Planning and preparation of gps survey

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Planning and preparation of gps survey

There are wide variety of GPS applications, which is matched by a similar diversity of user equipment and techniques. When these classes of hardware are used in the appropriate manner for relative positioning, the accuracy that is achieved ranges from a few metres in case of standard pseudo range based techniques, to the sub centimetre level in case of carrier phase based techniques. Although Single Point Positioning SPP accuracy of m is now possible, it is assumed that for most geo spatial applications only relative positioning are of relevance.

The following classes of relative positioning techniques can therefore be identified. Static and Kinematic GPS surveying techniques: High precision techniques based on post processing of carrier phase measurements 2. Real — Time Kinematic RTK : versatile high precision techniques that use carrier phase measurements in an instantaneous positioning mode.

There are essentially two types of conventional static GPS surveying techniques. The main weaknesses of such procedures are that the observation time is comparatively long, the results are obtained after the field survey and the field procedures are rigid. During the late s, considerable attention was paid to these issues, as they were considered to be unnecessarily restrictive for precise GPS technology.

If the length of the time required to collect phase data for a reliable solution could be shortened, then GPS survey productivity would improve and technology would be attractive for many more surveying applications.

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If the results could be obtained immediately after the measurements have been made, then GPS could be used for time critical missions such as engineering statement etc. In the last decade or so new GPS surveying methods have been developed with two liberating characteristics of a static antenna set up no longer having to be insisted upon b long observation sessions no longer essential in order to achieve survey level accuracy.

planning and preparation of gps survey

These modern GPS surveying techniques are given a variety of names by different GPS manufacturers, but the following generic technologies will be used here. All require the use of specialized hardware and software, as well as new field procedures. GPS receivers capable of executing these types of surveys can also be used for conventional static GPS surveying.

Although the field procedures are different from conventional static GPS surveying, the principles of planning, quality control and network processing are very similar. This is also referred to as fast-static or quick-static.

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The following characteristics distinguish rapid-static techniques from other methods of static GPS surveying:. The field procedures are much like those for conventional static GPS surveying except:. It is not possible to define exactly how much data needs to be collected in order to produce quality baselines every time, that is ambiguity fixed solutions.

Equipment user manuals typically give guide lines in this regard. The rapid-static technique is well suited, for short range applications such as control densification and engineering surveys or any job where many points need to be surveyed. Unlike kinematic and stop-and-go techniques there is no need to maintain lock on satellites when moving from one point to another.

There are in fact three stages to the operation.

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The initial ambiguity resolution: carried out before the stop-and-go survey commences. The determination of the ambiguities by the software can be carried out using any method, but in general it is one of the following:. The technique is well suited when many points close together have to be surveyed, and the terrain poses no problems in terms of signal disruption. The accuracy attainable is about the same as for rapid-static technique.

The technique can also be implemented in real time if a communication link is provided to transmit the data from the reference receiver to roving receiver. One negative characteristic of this technique is the requirement that signal lock must be maintained as the satellites by the user receiver as it moves from point to point. This may require special antenna mounts on vehicles if the survey is carried out over a large area.

This is a generalization of stop and go technique. Instead of only coordinating the stationary points and disregarding the trajectory of the roving antenna as it moves from point-to-point. The intention of kinematic surveying is to determine the position of antenna while it is in motion.

In many respects the technique is similar to stop-and-go technique. That is, ambiguities must be resolved before starting the survey, and ambiguities must be reinitialized during the survey when a cycle slip occurs. However for many applications such as positioning of an aircraft or ship, it is impractical to reinitialize the ambiguities if the roving antenna has to return to a stationary control point. Each of the high productivity GPS surveying technique has its strengths and weaknesses; however, all are less accurate than conventional GPS surveying technique.

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This should not be too great a draw back as it is not often necessary that relative accuracy of 1ppm be insisted upon. Often a combination of conventional static and GPS technique such as the ones described above makes for an ideal solution to a surveying problem.Surveying and land surveying is the measurement and mapping of our surrounding environment using mathematics, specialized technology and equipment.

Surveyors measure just about anything on the land, in the sky or on the ocean bed. They even measure polar ice-caps. Land surveyors work in the office and in the field. In the field, they use the latest technology such as high order GPS, Robotic Total Stations Theodolitesand aerial and terrestrial scanners to map an area, making computations and taking photos as evidence. In the office, Surveyors then use sophisticated software, such as Auto-cad to draft plans and map the onsite measurements.

