What is GPS in Surveying? How Does It Work?
What is GPS in Surveying? How Does It Work?
GPS is a very accurate navigation technology that uses satellite signals to establish a location on the Earth’s surface regardless of weather conditions.
It is dependent on GPS satellites far above the Earth which transmit signals containing the time and location of the satellite.
Any ground-based receiver which receives signals from four or more GPS satellites can utilize navigation equations to calculate its location on the Earth’s surface. Constant signaling can then update moving receivers’ speed and direction information.
GPS was originally created for military purposes, but has been available to public usage since the 1990s and is now utilized in popular applications such as mobile phones, automotive navigation systems, and, of course, surveying and mapping.
What exactly is GPS in surveying?
To comprehend the GPS surveying method, you must first comprehend what GPS is. GPS, or global positioning system, is a satellite-based navigation system.
GPS was initially developed for military use in the 1970s and became fully operational in 1993. Its use has since expanded to include consumer and business applications.
GPS employs a network of satellites that connect with ground-based receivers.
When a receiver requests data to compute its location, four or more GPS satellites interact with it, sending the satellite’s position, the time the data was sent, and the distance between the satellite and the receiver.
The information gathered from these satellites is then used to calculate the receiver’s latitude, longitude, and height.
If the receiver is moving, continuous data gathering can be used to determine the receiver’s changing position over time, which can be used to measure speed.
GPS can triangulate the signal and provide a location regardless of the weather or time of day.
While the majority of people are aware with GPS and have used it to some extent on their smartphones or automobile navigation systems, GPS is a tremendous tool for commercial applications.
It’s especially beneficial in the surveying sector. Surveying was one of the first commercial applications of GPS, owing to its ability to get latitudes and longitudes without the need to measure distances and angles between sites.
In conjunction with other surveying equipment, such as the Total Station, GPS technology provides surveyors with vital information to aid in the development of plans and models for client projects.
How GPS Surveying is done
GPS surveying use technology that is identical to that of practically any other GPS application; however, how surveyors use GPS differs dramatically. The main distinctions are in two areas: technology and usage.
Technology
Surveyors employ more advanced technologies than standard GPS programs to improve the accuracy of the data they collect.
Surveying receivers are far more complex and expensive than those used in a normal automotive navigation system, with higher-quality antennas and more advanced computation technologies.
Data Utilization
The data collected by surveyors from GPS technology is used in a different way than in a conventional navigation system; instead of using location data for navigation, the data is used to measure the distance between two places.
These measures are collected, modified, and displayed in a geographic information system, or GIS, for use in a survey model.
What Are the Best GPS Land Surveying Instruments?
GPS survey technology allows for almost instantaneous position, distance, and height measurements – the only need is that the instrument has an unobstructed view of the sky to receive signals from GPS satellites.
When used correctly, GPS for land surveying provides the highest level of accuracy and is significantly faster than traditional surveying approaches.
Diverse types of GPS land survey equipment are used for different purposes, although surveyors most commonly employ three ways of GPS measurement:
Observations in Real-Time Kinematics (RTK)
Real-Time Kinematic (RTK) observations, like baseline approaches, are used to calculate distances between a base station and a second receiver.
RTK Observations, on the other hand, use several points in rapid succession rather than monitoring the location of two locations over a long period of time.
The RTK approach, like the baseline method, has two receivers, one of which is a static base station.
The Rover Station, which moves about during the measurement period, is the other receiver. The position of the Rover Station is collected and saved in a matter of seconds. When the measuring period is over, the data is saved and used as survey data.
RTK observations are nearly as accurate as baseline observations, although their range is limited to around 20 kilometers.
This system maintains a high level of precision by concurrently collecting data at the Base Station and the Rover Station and correcting data in real time the exact position of the Base Station is known, so any differences can be utilized to correct the Rover Station’s position in real time. As a result, this strategy may swiftly collect survey data for smaller areas.
Static GPS Baseline
It is used to determine accurate coordinates for survey locations by simultaneously recording GPS data over a known and unknown survey point for at least 20 minutes.
The data is subsequently processed in the office to produce coordinates with an accuracy of better than 5mm, depending on the duration of the observations and satellite availability at the time of the measurements.
Continuously Operating Reference Stations (CORS).
This is where a survey-quality GPS receiver is permanently fixed in a site as a starting point for all GPS measurements in the district.
CORS is commonly used by mining operations, large engineering projects, and local governments. Surveyors’ GPS receivers can then collect field data and integrate it with CORS data to calculate positions.
