Corrections arrive but the fix is slow
Link latency or a mismatched mountpoint. The corrections are being received, but the differential age is large and updates are not timely, so the fixed solution takes a long time to converge.
TECH · fixslow20261010
Slow Fix and Drift: Check Corrections, Obstruction and Multipath in Order
A slow or drifting fixed solution is usually not a failed device but a problem in the corrections, the obstruction or the multipath; sorting the symptom into corrections, environment and link continuity, and recording before reproducing, gives a conclusion that holds.
Three common field blockers
The fixed solution comes and goes
Obstruction and multipath at the point. Reflections from a building face, a wall, a metal billboard or a water surface raise noise and reduce satellite availability at the same time.
Repeated reconnects
An unreasonable network-handover policy means the link cannot be re-established. When the mobile network switches frequently between 4G and Wi-Fi, the differential stream breaks and the fixed solution drops with it.
Device specifications (source parameters)
H13 centimetre-level RTK handheld terminal
- Full-constellation centimetre-level RTK, NTRIP CORS differential support, time to first fix <10s
- BeiDou-3 + GPS + GLONASS + Galileo + QZSS + SBAS
- 1-20Hz (10Hz default)
- 4G full-network + Bluetooth 5.1
- ISP high-definition screen + voice broadcast
- IP67, 2m drop resistance, 4000mAh, RTK runtime ≥20h, USB-C 5V/2A
H11 portable multi-frequency positioning terminal
- Three versions: BeiDou-only / dual-frequency / Pro
- Channels 128 / 128 / 1408 (the Pro uses the same module family as the H13, NebulasIV)
- RTK accuracy: horizontal 1cm+1ppm / 1cm+1ppm / 0.8cm+1ppm; elevation 2cm+1ppm / 2cm+1ppm / 1.5cm+1ppm
- Update rate 1-10Hz / 1-10Hz / 1-20Hz
- The Pro version supports more BeiDou / GPS / GLONASS / Galileo / QZSS / NavIC / SBAS frequencies
- 4G full-network CAT1 + NTRIP + MQTT + dual-mode Bluetooth
- OLED display, IP67
- USB-C, 5V/2A adapter
- GboxTools configuration
Registered model definitions (checked 20260929): handheld H13 (full-constellation multi-frequency professional-grade RTK handheld terminal, Pro tier only) / H11 (BeiDou-only, dual-frequency and Pro versions; overseas H11 ProEU for Europe and H11 ProEN for North America; brand name "Beidou Xingtan"); module MG20 (customizable RTK PCBA); antennas SK6640 / SK6608. The H11 Pro and H13 use the same module family (1408 channels, NebulasIV).
How to choose: a three-step diagnosis order
- Step one, check the differential: account, mountpoint and link. Record the mountpoint, data-source IP / domain, differential age, packet-loss times and reconnect count.
- Step two, change the point: raise the antenna and avoid wall and metal reflections. Raise the antenna and move it away from curtain walls and metal structures, then compare whether the fixed solution is stable over the same period.
- Step three, read the logs: record the fixed-solution state with time to identify whether it is the link or the environment. Align state changes, differential age and satellite count on one time axis, then judge the root cause.
Frequently asked questions
Is a slow fix always a device problem?
Usually not. Check the link and the environment first: whether the corrections update in time, whether the mountpoint matches, and whether the point has obstruction and multipath; then consider the device side.
How can drift be judged?
Look at whether repeated readings at the same static point are stable. Leave the receiver stationary at one position for a period, compare the range of the horizontal and elevation readings, and check this against the project accuracy requirement.
Should the frequency point be changed?
Confirm this against the on-site electromagnetic environment and the multipath conditions. Changing the frequency point is an environment-side adjustment; complete the differential and point checks first, then decide whether to adjust based on the actual records.