SparkFun RTK Torch – Compact, Waterproof Surveyor with RTK Functionality

Sparkfun RTK Torch, GNSS surveyor

El SparkFun RTK Torch is a compact, waterproof GNSS receiver that offers RTK functionality for high-precision measurements. Despite its portable size, the RTK Torch is packed with advanced technology. It features an ESP32-WROOM module that offers Wi-Fi and Bluetooth, as well as an RTK-compatible Unicore UM980 module that receives multi-frequency GNSS signals with high accuracy. It also includes an STM32WLE5CCU6 microcontroller from STMicroelectronics to obtain corrections via LoRa radio.

The RTK Torch is an evolution of the previous RTK Facet, but with significant improvements. It offers wider reception, greater precision and a more portable format. Like the Facet, the RTK Torch comes with a carrying case, 3m USB C to C charging cable, 65W PD wall adapter, and a 1/4″ to 5/8 antenna thread adapter ″.

In addition, adapts to various needs thanks to its different modes of operation:

  • GNSS positioning (accuracy of ~800 mm).
  • GNSS positioning with RTK (8mm precision), using a local base station.
  • GNSS positioning with PPP-RTK (14 to 60 mm precision), using PointPerfect corrections.
  • GNSS positioning with tilt compensation.
  • GNSS base station.
  • GNSS base station NTRIP server.

This device is perfect for tasks that require High-precision geolocation and GIS mapping (Geographic information system). It can be used in applications such as surveying, agriculture and construction such as surveying.

Although the RTK Torch has a housing Dust and water resistant (IP67 rating), is not recommended for permanent outdoor mounting. Of course, the device runs SparkFun's universal RTK Everywhere firmware, which is open source and hosted on GitHub. It also includes Zero-Touch RTK, a feature that allows fixes to be automatically uploaded using just Wi-Fi network credentials (available in select regions and with an initial free subscription).

You can also set your phone to receive NMEA data from the RTK Torch via Bluetooth. The device works with several GIS applications for Android and iOS, such as SW Maps (recommended), Survey Master Vespucci, QGIS and QField (these last three are open source).

Technical characteristics of the surveyor


As for the features or specifications Surveying device techniques are:

  • ESP32-WROOM Wireless Transceiver:
    • Dual-core Xtensa 32-bit @ 240MHz CPU
    • Memory 16MB flash, 2MB PSRAM, and 520KB SRAM
    • Wireless connectivity Wi-Fi 802.11b/g/n and Bluetooth 4.2 and BLE
  • Unicore UM980 GNSS receiver with 50Hz RTK information update rate
    • 1408-channel for GPS, GLONASS, Galileo, BeiDou, and QZSS signals
    • Horizontal measurement:
      • Autonomous: 1.5m
      • DGPS: 0.4m
      • RTK: 0.8cm + 1ppm
    • Vertical measurement:
      • Autonomous: 2.5m
      • DGPS: 0.8m
      • RTK: 1.5cm + 1ppm
    • Maximum altitude: 18km
    • Maximum speed: 515m/s
  • LoRa Radio STM32WLE5CCU6 MCU, Arm Cortex-M4 core @ 48MHz with LoRa built-in
  • USB-C for power and programming
  • Internal antenna: L1/L2/L5 with a gain of ≥ 2.3dBi
  • Tilt compensation via integrated IM19 unit
  • Power 7.2V 6.800mAh 49Wh battery with 10W charge
  • Others: button control, 1W amplifier/front-end (at 900MHz)
  • Weight: 428g
  • Sizes: 71x71x147mm

The RTK Torch can be purchased from the SparkFun store for an approximate price of €1500, with discounts available for bulk purchases. On the official website you can also find more information in the RTK Torch connection guide and in the RTK Everywhere manual.

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