Calculating Global Overlap Windows in Sequential Row Readout Image Sensors
Calculate global overlap by subtracting array readout time from total exposure; fire external illumination within this window to emulate global shuttering.
Trigger Jitter
Timing Variance
Temporal uncertainty between the arrival of a command signal and the actual start of a measurement event introduces errors in high speed data acquisition. The trigger jitter causes the sampling point to drift slightly from frame to frame or pulse to pulse. In synchronized multi camera systems, this variation prevents the sensors from capturing the same instant in time.
Clock Source
Precision of the internal oscillator and the logic used to decode the input pulse determine the magnitude of the instability. Digital noise or electromagnetic interference on the signal line can also contribute to trigger jitter by shifting the threshold crossing point. Shielded cabling and differential signaling are used to minimize these external influences.
Precision Measurement
Characterizing the variation requires a high speed oscilloscope to compare the input trigger to an output sync pulse. The standard deviation of this delay represents the trigger jitter and defines the temporal resolution limit of the instrument. High end controllers often have values in the picosecond range.
System Impact
Inconsistent timing leads to a loss of phase information in periodic signals and degrades the accuracy of time of flight measurements. Stabilization is achieved by using low noise power supplies and dedicated timing hardware.