Frequently Asked Questions

What is GPR?

GPR is an acronym for Ground Penetrating Radar, and as the name implies, it’s a radar system that you use to image the subsurface. It may be used on a host of different penetrable materials to detect and map features or objects within.

The technology has been widely accepted and is routinely used for various applications such as mapping utilities, bedrock, cavities/sinkholes, archaeological artifacts, and groundwater levels.

More recently, it has found use in military/ counter-terrorist, law enforcement, and search-and-rescue applications.
Other common names for GPR include impulse radar, geo radar, and ultra-wideband radar.

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Why use GPR?

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 rapidly, which also makes it an economical choice.

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

  • Safe – non-intrusive and non-disruptive
  • Efficient – quick to deploy, easy to operate, with rapid results
  • Versatile:
    – works through any penetrable media

    – can detect both metallic and non-metallic objects/ features

    – only requires single-sided access to investigate man-made infrastructure

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How does GPR work?

GPR works by transmitting a small pulse of ultra-wide band (UWB) electromagnetic energy into the material under investigation and then records the time it takes for some or all of that energy to be returned, along with a measure of its signal strength.

A GPR antenna, which contains both transmitting and receiving elements, is placed on, or very near 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 viewed in real-time on a suitable screen (pc/ tablet).

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

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What can GPR be used for?

GPR can be used for a broad range of applications.

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How deep can GPR detect?

GPR signal penetration is contingent upon the electrical properties of the ground 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 typically 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 don’t penetrate as deep.

– Ground/ soil properties – GPR signal penetration is affected by the dielectric properties of subsurface layers. It’s hard to estimate actual depth penetration for any given site until you are there. GPR works best in high resistive soils absent of 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/ gravely soils are relatively “good” for GPR, while clay-based soils are not. Even with dry ground composed of mostly sand/ gravel, a thin clay layer within the near surface can negatively affect GPR signal penetration.

– Water the presence and amount of moisture in sub-surface 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 almost impossible.

What frequency should I use?

A good advice is to use the lowest frequency possible for resolving what you want to see. A high frequency will cause reflections from smaller targets and this will make the radar image more difficult to interpret. This is often referred to as “clutter”.

How much does a GPR system cost?

Are you interested in budgetary pricing or a formal quotation? Use the contact form on our Contact Us page and one of our sales representatives will be in touch.

Is GPR dangerous?

GPR doesn’t pose any health threats. The use of GPR and the associated permissible radiated emissions are regulated in all significant markets and ImpulseRadar systems are certified to the latest international standards of CE, FCC and IC.

What are the benefits of Real-Time Sampling (RTS) technology?

All GPR systems need to sample analogue 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 results. Therefore, the sampling rate is an important specification that determines system performance.

Traditionally, GPR systems utilize a technique called ‘equivalent time-sampling,’ which requires a new pulse to be sent from the transmitting antenna for every sample recorded on the receiver end. Systems using this method are commonly known as conventional GPR.

However, modern components now make it possible to use a technique called real-time sampling or RTS, and this is the method used in ImpulseRadar designs. As the name implies, it means that the ‘real’ signal is captured directly, and in sharp contrast to conventional systems, it does not require repetition of the transmission-recording cycle. The result is a GPR system that gathers data thousands of times faster than a conventional one.

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Do you still have any questions?