Surveyors work on a diverse variety of projects from land subdivision and mining exploration, to tunnel building and major construction, which means no two days are the same. They are experts in determining land size and measurement. They also give advice and provide information to guide the work of engineers, architects and developers.

What is GPS?

Even smaller pieces of equipment can benefit from proper land surveys. According to Renishaw plc, laser scanning is not only used in land surveying but is being adopted in more and more industries, since it gives detailed, accurate data, very quickly, and with fewer manpower requirements, saving companies costs. Surveying is important and most of us depend on it so as to ensure order in the physical world around us.

Surveyors play an integral role in land development, from the planning and design of land subdivisions through to the final construction of roads, utilities and landscaping. Surveyors are the first people on any construction site, measuring and mapping the land. These primary measurements are then used by architects to understand and make the most of the unique landscape when designing and engineers to plan structures accurately and safely, ensuring buildings not only fit with the landscape but are able to be constructed.

Standardization, calibration and control systems are used in all industries, and when measuring, storing and processing data on-site, error sources are efficiently minimized. Problem areas are detected in time and actions are based on facts and figures.

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It is necessary to mark the boundaries on the ground, so that they are clear to observers standing on or near the property. Many properties have considerable problems in regard to improper bounding, miscalculations in past surveys, titles, easements, and wildlife crossings. Also many properties are created from multiple divisions of a larger piece over the course of years, and with every additional division the risk of miscalculation increases.

The result can be abutting properties not coinciding with adjacent parcels, resulting in gaps and overlaps. Many times a surveyor must solve a puzzle using pieces that do not exactly fit together. This essentially is a process of continual error correction and update, where official recordation documents countermand the previous and sometime erroneous survey documents recorded by older monuments and older survey methods.

Survey grade GNSS is used by Land surveyors for new township layouts, and by construction companies for survey control points and for staking out roads etc. It is needed for drone surveys for ground control points, and is increasingly used for precision agriculture.

According to Mr.

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Those that do not have such systems are looking to implement them soon. Ease of Use, flexibility and Support are the most important things to look for.It is dependent on GPS satellites high above the Earth which transmit signals containing the time and location of the satellite.

Constant signaling can then update speed and direction information for moving receivers. GPS was originally developed for military use but since the s has been open for civilian use and is now used in such common applications as mobile phones, car navigation systems, and of course surveying and mapping.

Surveying and mapping was one of the first commercial adaptations of GPS, as it provides a latitude and longitude position directly without the need to measure angles and distances between points. In practice, GPS technology is often incorporated into a Total Station to produce complete survey data. GPS receivers used for base line measurements are generally more complex and expensive than those in common use, requiring a high quality antenna.

Jurovich Surveying is a surveying company in Perth specialising in large infrastructure and mining projects around WA.

We also have teams working on residential and commercial projects around the Perth metropolitan area. Please call us on 08 or send an email via our contact form. What is GPS? Recent topics of Discussion What is a Setout Survey? What is a Setout Survey?

What is a Feature and Level Survey? What is a Cadastral Survey Plan? What is a Lease Area Survey?

planning and preparation of gps survey

What is Strata? What is the Process for a Built Strata Subdivision? What is the Process for a Survey Strata Subdivision? Can I Subdivide My Land? How to Subdivide My Block? What is a Total Station? What is CAD Software? What is GIS? What Are Enabling Works? What Are Bulk Earth Works?

What is Civil Construction?The links below provide an outline of the material for this lesson. Be sure to carefully read through the entire lesson before returning to Canvas to submit your assignments.

planning and preparation of gps survey

And it is still the preferred approach to establishing the most accurate positions, the control. And some components of static GPS control methods are useful in GPS methods where the receiver is on a moving platform.

It is interesting that there are some elements of static GPS, such as station diagrams, observations logs and to-reach descriptions that would rarely, if ever, be necessary in high-production dynamic work. And finally, there are aspects, though handled a bit differently in both categories of work that have utility in each. In this lesson, we start to get into the real details of how GPS work is done. If you have any questions now or at any point during this week, please feel free to post them to the Lesson 7 Discussion Forum.

To access the forum, return to Canvas and navigate to the Lesson 7 Discussion Forum in the Lesson 7 module. While you are there, feel free to post your own responses if you, too, are able to help out a classmate. Lesson 7 is one week in length.

