What is the difference between frequency and time domain GPR systems?
Frequency and time domain GPRs are in principle no different and in a perfect world would yield identical results. The reason that there are two different types of systems stems from various approaches of capturing wide band transient signals when direct capture is not electronically possible (A/D converters are not yet fast enough for most GPR applications). The result is a bunch of electronic mumbo jumbo that confuses non-electronic specialists. In the frequency domain, the signals are emitted as a sinusoidal wave. The response, as the frequency of the sinusoid changes over a given bandwidth, is extracted. The transfer function is measured by heterodyning or mixing techniques. By suitable signal manipulation (Fourier transform) echo strength versus delay time is extracted. These methods of implementation are called FM-CW and step frequency radars. In the time domain, all frequencies are emitted essentially at the same time and they constructively interfere to give pulses and create d
