US 7,480,056 B2 · Multi-pulse heterodyne sub-carrier interrogation of interferometric sensors

Abstract

A method for interrogating time-multiplexed interferometric sensors using multiple interrogation pulses so as to increases the allowable interrogation pulse duty-cycle and improve the signal-to-noise ratio. In each TDM repetition period a sequence of multiple interrogation pulses are generated. The pulses in the sequence are separated by a time that is equal to the sensor imbalance. The phase from pulse to pulse in each TDM time-slot is modulated at a different, linear rate such that the pulse in time-slot m will have an optical frequency that is shifted by mΔν, where Δν is the sub-carrier frequency. Because multiple reflections do not need to fade out the inventive method can enhance the signal-to-noise ratio of interferometric sensors such as inline Fabry-Perot sensors.

Claims10

Dependent claims

A method of interrogating interferometric sensors, comprising:

providing an optical network comprising multiple optical pathways from an optical transmitter to an optical receiver, where pairs of optical pathways form sensor interferometers, each sensor interferometer having a sensor imbalance;
generating a time-division multiplexed signal with a repetition period;
generating in each repetition period a sequence of interrogation pulses;
generating the sequence of interrogation pulses in Np transmission time slots in each repetition period such that consecutive time slots have a separation that corresponds to the sensor imbalance, wherein Np is greater than 2;
and
modulating the interrogation pulses such that the interrogation pulses produced in different time-slots have different optical frequencies.

3 more elements

Dependencies are inferred from the claim text.

Multi-pulse heterodyne sub-carrier interrogation of interferometric sensors

Life of this patent

Multi-pulse heterodyne sub-carrier interrogation of interferometric sensors

Life of this patent

Abstract

Claims10