Gated Cross Correlation Velocity: A Breakthrough Technology for Wastewater Flow Management

Recent years have brought increasing regulatory pressure on wastewater system operators, in turn causing an increased reliance on flow monitoring to understand actual system flows and hydraulic performance.The most recent advancement in velocity technology is based on gated cross-correlation, which operates in the “time domain” rather than the “frequency” domain used by Doppler based technology flow meters. The cross-correlation technology is a mathematically simpler and more reliable calculation than Doppler technology, but it was not practical in flow meters until the recent advancements in Digital Signal Processing (DSP) power in microchips.This paper will discuss both Doppler and Cross-correlation technologies and explain why crosscorrelation is superior in many applications. Data will be presented from the first three (3) North American installations of this technology. Accuracy has been independently verified by the end users to be within 1.1%, 2.6%, and 7.0% of true flows at each of the three installations.