TID

A time-interval digitizer measures the duration between two electrical events and outputs that measurement as a digital value. In practice, this means capturing the precise time when one signal arrives, waiting for a second signal, then calculating and reporting the elapsed time in nanoseconds or microseconds depending on the instrument's resolution. The result appears as a binary or decimal number that a computer or data logger can read and store.

TIDs sit at the intersection of analog timing and digital processing. A signal enters the start input, the internal clock begins counting, a signal enters the stop input, and the clock halts. The accumulated count is then converted to a value and latched to output registers. Resolution typically ranges from 100 picoseconds to 1 nanosecond in high-end laboratory versions, down to microsecond or millisecond resolution in simpler industrial models. Accuracy depends on clock stability; a TID with a 10 MHz clock carries a fundamental uncertainty of around 100 nanoseconds per measurement.

Variants and common uses

Single-channel TIDs measure one start-stop interval per trigger cycle. Multi-channel versions can measure multiple intervals simultaneously, useful in nuclear physics experiments, radar systems, and high-speed instrumentation where several time relationships need recording in a single event window. Some TIDs include pile-up rejection, which discards measurements if a second start pulse arrives before the first stop, preventing ambiguous results. Others offer adjustable input thresholds to tolerate noisy signals.

The device appears most often in particle detection, photon timing, time-correlated single-photon counting (TCSPC), and precision event-sequence recording. In industrial applications, TIDs measure propagation delays in cables, verify motor pulse timing, and timestamp sensor events relative to each other. They bridge the gap between analog phenomena that occur in nanoseconds and digital systems that operate in clock cycles.

Errors arise when input signals are slow-rising or contain noise, causing threshold-crossing ambiguity. Temperature drift in the internal oscillator or clock circuit can degrade accuracy over hours or days. Dead time, the period after a measurement during which the TID cannot accept new start pulses, limits measurement rate; modern TIDs may have dead times from tens to hundreds of nanoseconds.