Ground Penetrating Radar systems generally comprise two main components:
- A control unit, usually including a rechargeable battery to power the system.
- An antenna.
Compact all-in-one systems are also available; however, as they are fixed, they cannot be modified to suit different types of survey.
For a successful GPR site survey, we firmly believe that the survey must be conducted by a suitably trained and experienced surveyor, using the most appropriate GPR equipment available.
The core of our equipment pool that we use daily includes, but is not limited to, the following:
GPR Control units
The control unit contains the electronics that generate and control the GPR pulse of electromagnetic energy waves that the system’s antenna sends into the sub-surface.
The control unit also includes an in-built computer, although some systems use an external laptop. This saves the GPR data generated by the antenna’s receiver on a hard-drive or solid-state memory.
Most control units include an integral display unit, which enables a visual means of configuring the system for the survey. It also displays the GPR data in real-time, enabling preliminary interpretation of the data on-site. This helps to ensure that the objectives of the survey are being met. More detailed analysis is generally undertaken off-site by uploading the saved data files and using specialist software to process and interpret the data.
GSSI SIR 4000 control unit
The SIR4000 is a GPR data acquisition system and control unit from GSSI designed to operate with analogue and digital antennas, including the latest dual frequency antennas. Other improvements over the SIR3000, which it replaces, include advanced display modes and filtering capabilities for ‘in-the-field’ processing and imaging.
GSSI SIR 3000 control unit
The SIR-3000 is a small, lightweight control unit compatible with all GSSI antennas and offers a flexible option for multi-application users.
- Lightweight and portable
- Rugged and weather-resistant construction
- Windows-based user interface
- High-resolution colour screen
- Use handheld or mounted on a cart
- Removable, rechargeable batteries
- Compatible with all GSSI antennas
- GPS integration
- Internal data storage and removable compact flash card memory
GSSI SIR 30 multi-channel control unit
The SIR-30 from GSSI is a multi-channel GPR system offering a number of advantages over single-channel systems such as the SIR-3000. As the name suggests, multi-channel allows several antennas to be used simultaneously; in the case of the SIR-30 up to 4 (although you can piggy-back two units giving a total of 8 channels). The SIR-30 also offers real-time data-processing including migration, surface positioning, signal floor tracking and adaptive background removal.
Ideal for high-speed data collection of measuring pavement layer thickness, detection of cavities, airport runway assessment, detection of fouled/clean ballast and utility detection.
GPR antennae
The antenna, comprising a transmitter and receiver, sends the GPR signal from the control unit into the sub-surface as a series of pulses. Reflections are produced from changes and features within the sub-surface. These reflections, together with amplitude information and time-travel information, are received by the receiver. The data is sent back to the control unit, where it is saved electronically and for most systems, displayed on an integral screen.
GPR scans can be undertaken using antennas with different central frequencies. The resolution and detail of GPR data increases with higher antenna frequencies; however, the depth of penetration decreases. As a general rule, it is desirable to use the highest frequency possible while still meeting the objectives of the survey. When undertaking site surveys, we carry a range of antennas which may be suitable for the conditions likely to be encountered. This enables us to select the most suitable antenna for the survey. We often scan using multiple frequencies to ensure the best possible data is recorded.
GSSI 2600 MHz high-resolution antenna
The 2600 MHz antenna is an ultra-high resolution antenna suitable for the inspection of concrete structures, the location of embedded rebar, post-tension cables and conduits.
Specification
- Centre Frequency: 2600 MHz
- Depth Range: 0-0.4 m (0-12 in)
- Weight: 1.8 kg (4 lbs)
- Dimensions: 3.8x10x16.5 cm (1.5x4x6.5 in)
- Model 52600S
- Manufactured by: GSSI
Uses
Typical applications for the 2.6GHz antennae include:
- Concrete floor slab surveys
- Locating services and conduits in concrete slabs
- Locating Tendon Ducts in Post-Tensioned Concrete
- Locating underfloor heating pipes
- On-site rebar location and mark-up surveys
- Rebar mapping and concrete imaging
- Void location in construction and below slabs
GSSI 2000 MHz Palm antenna
The Palm Antenna is the most compact GSSI antenna available to date. It measures only 104.5?91.5?154.7 mm enabling it to be used in very tight and confined spaces. It is particularly good at scanning into corners, against walls and around obstructions (it can scan to within 45mm of an obstruction).
The antenna includes a dedicated survey wheel (located to the rear of the antenna, a replaceable skid plate, and removable handle to reduce antenna height, if necessary.
Specification
- Centre Frequency: 2000 MHz
- Penetration Depth: up to 400mm
- Uses: rebar location/mapping and concrete investigation
- Manufactured by: GSSI
Uses
On-site the main benefit of this antenna over others of a similar frequency is its compact size. This makes it very useful for scanning in areas where access is restricted, or where obstructions, such as pipes, ornate mouldings, etc. are present. Typical applications for the GSSI 2000 MHz Palm antennae include:
- Locating embedded metal in masonry
- Locating Tendon Ducts in Post-Tensioned Concrete
- On-site rebar location and mark-up surveys
- Rebar mapping and concrete imaging
GSSI 1600 MHz antenna
The 1600 MHz antenna is a high-resolution, all-purpose antenna suitable for the inspection of concrete structures to locate/map rebar, post-tensioned tendons and conduits. It is typically used for general investigation works including floor slabs, walls, bridge decks and shallow void detection.
