DGPS / GNSS Receiver
A DGPS or GNSS receiver calculates position from satellite signals and corrects it using a second reference receiver or a correction network, reaching centimetre accuracy. Unlike optical instruments it needs no line of sight between points, so a single operator can survey large open areas quickly.
Centimetre coordinates over open ground without a single line of sight - the fastest way to control a large site.
ALSO CALLED: DGPS · GNSS receiver · RTK rover · base and rover set · GPS survey instrument · CORS receiver · differential GPS
Typical specifications
Class-level figures. Individual models vary, so treat these as the range to check a quotation against rather than a guarantee.
- What it measures
- Absolute 3D position (latitude, longitude, ellipsoidal height)
- Typical RTK accuracy
- 8–15 mm horizontal, 15–30 mm vertical, baseline dependent
- Typical standalone accuracy
- 1–3 m without corrections
- Constellations
- GPS, GLONASS, Galileo, BeiDou and NavIC on modern receivers
- Correction sources
- Own base station, CORS network, NTRIP over mobile internet
- Common output
- Coordinate file, RINEX raw data, shapefile, DXF via office software
How a dgps / gnss receiver works
01
Track the satellites
The receiver locks onto signals from multiple constellations and measures the travel time of each, resolving a rough position within seconds.
02
Apply a correction
A base receiver on a known point, or a CORS network, measures the same satellites and broadcasts the local error. The rover subtracts it, collapsing metres of error to centimetres.
03
Fix the ambiguity
RTK resolves the whole number of carrier wavelengths between satellite and antenna. Once 'fixed', accuracy jumps from decimetres to centimetres - and a 'float' solution should never be recorded as final.
04
Transform to local grid
Satellite coordinates are global. A site calibration or projection ties them to the local grid and to mean sea level, which is what drawings and revenue records use.
What it is used for
- Control point and benchmark establishment
- Large-area topographic survey
- Boundary and cadastral coordinate capture
- Mining and quarry lease boundary marking
- Road and canal alignment surveys
- Georeferencing drone and LiDAR data
- Agricultural and plantation block mapping
- GIS data collection at survey grade
Who uses it
- Survey consultants
- Mining and quarry operators
- Irrigation and PWD departments
- Plantation and estate managers
- Infrastructure contractors
- GIS and remote sensing teams
How to choose a dgps / gnss receiver
Base-rover or network RTK
Your own base works anywhere, including sites with no mobile signal. Network RTK over NTRIP is lighter to carry but depends on coverage and a subscription. Kerala sites often need the base.
Constellation and channel count
More constellations means faster fixes and better performance near buildings and tree lines. On a state with as much canopy as Kerala, this matters more than headline accuracy figures.
Radio link range
If you run your own base, the UHF radio range decides your working radius. Terrain blocks it far more than the spec sheet suggests - check the realistic figure for hilly sites.
IMU tilt compensation
Tilt compensation lets you measure without levelling the pole, which is a genuine time saver on rough ground and against walls. It is now common rather than premium.
Data format openness
Insist on RINEX raw output. It keeps post-processing possible and means you are not locked to one vendor's office software forever.
What it costs
Cost depends on whether you buy a single rover working off a correction network or a full base-and-rover pair with radios, plus the controller and field software. Correction subscriptions are a recurring cost that is easy to leave out of a comparison. To confirm: DGPS/GNSS receiver and base-rover price bands
DGPS / GNSS Receiver vs the alternatives
DGPS / GNSS Receiver vs Total station
GNSS covers open ground several times faster with one person. A total station is unavoidable where sky view is blocked. Most professional surveys carry both and switch as the site changes.
Read about total stationDGPS / GNSS Receiver vs Handheld GPS mapper
A handheld mapper gives sub-metre to a few metres - fine for asset inventory and GIS. It is not survey grade and should never be used for boundary or level work.
Read about handheld gps mapperWhat Axisline does with a dgps / gnss receiver
FAQ
DGPS / GNSS Receiver - common questions
What is the difference between GPS and DGPS?
GPS on its own gives roughly one to three metres of accuracy. DGPS adds a correction from a second receiver at a known location, which removes most atmospheric and orbital error and brings accuracy down to centimetres. Survey work uses the corrected form; a phone or car navigation uses the uncorrected one.
How accurate is DGPS surveying?
A properly fixed RTK solution typically achieves 8–15 mm horizontally and 15–30 mm vertically, degrading as the distance from the base increases. Accuracy collapses if the receiver is only in float mode, near tall buildings, or under dense canopy - which is why open sky matters more than the receiver's price.
Does DGPS work under trees or inside buildings?
Poorly under dense canopy and not at all inside buildings. Satellite signals need a clear view of the sky, so plantations, forest and narrow urban streets degrade or block the fix. On such sites surveyors switch to a total station, or use GNSS only for control points in open clearings.
Do I need my own base station?
Only if network corrections are unavailable or unreliable at your site. A network RTK subscription over mobile internet is lighter and cheaper to start with, but many Kerala sites - quarries, hill terrain, interior plots - have weak coverage, and there a base-and-rover pair is the dependable option.
Can DGPS give elevation for contour work?
Yes, but with care. GNSS measures height above an ellipsoid, not above sea level, so a geoid model or a local levelling tie is needed to produce usable reduced levels. For precise level work over short distances, a digital or auto level remains more reliable than GNSS.
Need a dgps / gnss receiver - or the survey it produces?
Supply, calibration and service across Kerala and pan-India, with field crews covering all 14 districts.