Abstract: A method of dynamic range extension for heterodyne fiber-optic Interferometers, and more particularly towards the use of instantaneous carrier to extend the dynamic range of heterodyne fiber-optic interferometers. The method includes the providing of a heterodyne fiber-optic interferometer having a demodulator and an associated carrier frequency. The method also includes the determining of demodulator excessions. The detecting of the demodulator excessions and the determining of an appropriate correction factor is based on information from the instantaneous carrier frequency. The method also includes the introduction of the appropriate correction factor to the demodulator.

Abstract: A digital I/Q reprocessing demodulator and a process for significantly reducing arctangent computational loads. This is done by ensuring that all calculations are carried out in the linear part of the curve. The architecture of the demodulator is such that the demodulator 100 utilizes two I/Q stages. The first stage is utilized to determine a phase offset with regards to the free-running I/Q clocks. In the second processing stage, the phase of the I/Q reference signals are phase shifted based on the initial estimate such that the incoming carrier signal is nearly in-phase.