GTrace - G-Meter & Logger

About

Track day or mountain road, every G you used stays on record. GTrace turns your iPhone into a real G-meter. It draws the lateral and longitudinal G-forces from your cornering, braking and throttle as a live trace, then lets you replay the run against the map, your footage or the graphs. One-time purchase. No subscription, no in-app purchases. WHILE YOU DRIVE - Live G-G diagram, lateral and longitudinal G shown together - Trailing trace, with peak lateral and longitudinal G held on screen - Jerk shown as a crosshair, so you can see how smoothly you transfer load - Speed readout, switchable between km/h and mph - Audible alert when you exceed your chosen G threshold - Comfort and Sport modes with separate display ranges for street and track - Three display layouts: standard, info + speed, and video preview - Phone holder mode, so a vertically mounted phone still reads longitudinal G correctly MEASUREMENT - Gravity component removed to isolate true vehicle acceleration - 2nd-order Butterworth IIR low-pass filter with adjustable cutoff frequency - Configurable sampling rate - Axis inversion, so mounting orientation doesn't matter AFTER THE RUN - G-G heat map showing which part of the friction circle you actually used, so you can see the balance between cornering, braking and acceleration at a glance - Synced playback: G-G + map, G-G + video, G-G + acceleration graph, or map + graph, at adjustable playback speed - Time-series graphs for longitudinal G, lateral G, longitudinal jerk, lateral jerk and speed - GPS trace drawn on a map, with top and average speed RECORD AND SHARE - Voice recording, synced to the acceleration data for commentary and notes - Video recording with audio, played back with the G-G trace overlaid - CSV export for spreadsheets or your own analysis tools - Native binary format (.ggx) import and export, for backups and moving data between devices WHO IT'S FOR - Track day, sports driving and time attack enthusiasts - Drivers working on their technique on mountain roads - Anyone chasing smoother, more passenger-friendly load transfer - Motorsport competitors who want their practice data kept - Anyone who wants their car's behaviour in numbers English and Japanese. iPhone only, iOS 15.6 or later. Note: measurements use the iPhone's built-in accelerometer and gyroscope. Mount the phone firmly in the vehicle for accurate readings. Note: GPS trace and speed recording require location permission. Note: this app does not include lap timing.