The Emlid Reach RS4 is an all-band, all-constellation RTK GNSS receiver with built-in tilt compensation, a magnesium alloy body, and a dual-band UHF and LoRa radio system that transmits and receives on both frequencies. Designed for surveyors, drone-mapping operators, GIS crews, and construction teams who need centimeter-level positioning under tree canopy, in urban canyons, and at the edges of correction-network coverage, the RS4 tracks 672 channels across GPS, GLONASS, Galileo, BeiDou, QZSS, and NavIC — including the lower L5 and L6 bands that resist multipath and jamming. Pair it with a DJI, Autel, or Skydio RTK drone as a project-local base station, mount it on a survey pole for stake-out and topo, or set it up as a permanent CORS-style reference. Backed by Emlid Flow software and lifetime support from the manufacturer.
All-band RTK GNSS receiver. 672 channels, L1/L2/L5/L6 across every major constellation, 7 mm + 1 ppm RTK accuracy, no-angle-limit tilt compensation, IP68 magnesium body, 16-hour battery, and dual-band UHF + LoRa radios that transmit and receive.
Features
- All-band, all-constellation tracking: GPS L1C/A, L2C, L5; GLONASS L1OF, L2OF; Galileo E1-B/C, E5a, E6; BeiDou B1I, B1C, B2a, B3I; QZSS L1C/A, L1C/B, L2C, L5; NavIC L1-SPS and L5-SPS
- 672 channels — tracks 40+ satellites simultaneously for steadier fixes under canopy and in urban environments
- RTK positioning accuracy of 7 mm + 1 ppm horizontal, 14 mm + 1 ppm vertical, with typical convergence in under 5 seconds
- Next-generation tilt compensation with no angle limit, factory calibration, and a few-second initialization (no walking pattern required) — immune to magnetic interference because it's IMU-only
- Dual-band radio that transmits and receives on both UHF (410–470 MHz, up to 2 W, TRIMTALK 450S protocol) and LoRa (868/915 MHz, up to 1 W, license-free in most of North America)
- Built-in global LTE modem with nano-SIM slot for NTRIP corrections from the Emlid NTRIP Caster or third-party caster networks
- Magnesium alloy body — the same material class used in aerospace housings — for a lighter, stronger receiver than a polycarbonate-shell equivalent
- IP68 ingress protection, rated for dust, immersion, and continuous rain
- Operating temperature from -40 °C to +65 °C (-40 °F to +149 °F) for cold-weather survey work and hot-climate operations
- 16 hours of continuous battery life as an RTK rover with tilt enabled, from the internal 5000 mAh / 36 Wh Li-ion pack
- USB-C Power Delivery charging at 5/9/12/15 V — recharge from a laptop, USB-C wall brick, or field power bank
- Emlid Quick Release adapter mount (sold separately) eliminates pole backlash for accurate tilt measurements; standard 5/8"-UNC thread also accepts any survey pole or tripod
- 16 GB internal storage for RINEX, NMEA, LLH/XYZ, and UBX log files
- Wi-Fi 802.11 a/b/g/n and Bluetooth 5.1 for connection to Emlid Flow on iOS or Android
- Compatible with the Emlid Flow and Flow 360 ecosystem for project management, stake-out, layouts, line surveys, cut-and-fill, and as-built verification
- Lifetime expert support from Emlid included with every receiver
What it does
- RTK rover: Receives corrections over NTRIP (cellular or Wi-Fi), UHF radio, or LoRa radio and delivers centimeter-level position to Emlid Flow or any compatible data collector
- RTK base station: Logs a known point, computes corrections, and broadcasts them to a rover, a drone, a tractor autopilot, or a GPR system via Emlid NTRIP Caster, UHF, or LoRa
- PPK base: Records raw RINEX observations alongside drone-collected geotags for post-processed kinematic workflows in Emlid Studio or third-party photogrammetry tools
- Drone RTK base: Streams RTCM3 corrections to DJI, Autel, and Skydio RTK aircraft over Emlid NTRIP Caster or Local NTRIP for sub-2 cm geotag accuracy in the field
- Permanent base / CORS-style reference: External power input through the bottom connector lets the receiver run indefinitely on a 6–36 V supply for fixed installations
Specifications
| Specification | Value |
|---|---|
| Manufacturer | Emlid Tech Kft. (Budapest, Hungary) |
| Product | Reach RS4 multi-band RTK GNSS receiver |
| Constellations tracked | GPS, GLONASS, Galileo, BeiDou, QZSS, NavIC |
| Frequency bands | L1 / L2 / L5 / L6 |
| Channels | 672 |
| RTK accuracy (horizontal) | 7 mm + 1 ppm |
| RTK accuracy (vertical) | 14 mm + 1 ppm |
| PPK accuracy (horizontal) | 5 mm + 0.5 ppm |
