How do you plot negatives values in Polar Graph?

eze.manoukian · October 8, 2023, 6:55am

Hi everyone! First of all, thank you for your amazing job with the Kraken SDR, I’ve been using it for a month, and i have a doubt with the Polar plot.
I have a personal Api, that obtain the data from Kraken HTML page at “http://PI4_IP_ADDR:8081/DOA_value.html”.
As you describe:

“18-377. Full 360 degrees DOA output. First element specifies DOA power output at 0 degrees, second element power at 1 degrees etc. NOTE: Uses unit circle convention, so due EAST is classed as 0 degrees, NORTH 90 degrees and so on. Needs to be rotated into compass convention.” *

If I plot the 360 dB Values in a Polar Graph. I get the same plot as in “http://PI4_IP_ADDR:8080/doa”, but the problem is that I don’t have negatives values in the plot as you have (higher negative value in the center and 0 dB in the outter circunference.
So i came with a solution, I convert all 360 values to negative values. That fixed the axis problem with negative values, but the plot that i get it’s not like the one you draw.
So my question is, how do you plot it with that values? Am I doing something wrong?
I attach some examples of my tests.
Thank you all in advance.

krakenrf_carl · October 10, 2023, 1:49am

I don’t think there’s any problem with your left graph, it’s fine to specify the axes like that.

In Dash scattergl just normalizes it with zero on the outer edge for whatever reason.

eze.manoukian · October 10, 2023, 3:37pm

Thank you for your answer. I think i get it.
You took the max dB power of the 360 elements, thats your max value (0 dB), then you substract this maxvalue to the others.
Doing that, i get the same plot with the negative axes as you do.
Thanks for your help.