We report on a self-calibrated, swept frequency eddy current (SFEC) technique for characterization of surface conditions of materials such as residual stresses or service-induced degradation. We started with the lift-off normalized V-component signal technique, which was introduced to suppress the lift off noise and instrumentation effect. The technique was expanded to a wider frequency range by using multiple coils. Our theoretical study shows that the V-component signals are insensitive to coil dimensions, thus enabling multiple coil measurements in separate frequency bands, while yielding a continuous broad-band data. We demonstrate the technique on two surface-modified materials, namely Inconel 718 samples shot peened at 4A to 8A, and an Ag-1.5at%Al alloy subjected to surface oxidation. For each sample, the V-component signals measured using two dissimilar sets of coils and instruments were found to overlap, confirming that the signals are insensitive to coil dimensions and instrumentation. The bulk conductivities of the samples were determined by inverting the low frequency data. The bulk conductivities were then used to constrain model-based inversion of the high frequency data to obtain conductivity profiles from which the residual stress profile of the shot-peened Inconel 718 and the oxidization depth of the Ag-Al alloy can be inferred.