Correlation of interpolated time delayed communication signals

Correlation of a narrow bandwidth communication signal, uniformly sampled at separate receive sites, yields time-difference-of-arrival (TDOA) resolutions to one-half the sample-to-sample spacing. An interpolation scheme must be employed if smaller resolutions are required. Interpolation may be applied to the correlation envelope or as analyzed in this paper to intra-sample shift of one of the complex time waveforms. The magnitude of the correlation and position of the shift at the correlation maximum provide a quantitative measure of the interpolation scheme. The magnitude of the correlation coefficient is converted to an equivalent signal-to-noise (ESNR) for comparisons with conventional SNR measurements. The data presented uses interpolated samples that were generated by a short sum of adjacent sample sinc function products.