What is GPS/GNSS surveying?
As surveying equipment and software has become more intuitive and easy to use, many construction firms are bringing construction and building layout in-house on their jobsites, saving valuable time and money.
Global Positioning Systems (GPS) – or Global Navigation Satellite Systems (GNSS) as they are called today – are space-based satellite navigation systems that provide location and time information anywhere where there is an unobstructed line of sight to four or more GPS/GNSS satellites. The GPS system is maintained by the government and can be freely accessed by anyone with a GPS receiver.
GPS/GNSS surveys use signals transmitted by satellites with trajectories such that any point on the Earth’s surface can be determined at any time, in any weather conditions. The positioning accuracy depends on the type of GNSS receiver, and on the observation and processing techniques used.
Survey-grade GNSS receivers are very accurate and used to position survey markers, as well as in building and road construction. These dual-frequency receivers are capable of achieving accuracy of relative positioning down to a cm-level.
The two types of GPS/GNSS surveying are real time kinematic (RTK) and static GPS.
Real time kinematic (RTK) satellite navigation, most commonly used in land surveying, is a technique used to provide real-time corrections and up to centimeter-level accuracy.
Static GPS surveying typically uses a network or multiple baseline approach for positioning and may include multiple receivers, baselines, observational redundancies and sessions. Though this method provides the highest level of accuracy, it requires the longest observation times (anywhere from under one hour to five hours or more).
What Accessories Are Used with GPS/GNSS Equipment?
• Tribrachs/Adapters and Carriers
• External Antennas
• Data Storage
• Rover Rods
What is the advantage of GPS/GNSS surveying?
The advantage of GPS/GNSS compared with the use of a total station is that with GNSS surveying, the points to be measured do not have to be manually visible. If the sky is relatively unobstructed (by trees, buildings, etc.) and adequate satellite signals can be received, GNSS equipment can be applied to many survey tasks traditionally carried out with electronic total stations.
GNSS Reference Stations
Also known as a Continuously Operating Reference Station (CORS), a GNSS reference station is typically a multi-frequency GNSS receiver located at known coordinates, supplied with permanent power and connected to several communication devices.
A CORS typically logs GNSS data for use in post-processing tasks or supplies real-time GNSS correction data to DGPS and/or RTK applications. In many cases it performs both tasks, satisfying the demands of many different applications, including surveying, engineering, construction, geodetic control, GIS, monitoring, tectonic studies and hydrography.
GPS networks are primarily run by state and local governments. Some private networks have also invested in establishing permanent base stations in high-traffic locations. The State of Alabama, for example, is completely covered by the Department of Defense (DOT) and is a free network for customers with a GPS rover and data plan with a cellular provider.
What to look for when choosing GPS/GNSS equipment
When choosing GPS/GNSS equipment, the primary thing to consider is the type of project it will be used for. There is a wide range of uses for GPS/GNSS equipment for all types of layouts and measuring points.
When choosing which is right for you, consider your project, the type of software you are currently using, and if the equipment is compatible. While GPS/GNSS equipment can be purchased a la carte, most packages include the instrument as well as all of the required accessories.
Most Popular GPS/GNSS Receiver for the Value
The Leica iCON GPS 60 is one of the most popular GPS/GNSS receivers on the market today because of its intuitive software and overall ease of use. The Leica iCON GPS 60 is versatile enough to handle all construction-positioning tasks while meeting all of your requirements for reliable and accurate measurements.
With the Leica iCON GPS 60, positioning tasks are fast and easy. You can check grade or cut and fill, stake out points and lines and as-built checks. The unit acts as a mobile base station for your construction site, eliminating the need for a controller for base station setup and corrections can be streamed over the internet without radio.
Its intuitive display shows full status information on the instrument, making it easy to operate and configure. The Leica iCON GPS 60 also offers exceptional network capabilities, allowing you to use RTK network services for highly reliable GPS positions.
This multipurpose GPS solution can be used as a construction site GNSS base, rover or netrover in a supervisor’s vehicle onsite, saving time and increasing overall productivity.
Most Popular RTK GNSS Receiver
The Leica iCON GPS 60 is a popular RTK receiver because it delivers unmatched precision and performance in a rugged, compact unit that is designed to stand up to the harsh conditions typically found on construction sites.
The Leica iCON GPS 60 is intuitive and versatile enough to handle all construction-positioning tasks while meeting all of your requirements for reliable and accurate measurements. This unit uses superior GNSS technology for maximum accuracy and reliability, and its “future-proof” satellite tracking supports a wide range of satellite signals.
The Leica iCON GPS 60 can be used as a construction site GNSS base, rover or netrover in a supervisor’s vehicle onsite, saving time and increasing overall productivity.
This multipurpose GPS solution acts as a mobile base station for your construction site, eliminating the need for a controller for base station setup. Corrections can be easily streamed over the Internet without radio.
Positioning tasks are fast and easy with this unit and it is easy to operate and configure. You can check grade or cut-and-fill, stake out points and lines, and conduct as-built checks, and its intuitive display conveniently shows full status information on the instrument.
The Leica iCON GPS 60 GNSS SmartAntenna, available for accurate single-grade machine control applications, further increases the value of your investment.
Most Popular GNSS Receiver Base/Rover Kit
The Spectra Precision SP80, the latest release from Spectra Precision, is a next generation GNSS receiver that combines RTK technology with new GNSS processing.
The SP80 has a unique combination of communication technologies, including an integrated 3.5G GSM/UMTS modem, Bluetooth, Wi-Fi connectivity, and optional internal UHF transmit radio.
The cellular modem may be used for SMS (text message) and e-mail alerts, and the SP80 can connect to the internet from the field using WiFi hotspots, where available.
This package offers a base rover with internal radios, as well as an external long-range radio. This unit is unique because it includes an optional modular radio.
The SP80’s internal radio is a 2-watt radio, where most GNSS receivers have only a 1 watt radio, and the receiver comes with hot-swappable batteries and a two-year warranty out of the box.
The SP80 is typically priced under $14K and runs on Spectra Precision Survey Pro or FAST Survey software.