Galileo HAS for RTK: Free Positioning Without Internet
Galileo HAS (High Accuracy Service) is a free, satellite-delivered correction service broadcast by the Galileo constellation. Unlike CORS/NTRIP corrections delivered over the internet, HAS corrections are embedded directly in the Galileo signal — received by the antenna with no SIM card, no cellular data, and no base station required. Accuracy after convergence is ±20cm horizontal — not centimetre-level RTK Fixed, but sufficient for GIS mapping, rough stakeout, and environmental survey in areas with no CORS or cellular infrastructure. All APEKS receivers with UM980 support Galileo HAS natively in ApekSurv. Activate in Device → Data Link → HAS.
Two scenarios where surveyors traditionally lose RTK: open ocean, where no cellular data exists. And remote desert or jungle, where the nearest CORS station is 300km away. In both cases, the standard fix has always been to deploy a local base station — a workable solution on land, impossible at sea or in certain remote applications. Galileo HAS changes this. It delivers positioning corrections from the satellite signal itself — no internet, no SIM, no base station required. This guide explains what HAS delivers, how it differs from CORS and PPP, when it is the right correction source, and how to activate it on any APEKS receiver.
1. What Is Galileo HAS?
Galileo HAS (High Accuracy Service) is a free positioning correction service broadcast directly by the Galileo satellite constellation on the E6-B signal. It was declared operational in January 2023 and is now broadcast globally 24/7 with no subscription required.
The Galileo satellites broadcast precise satellite orbit and clock corrections on the E6-B signal. A compatible GNSS receiver (supporting E6-B reception and HAS decoding) receives these corrections directly through the antenna — no separate communication channel required. The receiver applies the corrections to its GNSS measurements and computes a high-accuracy position.
Key characteristics:
- Free of charge — no subscription, no registration
- Global coverage — anywhere the sky is visible, corrections are available
- No internet or cellular dependency — corrections arrive via satellite signal
- Compatible receivers: all APEKS receivers with UM980 board support E6-B and HAS decoding natively
2. How HAS Differs from CORS and PPP
To understand where Galileo HAS fits within a surveyor's technical toolkit, it must be compared directly against existing industry correction standards: Network RTK via CORS/NTRIP and traditional Precise Point Positioning (PPP).
| Feature | CORS/NTRIP | PPP | Galileo HAS |
|---|---|---|---|
| Delivery | Internet/4G | Internet/Satellite | Galileo E6-B satellite |
| Cost | Free (most national) | Free/paid | Free |
| Convergence time | 10–60 sec | 20–40 min | 5–15 min |
| Accuracy (converged) | ±8mm Fixed | ±3–10cm | ±20cm |
| Internet required | Yes | Yes (or satellite) | No |
| Base station required | Optional (CORS) / Required (remote) | No | No |
| Global coverage | No (depends on network) | Yes | Yes |
| Best use | Urban/semi-urban survey | Marine, remote, aviation | Remote survey, GIS, marine |
HAS sits between PPP and CORS in terms of convergence time and accuracy. It is faster to converge than traditional PPP and requires no internet. It is less accurate than CORS but requires no infrastructure. For remote land survey where ±20cm is acceptable and CORS is unavailable, HAS is the most practical option. For centimetre-accuracy work on remote sites, a local MAX5 base station remains the correct solution.
3. What Accuracy Can You Expect from HAS?
Galileo HAS Phase 1 (current) delivers horizontal accuracy of ±15–25cm after convergence, vertical accuracy of ±25–45cm after convergence, and a convergence time of 5–15 minutes from a cold start.
HAS requires time to compute the position solution after first activation. For the first 5–15 minutes, accuracy is degraded (±0.5–2m). After convergence, accuracy stabilises at ±15–25cm. Keep the receiver moving during convergence to maintain signal tracking continuity.
Comparison to other correction sources:
- HAS vs CORS Fixed: CORS delivers ±8mm vs HAS ±20cm — HAS is 25× less accurate in horizontal positioning.
