Analysis on the Effect of Spurious Signals of Transmission and Local Oscillation Signals in a Compact Radar

Abstract

The spurious signals of the transmission signal (FTX) and local oscillation signal (FLO) for a receiver are the factors that reduce the SNR(signal-to-noise ratio) performance of a radar. In particular, a spurious signal with a high-power level causes the radar to falsely indicate a target. However, the spurious emissions of a frequency synthesizer are unavoidable because of the nonlinearity of the RF active elements on the FTX and FLO paths. In this study, spurious requirements are provided to ensure the SNR performance of a compact radar. Consequently, the spurious power level should be lower than −55 dBc to −28 dBc according to the offset frequency in the FMICW mode. In addition, it should be lower than −50 dBc to −40 dBc within a linear frequency modulation bandwidth (LFMM) in the MPRF mode, and the spurious that are out of the LFMM do not impact the signal processing results.