Remote non-linearity detection via burst power dithering and EM based SNR Estimation

A new approach to detect the onset of saturation (1dB output compression point) at remote terminals is proposed in this paper. The proposed approach dithers the transmit power of periodic ranging bursts by a known amount and then estimates the received difference in Signal to Noise Ratio (SNR) and uses this metric to indicate whether the operating point of the Power Amplifier is in the linear range or not. The Expectation-Maximization (EM) Algorithm is used to achieve the ML estimate of the received SNR and is compared to the Cramer-Rao Lower Bound (CRLB). Application of this algorithm to a commercial satellite broadband system as well as simplifications to the algorithm to make it easier for implementation on FPGAs, are also discussed.