Abstract: Disclosed is a method of determining subsurface temperatures of a surveyed region. The method comprises using a transmitter to transmit a pulsed electromagnetic signal into the ground; using a receiver to detect a return signal following interaction of said transmitted signal with features of the subsurface and determining one or more temperatures within the subsurface from the return signal. The temperature may be determined from a dielectric constant of a subsurface region, as determined from the received signal.

Abstract: Disclosed is a method of, and computer program and apparatus for, identifying reflected signals, subsequent to their reflection within a medium. The method comprises obtaining return signals (100), resulting from measurements being performed over a measurement period. The measurement period comprises sub-periods, the return signals comprising reflected signals and noise. The plurality of return signals are partitioned into plural sets (220) of equal cardinality or as equal as possible such that their cardinality differs by no more than one. A stacked correlation value is determined (130) for the return signals by determining the mean of the return signals across the plural sets (230) and determining a correlation value of the plural sets over each of the time sub-periods (240). Peaks in the variation of the stacked correlation value over time can then be identified and each of the peaks in the variation of the stacked correlation value over time can be attributed to a reflected signal.

Abstract: Disclosed is a method of determining subsurface temperatures of a surveyed region. The method comprises using a transmitter to transmit a pulsed electromagnetic signal into the ground; using a receiver to detect a return signal following interaction of said transmitted signal with features of the subsurface and determining one or more temperatures within the subsurface from the return signal. The temperature may be determined from a dielectric constant of a subsurface region, as determined from the received signal.

Abstract: Disclosed is a method of, and computer program and apparatus for, identifying reflected signals, subsequent to their reflection within a medium. The method comprises obtaining return signals (100), resulting from measurements being performed over a measurement period. The measurement period comprises sub-periods, the return signals comprising reflected signals and noise. The plurality of return signals are partitioned into plural sets (220) of equal cardinality or as equal as possible such that their cardinality differs by no more than one. A stacked correlation value is determined (130) for the return signals by determining the mean of the return signals across the plural sets (230) and determining a correlation value of the plural sets over each of the time sub-periods (240). Peaks in the variation of the stacked correlation value over time can then be identified and each of the peaks in the variation of the stacked correlation value over time can be attributed to a reflected signal.