On Walter's request, his cross talk example to accompany the cross talk BIRD has been posted on the ATM web site: http://www.vhdl.org/pub/ibis/macromodel_wip/archive/20110308/walterkatz/ Impulse%20Crosstalk%20Matrix%20Explanation%20Using%20Touchstone%20Exampl e/Crosstalk.pdf Enjoy! Arpad ================================================