low pass equivalent processing is a method for use with a network analyzer , that gethers a sequence of ndata samples , each sample including real and imaginary components of a signal , over a frequency range from f1 to f2 in frequency steps of /, where f1 is greater than zero . the sequence of samples is processed to estimate a characteristic of the signal with respect to a selected discontinuity in the signal . the sequence of samples is converted to time domain , to generate time domain data over a range from zero to t . the selected discontinuity is identified as lying within a range of t1 to t2 . next , the phase of the time domain data is unwound to correct a portion of the phase error resulting from the one sided spectrum that is not dependent on the distance to the discontinuity through the network . next , the magnitude peak jmax of the data samples between time range t1 to t2 , is determined . the phase angles of the data at two points removed from the magnitude jmax by a number of data points dependent on the type of biasing window used in measurement of the data are used to determine a slope through jmax . from this information , an estimate is made of the location of the discontinuity in the network . the phase of the time domain data is unwrapped in response to that estimate of location according to an empirically derived equation .