OT: Software measuring S/N and signal strength thru soundcard?

[TF3KX]

In comparing antennas it would be nice to be able to run signals from the RX to a soundcard, and do analysis of signal strengths and S/N.  Numerical data would give more info than comparing by ear.

Actually, the K2 with its two antenna inputs is an ideal rig to this kind of experiments.  Any suggestions for such software?

73 - Kristinn, TF3KX