Sorta accurate. To the millisecond.
NSAT is an iOS timing app for open-road time-speed-distance racing — Silver State Classic, NORC, Big Bend. It pairs with a RaceBox GPS receiver, starts the clock by itself at your assigned GPS-synchronized start time, and stops it the instant the front of your car crosses the finish line. Your score is one number: variance from perfect.
Live demo on compressed time — in the app, the start is your event-assigned time and there is no start button to press.
The big idea
Open-road racing is scored against time, not against other cars on the road. NSAT is built around the three facts of that format.
You set a start time, synchronized to GPS atomic time. When the satellite clock reaches it, the timer starts on its own — interpolated between GPS packets, finer than the receiver's update rate.
The finish is a coordinate, not a button press. When your position crosses the finish latitude or longitude in the course's direction of travel, the timer stops — offset so it's your nose, not your antenna.
Course distance ÷ target speed = a perfect time. Everything on screen exists to drive your variance from that time to zero at the line.
In the cockpit
Black screen, maximum brightness, thin monospaced digits — readable in desert sun. Every card on this page borrows its color from the instrument it describes.
The average speed that brings variance to exactly zero at the line — live, from mile 5 until the final minute of the run.
Finished leg one 12 seconds slow? Flip one toggle and leg two paces you 12 seconds fast, so the two legs net out. Logs still score true.
Lose GPS in an underpass near the line and the app projects your last known speed to the finish — recorded, and clearly marked as estimated.
Tell it how far the antenna sits behind the front of the car (0–22 ft) and the finish threshold shifts to match. The car finishes, not the puck.
Start and finish are interpolated inside the GPS packet interval, with distance blended to the surveyed finish coordinate over the final miles.
Course, coordinates, speeds, times, variance, finish type — saved automatically and exportable as CSV straight into the Files app.
A run, start to finish
Connect the RaceBox and wait for race quality: full 3D fix, horizontal accuracy under one meter, nanosecond time resolved. The app won't arm until all four lights are green.
Pick the course leg, set target speed, confirm the GPS offset, decide on the variance offset — then dial in the assigned start time last, in 30-second clicks.
The GPS clock reaches the start time and the timer is running. The display reorganizes: elapsed time, live variance, distance in the title bar. Drive.
Green means ahead, red means behind. REC SPEED tells you the exact average to hold from here to arrive at zero.
The finish card goes red at one mile out. The crossing is detected on the course's axis, interpolated between packets, and corrected for the car's nose.
Final time, perfect time, variance to the millisecond, average and top speed — on screen, in the log, and in the CSV.
Documentation
The full guide — setup, the automatic start, in-run displays, the three finish types, chasing zero across legs, and troubleshooting — is embedded in the app itself (the book icon), printable and emailable from inside it, and kept in this repository as markdown.
Read NSAT-User-Guide.md