Specification
- Centre Frequency: 1600 MHz
- Penetration Depth: up to 500mm (in concrete)
- Uses: Rebar location/mapping, concrete investigation and shallow void detection
- Manufactured by: GSSI
Uses
Typical applications for the 600 MHz antennae include:
- Chimney flue location
- Concrete floor slab surveys
- Locating services and conduits in concrete slabs
- Locating embedded metal in masonry
- Locating Tendon Ducts in Post-Tensioned Concrete
- Locating underfloor heating pipes
- On-site rebar location and mark-up surveys
- Rebar mapping and concrete imaging
- Retaining wall surveys
- Void location in construction and below slabs
- Wall and slab thickness measurement
GSSI 900 MHz antenna
The 900 MHz antenna is suitable for numerous applications requiring shallow penetration down to 0.9 m, including void detection, concrete/construction thickness measurement and shallow utility location. It can also be used for location of deeper rebar.
Specification
- Centre Frequency: 900 MHz
- Penetration Depth: up to 900mm
- Uses: deeper rebar location/mapping, void detection, shallow utility
- Manufactured by: GSSI
Uses
Typical applications for the 900MHz antennae include:
- Chimney flue location
- Locating embedded metal in masonry
- Retaining wall surveys
- Void location in construction and below slabs
- Wall and slab thickness measurement
- Railway ballast thickness and evaluation
GSSI 400 MHz antenna
The 400 MHz antenna is most commonly used for detection and mapping of utilities, as well as shallow engineering and environmental applications.
Specification
Centre Frequency: 400 MHz
Penetration Depth: up to 2m
Uses: Utility, engineering, environmental, void detection
Manufactured by: GSS
Uses
Typical applications for the 400 MHz antennae include:
- Retaining wall surveys
- Void location in construction and below slabs
- Wall and slab thickness measurement
- Railway ballast thickness and evaluation
GSSI 300/800 MHz dual-frequency antenna
The 300/800MHz dual frequency (DF) antenna records two sets of data (one for each antenna frequency) enabling shallow and deeper targets to be detected at optimum resolution. The resolution and detail of GPR scan data decrease with lower antenna frequencies; it is, therefore, desirable to use the highest frequency possible, while still meeting the objectives of the survey. The data can be merged using Radan software to display both sets of data in a merged file making data analysis and interpretation easier and more efficient.
Specification
- Centre Frequencies: 300 and 800 MHz
- Penetration Depth: up to 4m
- Uses: utility surveys, archaeology, deep construction detail
- Manufactured by: GSSI
Uses
Typical applications for the 300/800 MHz dual-frequency antenna include:
- Retaining wall surveys
- Void location in construction and below slabs
- Wall and slab thickness measurement
- Railway ballast thickness and evaluation
GSSI 270 MHz antenna
The 270 MHz is suitable for detection and mapping of deeper utilities, as well as shallow engineering and environmental applications.
Specification
- Centre Frequency: 270 MHz
- Penetration Depth: up to 6m
- Uses: Utility, engineering, geotechnical
- Manufactured by: GSSI
All-in-one GPR systems
There is an increasing number of all-in-one GPR systems available. These typically house the control unit, antenna and power supply all in one unit. Because the component parts are all fixed, the main advantage of these systems is that they are mostly pre-configured and hence simple to use. They are, however, also very limiting. As the component parts are fixed, they lack versatility and components can’t be interchanged to suit site and survey conditions. For this reason, they tend to be one-trick ponies and are designed for a specific survey type.
GSSI UtilityScan DF
The GSSI UtilityScan DF is a dual-frequency GPR system designed for utility location. It features a digital dual-frequency antenna (300 and 800 MHz) allowing shallow and deep targets to be detected simultaneously with a single pass of the antenna. This reduces time on site, whilst at the same time improving utility detection rate.
Data Display
The UtilityScan DF has several modes to view the data in real-time during data collection:
- Split View – allows the two channels to be viewed simultaneously, aligned one above the other
- Blend Mode: This displays a multi-frequency data fusion in real time combining the high-resolution near-surface data (800MHz) with the lower depth detail (300MHz) in a single view
Flexibility
Although the UtilityScan DF is primarily designed for utility surveys, we are finding it useful for other GPR surveys such as:
- Detection of underground obstructions
- Locating underground voids, especially under concrete or asphalt pavements
- Burial sites
- Geological investigation
- Archaeology
Manufactured by: GSSI
StructureScan Mini 3D
The StructureScan Mini is an all-in-one GPR system for concrete inspection. With a 1.5GHz antenna, this handheld system is useful for rebar detection to depths of up to 400mm. Integral software on the 3D model provides a plan view of reinforcement (an x-ray like image). Our unit is mainly used by our Building Inspection department for rebar detection prior to coring, for which it is ideally suited.
Specification
- Centre Frequency: 1.5 GHz
- Penetration Depth: up to 400mm
- Uses: detection of rebar, conduits and post-tension cables
- Manufactured by: GSSI
GSSI StructureScan Mini XT
The StructureScan Mini XT? is an all-in-one GPR system for concrete inspection. With a 2700 MHz antenna, this handheld system is useful for rebar detection to depths of up to 400mm. Integral software on the 3D model provides a plan view of reinforcement. The system can also be used with the following add-on accessories: Palm XT external antenna, LineTrac XT, and an extension pole.
Specification
- Centre Frequency: 2700 MHz
- Penetration Depth: up to 350mm in concrete
- Uses: detection of rebar, conduits and post-tension cables, voids and slab thickness measurement
- Manufactured by: GSSI