Before modern applied sciences took part in the creation of complex machinery, land surveying techniques required manual excavation, which often harmed the condition of the prospected subsurface.
Enter Ground Penetrating Radar (GPR), a non-invasive subsurface location equipment that transmits reflected signals from the ground to a digital media receiver.
Understanding the Anatomy of a GPR System
Total Scan & Survey says a GPR system holds five main components that interact with each other depending on their functionality. The location of these components depends on the type of system and application intended for its use.
- Encoder – The encoder measures the distance to a targeted area and triggers the pulse for the radar signal at varying distances. It is a mechanical device that resembles a wheel.
- A/D Converter – The A/D converter bridges the data between the GPR antennas and the control unit. It is also responsible for connecting the encoder from where it receives a pulse trigger.
- PC / Monitor – The PC / monitor reflects the GPR information in real time and enables the user to save, operate and analyse the gathered data.
- Control Unit – As the name suggests, the control unit is where the central processing of a GPR system happens. It is responsible for coordinating all the processes of the GPR components together.
- Antennas – While the control unit does all the data processing, the antennas act as its legs to feed information to the GPR. As a rule of thumb, the higher antenna frequency set, the better the resolution, but at the cost of depth penetration.
The Nonconductive Detection Capability
The primary advantage of GPR against traditional subsurface location technique is the ability to locate metallic and non-metallic objects alike.
GPR works by sending radar pulses into a subsurface material and recording its strength feedback time. With this, the equipment can track the location and depth of an object deep within a buried subsurface. Other benefits of GPR include:
- Smooth facilitation of large areas
- Single person operation requirement
- Avoidance of misplaced excavations
An In-depth Look at GPR Scanning
The depth reach of GPR unit depends on three factors:
- Subsurface/ soil type
- Antenna setting
- Size of targeted surface
A GPR can penetrate ice, rock, soil and asphalt, but will have a different result because each type of a subsurface conducts frequencies differently. Lower frequency antenna setting penetrates deep into a subsurface, but there will be a loss in resolution.
Whatever the purpose of a land survey is, it’s necessary to try less invasive approach first to prevent unneeded and harmful excavations from happening.