Numerous countries have a CORS network that is used by many sectors.
Australia’s CORS network is the Australian Regional GPS Network, and it employs an online processing system to provide data over the internet within 24 hours and provide positions with a precision of a few centimeters.
Local CORS networks are also utilized to deliver instant positions, similar to the RTK approach, by employing a mobile phone data link to provide a coordinate correction to the surveyor and their rover.
GPS Land Survey instruments
Certain tools are necessary for the correct application of GPS land surveying methodologies. The following is a quick rundown of the most common GPS land survey instruments:
GPS Receiver – In order to perform computations, this equipment must receive signals from GPS satellites. These instruments are available with a number of optional features, including multiple band channels, built-in Bluetooth and Wi-Fi technologies, and OLED screens.
GPS Rover Rods – These tools can be used to expand the reach of the rover. They can be built of a variety of long-lasting materials and available in a variety of lengths.
GPS Poles – These poles, which are used to mount GPS surveying equipment, are typically lightweight but sturdy, and come in a variety of lengths.
GPS Bipods/Tripods – For improved stability when installing GPS equipment, bipods and tripods are available in a variety of lengths and sizes.
GPS Antennae – This piece of hardware allows GPS devices to receive signals from satellites. Many systems include an inbuilt antenna, however extra antennas can be purchased to increase the signal.
Total Station – A total station is a device that combines an electronic theodolite, an electronic distance measurement (EDM) device, and software that runs on an external computer to determine the coordinates of survey locations using angles and distances. It could also use GPS technology to produce more accurate findings.
GPS Advantages
They include:
Mobility: GPS systems are fairly mobile, with the ability to be carried within backpacks or placed on vehicles to collect data fast and across a large region.
When used in conjunction with CORS systems, transportable GPS survey equipment can provide real-time data.
Speed: When compared to traditional surveying procedures that relied on significant measuring and calculations, GPS technology is exceedingly fast.
GPS now offers near-instantaneous data and can automatically compare that data to provide correct results swiftly, often in a matter of minutes. Survey teams can generate faster results and organizations can make better decisions with faster data.
Accuracy: The ultimate concern of stakeholders is the accuracy of GPS survey equipment. In the end, it is determined by who conducts the survey. Inaccuracy can be harmed by insufficient equipment and untrained users.
However, by combining sophisticated GPS technology with experienced knowledge and high-quality software, you may reach high levels of accuracy every time.
Flexibility: Unlike traditional surveying techniques, GPS surveying can operate in inclement weather.
Even if survey stations are out of sight of one another owing to line-of-sight limitations or bad weather, GPS technology can nevertheless measure their positions and provide precise location data.
This is very beneficial for surveying coasts and rivers where there are few land-based reference points, which is especially valuable for marine navigation and construction activities.
GPS Disadvantages
The disadvantages of GPS surveying include the following:
- The sole disadvantage is that GPS stations must have a clear line of communication with satellites, limiting the value of GPS surveying in locations with trees or towering buildings.
Location accuracy is affected by the type of surveyed area, the location of manned survey stations, and regular changes in satellite orbits.
Therefore, absolute location accuracy varies depending on where you are and how far away your survey equipment is from a GPS station or CORS.
- Inaccuracy also occurs when measuring locations without taking into account airborne radio waves and electromagnetic interference (EMI).
- Reference stations are dependent on network conditions, including local conditions and weather, making it hard to ensure that all stations receive reliable signals from satellites.
- Another disadvantage is that GPS surveying may not provide accurate results in areas near the earth’s poles because of their high incidence of EMI.
- Last but not least, this technology requires expensive equipment, which limits its market to large organizations and businesses.
Uses of GPS Surveying
They are:
- GPS is particularly effective for surveying coastlines and rivers, where there are few land-based reference points.
The nautical charts that alert mariners to shifting water depths and undersea hazards are created by survey vessels by combining GPS positions with sonar depth soundings.
- GPS technology is also used to create high-resolution aerial maps of large regions, and can improve the accuracy of existing maps by editing previously collected positions and using them to generate a new digital map.
- Surveyors can use GPS technology to measure the distance from one point in an area to another, or from a point on the ground to an object directly above it.
- GPS is also used for volume surveying, where surveyors measure volumes of materials such as oil or rock extracted from mine shafts.
- Because of its small cost, GPS surveying is also becoming an option for smaller developers who are beginning to expand their businesses.
- In developing countries, the use of GPS surveying to measure and map vertical heights for construction purposes is a very successful method for data collection.
FAQs
What are the advantages of GPS in surveying?