| PPK accuracy (vertical) | 10 mm + 1 ppm |
| Static accuracy (horizontal) | 4 mm + 0.5 ppm |
| Static accuracy (vertical) | 8 mm + 1 ppm |
| Tilt compensation | RTK + 2 mm + 0.3 mm per degree of tilt, no angle limit |
| Convergence time | ~5 seconds typical |
| Update rate | Up to 10 Hz |
| UHF radio | 410–470 MHz, TRIMTALK 450S, up to 2 W, transmit and receive |
| LoRa radio | 868 / 915 MHz, up to 1 W, transmit and receive (license-free in most of North America at 915 MHz) |
| LTE modem | Global bands, nano-SIM slot |
| Wi-Fi | 802.11 a/b/g/n |
| Bluetooth | 5.1 (BR/EDR + LE) |
| Ports | USB-C, RS-232 (via bottom connector) |
| Internal storage | 16 GB |
| Data formats | RTCM3 corrections; NMEA, LLH/XYZ position output; RINEX, NMEA, LLH/XYZ, UBX logging |
| Battery | 5000 mAh Li-ion, 7.2 V, 36 Wh, integrated (not user-replaceable) |
| Battery life | 16 hours as RTK rover with tilt |
| Charging | USB-C Power Delivery (5/9/12/15 V at 3 A) |
| External power input | 6–36 V via bottom connector |
| Body | Magnesium alloy |
| Ingress protection | IP68 |
| Operating temperature | -40 °C to +65 °C (-40 °F to +149 °F) |
| Dimensions | 128.6 × 128.6 × 99.3 mm (5.06 × 5.06 × 3.91 in) |
| Weight | 927 g (2.04 lb) |
| Mount | 5/8"-UNC threaded insert |
| Software included | Emlid Flow (iOS, Android), Emlid Flow 360 (cloud), Emlid Studio (PPK post-processing) |
| Support | Lifetime expert support from Emlid |
Who this is for
- Land surveyors needing a single all-band receiver that handles base, rover, tilt, and NTRIP duty without juggling separate radios or correction services
- Drone mapping operators flying DJI Phantom 4 RTK, Mavic 3 Enterprise, Matrice 30/30T, Matrice 300/350 RTK, Matrice 4 Series, Autel EVO II RTK, or Skydio X10 platforms who want a project-local base for centimeter geotags instead of relying on public CORS
- Construction crews running stake-out, layouts, cut-and-fill, and as-built verification daily, where the tilt compensation removes the need to plumb the pole over every point
- GIS and asset-mapping teams collecting points and lines under tree canopy or near buildings, where the all-band L5/L6 tracking and improved antenna keep fixes stable
- Archaeology, environmental, and research crews working in cold or hot climates where IP68 rating and the -40 to +65 °C range matter
- Precision agriculture operators integrating an RTK base with tractor autopilots, where the external power input keeps the receiver running on a 12 V or 24 V supply indefinitely
- Public-safety and emergency-mapping programs that need a portable, rugged base station for incident-area surveys without dependence on cellular coverage
- Existing Reach RS2+ or RS3 owners upgrading for transmit-and-receive on both UHF and LoRa (the RS3 only received on UHF), faster tilt initialization, and the magnesium body
What's included
- 1 × Emlid Reach RS4 receiver
- 1 × Carrying case
- 1 × USB-C cable
Please note: Survey pole, tripod, Emlid Quick Release adapter, UHF antenna whip, LoRa antenna whip, nano-SIM card, NTRIP service subscription, and data collector (tablet or phone running Emlid Flow) are sold separately. The receiver ships with a built-in modem but no SIM card — supply your own or use Wi-Fi tethering for cellular NTRIP. For tilt-compensation work, the Emlid Quick Release adapter is strongly recommended to eliminate pole backlash.
Reach RS4 vs. Reach RS3 vs. Reach RS2+
Emlid's current field-ready RTK lineup gives surveyors three tiers:
- Reach RS2+: Multi-band RTK receiver with LoRa radio (transmit and receive) but no UHF, no tilt compensation, and a polycarbonate body. The value option for crews that mostly work over LoRa or NTRIP and don't need tilt.
- Reach RS3: Multi-band RTK receiver with tilt compensation, LoRa transmit-and-receive, and UHF receive-only. Discontinued or de-emphasized as the RS4 takes over, but still in inventory at some dealers.
- Reach RS4 (this product): All-band (adds L5/L6 to the L1/L2 stack), 672 channels, magnesium body, faster tilt initialization with no angle limit, and transmit-and-receive on both UHF and LoRa. The flagship single-IMU receiver in the lineup.
- Reach RS4 Pro (sold separately): Adds a dual-camera AR system for visual stake-out and point capture; same GNSS engine, IMU, and radio system as the RS4. Pick the Pro if the workflow benefits from camera-aided positioning in confined, obstructed, or visually marked areas.