See the Calendar in Canvas for specific due dates. To finish this lesson, you must complete the activities listed below. You may find it useful to print this page out first so that you can follow along with the directions. It is used to smooth the effects of system and sensor noise in large datasets. In other words, a Kalman filter is a set of equations that can tease an estimate of the actual signal, meaning the signal with the minimum mean square error, from noisy sensor measurements.

Kalman filtering is used to ensure the quality of some of the MCS calculations, and many GPS receivers utilize Kalman filtering to estimate positions. Kalman filtering can be illustrated by the example of an automobile speedometer. The driver might estimate the actual speed at 68 mph. Despite its vacillation, the needle has reacted as the driver thought it should.

It went higher as the car accelerated. This behavior illustrates a predictable correlation between one variable, acceleration, and another, speed. The driver is illustrating adaptive gainmeaning that he is fine-tuning his model as he receives new information about the measurements. As he does, a truer picture of the relationship between the readings from the speedometer and his actual speed emerges, without recording every single number as the needle jumps around.

Without this ability to take the huge amounts of satellite data and condense it into a manageable number of components, GPS processors would be overwhelmed.As you recall from Chapter 1, geographic data represent spatial locations and non-spatial attributes measured at certain times.

We defined "feature" as a set of positions that specifies the location and extent of an entity. Positions, then, are a fundamental element of geographic data.

Like the letters that make up these words, positions are the building blocks from which features are constructed. A property boundary, for example, is made up of a set of positions connected by line segments.

planning and preparation of gps survey

In theory, a single position is a "0-dimensional" feature: an infinitesimally small point from which 1-dimensional, 2-dimensional, and 3-dimensional features lines, areas, and volumes are formed. In practice, positions occupy 2- or 3-dimensional areas as a result of the limited resolution of measurement technologies and the limited precision of location coordinates. Resolution and precision are two aspects of data quality. This chapter explores the technologies and procedures used to produce positional data, and the factors that determine its quality.

Take a minute to complete any of the Try This activities that you encounter throughout the chapter. These are fun, thought-provoking exercises to help you better understand the ideas presented in the chapter. Quality is a characteristic of comparable things that allows us to decide that one thing is better than another. In the context of geographic data, the ultimate standard of quality is the degree to which a data set is fit for use in a particular application.

That standard is called validity. The standard varies from one application to another. In general, however, the key criteria are how much error is present in a data set, and how much error is acceptable. Some degree of error is always present in all three components of geographic data: features, attributes, and time. Perfect data would fully describe the location, extent, and characteristics of phenomena exactly as they occur at every moment.

Like the proverbial scale map, however, perfect data would be too large, and too detailed to be of any practical use. Not to mention impossibly expensive to create in the first place! Positions are the products of measurements.

All measurements contain some degree of error. Errors are introduced in the original act of measuring locations on the Earth surface. Errors are also introduced when second- and third-generation data is produced, say, by scanning or digitizing a paper map. In general, there are three sources of error in measurement: human beings, the environment in which they work, and the measurement instruments they use.

Human errors include mistakes, such as reading an instrument incorrectly, and judgments. Judgment becomes a factor when the phenomenon that is being measured is not directly observable like an aquiferor has ambiguous boundaries like a soil unit.

Environmental characteristicssuch as variations in temperature, gravity, and magnetic declination, also result in measurement errors. Instrument errors follow from the fact that space is continuous. There is no limit to how precisely a position can be specified. Measurements, however, can be only so precise. No matter what instrument, there is always a limit to how small a difference is detectable. That limit is called resolution.

Figure 5. The two grid patterns represent the smallest objects that can be detected by the instruments. The pattern at left represents a higher-resolution instrument. The resolution of an instrument affects the precision of measurements taken with it. In the illustration below, the measurement at left, which was taken with the higher-resolution instrument, is more precise than the measurement at right.Being able to reach these extra satellites improves reliability and accuracy.

As the term GPS is still commonly used and well understood, it is used for the rest of this article. Initially developed for military use, GPS is now part of everyday life. A few of the many things that GPS is used in include: mobile phones, in-car navigation and search and rescue equipment. But there is a wide variety of equipment and techniques that can be used for surveying. GPS was rapidly adapted for surveying, as it can give a position Latitude, Longitude and Height directly, without the need to measure angles and distances between intermediate points.

Survey control could now be established almost anywhere and it was only necessary to have a clear view of the sky so the signal from the GPS satellites could be received clearly.