- HAS vs Float: HAS (±20cm converged) is similar to Float accuracy — both are sub-metre but not survey grade.
- HAS vs Single: HAS is 10–20× more accurate than uncorrected single-point GNSS (±3–5m).
Suitable applications include GIS field data collection (±0.5m acceptable), rough environmental monitoring point establishment, maritime survey where sub-metre is sufficient, and preliminary route planning in remote areas.
It is not suitable for cadastral survey, construction stakeout, topographic survey, mining, or any application with accuracy requirements tighter than ±200mm.
4. When to Use HAS vs CORS vs Base+Rover
Use CORS/NTRIP. Fastest setup, highest accuracy (±8mm Fixed), no additional hardware. Connect via 4G NTRIP in ApekSurv. HAS is not needed here.
Deploy MAX5 base station on a known control point. 5W LoRa covers 25km. Full Fixed RTK accuracy throughout the site. This is the correct solution for all professional survey work in remote areas. Refer to our comprehensive base station deployment guide.
Activate Galileo HAS in ApekSurv. Allow 5–15 minutes for convergence. Use for GIS mapping, rough stakeout verification, or environmental data collection only. Do not use HAS for survey work requiring ±20mm or better accuracy.
5. How to Activate HAS on an APEKS Receiver
All APEKS receivers with UM980 board (including AP10, AP20, AP20 AR, AP40 Laser+, and AP80 Pro) support Galileo E6-B and HAS natively. Confirm the firmware version is current via OTA update in ApekSurv. HAS support was introduced in UM980 firmware version 3.x.
On the controller, open ApekSurv → Device → Data Link. The correction source list shows NTRIP, Radio, and HAS as available options.
Tap HAS. No credentials, server address, or SIM card are required. The receiver begins tracking the Galileo E6-B signal and decoding HAS correction packets from the satellite broadcast.
The solution status transitions: Single → HAS (converging) → HAS (converged). Convergence indicator on ApekSurv shows the current accuracy estimate. Wait until convergence is complete before recording any data. Typical convergence: 5–15 minutes. Keep the receiver moving or tracking in open sky during convergence.
After convergence, occupy a known control point or landmark with known coordinates. Compare the HAS position against the known value — typical agreement at convergence is ±20–30cm. If agreement is within your project tolerance, begin data collection. Record the convergence time in the field book.
6. The Core Limitations of Galileo HAS
Symptom: The receiver has been in HAS mode for 20+ minutes but convergence has not completed. Accuracy estimate remains above 0.5m. The receiver never reaches the expected ±20cm level.
Cause: HAS convergence requires continuous tracking of multiple Galileo E6-B signals. Dense tree canopy, buildings, or narrow sky view interrupt signal continuity and reset or delay convergence. HAS is significantly more sensitive to sky obstruction than standard RTK because the satellite-delivered corrections require clean signal from a specific constellation and frequency.
Fix: Move to an open sky location with minimal obstruction above 15° elevation. Allow convergence to complete before moving into the working area. Once converged, the solution maintains better under moderate obstruction than during convergence.
Symptom: The surveyor activates HAS on a remote site and begins stakeout. Points are placed ±0.3–0.5m from the design position. The engineering team rejects the work as outside tolerance.
Cause: HAS delivers ±20cm after convergence — not ±8mm RTK Fixed. For construction stakeout, cadastral, or any application requiring centimetre accuracy, HAS is the wrong correction source regardless of how convenient it is.
Fix: Deploy a MAX5 base station on a known control point. Full Fixed RTK accuracy is available within 10 minutes of MAX5 setup, covers 25km of site, and requires no internet. HAS is for GIS and reconnaissance applications only — not for engineered survey work.
Symptom: The HAS solution appeared to converge correctly but position values are slowly drifting during the field session. Control point checks show increasing discrepancy over time.