DJI RTK drone integration
The Reach RS4 acts as a base station for DJI Enterprise aircraft that support NTRIP corrections, including the Phantom 4 RTK, Mavic 3 Enterprise / Mavic 3 Multispectral / Mavic 3 Thermal, Matrice 30 / 30T, Matrice 300 RTK / 350 RTK, and Matrice 4 Series. The workflow:
- Set up the RS4 over a known point or run an averaged single-point base
- Stream RTCM3 corrections out over Emlid NTRIP Caster (internet) or Local NTRIP (Wi-Fi to the drone controller)
- Connect the DJI remote controller to the same Emlid Caster mount point or local Wi-Fi NTRIP source
- Fly the mission — the drone applies corrections in real time for centimeter-accurate geotags
- Process the geotagged images in any photogrammetry pipeline (Pix4D, Metashape, DJI Terra, etc.) for survey-grade orthomosaics, point clouds, and DEMs
The Reach RS4 also supports PPK workflows: log raw RINEX on the receiver during the flight, sync against the drone's onboard log file in Emlid Studio after landing, and produce corrected positions even if real-time RTK was unstable.
FAQ
What's the difference between the Reach RS4 and the Reach RS4 Pro?
Same GNSS engine, same IMU, same radio system, same battery and body. The Pro adds a dual-camera AR module for visual stake-out and visual point capture — useful for survey work in confined spaces, marked locations, or anywhere a camera-aided workflow speeds things up. The standard RS4 is the right choice for crews who don't need the camera workflow and want to keep cost lower.
Does the RS4 work as a base station for DJI Phantom 4 RTK or Mavic 3 Enterprise?
Yes. The RS4 streams RTCM3 corrections over Emlid NTRIP Caster (cloud) or Local NTRIP (Wi-Fi) to any DJI Enterprise aircraft that accepts NTRIP input, including Phantom 4 RTK, Mavic 3E / 3M / 3T, Matrice 30 / 30T, Matrice 300 / 350 RTK, and the Matrice 4 Series. Emlid publishes step-by-step DJI integration guides in their documentation.
How is the tilt compensation different from the RS3?
The RS4 IMU initializes in a few seconds with natural pole movement — no walking pattern, no specific calibration dance. There's no angle limit, so the receiver stays accurate even when the pole is significantly tilted. The RS3 needed roughly 20 meters of walking or 10–20 seconds of tilting to initialize, and was rated up to 60° of tilt. The RS4's new IMU is the practical reason most users upgrade.
Does the LoRa radio require a license in the US?
No. The RS4's LoRa radio operates in the 915 MHz ISM band and supports up to 1 W of transmit power, which is within the FCC's license-free Part 15 limits for that band in the United States. The UHF radio (410–470 MHz) is a different matter — many UHF allocations require an FCC license depending on the frequency and use case. If you only use the LoRa link, no license paperwork is needed in the US.
Can I use the RS4 without a cellular connection?
Yes. The receiver runs corrections over UHF radio, LoRa radio, or Wi-Fi (Local NTRIP), so a cellular SIM is optional. For crews that work in areas without LTE coverage — remote sites, forested canyons, foreign countries without roaming — set up the RS4 as a base over LoRa to a rover, or use Local NTRIP from the base to a drone controller over Wi-Fi.
What software comes with the RS4?
Emlid Flow (free mobile app for iOS and Android) handles project setup, point collection, stake-out, base configuration, and NTRIP connections. Emlid Flow 360 (free cloud service) syncs projects between field and office and lets multiple team members collaborate. Emlid Studio (free desktop app) handles PPK post-processing of RINEX logs. All three are included with the receiver — no subscription required.
What's the warranty?
Emlid covers the Reach RS4 against manufacturing defects under their standard warranty terms. The receiver also includes lifetime expert technical support — the support team responds within 24 hours and helps with everything from initial setup to specific drone integrations. Contact Emlid or your authorized dealer for warranty service.
Where does it ship from?
Emlid ships from a Chicago warehouse to US customers via FedEx and UPS, with typical 2-7 day delivery. Emlid is a Hungarian company (headquartered in Budapest) with global distribution through authorized dealers.
Can I check it on an airline?
The Reach RS4's battery is 36 Wh — well under the FAA / IATA 100 Wh threshold for lithium-ion batteries in carry-on. The receiver and battery travel as a single integrated unit (the battery isn't user-removable), so the whole receiver should travel as carry-on with you. Don't check it in luggage — embedded lithium batteries above the spare-battery thresholds should not go in checked baggage. Verify your specific airline's policy before traveling.
Do I need a separate data collector?
Yes — you'll need a phone or tablet running Emlid Flow (iOS or Android). Most surveyors use a ruggedized tablet (Samsung Galaxy Tab Active series, iPad with a case, or a dedicated ruggedized Android tablet) for field work. Emlid Flow is a free download and doesn't require a paid subscription.
