usage examples:
osmocom_fft -a "rtl=0" -f 100e6 -s 2.4e6 -g 15
osmocom_siggen_gui -a "hackrf=0" -s 5e6 -f 100e6 --sine
osmocom_siggen_gui -a "hackrf=0" -s 5e6 -f 100e6 --sweep -x 2M -y 1 -c34
known issues:
- switching between siggen modes is broken at the moment (WIP) and has
to be made via cli switches only.
- filter bandwidth controls have no effect for TX (this has to be
investigated)
