A tough, water resistant and repairable survey device built for cave surveyors.
Connects to TopoDroid & SexyTopo. Developed and manufactured in the UK.
Designed for wet and muddy caves, here are eleven things cavers asked me to build into the DiscoX.
Each one makes your survey project just a little easier.
F/01
RGB status LED & Disco Mode
The device keeps you up to date with it's reading status via an RGB LED light band around it's edge: red for stabilising, green for reading taken, purple for leg detected. If you hold down the second button disco mode activates and you're ready to party.
F/02
Fully repairable
Every component can be sourced, salvaged, 3D printed or laser cut. The DiscoX is designed to be repaired not replaced.
F/03
Paperless survey
Being able to send readings to your phone is a must for modern surveying, the DiscoX is compatible with both sexytopo and topodroid.
F/04
Onboard calibration
An intuitive calibration algorithm runs entirely on the device with instructions that show up on the screen, there's also more comprehensive guide here.
F/05
Anomaly detection
A single bad reading can ruin your survey. The DiscoX comes with a built in error checking feature. Put the device too close to your helmet light, watch or a bolt and it'll let you know.
F/06
Extended Bluetooth range
The latest firmware uses Coded-PHY to transfer data bits with extra redundancy, error correction and symbol spreading extending connection range significantly (up to 40m in testing).
F/07
Sealed USB-C
A waterproof data enabled USB-C port allows you to charge your device, update your device configuration and flash new firmware without opening up the device.
F/08
Configurable
All the important settings can be edited from the in device menu, but plug in and you can edit the settings.json file for a whole host of nerdy config changes.
F/09
Accurate battery level indicator
Contains a dedicated battery monitoring chip for reliable charge readings, a surprisingly difficult thing to measure but worth it for knowing how much life's left in the device.
F/10
Gorilla Glass & Quartz
With a scratch-resistant Gorilla Glass display cover and quartz glass laser protector you'll be able to lick your device clean secure in the knowledge you won't scratch your laser.
F/11
Open & reprogrammable
Build with C++ or optionally CircuitPython. Inspect the code, modify behaviour, missing a feature you want? Copy my code and flash your own firmware, mess it up and you can just reflash the latest release.
Field benchmark
Tested against the competition.
Fourteen legs surveyed in Giants Hole, Derbyshire, on 2026-02-28 — DiscoX measured side-by-side
against SAP, DistoX2, and Cavway. The numbers speak for themselves.
GIANTS HOLE · 2026-02-28 · 14 LEGS
Mean error · short-cal
4.5 cm
DiscoX (short-cal) places second of five devices — on par with Cavway, well ahead of DistoX2 and SAP.
Versus DistoX2
−41%
DiscoX short-cal produced 41% lower mean error than the DistoX2 across the same 14 legs.
Fore/back symmetry
±0.5cm
Foresight and backsight errors stay tightly matched — a sign of good sensor calibration and low drift.
Technical spec
What's inside.
A breakdown of the hardware, sensors and components that make the DiscoX a well-specced cave survey instrument.
Range
Up to 100m in ideal conditions
Connectivity
Bluetooth (Coded-PHY) compatible with TopoDroid v6 & SexyTopo
Interface
4 membrane buttons
Display cover
Gorilla Glass
Laser cover
Quartz glass
Processor
M4 microcontroller
Battery
1200mAh · ~125mA average draw
Charging
USB-C · resin-sealed port
Case
Polycarbonate & PETG · internal epoxy coating
Water resistance
Sealed design — theoretically waterproof, not guaranteed for submersion