The main advantages of GPS surveying are the following:
- Today’s technology is affordable, on par with conventional surveying and even cheaper than total station measuring equipment.
Compared to traditional surveying methods, GPS survey techniques are quieter and faster, which translates into better spatial accuracy.
- GPS technology can be used in a wide range of conditions, even in areas where they could not be used without a total station or other special equipment.
It can be used in locations with high electromagnetic interference, where normally it would not function.
- Surveyors can measure the distance between two points in an area, and between a point on the ground and an object directly above it without having to repeat measurements or calculating distances.
They can check vertical positions in areas where it might be difficult to partially survey with a total station or traditional surveying methods.
What are the disadvantages of GPS in surveying?
One of the disadvantages of GPS surveying is the possibility that measurements will be inaccurate if survey stations are not aligned well or there are unintentional measurement errors.
In addition, it is also possible to receive false data when using GPS surveying techniques in areas with lots of buildings or trees.
What are some uses of GPS in surveying?
Uses of GPS surveying include the following:
- GPS is used to measure the distance from one point in an area to another, and from a point on the ground to an object directly above it.
- GPS is also used for volume surveying, where surveyors measure volumes of materials such as oil or rock extracted from mine shafts.
- Because of its small cost, GPS surveying is also becoming an option for smaller developers who are beginning to expand their businesses.
- In developing countries, the use of GPS surveying to measure and map vertical heights for construction purposes is a very successful methods for data collection.
What are the applications of GPS?
Global Positioning System uses are broadly classified into five categories:
- Determining a position – determining a location
- Navigation- Getting from one place to another
- Tracking -tracking of an object’s or an individual’s movement.
- Mapping is the process of making maps of the world.
- Timing – delivering exact timing to the world.
What are surveying tools?
Theodolite, measuring tape, total station, 3D scanners, GPS/GNSS, level, and rod are the most common surveying tools used around the world. When not in use, most instruments screw onto a tripod. Tape measures are frequently used for measuring shorter distances.
What is GPS in Surveying?
A GPS survey is a survey technique in which position information obtained from satellites is used to determine the ground measurement data.
The position measurements are collected for use as coordinates or map coordinates (often referred to as points or locations) that can be used in further processing.
Every GPS device sends out small packets of information with each update of its satellite signals. They contain the ephemerides, which are the orbital elements that determine the precise location of each satellite at a given moment in time.
How Does It Work?
The technique works by using two GPS receivers. These receivers are placed at each end of a line to be measured.
The receivers then collect GPS data simultaneously for at least 20 minutes the exact duration of the observation period varies based on how long the line is and how accurate the measurements need to be.
Can I survey my own property with GPS?
You’ll need a plat, mortgage map, or official land survey of your property, which shows the distance and bearing from one corner to the next. Mark a waypoint at the starting corner of your property with your GPS or the mapping tools in ExpertGPS.
How accurate is a GPS?
If you’re outside and can see the open sky, your phone’s GPS accuracy is roughly five meters, and it’s been that way for a long. That’s about as precise as the most precise systems available for land surveying, which are called total stations.
If you’re outdoors in dense vegetation, your accuracy may drop to somewhere between one and two meters.
How much money can I save with GPS-enabled equipment?
The first step is to determine the accuracy you need. The price of a complete system can vary greatly.
The best way to determine the price of a system that meets your requirements is to contact an ExpertGPS representative.
How accurate must I be?
If you’re going to use GPS surveying for pipeline surveys in the oil industry, for example, your accuracy must meet the standards required by major environmental agencies like the states of Texas and New Mexico.
How do you read GPS coordinates?
Starting with latitude, longitude is divided into degrees, minutes, seconds, and directions. For example, 41° 56′ 54.3732″ N, 87° 39′ 19.2024″ W would be interpreted as 41 degrees, 56 minutes, 54.3732 seconds north, and 87 degrees, 39 minutes, 19.2024 seconds west.
How do I find my lot pins?
Measure back about 15 feet from your front curb in the location where you believe your marker should be.
Start by using a metal detector and then digging. The marking should be approximately 6-10 inches below the surface. Newer survey pins may have a colorful cap on top with numbers.
Who invented GPS?
Roger L. Easton and Bradford Parkinson invented GPS. The first broadcast by the satellites used to locate positions was made in February of 1978.
Who is responsible for GPS?
The responsibility for operating and maintaining the world’s GPS system falls under the purview of the United States Air Force.
The operation and maintenance of GPS have been contracted out to a number of private businesses, including L-3 Communications and Raytheon.
