The antenna described in the previous post and the preliminary results encouraged me to get the thing on the roof. April 1st (no joke!) seemed the right time. Hardly any rain according to the radar. So i filled the bag with tools, tape and tywraps and… the gateway with the antenna. After some nerve-racking moves i found myself on the flat roof of our house. Then it started raining.
I could use the left over PVC pole of the ADSB antenna which moved to a higher spot two years ago. After some 20 minutes it was time for the photo shoot and safely move back in, all drenched. But excited to see if my gateway would be back online.
Now, with the gear on the roof it’s time to drive around and check the new coverage. Thing look good, very good! But how to compare the current coverage with the previous?
Plotting with Basemap and Python
I decided to dive into the world of map plotting using Python. Mathplotlib and Basemap appear to be the defacto standard. So i installed both and managed to follow the guide from http://introtopython.org/visualization_earthquakes.html. Then i downloaded the CSV data for my tracker node from TTNMapper.org for the past 2 weeks and filtered that data to my gateway. I downloaded a comparison dataset for the testdrive i just did and plotted RSSI radials for both datasets on the map. Compare the results:
Well worth the trouble i think! I did the same, now for the SNR values (ranging from -5 to +5 dB in steps of 2 dB). As expected the results are quite comparable.
Now let’s hope the Scotchfil will keep the rain from the cable…