Using RTK GNSS as a Base Station for DJI Drone Survey
Yes. Any APEKS RTK receiver (AP10, AP20, AP40 Laser+, AP80 Pro) can be configured as a local GNSS base station broadcasting RTCM corrections to a DJI drone via NTRIP over the internet — the same protocol DJI's own D-RTK 2 base station uses. The drone's onboard RTK module receives corrections from the APEKS base via your local network or a mobile hotspot, achieving centimetre-level positioning without a CORS subscription and without purchasing a dedicated DJI D-RTK 2 unit. For large survey areas, the APEKS MAX5 dedicated base station with 5W LoRa and 25 km range provides extended coverage beyond what a rover-as-base configuration can deliver.
Why Use a Ground RTK Base Station for Drone Survey?
DJI's RTK-capable drones — the Phantom 4 RTK, Matrice 300 RTK, Matrice 350 RTK, and Mavic 3 Enterprise series — achieve centimetre-level accuracy in two ways: CORS network via NTRIP, or a local ground base station. Both deliver the same Fixed solution accuracy. The choice between them depends on site conditions.
CORS NETWORK (NTRIP): Convenient where coverage exists. No additional hardware. Requires cellular data connectivity on both the drone controller and the base station link. Baseline accuracy degrades beyond 50–70 km from the nearest CORS station. Not available on remote sites, desert corridors, or offshore locations.
LOCAL GROUND BASE STATION: Self-contained correction source on a known control point. No CORS subscription. No cellular dependency for the correction link itself. Baseline is short — typically under 5 km for drone survey — giving maximum Fixed accuracy. Works on any remote site regardless of network infrastructure.
WHEN A LOCAL BASE IS THE CORRECT CHOICE: Remote project areas without reliable CORS coverage. Sites where cellular data is unstable or unavailable. Projects requiring tight baseline control for high-accuracy photogrammetric outputs. Multi-drone operations where all aircraft need corrections from a single trusted source.
How DJI RTK Drone Positioning Works
DJI RTK drones carry an onboard dual-frequency GNSS receiver that processes carrier-phase measurements. To resolve centimetre-level position, the drone needs correction data from a reference station at a known coordinate — this resolves the carrier-phase ambiguity that separates ±8mm Fixed accuracy from ±1–3m standalone GNSS accuracy.
THE CORRECTION LINK: DJI drones receive corrections via the DJI RC Pro controller, which connects to the correction source over WiFi or mobile data using NTRIP protocol — the same standard used by CORS networks worldwide. The correction source can be:
- A DJI D-RTK 2 base station (DJI's proprietary unit)
- A CORS network NTRIP caster (via mobile data)
- Any third-party GNSS base station broadcasting RTCM via an NTRIP caster — including APEKS receivers
RTCM COMPATIBILITY: APEKS receivers broadcast RTCM 2.x and 3.x correction formats. DJI RTK systems accept standard RTCM 3.x. The two systems are fully compatible — no firmware modification required on either side.
Using an APEKS Receiver as a DJI Base Station
Any APEKS receiver configured as a base station becomes an NTRIP caster that the DJI RC Pro controller connects to over WiFi or mobile data — exactly as it would connect to a CORS network.
THE SETUP IN PRINCIPLE:
- APEKS receiver set up on a known control point, configured as base station in ApekSurv
- Receiver broadcasts RTCM 3.x corrections
- A mobile hotspot (phone or dedicated device) shares the corrections via WiFi to the DJI RC Pro controller
- DJI controller connects to the APEKS NTRIP stream as it would any CORS network
- Drone receives centimetre-level corrections in flight
ACCURACY: With a correctly coordinated base position on a known control point, the drone achieves the same ±8mm horizontal Fixed accuracy as any CORS-based workflow. The baseline (distance from base to drone) is typically under 5 km for standard drone survey — well within the reliable RTK range of any APEKS receiver.
COST ADVANTAGE: DJI D-RTK 2 is a single-purpose base station. An APEKS receiver configured as a base also functions as a full-capability survey rover — the same equipment serves both the drone base station role and all ground survey operations on the same project.
Step-by-Step Setup
Set up the APEKS receiver on a known control point: Place the receiver on a tripod over a known control monument or an established project benchmark. Enter the precise control point coordinates in ApekSurv. Configure the receiver as a base station. The receiver begins broadcasting RTCM 3.x corrections.
