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Gullik Webjorn gullik.webjorn at corevalue.seHello Harald et.al. On 2019-01-17 23:18, Harald Welte wrote: > 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? Yes, I am surprised myself, but I documented what I saw. Note also I checked at two different levels. I will probably redo these tests as I get a more output and a "better test range". >> 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. Yes, currently I use a linear amp designed as a preamp, but output level is a bit below 1 dB compression point, so we are operating linear, current output is 8-9 dBm, which enables extending the test range. I am limited to 100 mW indoor, +20 dBm. >> Else, I am impressed, good value for a low price tag. I had expected far >> worse than indicated accuracy. > Regards, > Harald >