A filtering system is provided for acquiring and processing signals using a sampled filter for signal separation and signal enhancement; such as for determing locations, distances, and times in a geophysical exploration system. Signature signals permit mixing and seperation with sampled filters, such as for sharing common circuitry and for increasing the amount of acquired information. A sampled filter, such as a digital correlator, is provided for generating high resolution output data in response to low resolution input data processed with low resolution computation circuits. A real-time time-domain correlator is provided with single-bit resolution computational elements to provide improved correclation filtering. A high speed real-time correlator is provided to enhance signals with copositing-after-correlation and with correlation using a plurality of correlation operators.