Method for picosecond time interval measurements based on frequency-switching sinusoidal shape

If the wave output by a voltage controlled oscillator (VCO) has the property of having no phase jump also when its frequency is swiftly changed, the measures of the phase before and after a fast frequency change can be used for calculating the time at which such event has occurred. Based on this property, a precise time measurement instrument has been designed and built. A non-optimised version has better than 100ps resolution full width at half maximum, is VCO drift compensated and is able to time events against a stable clock running at 312.5MHz. The VCO frequency of the prototype jumps from 47 to 59MHz. The analogue hardware is fairly limited. Applications may range from particle timing to time resolved fluorescence spectroscopy to range finding through time-of-flight methods.