What GPS telemetry can and cannot tell you

Understand GPS lap timing, track recognition and estimated braking in Purple Sector, and why GPS-only recordings cannot establish measured pedal technique.

By Purple Sector. Published and reviewed 29 September 2026.

Open your own file See a sample debrief

The map closed on T3, marked +0.87 s, with both laps' lines through the corner. — Shown: a real MyChron 5 session at Queensland Raceway National. A file from any logger Purple Sector reads opens in the same view.

GPS is position and time, not pedal telemetry

A GPS-only recording can support lap timing, speed comparisons and a recorded route when the fixes are usable. It does not contain measured brake pressure, throttle position or steering angle. Purple Sector labels estimates and withholds findings when the recording cannot support them.

Recorded channels and estimates answer different questions

Scroll to compare all columns.

Available data	What it can support	What it does not establish
GPS position and timestamps	Recorded path, course comparison and timing crossings	Surveyed track edges or centimetre-accurate line placement
Speed	Speed changes and comparison of entry, corner and exit	Which pedal caused every speed change
Measured brake or throttle	Recorded control timing and channel-supported findings	A universal ideal braking point
Derived braking estimate	A qualified location estimate from available evidence	Measured brake pressure or exact pedal application

Why does GPS update rate matter?

Rows in an export are not necessarily independent GPS fixes. A logger can repeat positions or interpolate them while writing other channels more often. The meaningful location resolution follows the GPS updates and their quality. A dense export cannot turn a low-rate GPS receiver into a higher-rate measurement.

Purple Sector carries recording-rate and quality information into its analysis and coaching evidence. Small point movements should be read against those bounds. Receiver noise, rounding, gaps or a bad fix can create apparent differences that are not driving changes.

Why is a track or turn number sometimes missing?

A circuit name, layout and turn number are claims about a real place. Purple Sector publishes only the track identity the recorded path can support. Public circuit maps show recognised layouts and explain where turn numbering comes from. Recognition coverage and independently surveyed geographic accuracy are different things.

When the route cannot be established, the workspace can still show the recording’s available trace or channels. It does not invent a layout or upgrade a turn detected from your lap into an official circuit number.

Circuit Italia, Luddenham Raceway, Oakburn Park Raceway, Lakeside Park and Wilby Motorsport Park publish no official turn numbers, so their maps carry Purple Sector’s own numbering, labelled as such. At Queensland Raceway, Euromarque Motorsport Park (Ruapuna), Highlands Motorsport Park, Manfeild Circuit Chris Amon and Shannonville Motorsport Park, some layout lengths are measured over a lap of the mapped route because the published figure does not match the route; those pages print both figures.

How should I use GPS-only findings?

Start with repeatable, visible differences in speed and time. Check multiple valid laps when possible, keep the stated uncertainty, and treat estimated braking as a location to investigate rather than proof of pedal technique. If you need to evaluate brake release or throttle application, use a logger that actually records those channels.

Guides by logger: AiM (MyChron, Solo) · RaceBox · VBOX · RaceChrono · Harry's LapTimer · TrackAddict · MoTeC · Garmin Catalyst · GoPro · Alfano.