User Guide

Dead Zone Guide

Understand when the QTFM Gen-2 enters its dead zone, and how to orient the sensor head to avoid it — anywhere on Earth.

What is the dead zone?

The QTFM Gen-2 becomes non-operational — enters a “dead zone” — when the arrow-marked sensor axis is aligned within a 7° cone of the direction of Earth’s magnetic field.

Any data collected in the dead zone is invalid and automatically flagged. As soon as the sensor head is oriented away from the dead zone, the sensor is operational again — no restart required.

The QTFM Gen-2 dead zone is the smallest of its kind in the industry, with only a single axial dead zone.

Earth’s field θ = 7° Sensor axis Dead zone cone
Dead zone: sensor axis within ±7° of the Earth’s field direction (typically <5°)

Orientation at a glance

Operational — not in a dead zone
Earth’s field Sensor axis
Ideal case: sensor axis perpendicular to Earth’s field
Dead zone — not operational
Earth’s field Sensor axis aligned with field
Sensor axis aligned with Earth’s field — data flagged invalid

Avoiding the dead zone

Recommended mounting by region

Orient the sensor axis roughly perpendicular to the local field direction, and the sensor stays operational through full 360° yaw maneuvers — ideal for UAV surveys.

Away from the equator

In regions such as the USA and Europe, Earth’s field points steeply into the ground. Mount the sensor head with its axis parallel to the ground.

GROUND Earth’s field Sensor axis
Sensor axis parallel to ground → 360° yaw maneuverability

Near the equator

Near the equator, Earth’s field runs roughly parallel to the ground. Mount the sensor head with its axis perpendicular to the ground.

GROUND Earth’s field Sensor axis
Sensor axis perpendicular to ground → 360° yaw maneuverability
Not sure of your local field direction? Check the magnetic inclination at your survey site with the NOAA magnetic field calculator →
Original PDF Back to User Guide