Single-channel, single-frequency is the most common type of GPR. A transmitter antenna sends a short pulse of electromagnetic radiation at one given frequency (with some bandwidth around it). The pulse travels through the material until it finds another material with different dielectric properties. A fraction of the pulse is reflected backwards and returns to the receiver antenna. The amplitude, polarization and travel time of the pulse is measured by the receiver, displayed and stored by the control unit.
Penetration depth from the subsurface depends on the signal frequency and conductivity of the subsurface material (conductive materials attenuate more the radio signals). The velocity and attenuation of a propagated wave signal relies on the frequency of the transmitter (soils and rock are dispersive in nature, especially in the low frequency range).
Once field data is collected, processing and interpretation are conducted to address the problem that required GPR surveying. After exporting files from a GPR system to a desktop computer, profiles can be viewed and processed to extract the desired information. The processed wave record is represented by a narrow vertical data-column with amplitudes converted into colors known as a radargram. Basically, a radargram is a color image into which the reflected signals are converted using preprocessing amplification gains to enhance the image readability. Reflection shapes, location of anomalies, contrast and color intensity are the important elements used in the interpretation.