[adrian_b]

For someone making hobby electronics experiments, an FPGA can be used to make a cheap (but with modest performances) logic analyzer and digital oscilloscope (and test signal generator, if desired).

Many years ago, that would have been the only solution to avoid paying thousands of dollars for a professional instrument.

However, nowadays there exist a number of commercial solutions for such cheap instruments, which are made exactly like this, i.e. with an FPGA surrounded by appropriate I/O circuits and connectors, some USB or Ethernet interface for the PC and some capture software.

These have the advantage that are ready to use out of the box, but making yourself such an instrument can be instructive.