GPS is similar in some ways to the Trilateration and EDM previously discussed, except that the known positions are now the GPS satellites and their orbits 20, km in space. The equipment and calculations are extremely complex, but for the user the process is generally very simple.

In the commonly available receivers, the GPS receiver almost instantly works out its position Latitude, Longitude and Height with an uncertainty of a few metres, from the data broadcast by the satellites. This data includes a description of the satellites changing position its orbit and the time the data was transmitted.

The GPS receivers used for surveying are generally more complex and expensive than those used in everyday life.

GPS Surveying Techniques

They use the two frequencies broadcast by the GPS satellites. The physical characteristic of the GPS signal the phase and sophisticated calculation methods to greatly improve the accuracy of the positions obtained. These receivers usually have a separate high-quality antenna. They collect data from the same GPS satellites at the same time. The duration of these simultaneous observations varies with the length of the line and the accuracy needed, but is typically an hour or more.

When the data from both points is later combined, the difference in position Latitude, Longitude and Height between the two points is calculated with special software. Many of the uncertainties of GPS positioning are minimized in these calculations because the distortions in the observations are similar at each end of the baseline and cancel out.

The accuracy obtained from this method depends on the duration of the observations, but is typically about 1 part per million 1 millimetre per kilometre so a difference in position can be measured over 30 kilometres with an uncertainty of about 30 mm, or about mm over kilometres.

Because the GPS satellites are in a very high orbit 20, km the ends of the GPS baseline can be hundreds, or even thousands of kilometres apart and still observe the same satellites. Although a single baseline from a known position is enough to give the position at the other end of the baseline, additional GPS baselines to other points are often measured to give a check on the results and an estimate of the uncertainty of the calculated position.

There are many variations on this type of GPS surveying. Generally it is similar to the GPS baseline method, except that while one GPS receiver remains on a known position Base Stationthe other moves between points and it only needs to be at each point for a few seconds. Corrections to the GPS data based on the known Base Station position and its position computed from the GPS may be immediately transmitted from the receiver on the Base Station to the receiver at the other end of the line the remote station.

The position of the remote station can then be computed and stored, all within a few seconds. Radios or mobile phones can be used to transmit the corrections. Although this method can give similar accuracy to the baseline method previously described, to do so this method is generally limited to a distance of about 20 kilometres.

GPS Real-time baseline measurements. A survey-quality GPS receiver may be permanently installed in a convenient location with a known position, to be used as the starting point for any GPS measurements in the district.

Land surveying and its importance

This could be for a project such as a mine site or major engineering project, or in a town for local government use. If there is more than one CORS available, the unknown position can be calculated with respect to these multiple known positions, giving more confidence in the results. They also provide data for scientific studies such as plate tectonics and meteorology.Are you seeking for a land measurement app for Android or iPhone?

Do you need to calculate an area fast and easy? Here, you will find a land survey app for iPhone or Android which will meet all your requirements in It includes various marking modes, such as the high-speed marking of distance, terrain, and smart marking with increased accuracy in the placement of points. You can save, edit, collect in groups, assign names, delete or exchange measured data with other users. If necessary, you can measure the data in motion. You can connect a GPS, which also improves the accuracy of the original information.

Convenient and beautiful design allows you to add thumbnails to existing dimensions, paint over selected points or fields. And the most innovative feature of the program is the automatic generation of links with the limits of the selected area, route or marked directionwhich can be sent to friends. GPS Fields Area Measure will be indispensable for calculating routes and distances when conducting various sporting events or planning trips. And also for farmers, gardeners, construction companies, pilots.

With this program, agricultural, construction and other work on measurement and planning will not take as much time as if it was done manually.

7 Best land surveying apps for Android & iOS 2019

You can also check: Multifunctional outdoor navigation app: Locus Map Review. You can record location details with it and save them in a single survey. The details can be easily edited through the edit function.

The interface and management are simple. Capture and Store latitude and longitude of a Location. Field workers, farmers, engineers, GIS students, and professionals will appreciate Land Calculator application. There are three methods available: Walking Survey make survey walking or driving fields perimeterMap Tools draw any shape on a map or enter coordinates.

Geo Measure Area Calculator is the most useful land surveying application for iPhone users. Are you going to buy some property and calculate its area? It calculates GPS area with great accuracy. There are two methods of measurement available: put markers manually on MAP or record your position using GPS service.


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