[SOLVED] adjusting start/stop frequency in the software

rsugden

Hello,
I am using an openQCM-Q device to measure viscosity as a function of change in frequency and density. I am currently trying to measure glycerine but the expected drop in frequency is somewhere in the ballpark of 44KHz which is well below the starting (lowest) frequency in the measurement range. Ignorant to this problem, I tried anyway and got data that became strange and periodic around that lower limit. Is there a way to adjust the measurement range so it includes the expected frequency after the target drop?
Thanks a bunch,
Rick

marco.mauro

Hi Rick,

there is a way to change or adjust the measurement range, that is by changing the lower frequency of the frequency sweep range.

It is necessary to do that by slightly change the python code.
Browse to the openQCM Q-1 directory

...\openQCM_Q-1_py_v2.1\OPENQCM\openQCM\core

and open the file constants.py

Here the piece of code you need to modify for changing the lower frequency of the sweep range for the fundamental frequency:

#--------------
# 10MHz
#--------------
# left and right frequencies
########################################
# MODIFY THE SWEEP PARAMETER HERE
########################################
L10_fundamental = 7500 # change lower frequency sweep
R10_fundamental = 2500 

you need to adjust the frequency sweep range with the variation of 44KHz you expect for glycerol

rsugden

Thank you Marco!

marco.mauro

you're welcome, please let me know if the patch works fine for you

rsugden

Although I'm not completely sure what the 7500 represents, I increased it by a lot and I was able to get readings for the range i wanted.
thanks again

marco.mauro

thank you for the feedback
L10_fundamental parameter is the left frequency side starting from the peak frequency.