Signal acquisition and distance variation measurement system for laser ranging interferometers

The invention refers to a signal acquisition and distance variation measurement system for laser ranging interferometers, in particular for use in a space application, having a signal acquisition unit. The signal acquisition unit comprises a frequency detection subsystem (100) for detecting the frequency of a measurement signal (MS) of a received laser beam which is buried in noise wherein the frequency detection subsystem (100) comprises an acquisition subsystem (110) with a wavelet packet decomposition unit (1) and a phase/frequency detector PLL (120); a main PLL unit (200) being coupled to the frequency detection subsystem (100) for receiving the detected frequency of the measurement signal (MS) for phase estimation of the measurement signal (MS); and a phasemeter band detection subsystem (300) for detecting whether the frequency of the measurement signal (MS) is higher or lower than the frequency of a reference signal of a reference laser beam by operating a known change to the frequency of the reference signal and measuring the consequent change in the frequency of an interference signal for having the phase of reference signal locked to the phase of the measurement signal.