Here, we disclose the design and implementation of a phase sensitive rate meter (rate meter), that performs phase sensitive detection techniques on pulsed input signals. The rate meter transforms discrete voltage pulses to smooth dc voltage levels that are proportional to pulse rate (ie. number of pulses per second) and that further performs phase sensitive detection of s mall changes in the pulse rate. Our implementation of the rate meter has demonstrated performance at pulse rates from 2,000 l/s to 500,000 1 /s. We have tested the rate meter in the context of pulsed signals from single-photon detectors, using the phase sensitive detection to track a moving peak in the photon rate' s response to a changing experimental parameter.
The invention allows real-time, phase-sensitive processing of pulsed signals. Current practice is to count pulses electronically, transfer the counts to a computer for numerical processing. The disadvantage of this current practice is that data transfer and processing are performed subject to scheduling by the computer’s operating system, leading to potential delays. Our invention processes the signal continuously.