LimeNET Micro

historical

Hi Keith,

On Sun, Feb 24, 2019 at 05:04:33PM +0100, Keith wrote:
> The new product from Lime is marked to start shipping tomorrow. 

That's good news.

> As far as I understand it is basically the LimeSDR mini with a GPS
> disciplined clock and a Raspberry Pi module, so it /should/ run
> osmo-bts + osmo-trx-lms fine, and without clocking issues.

That is about as much as I know about it, yes.

> I was wondering if anybody else has looked at it, has comments, or has
> or is thinking of ordering one?

I have seen early prototypes at a trade show and have been in some
discussion with Lime about it in the past.  However, I don't know any
more about the device other than what's published by Lime.

It's definitely an interesting device to play with.  I'm looking forward
to that.

However, irrespective of the stable enough clock reference we are still
experiencing a couple of issues when using OsmoTRX with LimeSDR (usb and
mini).  It's yet to be determined what exactly is the root cause of all
of this, as we're using a rather low sample rate and slow, ancient
narrow-band systems like GSM/GPRS/EGPRS shouldn't be a challenge at all
for powerful SDR devices.   It's not clear whether those porblems are
caused by the hardware, gateware, USB host controllers, the
kernel/drivers, LimeSuite or OsmoTRX.

Several of the problems users are experiencing are USB related.  IIRC,
the LimeNET micro used some other interface between the LMS-chip and the
Raspi compute module than USB.  So it may be that the USB related
troubles are becoming irrelevant on this new platform.

I'd definitely love to see the Osmocom stack perform better with LimeSDR
based devices, but I have the feeling that a significant amount of
debugging is required, and the number of areas required to understand
make the number of people available to work on them quite small: One
needs to understand the GSM radio interface, the Osmocom stack,
LimeSuite, USB protocol and Linux system level instrumentation /
debugging of realtime/latency issues which is IMHO a rather rare
combination of expert areas to come by :/

Please note I'm not trying to discourage anyone from buying/using
LiemSDR devices.  I'm just saying that so far, particularly with
the Osmocom stack, there are some [so far] hard to resolve problems
with the existing USB-based devices.  Any help in those areas is very
much appreciated!

Regards,
	Harald

-- 
- Harald Welte <laforge at gnumonks.org>           http://laforge.gnumonks.org/
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