The paper deals with detection problematic with Electronic Warfare (EW) emphasis. In a radar context, the knowledge of the signal characteristics allows the use of matched filter to improve Signal to Noise Ratio and detect target. In an EW context, a receiver should detect an unknown radar signal and estimate its parameters. For pulse duration inferior or equal to several microseconds, architecture and signal processing are well-known. For longer pulse duration, some solutions using the Wigner-Ville Distribution (WVD) were proposed in particular for Frequency Modulation Continuous Wave (FMCW), where instantaneous frequency evolves slowly. This paper proposes to compare performances between WVD and quadratic detector (QD) in an EW context. The performances are given through the analysis of the Receiving Operator Characteristic (ROC). The impact of noise error estimation on both detector performances is also analyzed.