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Insight to GPS Surveying Systems

written by: Om Thoke • edited by: Lamar Stonecypher • updated: 3/31/2010

This article covers the GPS surveying basics, and provides a complete insight to the GPS surveying systems including overview of GPS technology, as well as the application of GPS in surveying.

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    What are GPS Systems?

    GPS (acronym for Global Positioning System) is a tracking system that provides reliable positioning, navigation, and timing services to worldwide users on a continuous basis. GPS surveying systems help in collecting valuable data for a number of purposes; here’s an insight to GPS surveying basics.

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    GPS Surveying Basics

    GPS Surveying Systems work in all kinds of weather, day and night, anywhere on or near the earth, which has an unobstructed view of four or more GPS satellites.

    Coming to the core GPS surveying technique, three satellites are used for tracking the object along the longitude and latitude, while the fourth satellite is used for time and position correction of the receiver; thereby providing accurate position of the object of interest.

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    Parameters That Affect GPS Surveying Accuracy

    GPS Surveying Atmospheric Effects: Inconsistencies of atmospheric conditions affect the speed of the GPS signals as they pass through the atmosphere. Ionospheric delay of a microwave signal, due to dispersion, depends on its frequency.

    Multipath Effects: Error is caused due to the radio signals reflecting off surrounding terrain; buildings, canyon walls, hard ground, etc. These delayed signals can cause inaccuracy in GPS readings. A variety of techniques, most notably narrow correlator spacing aids in correction.

    Errors in Satellite's Atomic Clocks: They basically experience noise and clock drift errors. These errors can be eliminated by differential GPS, which works on principle of simultaneous usage of two or more receivers at several survey points.

    GPS surveying systems have to consider all these parameters, enable adequate amount of tolerance for correction in order to obtain the precise position of the object.

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    More on the GPS Surveying Systems

    Present day surveying systems are designed for demanding surveying applications. Here are some common applications of GPS surveying systems -

    gps-surveying-system • Even the entry level systems provide a good blend of centimeter-level and post-processed static survey capabilities with real-time mapping and navigation.

    • The latest surveying systems come with signal prediction for intermittent RTK signals, helping them to continue working despite an interruption.

    • With the latest CMRx protocol, maximum compression can be obtained for optimizing communications bandwidth, and all the signals and satellites (currently in view) can be utilized in the best possible manner.

    • Most surveying systems support a wide range of satellite signals ranging from GPS L2C and L5, GLONASS L1/L2 signals, down to the experimental GIOVE-B, and GIOVE-A test satellites for testing purposes as well as signal evaluation.

    • A built-in TX/RX UHF radio in any GPS surveying system provides high levels of flexibility for base/rover operation.

    • GPS surveying units are also helpful in assessment of status of base receivers and remote configurations; post processing data can be downloaded and additional trips can be saved.

    Additional features of GPS Surveying Systems include land navigation screens, and built-in map databases that allow users to track their position on highways, waterways, and even railways, while displaying bearing, heading, distance and speed.

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    GPS Surveying Techniques

    In most of the GPS surveying techniques, surveyors perform job-site location and point reconnaissance carefully. By simply entering the coordinates, the user can navigate to within 3-5 meters of the nearest known point.

    In contrast to the traditional optical surveying equipments, GPS doesn't require LOS (line of sight) between the survey points. Users usually employ two-receiver configuration or choose to expand the system to involving usage of 3 or more receivers, for gaining enhanced productivity.

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    Conclusion

    So, there you have it; everything about the GPS surveying basics, and its applications. With GPS satellites in place, and highly advanced surveying systems in the market; tracking couldn’t be easier and traveling wouldn’t be more pleasurable!

    You may also want to explore the USB GPS receivers and find handy info on Using Your Cell Phone as GPS Receiver

    If you want to add GPS to your iPhone, you can check out these cool ways of adding a GPS receiver to the iPhone