Create an NTRIP hotspot: Connect a mobile phone or WiFi hotspot device to the APEKS receiver via Bluetooth or USB. Use an NTRIP server app (such as SNIP or a mobile NTRIP caster app) to rebroadcast the APEKS corrections as an NTRIP stream accessible over the local WiFi hotspot.
Connect the DJI RC Pro to the NTRIP stream: On the DJI RC Pro controller, navigate to RTK Settings. Select Custom Network RTK. Enter the NTRIP caster IP address (your hotspot device's IP), port, mountpoint, and credentials. The controller connects to the APEKS RTCM stream.
Verify RTK Fixed on the drone: Power on the drone. In the DJI Pilot 2 app, confirm that the drone's RTK status shows Fixed — not Float. Do not begin the survey mission until Fixed is confirmed.
Verify on a known ground check point: Before flying, verify the base station coordinate by checking the receiver position against the known control point. Any error in the base coordinate propagates into every drone photo position. A 10mm base error introduces a 10mm systematic offset across the entire survey.
Fly the mission: With RTK Fixed confirmed, fly the planned mission in DJI Pilot 2. The drone tags each photo with a centimetre-accurate position derived from the APEKS base corrections. Import the geotagged photos into your photogrammetry software (DJI Terra, Pix4D, Agisoft Metashape) for processing.
APEKS Base Station Options — Which to Choose
Single drone, project area under 5 km radius: Any AP10 or AP20 configured as base. 2W UHF radio is not needed for drone base work — the correction link is via NTRIP over WiFi, not radio. The AP10 or AP20 occupies the control point, connects to a hotspot, and broadcasts corrections while the rover team continues ground survey work. No dedicated base hardware required if AP10/AP20 is already in the kit.
Large project area, multiple drones, or multi-day remote deployment: MAX5 dedicated base station. 13,200 mAh battery runs 8+ hours without external power. OLED display confirms base status without a controller. No rover capacity consumed — all AP rovers remain available for ground survey while MAX5 handles the base role for both drone and ground operations simultaneously.
Combined drone survey + ground laser measurement on the same site: MAX5 as base + AP40 Laser+ as ground rover. MAX5 provides corrections to both the drone and the AP40 Laser+ simultaneously. Ground laser measurements and drone photogrammetry share the same base coordinate — datasets align in post-processing without additional control point reconciliation.
The Core Problems This Solves
Symptom: The drone survey site is a desert infrastructure corridor, highland terrain, or remote agricultural area where no CORS network is available and cellular data is unreliable. The DJI RC Pro cannot connect to an NTRIP source. The drone falls back to standalone GNSS at ±1–3m accuracy — insufficient for mapping outputs that require centimetre ground control.
Cause: CORS networks are concentrated in urban and semi-urban areas. Remote sites — pipeline corridors, transmission line routes, agricultural zones in the Cerrado or Sahel — frequently lie 100–200 km from the nearest CORS station, making NTRIP-based correction impractical.
Fix: Deploy APEKS MAX5 base station on a known control point at the site. The MAX5 broadcasts corrections via NTRIP over a local WiFi hotspot to the DJI RC Pro. No cellular data required for the correction link. 13,200 mAh battery runs the full survey day without external power. The drone achieves centimetre Fixed accuracy anywhere within hotspot range of the base.
Symptom: The survey firm needs RTK accuracy for drone operations but does not own a DJI D-RTK 2 base station. Purchasing one adds significant cost for a single-purpose unit that cannot be used for any ground survey operation.
Cause: The DJI D-RTK 2 is purpose-built for DJI drone base station use only. It cannot function as a ground survey rover, cannot be used for stakeout or topographic pickup, and has no field display or standalone operation mode useful for ground crews.
Fix: An APEKS receiver already in the survey kit — AP10, AP20, AP40 Laser+, or AP80 Pro — doubles as the drone base station at zero additional hardware cost. The same receiver that runs ground survey in the morning becomes the drone base station in the afternoon. One piece of equipment. Two workflows. No additional purchase.
Symptom: Drone survey outputs (orthomosaic, DSM) show a systematic horizontal or vertical offset when checked against ground control points. The offset is consistent across the entire survey area — not random. All photos are shifted by the same amount in the same direction.
Cause: The base station was set up on an incorrectly coordinated position, or an estimated position rather than a known control point. Every drone photo position is derived relative to the base coordinate — a 50mm base error introduces a 50mm systematic offset across all photo positions and the final processed output.
