System for providing an amplitude value and a phase delay value (Φ) which relate to a signal to be measured (s(t)) having sinusoidal variations over time (t) with a frequency F, said system comprising: - a synthesis unit, adapted to generate a reference signal (r(t)) having a sinusoidal form of time-variations, in continual phase coherence with the signal to be measured (s(t)), said reference signal having an amplitude (A ref) larger than the amplitude of the signal to be measured (s(t)) and having a frequency equal to F ref = F x P/Q, where P and Q are two fixed, non-zero positive integers, P being greater than Q; - a comparator connected to receive the signal to be measured (s(t)) and the reference signal (r(t)) on two inputs of said comparator, and adapted to output a signal transition each time the signal to be measured becomes less than the reference signal, or each time the signal to be measured becomes greater than the reference signal; - a latch register connected to receive instantaneous values on a data input of said register, and to receive a signal that is outputted by the comparator on an enabling input of said register, and adapted to select those of the instantaneous values (ψ k) that are received by said register at the same time as a transition of the signal produced by the comparator, the comparator and the register thus forming an acquisition channel for the signal to be measured (s(t)); and - a computation unit connected to receive the selected values, and adapted to calculate the values of the amplitude and phase delay (Φ) of the signal to be measured (s(t)) from said selected values, characterized in that the latch register is connected for receiving instantaneous values of a phase (ψ(t)) of the reference signal (r(t)) on the data input of said register, and the computation unit is connected for receiving the selected values (ψ k) of the phase (ψ(t)) of the reference signal (r(t)), and is adapted for calculating the values of the amplitude and phase delay (Φ) of the signal to be measured (s(t)) from said values selected for the phase of the reference signal, and in that the computation unit is adapted to calculate an in-phase amplitude value of the signal to be measured (s(t)), equal to a·cosΦ where Φ is the value of the phase delay of the signal to be measured and a is a quotient of the amplitude of the signal to be measured (s(t)) divided by the amplitude (A ref) of the reference signal (r(t)), and a quadrature amplitude value of the signal to be measured, equal to a·sinΦ, from a system of affine equations having coefficients, for the in-phase amplitude and the quadrature amplitude of the signal to be measured (s(t)), which depend on the selected values (ψ k) for the phase of the reference signal (r(t)). - a synthesis unit, adapted to generate a reference signal (r(t)) having a sinusoidal form of time-variations, in continual phase coherence with the signal to be measured (s(t)), said reference signal having an amplitude (A ref) larger than the amplitude of the signal to be measured (s(t)) and having a frequency equal to F ref = F x P/Q, where P and Q are two fixed, non-zero positive integers, P being greater than Q; - a comparator connected to receive the signal to be measured (s(t)) and the reference signal (r(t)) on two inputs of said comparator, and adapted to output a signal transition each time the signal to be measured becomes less than the reference signal, or each time the signal to be measured becomes greater than the reference signal; - a latch register connected to receive instantaneous values on a data input of said register, and to receive a signal that is outputted by the comparator on an enabling input of said register, and adapted to select those of the instantaneous values (ψ k) that are received by said register at the same time as a transition of the signal produced by the comparator, the comparator and the register thus forming an acquisition channel for the signal to be measured (s(t)); and - a computation unit connected to receive the selected values, and adapted to calculate the values of the amplitude and phase delay (Φ) of the signal to be measured (s(t)) from said selected values,