Abstract: Methods and apparatuses are described for detecting volumetric moisture content and conductivity in various media based on a time-domain reflectometry (TDR) system wherein successive fast transitions are injected into a transmission line immersed in a medium of interest, and a characteristic received waveform is digitized and analyzed by continuously sampling multiple received waveforms at short time intervals. One method transmits a timing signal along a shielded transmission line while a coincident signal is transmitted through the medium of interest. Another method propagates the waveform along a transmission line, that may be either shorted or open-ended, and observes a reflected, rather than transmitted, waveform with a receiver connected to the same end of the transmission line as the transmitter.