Filters · 10 min read
Kalman vs particle filters: when to use which
A practical guide, with code, to choosing the right estimator.
Coming soon
Navigation notes
Navigation without GPS, explained
Plain-English notes on GNSS, sensor fusion and estimation, from someone who works on it every day.
Featured · GNSS · 7 min read
How GPS jamming actually works
Why a cheap transmitter can drown out satellites 20,000 km away, what that looks like to a receiver, and what you can do about it.
Checklist · 5 min read
Is your drone GNSS-resilient?
Twelve questions to ask before you fly somewhere GPS can’t be trusted.
Coming soon
Inertial · 8 min read
Dead-reckoning drift, explained
Why small sensor errors grow into big position errors, and how to slow them down.
Coming soon
Polarisation · 6 min read
What the sky’s polarisation can tell a robot
The compass bees use, and how cameras can borrow it.
Coming soon
Magnetics · 9 min read
Navigating by the Earth’s magnetic map
How magnetic anomaly maps can stand in for satellites.
Coming soon
Spoofing · 7 min read
How GPS spoofing works
Fake signals, a false position, and the signs that give it away.
Coming soon
Interference · 8 min read
Jamming or spoofing? Reading the receiver logs
The C/N0 and gain patterns that tell the two apart.
Coming soon
Jamming · 6 min read
What a jammer does to the correlator
Why a weak signal survives noise, but not a transmitter nearby.
Coming soon
Spoofing · 6 min read
Taking over a receiver without a jump
How a careful spoofer lifts off the tracking point.
Coming soon
Inertial · 7 min read
Reading an Allan deviation plot
The noise terms you can read straight off a log-log chart.
Coming soon
GNSS · 5 min read
Satellite geometry and DOP
Why the same receiver does worse between tall buildings.
Coming soon
Integrity · 8 min read
Integrity and the Stanford plot
How to show a system never understates its own error.
Coming soon
Magnetics · 6 min read
Calibrating a magnetometer
Hard iron, soft iron, and why the compass points at the motors.
Coming soon
Antennas · 5 min read
Choosing a GNSS antenna
Phase centres, choke rings and why the mount matters.
Coming soon