Signal acquisition and distance variation measurement system for laser ranging interferometers

A signal acquisition and distance variation measurement system for laser ranging interferometers having a signal acquisition unit, comprising:

• a frequency detection subsystem configured to detect the frequency of a measurement signal of a received laser beam which is buried in noise, wherein the frequency detection subsystem comprises an acquisition subsystem with a wavelet packet decomposition unit and a phase/frequency detector PLL;
• a main PLL unit being coupled to the frequency detection subsystem configured to receive the detected frequency of the measurement signal for phase estimation of the measurement signal;
• a phasemeter band detection subsystem configured to detect whether the frequency of the measurement signal 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 the reference signal locked to the phase of the measurement signal.