High-speed imaging leaves no room for uncertainty. Even a slight variation in frame timing can distort measurements, throw off synchronization, or compromise results. To verify our cameras with absolute confidence, IDT developed the GPS Chronograph—a timing reference that measures events down to one millionth of a second.
Reading the Display
At the heart of the GPS Chronograph is a vertical LED array arranged like a modern take on the abacus. Each column represents a fixed time interval, from 100 milliseconds down to 1 microsecond. Within each column, individual LEDs light up to show where an incoming pulse falls within that slice of time.
For example, a camera running at 20,000 frames per second produces a pulse every 50 microseconds. On the Chronograph’s display, those pulses create a precise, repeating pattern in the 100 µs and 10 µs columns. Recording the display with a high-speed camera allows frame-by-frame verification of timing accuracy, revealing even the smallest drift or irregularity.
Design and Operation
The GPS Chronograph locks to UTC time using a one-pulse-per-second (1PPS) signal from a GPS satellite receiver. Incoming pulses from a camera trigger or strobe are displayed in real time with no buffering or processing delay. A front-panel threshold control lets the operator fine-tune signal sensitivity, while loop-through connectors make it easy to pass the reference signal to other devices.
This direct, visual feedback means there’s no ambiguity. The LED grid provides an immediate record of exactly when each event occurred, referenced to GPS time and ready for review in post-capture analysis.
The GPS Chronograph uses an abacus-like LED grid, where each column represents a time scale from 100 ms down to 1 µs. Just as beads on an abacus represent numbers, the illuminated LEDs mark exact event timing—visible, countable, and anchored to GPS time.
Application
The GPS Chronograph was built to meet our own demanding standards for camera verification. It is now used internally to confirm frame rate accuracy, validate shutter behavior, and synchronize systems across GPS time. By combining microsecond-level resolution with a clear, camera-readable display, it turns abstract timing data into something you can literally see—and trust.
