GREYFATHOM™ Offline-first field terminals · Iowa City
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User manual

GFT-5 Mini Terminal

DocumentGF-UM-GFT-5
RevisionA
Date2026-09-07
Applies toGFT-5, all serials
SoftwareGREYFATHOM OS v1.x

1. Overview

A Linux handheld that runs the complete GREYFATHOM OS suite with an onboard mesh radio, in a printed carbon-nylon chassis drawn around the electronics from the first millimetre.

GFT-5 printed and machined parts, rendered from the production CAD
GFT-5 printed and machined parts, rendered from the production CAD

In the box

  • GFT-5, assembled, flashed and burn-in tested
  • GREYFATHOM OS installed with every tool enabled
  • Signed bench test report
  • Printed quick card

The signed bench test report is this unit's baseline: what was fitted, what was tested, what it read. Keep it with the serial number; the warranty form asks for both. See a sample report.

2. Specifications

ComputeRaspberry Pi 5
Display5″ Raspberry Pi Touch Display 2, 720 × 1280, capacitive touch
RadioLoRa mesh radio, fitted
GNSSReceiver fitted where ordered
StoragemicroSD or NVMe, per order
PowerInternal cell, USB-C charge; IP66 metal power button
EnclosurePrinted carbon-nylon chassis, 145 × 114 × 46 mm, 147 g shell; vented rear or machined cold-plate
IngressNot sealed in this release; IP66 rating applies to the power button only

3. Getting started

  1. Charge before first use. USB-C, any decent supply. A full cell is the first thing you want to know you have.
  2. Hold the power button. The GREYFATHOM boot screen, then the console. No login, no desktop.
  3. Open Health and run the self-test. It checks the radio, receiver and storage actually fitted to this unit and reports each green or not. Do it now, and before any day that matters.
  4. Tap ☾ in the top bar. Pure red for adapted eyes; tap again to return.
  5. Open Radio Config. Nodes shipped with this unit appear here, already on the same channel.

4. Operation

Every tool is a tile on one fullscreen console. Open a tool, use it, come back; there is nothing behind the launcher. Tiles marked "hardware not detected" belong to tools whose part is not fitted to this unit.

  • Comms shows the nodes whose signal is arriving now. Pick a node or the channel, type, send. Short messages arrive faster.
  • Radio Config shows channel, key, region and power. Nothing is written to the radio until Apply; reboot, shutdown and factory reset each confirm first. Works over USB or Bluetooth LE.
  • Position needs sky. First fix after a long time off can take two minutes; after that, seconds. Every logbook entry and note carries the fix automatically.
  • Maps draws from tiles cached on the unit. Load regions through Files before leaving coverage.
  • Logbook entries are time- and position-stamped on the spot, kept per operator, exported to USB or the unit's storage. Notes is the fast version.
  • AI Assistant is a language model on the Pi itself — llama.cpp with Qwen 3, plus Ollama. Drop any .gguf in through Files to swap the model. Nothing typed leaves the unit.
  • Phone Link runs as a boot service. Join the unit's Wi-Fi from a phone and open http://192.168.4.1:8471.
  • Power shows battery state and live draw; profiles trade performance for endurance.

5. Power

Charge over USB-C. Power shows the state and what each tool costs to run. Pick the endurance profile for a long day and performance when a charger is near. Cells lose capacity below freezing; keep the unit inside a jacket when it is not in use.

6. Updates and backups

  • Updates arrive as a signed image on a card. Each package carries a sha-256 manifest verified twice and a regression battery that must pass before it is accepted. Rollback is one tap in Field Ops.
  • Logbook and notes live on the card with you and survive an update.
  • Export the unit's identity — serial, keys, settings — to a USB stick from Field Ops. Restoring onto a fresh image is two taps, with an automatic backup first.
  • v1.x updates are free. Release notes are in the Master Guide.

7. Maintenance and care

  • Not sealed. The printed chassis is not sealed in this release; the IP66 rating belongs to the power button. Rain is fine, submersion is not.
  • Heat. Carbon-nylon softens in a closed car in summer; the machined cold-plate helps under load but is not a substitute for shade.
  • Screen. Anti-glare glass; microfibre only. The TPU port flap keeps grit out of USB-C — close it.
  • Cleaning. Damp cloth on the shell. No solvents.
  • Storage. Charge to about half, power off, store cool and dry. Top up every three months. Export the identity card before long storage.

Printed and machined parts

Front bezel, rear shell (vented or plain), heatsink plate and bracket, TPU port flap. Files and kits are on the build page.

8. Troubleshooting

What you seeTry this
Screen stays darkCharge for twenty minutes, then hold the power button. The power LED tells you if the cell is flat.
A tile says hardware not detectedThat part is not fitted or not seated. Health names it.
No fix in PositionSky, not glass. Two minutes outside. Health should report the receiver green.
A node does not appear in CommsSame channel and key on both? Then height and line of sight before anything else.
Map is blankNo tiles cached here. Load the region through Files before leaving coverage.
Something stopped after an updateRoll back — one tap in Field Ops. Then use the warranty form.

9. Warranty and support

Thirty-day returns. Every unit is serial-tracked. If a unit is not right, the warranty section on the contact page is the fast path; include the serial and, if you have it, the bench report. General questions: the User Guide, the FAQ, and the community, where other owners are usually there first.

10. Revision history

RevDateChangePages
A2026-09-07Initial release for the Pelican-case line and screen-size designations.All

GREYFATHOM Systems, Iowa City. Pelican is a trademark of Pelican Products, Inc.; Raspberry Pi of Raspberry Pi Ltd; Meshtastic of Meshtastic LLC; Heltec of Heltec Automation. GREYFATHOM is not affiliated with any of them.