Bunnie and Xobs who designed fernvale did
run standard firmware/OS on some similar 6260 based devices. Maybe we could
track down a good firmware and test on fernvale.

For what it's worth the fernvale isn't exactly my main target. I would much rather
use a SIM800 module or eventually design of my own.

> Has anyone actually done it and posted howto instructions?  If not,
> then how do you know if the RF hw on your Fernvale kit is actually any
> good and not physically defective?  Whoever physically manufactured
> those Fernvale boards sold by Sysmocom, have they actually tested
> their RF hw and how?  And what about calibration - have they performed
> individual per-unit calibration of various RF parameters on those
> Fernvale kits like every standard GSM MS hardware manufacturer is
> required to?

I don't have any clue about these details. Will have to rely on Harald or
maybe inquire of Bunnie and Xobs.

> I calibrate my FCDEV3B boards at production time, use
> the calibration procedure to also serve as a test of the RF tract, and
> ship every unit with turnkey-working official firmware and a fully
> valid and legitimate IMEI, fully fit for operation as an MS on public
> GSM networks - do they do likewise or not?  If not, then they are
> substandard.
> 
> M~

Thanks for your efforts,
Craig
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