Fix: Always set up the APEKS base on a coordinated control point — an established survey monument, a previously RTK-coordinated nail, or a point established by static GNSS on a prior session. Enter the known coordinate manually in ApekSurv rather than letting the receiver autonomously determine its own position. Verify the base position before flying by comparing the receiver's displayed coordinate against the known value — they must agree within 20mm.
Field Deployment Scenarios
SCENARIO 1 — REMOTE INFRASTRUCTURE CORRIDOR (NO CORS): MAX5 base on project control monument at corridor midpoint. Mobile hotspot shares RTCM corrections over WiFi to DJI RC Pro. Drone achieves Fixed RTK throughout the corridor flight. AP40 Laser+ rover simultaneously receives MAX5 corrections via LoRa for ground laser measurements along the same corridor. Both datasets share the same base coordinate — they align in post-processing without additional reconciliation.
SCENARIO 2 — URBAN CONSTRUCTION SITE (CORS AVAILABLE): AP20 configured as base on site benchmark. APEKS base supplements CORS where multipath from surrounding buildings degrades the CORS baseline. Short baseline from on-site base to drone gives tighter Fixed solution than a distant CORS station. Ground crew uses second AP20 as rover for stakeout while drone surveys the wider site simultaneously.
SCENARIO 3 — AGRICULTURAL MAPPING (LARGE AREA, MULTI-FLIGHT): MAX5 base on a central farm benchmark. Multiple drone flights across a large agricultural property all reference the same MAX5 base coordinate. 8+ hour battery covers a full day of multi-flight operations. APS1 handheld rover simultaneously collects boundary and infrastructure GIS data from the same MAX5 base.
FAQ
Which DJI drones are compatible with a third-party NTRIP base station?
DJI RTK-capable drones that accept Custom Network RTK input via the DJI RC Pro controller include: Phantom 4 RTK, Matrice 300 RTK, Matrice 350 RTK, Mavic 3 Enterprise (RTK variant), and Zenmuse P1/L1 payload configurations. All of these accept standard RTCM 3.x corrections from any NTRIP source — including APEKS receivers. Verify your specific DJI firmware version supports Custom Network RTK in the DJI Pilot 2 app settings before deployment.
Does the APEKS base station need to be on a known control point?
Yes, for centimetre-accuracy outputs it must be on a known coordinate. If you set the base on an unknown position (autonomous GNSS position), the drone will achieve centimetre accuracy relative to the base — but the absolute position of the entire survey will be as accurate as the base's GNSS position, typically ±1–3m. For photogrammetric mapping where absolute accuracy matters, always set the base on a coordinated control point and enter the known coordinate manually in ApekSurv.
Can I use the MAX5 as a base for both the drone and ground survey simultaneously?
Yes. The MAX5 broadcasts corrections to all receivers within range simultaneously — there is no limit on the number of connections. A DJI drone receiving corrections via WiFi hotspot and an AP40 Laser+ rover receiving corrections via LoRa radio can both operate from the same MAX5 base at the same time. Both datasets share the same base coordinate and align in post-processing without additional reconciliation.
What is the range between the APEKS base and the DJI drone?
For the NTRIP-over-WiFi correction link, range is limited by the WiFi hotspot — typically 50–100m from the hotspot device. This is not a limitation in practice because the hotspot travels with the ground crew near the base, and the drone receives corrections via the DJI RC Pro controller (which connects to the hotspot), not directly from the GNSS receiver. The drone can fly several kilometres from the base and still receive corrections via the RC Pro's connection to the hotspot.
YOUR RTK RECEIVER IS ALREADY A DJI BASE STATION.
Any APEKS receiver — AP10, AP20, AP40 Laser+, AP80 Pro, or MAX5 — can serve as the RTK base station for your DJI drone survey. Centimetre accuracy. No CORS required. No D-RTK 2 required. One piece of equipment. Two workflows.
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- DJI — Phantom 4 RTK User Manual, 2024
- DJI — Matrice 350 RTK Release Notes, 2025
- DJI — Custom Network RTK Setup Guide, DJI Pilot 2
- ISO 17123-8:2015 — Field Procedures for GNSS RTK
- RTCM Standard 10403.3 — Differential GNSS Services
- APEKS MAX5 Base Station Technical Datasheet, 2026
- ApekSurv Field Software User Guide, 2026