Vector Network Analyzer

[marukqs]

Hi,

I would like to use LimeSDR as HF,VHF,UHF antenna analyzer. I have ordered SWR Reflection Bridge from ebay.

Now I have a few questions regarding this script before I have started to experiment:

1) this script uploads HEX code to LimeSDR. Is it possible to brick the board if something goes wrong during the HEX file upload?
2) is it possible to select specific TX and RX antennas? (e.g., I need to select LNAL for RX)
3) how to select specific frequency range?

73,
Marijus

[andrewback]

HI @marukqs, just received back answers to your questions from the engineering team:

The HEX file is loaded to SRAM of LMS7002M microcontroller, so it can't brick the board.

Yes, it is possible to change TX and RX channels:

RX channel can be changed in line 16:
LNA = 'LNAH'
Change it to
LNA = 'LNAL'
to use LNAL.

TX channel is selected in lines 205 and 206:
TRF.SEL_BAND1_TRF = 0
TRF.SEL_BAND2_TRF = 1
Change it to
TRF.SEL_BAND1_TRF = 1
TRF.SEL_BAND2_TRF = 0
to get the low frequency output.

Frequency band can be selected by changing the starFreq, endFreq and nPoints:
startFreq= 2.30e9
endFreq = 2.6e9
nPoints = 101

[jkassot]

Hi Andrew,
I got my LimeSDR a couple of days ago and I am trying to install cyLimeLib in order to run the VNA utils.
I am using 64-bit Win 10. When I try to install the Lib by running setup.py, I get an error:
from Cython.Distutils import build_ext
No module named Cython.Distutils
See below screenshot:

Any idea what the problem is?

Thanks,

Ioannis

[M0GLO]

Locate the Python libraries and add them to your path, that should help.

[jkassot]

I installed the Microsoft Visual C++ Compiler for Python at my windows 10.
However, I cannot find the Cython library to include in the Python Path and import it.
Is it hidden somewhere? Or am I missing another dependency?

Thanks!

Update: Never mind I got Cython install with pip command.
I thought that pip worked only in Linux, but apparently there is a pip.exe.
Once I put pip.exe in the Path, it run and unstalled the missing libs.

Thanks!!

[marukqs]

Hello,

if I set the frequencies lower than 240 MHZ, I get the following error:

ValueError: Not Valid LO Frequency. 240 MHz< FLO < 3.8 GHz_

To resolve this, I have tried to remove this limit in LMS7002_SX.py - but then things get more complex, related to frequency divider coefficients.

How can I set frequencies lower than 240MHz (e.g., I need to TX on HF as low as 3.5 MHz)?

[marukqs]

I did the following modifications for LMS7002_SX and it is transmitting something

Line 1056:

 if not (3.0e6<=F_LO<=3.8e9):
             raise ValueError("Not Valid LO Frequency. 3 MHz< F_LO < 3.8 GHz")

and in measureVNA.py on line 196 I have changed NCOFreq from 100e3 to 100

However I still cannot get start scanning from 3MHz.

[jkassot]

I successfully run measureVNA.py and calculateVNA.py which stored .s1p values in a text file
Then, I tried to use the -plot switch to get the data plotted.

Unfortunately, I got the following error:

If instead of 'plot' switch , I use 'plotFig' switch as I can read in the calculateVNA code, I get no fault, the program terminates with exit code (0), but no plots displayed on screen or stored in a file.

Any idea what is wrong?

[Axeman]

Try python3 calculate...

[jkassot]

I suspected that it may require Python 3.
I am using Win10 and I tried installing numpy at python 3.5 and 3.6 , but it failed in both cases.
Without numpy cannot run the VNA programs.
However, numpy installs OK for Python 2.7 under Win10.
Does anybody know which Python 3 and Numpy versions are compatible under Win10 -64?

[Axeman]

This version of pySmithPlot has a fix for the syntax error. I was able to use it on Linux.

[jkassot]

Thanks!
It also works on Win10 and Python 2.7