Checking out LimeSDR Mini with osmocom. It seems good!!

[Harald Welte]

Hi Gullik,

thanks a lot for your extensive measurement and testing, as well as the
report here to this list.

On Tue, Jan 15, 2019 at 04:13:29PM +0100, Gullik Webjorn wrote:
> So, for practical purposes the LimeSDR mini provides 0 dBm ( +/- 1.4 dBm )

Yes, that's more in-line with what I remember. Depending on unit and frequency,
I think the expected level is roughly between 0 and 4 dBm.

> Level on uplink -54 dBm, indicated on spectrum analyzer -53 (-63) dBm.

So you're saying that the level displayed in the 'show lchan' actually was
almost exactly the measrued level (-53 dBm)?  That's a very big surprise
to me.  As far as I understand, the LimeSuite API never reports any absolute values,
but rather only in dBFS (dB to full scale).  So it's a bit of a mystery
how you can get such an accurate reading?

> For practical use outside a lab output is far too low. My plan is to add a
> small simple booster
> to bring level up to +15 which would allow me to cover my 2 acre lot without
> breaking any rules.

We made some osmo-bts-amp / osmo-bts-pa designs and devices some time ago,
but they only have 10dB gain.  They were made to go from +23 to +33 dBm,
and not for such low input signals, where higher gain stages are required.

Make surey you carefully look at your spectrum and use transmit filters to
suppress the harmonics that your PA will be generating.

> Else, I am impressed, good value for a low price tag. I had expected far
> worse than indicated accuracy.

Regards,
	Harald


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