4G + CORS (network RTK)
The rover connects over the cellular network to an NTRIP broadcast source and pulls differential corrections with an account. Wide coverage and no base station to build, which suits cross-region and highly mobile work.
TECH · link-diff-20261008
Differential Data Transport: 4G, Radio and CORS
There are three differential data links: public 4G over NTRIP/CORS, self-broadcast over a UHF radio, and a self-built base station with network backhaul. Choose the wrong link and the field result is either a slow fix or a fallback to single-point positioning.
Three links, and what each solves
The point of differential data is to send the base station's observations to the rover in a fixed format (commonly RTCM 3.x). How they are sent determines where each link fits.
Radio (UHF data link)
A self-built base station broadcasts RTCM directly over a data radio, with no dependence on the public network or data traffic. Suited to fixed work areas and to mountain or mining sites with no cellular signal.
Self-built base station + network backhaul
The base station is set on a known point, and its observations are sent back to a centre over 4G or a network bridge for forwarding. This covers long-term fixed points together with centralised management.
How to decide quickly
Stable public network in the work area: prefer 4G/CORS. Fixed area with no public network: build a base station with a UHF radio. Long-term unattended operation that also needs centralised management: base station with network backhaul.
Links supported by current devices (source data)
H13 centimetre-level RTK handheld terminal
Multi-constellation centimetre-level RTK; NTRIP CORS differential; fixed-solution convergence <10s.
Constellations: BeiDou-3 + GPS + GLONASS + Galileo + QZSS + SBAS; update rate 1–20Hz (10Hz default).
Communication: full-network 4G + Bluetooth 5.1; ISP high-definition display with voice prompts.
Enclosure: IP67, 2m drop resistance, 4000mAh, RTK runtime ≥20h; USB-C 5V/2A.
H11 portable multi-frequency terminal
Three versions: BeiDou-only, dual-frequency and Pro; channels 128 / 128 / 1408 (the Pro shares a module with the H13, NebulasIV).
RTK accuracy: horizontal 1cm+1ppm / 1cm+1ppm / 0.8cm+1ppm; vertical 2cm+1ppm / 2cm+1ppm / 1.5cm+1ppm.
Links: full-network 4G CAT1 + NTRIP + MQTT + dual-mode Bluetooth; OLED display, IP67; USB-C, 5V/2A adapter; configured with GboxTools.
MG20 customizable RTK PCBA module
UM980 + 4G + Bluetooth; 1408 channels (NebulasIV); supply range 5–30V.
Frequencies: BeiDou B1I/B2I/B3I/B1C/B2a/B2b, GPS L1/L2/L5, GLONASS L1/L2, Galileo E1/E5a/E5b/E6, QZSS L1/L2/L5/L6.
RTK accuracy (RMS): horizontal 0.8cm+1ppm, vertical 1.5cm+1ppm; cold start <20s; differential data can be carried over NTRIP or forwarded through a local serial port or radio.
Feature image
How to choose a link
Check first whether the work area has a public network
With signal, prefer 4G/CORS and skip the base station; without it, consider a UHF radio.
Then check whether the work area is fixed
Fixed, long-term points suit a self-built base station with network backhaul, set up once and used long term.
Settle the protocol and platform definitions last
RTCM version, reporting rate, coordinate system and declassification requirements, agreed once per project.
Frequently asked questions
Can 4G and radio be used at the same time?
Yes. Use CORS when a public network is available, and switch automatically to the local radio when it drops, which reduces on-site downtime.
How far does a radio reach?
It depends on power, terrain and antenna height; several kilometres in open areas, but city and mountain sites have to be tested on site.
Does the differential data format have to be consistent?
Yes. Configure the base and rover with the same RTCM version and coordinate system so the fixed solution does not drop repeatedly.