18 Jan
2019
18 Jan
'19
12:39 a.m.
Hello Harald et.al.
On 2019-01-17 23:18, Harald Welte wrote:
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.
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:
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".
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