Two LPI signal detection and parameter estimation methods are analyzed in a non-cooperative context. The first method is based on the time-frequency signal analysis along with pattern recognition techniques. The second one is based on the estimation of a periodic autocorrelation function. Frequency modulation continuous wave (FMCW) signals are analyzed as a class of waveforms often used in LPI radars. Experimentally obtained signals are used in tests. An experiment with a real FMCW signal transceiver and a receiver is carried out and the obtained signal analysis results are presented.