A method of operating an ultrasound signal generator includes generating a stimulus signal and receiving a returned signal. The Signal to Noise Ratio (SNR) of the returned signal is computed. The SNR is compared to an optimal SNR range. A control signal is generated to control the transmission power of the stimulus signal. A new stimulus signal is generated at the new transmission power. A device for collecting and analyzing a quasi-periodic signal includes a SNR calculator that computes the SNR of a returned signal. A signal analysis selector selects between a first and a second signal analysis technique. A transmission power controller compares the computed SNR with an optimal SNR range for the selected technique and modifies the transmission power as a result of this comparison.
