Spectrum display configuration

ShowSpectrum (s) (`spectrum`)

If set to a value spectrum >= 0, the spectrum mode is started after reboot (otherwise, the scan mode).

If spectrum > 0, the spectrum display will be active only for spectrum seconds and then automatically switch to scan mode.

Set to -1 to disable spectrum display

Starting frequency in MHz, usually 400 MHz

Configuration value for RXBW during spectrum recording (needs additional testing, probably we should (also) set AGCBW?)

Display MHz values (start, end) in display in spectrum mode

RSSI value at bottom edge of display