source code from : http://gitlab.oe5xbl.ampr.org/oe5hpm/dxlAPRS
commit ID        : 6f75aa58501eab7dd8b04fc5324f169882bd28b8
title            : add fsk4rx and ra02waterfall
Signed-off-by: Hannes Schmelzer <oe5hpm@oevsv.at>
add fsk4rx and ra02waterfall Signed-off-by: Hannes Schmelzer <oe5hpm@oevsv.at>