Limesdr mini frequency tune offset out of specifications

General Discussion
1

Hi all, i’m Andrea

My limesdr mini works great but i cannot solve this issue :
A carrier exactly at 200.000.000 Hz (± 10 Hz) is tuned by my lime
at 200.003.100 Hz. This big offset is almost temperature independent
the spec. says max ±4 ppm so ± 800 Hz @200 Mhz …

I consider this an issue, maybe relating to some missing calibration

I have experimented this with SDRConsole 3 windows and using the ExtIO driver with HDSdr

LimeQuickTest shows all test passed.

My Gateware is 1.29

I have not found any information on how to calibrate the frequency of the master oscillator.

Somone can help me on how to solve this ?

thank you in advance
kind regards
Andrea

2

Hi all again
After some further researches and test i found a solution !

There is a parameter called ADC found on LimeSuite GUI
under ‘Modules’ / ‘Board Control’
This parameter calibrates the internal VCTCXO.
I have found this informations in
https://wiki.myriadrf.org/Getting_Started_with_LimeSDR-USB_and_LimeSuiteGUI
section 12.3 T uning VCTCXO Using DAC
The “Board Related Controls” window interface for LimeSDR mini
is slight different but the meaning of DAC parameter is the same
On my board setting this DAC = 163 solves my issues.

Finally my 200.000.000 Hz reference is tuned by my lime at (almost) 200.000.000 Hz :slight_smile:

Andrea

1 Like