Emlid Reach RS4 is a flagship all-band RTK GNSS receiver built for speed and reliability. Its next-generation IMU delivers tilt compensation with centimeter precision, initializing in about 5 to 7 seconds; a quick-release mount preserves accuracy. A 672-channel engine and antenna track L1/L2/L5/L6 across GPS, GLONASS, Galileo, BeiDou, QZSS, and NavIC. Run as base or rover via dual-band radios: UHF (up to 2 W where licensed) and LoRa (up to 1 W). Magnesium alloy, IP68, and −40 to +149 °F (−40 to +65 °C) for year-round fieldwork.

High-Accuracy, Even Under Canopy

The Reach RS4 tracks every major constellation and band—including L1/L2/L5/L6—on a 672-channel engine. Lower-frequency L5/L6 signals and a redesigned antenna improve multipath resistance, so you keep a stable fix beneath tree cover and in reflective urban sites while tracking 40+ satellites concurrently.

RTK precision: H: 7 mm + 1 ppm (≈ 0.28 in + 1 ppm), V: 14 mm + 1 ppm (≈ 0.55 in + 1 ppm). Fix time: typically under 5 seconds.

• All-band GNSS: L1/L2/L5/L6
• GPS, GLONASS, Galileo, BeiDou, QZSS, NavIC
• 672 channels with improved antenna design
• Centimeter-level results in canopy and dense urban environments
• Fast initialization for rapid first fix

Next-Gen Tilt Compensation

Work accurately without leveling. The Reach RS4 maintains centimeter precision while the pole is tilted, with a typical specification of RTK + 2 mm + 0.3 mm/°. The compensation mechanism activates with a few quick moves and stays stable through the session, so you keep moving even in tight corridors and near obstructions.

Fast start, no recalibration. Initialization typically takes 5–7 seconds. Each unit is factory-calibrated, so there is no field calibration to manage.

Designed for difficult environments. The IMU is immune to magnetic interference, which helps maintain accuracy around vehicles, steel structures, and electronics. There is no practical angle limit for the algorithm within normal field use.

• Example performance: ~18 mm at 30° tilt (≈ 0.71 in).
• Typical spec: RTK + 2 mm + 0.3 mm/° tilt error.
• 5–7 s initialization; remains stable during long surveys.
• Factory-calibrated; no user calibration required.
• Magnetically immune IMU for urban and industrial sites.

Quick Release Mount

The RS4 quick release mount is engineered for tilt workflows. A backlash-free thread and keyed interface lock the receiver to the survey pole, removing wobble that could bias the IMU during tilt. Attachment is fast and repeatable, and the rigid coupling keeps geometry stable through rotation, stakeout, and transport.

Base and Rover

NTRIP

Run RTK in RTCM3 via VRS/CORS networks, or set another GNSS as an NTRIP base using Emlid NTRIP Caster.

Emlid Corrections

Powered by Point One Navigation, Emlid Corrections, is a VRS RTK correction service built into Emlid receivers. It delivers 1-2 cm horizontal and vertical accuracy over the internet, no base station required, no NTRIP configuration needed. 

The service is activated directly in Emlid Flow — either by claiming the included free year, or by entering a purchased license key.*

Compatible devices: Reach RX2, RS4, RS4 Pro, RS3, RX, RS2, RS2+ 

*Emlid Corrections is activated through Emlid Flow — either by claiming the included free year, or by entering a license key. Once active, corrections are delivered automatically with no manual NTRIP setup.

Each license is tied to a single device and is non-transferable. The license is global — it covers all regions currently supported by the network, including any future expansions.

The service is currently available in US, Europe, Australia, New Zealand and many other countries. Review the coverage map for more supported regions. 

Dual-Band Radio

UHF 450 MHz

• Transmit and receive corrections.
• Up to 2 W output (licensing may be required by local regulations).
• Compatible with Reach and third-party receivers supporting TRIMTALK 450S.

LoRa 915 MHz

• Transmit and receive corrections.
• Up to 1 W output (optimized for license-free use in North America).
• Interoperable with Reach receivers for simple base–rover links.

Built to Perform in Extreme Conditions

Magnesium Alloy Body

The RS4 uses a magnesium-alloy enclosure for high strength at low weight. This premium material is common in aerospace and high-end electronics and holds up to jobsite abuse without adding bulk.

16 Hours on One Charge

Work a full day without swapping gear. RS4 runs up to 16 hours on a single charge and tops up via USB-C or a power bank for flexible recharging in the field.

Waterproof and Dustproof

Rated IP68 for sealed, weatherproof operation in rain, snow, and dusty construction environments. Keep surveying when conditions turn rough.

Wide Operating Temperature

Engineered for year-round use from −40 to +65 °C (−40 to +149 °F) without compromising performance or stability.

Software For Every Stage Of Your Project

Emlid Flow pairs with the Flow 360 cloud to keep devices, projects, and code lists in sync on iOS and Android. Field updates appear in the office in near real time, so teams stay aligned and work from the same, current dataset.

Coordinate Your Team

Invite teammates, share projects, and control access. Track field progress from the office and exchange files without email or manual merges. A single, consistent interface reduces training time and keeps crews productive.

• Add users, assign permissions, and share active jobs.
• View project status and sync changes instantly between field and office.
• One workflow across the team with always up-to-date data.

Execute Projects On Site

Use Flow tools to set up the receiver, collect features, create linework, and stake designs with confidence. Results are organized for fast handoff to the office.

• Topographic surveys for terrain and elevation capture.
• Stakeout and layouts for points, lines, and markers.
• Line and road surveys for centerlines, offsets, and curves.
• Cut and fill calculations for earthworks and stockpiles.
• As-built verification against design plans.

Use Cases

Land Surveying & Construction

Pair Reach RS4 with Emlid Flow to handle everyday and advanced site work with speed and consistency. Teams stay aligned through shared projects and real-time sync, while the receiver’s all-band tracking and fast tilt compensation maintain accuracy in tight, obstructed areas.

Drone Mapping

Use RS4 as a base station for RTK or for PPK post-processing with logged RINEX files. Dual-band radios and NTRIP support provide flexible correction delivery on varied sites, and improved multipath resistance helps when placing control near canopy or reflective surfaces.