CITS880s controlled impedance tester now features Launch Point Extrapolation (LPE) for fabricator-level instantaneous measurement and control on high-speed PCBs. LPE is a line-fit technique deployed on thinner traces which exhibit significant slope arising from DC and AC resistance along the trace. LPE “projects the impedance back” to a point close to the start of the trace where the influence of the DC and AC resistance on the measurement is minimal. In conjunction with 2D field solvers, is said to yield significant improvement in correlation between measured and modelled impedance. With high-speed IPS probes, tests trace lengths 2 to 3" shorter than previous versions. Outputs reports using novel software or in Excel-compatible format. 

Polar Instruments,  http://www.polarinstruments.com/