Fecha de publicación: -- Fuente: Wipo "digitalization" A digital filtering system is provided for communicating and processing signals using a digital filter for signal separation and signal enhancement. A digital correlator is provided for generating high resolution output data in response to low resolution input data processed with low resolution computational circuits. In one embodiment, a real-time time-domain correlator is provided with single-bit resolution computational elements to implement the correlation filtering operation. Use of the high speed real-time correlator of the present invention permits further enhancement of signals with the capability of compositing-after-correlation and with the capability of correlation using a plurality of correlation operators. Particular advantages are achieved with the use of the real-time correlator in a geophysical exploration system embodiment and in a communication embodiment. Systems applications of the digital filter includes a communications modem for modulating and demodulating chirp signals to enhance data communication and compositing-after-correlation in a geophysical exploration system. Detailed circuitry is provided to implement such systems including an improved chirp signal generator, a multi-chirp signal generator, a chirp modulator, and a correlation demodulator.