Hi!
Received LimeSDR Mini and have problems using it. It has spurs with high level (over 30 dB) on every band even when RX terminated with 50 Ohms. Also - when I connect even small antenna such as short (10 cm) wire - it makes lot of fantoms from FM stations - on all frequencies. Recorded some video about it: https://youtu.be/SIayUiQVwyc
QuickTest reports no problems.
Changing computer, changing bandwidth makes no difference.
What can I do?
Is your LimeSDR in a metal enclosure? I found there is less interference when using a grounded metal case. Also try adjusting amplifier gains.
There are 3 amplifiers in the receive signal path.I don’t think there ar any filters in front of the first one ( TIA ). In absence of external FM reject or preselector filters it will amplify everything including mirror FM stations act. Lower the gain and you’ll see some improvement. Make up for the lost gain with PGA that is behind a low pass filter. Lna also helps. I don’t remember where is it in the signal path.
Also make sure you’re using a filter ( for HF I use low pass filter lpf) and that it is set to proper bandwidth. You can set this in LimeSuite. I suggest you experiment with filter and gain settings while watching the results through an app like SDRConsole v3. This is what I did.
However the best I’ve done for receiving HF signals is to buy a transverter as I didn’t want to modify the LimeSDR inputs. If I wanted to improve LimeSDR further I would add a preselector.
Lukf, thanks.
Changing amplifying makes no differens - still same spurs. Filters will not help - because problem exists even when RX input terminated with 50 Ohms resistor directly on the SMA connector.
FM stations does not overload it - because they have low level (10…20 dB) - spurs have higher level up to 40 (!!) dB over noise.
Metal enclosure also will not help - because of VERY high level of spurs.
Think that the board have some kind of defect.
I’ve noticed a similar issue with the LimeSDR mini.
I’ve tried LPF filters in GNURadio using gr-limesdr, to no effect.
here is a video i made going from 60mhz to 2ghz
lime mini is 50ohm terminated
https://www.youtube.com/watch?v=4CC682k7z5o&feature=youtu.be
en1gma - looks good. Still think that my board comes to me with defect. I have 4 other SDRs, including AirSPY and its ok, but LimeSDRMini doesn’t work properly at all.
Is there a chance to change board - anyone knows?