Quick Answer
How do you set up an RTK base station for construction?
Set the base receiver over a known control point, enter the point coordinates into the base controller, configure the correction broadcast method (UHF radio or cellular/NTRIP), and verify rover receivers are achieving RTK Fixed status before beginning work. Always occupy a known point with the base — never use autonomous base positioning for stakeout work.
How to Set Up an RTK Base Station for Construction
Applies to: Trimble R10/R12 Base, Topcon HiPer HR Base, Leica GS18 Base, Spectra SP80 Base
The RTK base station is the accuracy anchor for every rover working on your site. Set it up correctly on a known control point and every rover within radio range inherits centimeter-level accuracy. Set it up on an incorrect position or wrong coordinates, and every rover on the job is consistently wrong — the worst kind of error because it looks right. This guide covers the complete base station setup workflow for construction crews who rely on their own base rather than a network correction service.
Step 1: Choose and Prepare the Base Location
Select a base location that provides clear radio or cellular communication to all rover working areas. For UHF radio correction broadcast, elevation helps — higher ground extends radio range significantly. Avoid locations with large metal structures immediately adjacent (generators, containers, vehicles) as they can cause multipath that degrades the base's own position quality.
The base must occupy a known control point with surveyed coordinates in the project's reference frame. Do not use an autonomously determined position as a base for stakeout — autonomous GPS positions can be 1-3 meters from the true position, and any error at the base propagates to all rovers. If no control points are accessible at a good base location, you can set a temporary control point by occupying it for 30+ minutes in static mode and processing against a nearby CORS network station.
Step 2: Set Up the Tripod and Receiver
Extend the tripod over the control point and set the tripod head approximately level. Attach the tribrach and GNSS receiver. Center the receiver over the control point using the optical or laser plummet — for base station work, aim for centering within 3mm. Level using the tribrach footscrews until the electronic bubble is within the compensator range.
Measure the antenna height: the height from the control monument top to the antenna reference point (ARP). On most Trimble, Topcon, and Leica receivers, the ARP is at the bottom of the receiver case. Measure with a tape and record to the nearest millimeter. Antenna height errors shift all rover elevation measurements by the same amount — if you measure 1.500m but enter 1.600m, every elevation reading from every rover is 0.1m wrong.
Step 3: Configure the Base in the Controller
Connect the field controller to the base receiver via Bluetooth or cable. In Trimble Access, navigate to Survey > Start Base Receiver. Select "Known Point" and enter the control point coordinates (northing, easting, elevation) and the antenna height. In Magnet Field (Topcon), go to Survey > Base Setup. In Leica Captivate, navigate to Go to Work > Setup > Base.
Confirm the coordinate system and datum match the project control: NAD83 vs. WGS84, State Plane zone, or site-calibrated local system. A datum mismatch at the base shifts all rover positions systematically. This is the most common source of GPS stakeout errors on multi-crew projects where different setups use different coordinate system configurations.
Step 4: Configure the Correction Broadcast
For UHF radio broadcast, select the correct radio frequency and protocol (CMR+, RTCM 3.2, or the protocol your rovers expect). Set the transmission interval — 1-second intervals are standard. Confirm the radio antenna is connected and the transmit indicator light is active on the radio unit.
For cellular/NTRIP rebroadcast (available on Trimble VRS Now, Topcon TopNET Live, and similar), configure the receiver to connect to the NTRIP caster using your account credentials and create a mount point for your rovers. Cellular broadcast eliminates radio range limitations but requires signal coverage on site.
Step 5: Verify Rover Initialization
Take a rover receiver to a known control point at the far edge of your working area and initialize RTK from the base correction signal. Confirm RTK Fixed status and verify the rover's reported position against the known coordinates. Acceptable residuals: under 0.02m horizontal, under 0.05m vertical for local base RTK. If residuals are large, check base coordinates, antenna height, and coordinate system settings before sending rovers to work.
Frequently Asked Questions
How far can a UHF radio RTK base station reach?
Typical UHF radio range is 5-10 km in open terrain with the base antenna elevated. Range drops significantly in valleys, around large structures, or with low-mounted antennas. For sites larger than 3-4 km across, consider cellular-based correction or multiple base stations.
Can I use an autonomous base position for construction stakeout?
No. Autonomous base positions can be 1-3 meters from the true position. Using an autonomous base position means all your stakeout points will be shifted by that error. Always occupy a known control point with known coordinates.
What is the difference between RTK and NTRIP?
RTK is the correction technique (Real-Time Kinematic carrier phase processing). NTRIP is a protocol for delivering RTK corrections over the internet. An RTK base station can broadcast corrections via local UHF radio or via NTRIP over cellular — both deliver the same RTK accuracy to the rover.
How long does it take for rovers to initialize after the base is set up?
With a good correction signal and open sky view, rovers typically initialize RTK Fixed in 30-90 seconds. In poor sky conditions or at the edge of radio range, initialization can take 2-5 minutes. If a rover does not initialize within 5 minutes, check the correction signal, sky obstruction, and satellite count.
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