Ground Penetrating Radar (GPR) works by sending a tiny pulse of radio frequency energy into a material and recording the strength and the time required for the return of any reflected signal. A series of pulses along a line make up what is called a scan or radargram. Reflections are produced whenever the energy pulse enters into a material with different electrical conduction properties or dielectric permittivity from the material it left. The strength, or amplitude, of the reflection is determined by the contrast in the dielectric constants and conductivities of the two materials. This means that a pulse which moves from dry sand (dielectric of 5) to wet sand (dielectric of 30) will produce a very strong reflection, while moving from dry sand (5) to limestone (7) will produce a relatively weak reflection. This makes this method pratically suited to non-invasive void detection including under floor slabs, locating tomos, old mine workings and tunnel gullies.

Southern Geophysical Ltd has a wide range of GPR systems and over 20 years experience using systems from ultra high resolution systems for building inspection to very low frequency systems for deep mining applications. Southern Geophysical Ltd uses GPR for:

• Sinkhole & Void Locating
• Concrete Scanning
• Utility Locating
• Tank (UST) & Drum Locating
• Bridge Deck Inspection
• Balcony Inspection
• Golf Course Mapping
• Forensic (Grave) & Tunnel Mapping
• Deterioration Mapping
• Roadway Inspection

Ground penetrating radar is often referred to by other names depending on the service being undertaken. A few of the commonly used names are: Concrete scanning, concrete X-Ray, GPR NDT, underground utility locating.