Our solutions are based on automatic data collection from VNA and our Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) routines. You may find more information in the following application note references.

"High-Speed Interconnection Characterization using Time Domain Network Analysis"
by Roger B. Marks, Donald C. DeGroot, and Jeffrey A. Jargon

"Optimizing Time-Domain Network Analysis"
by Donald C. DeGroot and Roger B. Marks