Many people get their start with the radio waves by plugging in an inexpensive RTL-SDR into their computer. Others use these to monitor satellites and scan the bands for DX, or as a home APRS receiver. Maybe you have some big iron, like a Flex Radio. Discuss them all here in the SDR category.
The beauty of SDR is that software processes the signal vs hardware, and as such, can be updated if there are issues. SDR is the radio of the future, but here now.