you are in a folder where you don’t have write permission.
to get back to the home directory you should have write permissions there.
then run the wget command again and follow the instructions.
i don’t particularly like the gain script.
i would use the tabular display of your local map
Sort the planes by RSSI by clicking on the column head (twice or until it’s sorted with values closer to 0 at the top)
The closer to 0 a value is the stronger the signal.
Make sure not too many have a value > -3
If you have no planes > -6 or so just go ahead and increase the gain.
Now if you have sometimes low traffic coming close by (general aviation for example)
their signal might become too strong.
So if on the map you use the button “show all track” and some low level tracks are interrupted near the receiver that’s a good hint that your gain was too high to receive them.
(assuming they didn’t duck behind a hill or something)