Frequently Asked Questions

As a safe and non-disruptive method, GPR is the ideal way to investigate the subsurface for a wide range of applications. Deploying GPR in the field is easy and sites can be scanned quickly, making it an economical option as well.

Originally started as a non-destructive technique for geophysical investigations, GPR can be used to gain information about what lies beneath the earth's surface and to non-destructively detect and map both natural geological features and man-made buried infrastructure.

• Efficient: Quick to deploy, easy to operate, with fast results
• Safe: Non-intrusive and non-disruptive
• Versatile:
• Works through any penetrable medium
• Can detect both metallic and non-metallic objects/features
• Only requires single-sided access to investigate man-made infrastructure man

GPR works by transmitting a small pulse of ultra-wideband (UWB) electromagnetic energy to the material being investigated and then recording the time it takes to return some or all of that energy, along with a measure of the signal strength.

A GPR antenna, containing both transmitting and receiving elements, is placed on or very close to the surface of the ground (or material under investigation) and moved across it to scan the area.

By continuously transmitting pulses and recording the associated returns, a radargram image of the subsurface can be generated and displayed in real time on a suitable display (PC/tablet).

Changes in the composition of the subsurface can be seen based on air, mineral and water content, the presence of bedrock or other geological features, and objects such as buried utility lines.

GPR can be used for a wide range of applications.

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GPR signal penetration depends on the electrical properties of the soil or penetrable material under investigation, as well as other variables including antenna frequency. Depth range will decrease when there is an increase in electrical conductivity, as is often associated with clay-rich soils and higher moisture content.

Antenna Frequency – Lower frequencies penetrate deeper (due to longer wavelength) but offer less resolution in shallower layers. Higher frequencies provide higher resolution in shallow layers but do not penetrate as deeply.

Soil/Terrain Properties – GPR signal penetration is affected by the dielectric properties of the subsurface layers. It is difficult to estimate actual depth penetration for a given site until you are there. GPR works best in high resistivity soils with no conductive layers. Just like a sheet of paper right in front of your eyes can block your view, a thin layer of electrically conductive material underground can block the GPR signal. For example, dry sandy/gravelly soils are relatively “good” for GPR, while clay soils are not. Even with dry soil composed primarily of sand/gravel, a thin layer of clay within the nearby surface can negatively affect GPR signal penetration.

Water The presence and amount of moisture in the underground layers also has an impact on GPR signal performance. Dry soils are more favorable for GPR, while wet soils become more challenging. Saturated clay soil can make GPR nearly impossible.

A good tip is to use the lowest frequency possible to resolve what you want to see. A high frequency will cause reflections from smaller targets and this will make the radar image harder to interpret. This is often referred to as "clutter."

GPR does not pose any health threat. The use of GPR and the associated permissible radiated emissions are regulated in all major markets and ImpulseRadar systems are certified to the latest international CE, FCC and IC standards.

All GPR systems need to sample analog signals from the antenna and digitize them for processing and display. The sampling method, as well as the rate at which samples are taken, can significantly affect the quality of the results. Therefore, the sampling rate is an important specification that determines the performance of the system.

Traditionally, GPR systems use a technique called 'equivalent time sampling', which requires a new pulse to be sent from the transmitting antenna for each sample recorded at the receiver end. Systems that use this method are commonly referred to as conventional GPR.

However, modern components now allow a technique called real-time sampling or RTS to be used, and this is the method used in ImpulseRadar designs. As the name implies, it means that the 'real' signal is captured directly and, in stark contrast to conventional systems, does not require the transmission-recording cycle to be repeated. The result is a GPR system that collects data thousands of times faster than a conventional one.