SparkFun RTK Torch is a compact and waterproof GNSS surveyor with RTK functionality

SparkFun’s RTK Torch is a real-time kinematic (RTK) surveying device that offers tri-band reception, tilt compensation, and millimeter accuracy in a portable, waterproof enclosure.

It features an ESP32-WROOM module with 16MB flash and 2MB PSRAM, providing Wi-Fi and Bluetooth functionality. The onboard RTK-capable Unicore UM980 module receives various GNSS frequencies with high accuracy and supports all available constellations and frequencies. Also included is an STMicroelectronics STM32WLE5CCU6 MCU for obtaining corrections via LoRa radio.

The RTK Torch builds on the earlier RTK Facet, adding improvements such as wider reception, higher precision, and a more portable form factor. Like the Facet, the RTK Torch comes in a bundle that includes a carrying case, a 3m USB C-to-C charging cable, a 65W PD wall adapter, and a 1/4in. to 5/8in. antenna thread adapter.

It supports several operating modes including

GNSS Positioning (~800mm accuracy) – also known as ‘Rover’
GNSS Positioning with RTK (8mm accuracy) – using a local base station
GNSS Positioning with PPP-RTK (14 to 60mm accuracy) – using PointPerfect corrections
GNSS Positioning with Tilt Compensation
GNSS Base Station
GNSS Base Station NTRIP Server

It is well-suited for high-precision geolocation and GIS (Geographic Information System) mapping and can be used in applications such as land surveying, agriculture, and construction.

We have covered other GNSS RTK products with centimeter accuracy in the past, including HYFIX’s RTK Rover, ROCK Base, and the simpleRTK2B-SBC board.

SparkFun RTK Torch specifications:

Wireless Transceiver – ESP32-WROOM module
- CPU – Dual-core Xtensa 32-bit microprocessor @ 240MHz
- Memory and Storage – 16MB flash, 2MB PSRAM, and 520KB internal SRAM
- Wireless – Wi-Fi 802.11b/g/n, and Bluetooth (4.2 and BLE)
GNSS Receiver – Unicore UM980 module, with 50Hz RTK data update rate
- 1408-channel concurrent reception of GPS, GLONASS, Galileo, BeiDou, and QZSS signals
- Horizontal Accuracy
  - Autonomous: 1.5m
  - DGPS: 0.4m
  - RTK: 0.8cm + 1 ppm
- Vertical Accuracy
  - Autonomous: 2.5m
  - DGPS: 0.8m
  - RTK: 1.5cm + 1 ppm
- Max Altitude: 18km (11 miles)
- Max Velocity: 515m/s (1152mph)
LoRa Radio – STM32WLE5CCU6 MCU, Arm Cortex-M4 core @ 48MHz with built-in LoRa
USB – USB-C for power delivery and programming
Internal Antenna: L1/L2/L5 with ≥ 2.3dBi gain
Tilt Compensation – IM19 inertial management unit
Misc – 7.2V 6.8Ahr 49Whr battery with 10W charging, single push-button control, 1W amplifier/front-end (centered at 900MHz)
Weight – 428g (0.94lbs)
Dimensions – 71 x 71 x 147mm

While the SparkFun RTK Torch comes in an enclosure rated IP67 (dust resistant and protection against immersion in water up to 1m), it is not recommended for permanent outdoor mounting.

It runs SparkFun’s universal firmware for RTK products, RTK Everywhere, which is open-source and hosted on GitHub. It also includes Zero-Touch RTK, a feature that enables the device to load corrections automatically with only the credentials for a Wi-Fi network. These corrections are retrieved via Wi-Fi from u-blox PointPerfect and are only available in the US, EU, and some parts of Australia, Canada, Brazil, and Korea. The product comes with a one-month free subscription to PointPerfect.

You can set up your phone to receive NMEA output from the RTK Torch over Bluetooth. The RTK Torch works with several Android and iOS GIS apps such as SW Maps (recommended), Survey Master Vespucci, QGIS, and QField with the last three being open-source.

With just the press of a button, the RTK Torch is the fastest way to take millimeter-grade measurements. By connecting your phone to the RTK Torch over Bluetooth, your phone or tablet can receive the NMEA output and work with most GIS software. This is exactly how professional-grade surveying devices have been operating for the past decade – we just made it faster, more precise, and a lot more economical.

The RTK Torch can be purchased via SparkFun’s shop and is currently priced at about $1500, with bulk discounts available. You can find more information about the product in the RTK Torch hookup guide and the RTK Everywhere manual.

Tomisin Olujinmi

Tomisin is a writer specializing in hardware product reviews, comparisons, and explainers. He is very passionate about small form factor and single-board computers.