Thanks @euquiq for a more common solution to the bug.
Added RX gain control.
Now we have full gain controls!
Merged PTT and Voice activation into one option selector.(allowing RIGHT BUTTON to work with PTT off)
A bug that enabling audio RX resets the TX gain (perhaps because that changing to receiving mode modifies some registers) inspired me to add this gain control.
Commented out some steps which don't require for the VU meter to work again.
Moved some widgets for gain control.
Added CRC calculation for Vaisala radiosondes.
Added a Checkbox on APP for turning ON / OFF CRC. When CRC on, malformed packets are ignored.
Connected existing CRC function for METEOMAN sondes, using the same "CRC" checkbox logic.
Added the Vaisala RS41 data packet decoding.
Changed the default freq from 402.0 to 402.7 Mhz, since it is more popular freq.
Lowered the frequency stepping, so it is easier to fine-tune the exact freq center, if needed.
Sonde's Serial ID is passed into the VIEW MAP, so now the sonde is labelled on the map.
Earlier code did not start with squelch totally open, but a tiny bit closed. (now at app loading, squelch is truly set up with the same value it shows on screen).
I also hardcoded the NFM sampling rate and baseband bandwidth. It seemed "the right thing to do".
You can enable RX and adjust VOLUME and SQUELCH into your liking.
Sadly enough, you will NOT be able to use VOICE ACTIVATION when RX is enabled (to ensure there will be NO audio feedback defeating the VA sensing)
A "bug" that won over me, but perhaps and hopefully other coder can easily fix: The Vumeter will momentarily "dissappear" when enabling RX. But it will reappear as soon as you start TX. Or when you turn off RX.
I enabled the PEAK LEVEL MARK on the Vumeter, so you can easily see in which level your input voice / signal is peaking and regulate the MIC gain accordingly in an easier / more robust way.
Side enhancement: Took off the dark green, yellow and red coloring from the vumeter when no signal is present, and replaced it with dark_grey. I know that some coloring is "eye-candy" but the vu-meter is more readable with this new contrast.
The file rename function needs to be called with full_path/old_name and full_path/new_name.
Instead, it was called with full_path/old_name and new_name ... thus the renamed file ended on the root dir (path not preserved).
Squelch value now goes from -90 to +20 and it's directly compared against the max_db parameter returned from each freq scanned by the radio subsystem, with no adjusts or manipulation (you adjust the number as will be used).
Less squelch means weaker signals will trigger it. (as expected).
There was a tiny cosmetic bug when you deleted a frequency from the scanning memory: The description was not erased from screen and you could see it while the scan did not resume.
There was another bug on the pause button: If you asked for another manual scan range when paused, the button kept the text "RESUME" (its text was not reset to "PAUSE" again).
