Handheld GPS

Overview

A handheld GPS is a self-contained outdoor navigator: it fixes its position from satellites, draws it on a stored map, and survives rain, drops, and cold far from any charger. The Display Module uses a transflective panel that stays readable in direct sun, paired with a touchscreen and a Button Pad that works with gloves. Position comes from the GNSS Module, and the Altimeter & Compass adds elevation and a heading that works even when standing still. The Mainboard runs the navigation software off onboard map flash, the Battery Pack uses a removable cell so spares can be swapped on the trail, and a sealed Rugged Housing keeps water and dust out. A Expansion Ports port set adds map cards and a charging connection.

How it works

The GNSS Module receiver listens to several satellite constellations at once through its GNSS Antenna. By measuring how long each satellite's signal took to arrive, it solves for the distance to four or more of them and trilaterates a position, refining it with SBAS corrections for a few-metre fix. Tracking many constellations and frequency bands lets it hold a lock under tree cover and in canyons where a single-band receiver would drop out.

Because a satellite fix alone gives a noisy altitude, the Altimeter & Compass Barometric Altimeter derives elevation from air pressure instead, and its magnetometer supplies a compass bearing the moment the user stops walking, GNSS heading needs motion, a magnetic compass does not. The Mainboard SoC merges position, elevation, and heading, then renders the user's location onto the basemap held in Flash Storage, expandable through the Expansion Ports microSD slot. All of it runs from a single Battery Pack cell so a spare can keep a multi-day trip going.