Abstract: A control loop (10) for producing an output signal with a stable nominal frequency is provided. The control loop includes inputs for reference (11) and oscillator (25) output signals, a beat frequency generator (12) for producing a signal with a frequency that is the difference between the oscillator and reference signal frequencies, an ADC (14) to convert the beat frequency to a digital beat frequency signal, an estimator (17) for estimating the frequency or phase of the beat signal, an adder (18) for combining an offset and modulation signal and the estimated frequency or phase of the beat signal into an added signal, and a DAC (23) for generating an analogue control signal for controlling the oscillator output frequency.

Abstract: The present invention relates to a method and hardware for estimating the frequency offset of a signal. The method includes obtaining samples of the signal at at least two instants in time, and utilising the samples in a mathematical equation relating estimated offset frequency to the samples, wherein the mathematical equation is derived based on the premise of a modulating signal with a complex frequency.