Likelihood Method for Recognition of Polyphase-coded Radar Signals
Yu Liu · Modern Radar · 2009
The recognition algorithm of the polyphase-coded radar signals is discussed in this paper.Polyphase-coded radar signal classification rules based on likelihood function are derived and the implementation steps of the rules are presented.First,carrier frequency,amplitude and code period of the received signal are estimated.When the pulse width and the code period are of prior knowledge,the phase modulation of the polyphase-coded signals can be determined.Therefore the local reference signals are generated.Now a hypothesis testing can be established.The output of the log-likelihood function was compared with the thresholds.If the output is greater than unity and only bigger than one of the thresholds of the polyphase-coded radar signals,the type of the received signal would be identical with that of the reference signal,which generates the maximum output.Otherwise,it is an unknown signal.The simulation results show that this method can recognize the polyphase-coded signals at low signal-to-noise ratio.