Spectran is a program to do real time or deferred spectral analysis / waterfall display, in addition to real time audio filtering (band pass, denoising, band reject and CW peaking) of audio signals, using the PC sound card to digitize the input analog signal, or taking as input a WAV file. Its characteristics are well suited to dig weak signals buried into noise, thanks to a selectable bin size down to 21 millihertz. On the opposite site, it can visualize normal CW signals, resolving individual dots and dashes (with a reasonably fast PC).