It was a nice surprise to get an SSTV picture from the ISS on its 6:43p.m. pass.
The data compression might account for some of the patterning on the picture.
The transmissions are on the usual downlink frequency of 145.800MHz. You can read about how to do it on the AMSAT website here. But you don't need anything more sophisticated than a scanning receiver speaker output connected to the sound card line input. I just use my normal "white stick" colinear antenna, but a 1/4 whip, or even a rubber duck should pick something up.
I use the Orbital Prediction Page on the AMSAT website to find out when the ISS is coming over.