Realistic Estimation of Signal-to-Noise Ratio in Microwave Receivers

Abstract

Signal-to-noise ratio (SNR) is the foremost parameter which provides insight into the design and performance of any receiver. The pulse parameters accuracy and probability of detection of a receiver are directly estimated by calculating the SNR. Measurement of SNRRf (SNR at RF level) and SNRvideo(SNR at video level) in analog receivers has brought much disagreement among different authors. This paper presents a straightforward methodology for estimating the SNRRf and SNRvideo in microwave receivers in both theoretical and practical sense. The calculations and practical experiments are performed by employing successive detector log video amplifier (SDLVA) receiver which is the basic component used in electronic warfare (EW) systems for transforming radio frequency (RF) signals into a baseband (video) signals. The relation between SNRRf and SNRvideo is explained and a new formulation is proposed for the noise limited case of SDLVA. The proposed methodology is validated by using a broadband SDLVA receiver having an operational frequency as 2 - 18 GHz, video logging slope as 50 mV/dB, and dynamic range as 75 dB. In general, the proposed method can be employed to estimate SNR of any microwave receiver.