Cause: HAS accuracy is affected by satellite geometry changes during the day and ionospheric conditions. Unlike RTK Fixed, which locks integer ambiguities and maintains centimetre stability, HAS is a float-type solution that varies with the quality of the broadcast corrections and signal reception conditions.
Fix: Re-check a known control point every 30–60 minutes during long HAS sessions. If drift exceeds the project tolerance, suspend collection and re-converge from a clear sky location. For sessions longer than 2 hours, consider deploying a local base station for stable reference.
7. HAS + MAX5 Combined Workflow
For remote sites where the primary survey work requires Fixed RTK accuracy but a secondary team needs to collect reconnaissance or GIS data simultaneously, a dual-tier field workflow maximizes productivity.
- Primary team: AP40 Laser+ or AP20 AR rover connected to MAX5 base via LoRa. Full Fixed RTK ±8mm for production survey within 25km of base.
- Secondary team: APS1 handheld in HAS mode. No base connection required. ±20cm for GIS data collection, environmental monitoring, or access road reconnaissance anywhere on site — including areas beyond the MAX5 radio range.
Both teams work simultaneously from the same MAX5-controlled reference framework for the production areas. The HAS team independently covers reconnaissance zones where Fixed RTK is not required. This workflow maximises field team productivity on large remote projects where coverage exceeds the MAX5 radio range.
8. FAQ
Is Galileo HAS truly free and permanent?
Yes. Galileo HAS is a public European Space Agency service, free for all users worldwide with no subscription, registration, or annual fee. The service entered full operational capability in 2023 and is planned as a permanent component of the Galileo constellation's service offering. There is no mechanism by which the service would be withdrawn from end users, as it is a sovereign European infrastructure rather than a commercial offering.
Does HAS work in China, the Middle East, or Africa?
Yes. HAS is global. The Galileo satellites orbit at approximately 23,000km altitude and provide continuous coverage worldwide. Any location with an unobstructed view of the sky can receive HAS corrections. Coverage quality is consistent across all APEKS target markets including Indonesia, Saudi Arabia, Brazil, Nigeria, and remote Australia.
Can I combine HAS with my CORS connection?
No. HAS and CORS/NTRIP are mutually exclusive correction sources — you select one in ApekSurv's Data Link settings. In areas with CORS coverage, CORS always delivers higher accuracy and faster convergence. Use CORS where available; switch to HAS only when CORS and cellular are both unavailable.
How is HAS different from PPP?
Both HAS and PPP deliver corrections without requiring a local base station. HAS broadcasts corrections via the Galileo E6-B satellite signal, requiring no internet. Traditional PPP delivers corrections over the internet or via satellite data link. HAS converges in 5–15 minutes; traditional PPP can take 20–40 minutes. Both deliver similar final accuracy (±10–30cm). HAS is simpler to use and requires no subscription or data connection.
What is the accuracy of HAS compared to Fixed RTK?
HAS converged accuracy is approximately ±15–25cm horizontal and ±25–45cm vertical. Fixed RTK accuracy is ±8mm horizontal and ±15mm vertical — roughly 20–30 times more accurate in horizontal positioning. HAS is suitable for GIS mapping and rough stakeout where sub-metre accuracy is acceptable. It is not suitable for cadastral, construction, topographic, or any engineered survey application where accuracy requirements are tighter than ±200mm.
NO SIM. NO BASE. NO LIMITS.
All APEKS receivers support Galileo HAS via UM980 — free satellite corrections anywhere on Earth, no subscription required. For centimetre accuracy on remote sites, pair with MAX5 for full Fixed RTK without CORS.
Send an Inquiry → WhatsApp Us →References
- European Space Agency — Galileo HAS Service Definition Document, 2023
- ISO 17123-8:2015 — Field Procedures for GNSS RTK
- Unicore Communications UM980 Product Brief
- APEKS MAX5 Base Station Technical Datasheet, 2026
- ApekSurv Field Software User Guide, 2026