Multiple access interference in ultra-wide bandwidth systems is non-Gaussian distributed. Several non-Gaussian detectors have been proposed in the literature for improved signal detection in multiuser environments. The simplified Gaussian-Laplacian mixed model receiver which was derived based on a Laplacian model assumption for the distribution of the multiple access interference is known to perform well in realistic ultrawide bandwidth channels. This paper addresses the problem of estimating the receiver noise and interference parameters of the simplified Gaussian-Laplacian mixed model receiver. Simple estimators are derived for the scaling parameters of the Gaussian and Laplacian noise models, and an alternative expression is derived for the receiver constant eta. The Cramer-Rao lower bounds for the scaling parameters of both noise distributions and the parameter eta are also derived. The proposed estimator scheme is tested on realistic, multiple access ultra-wide bandwidth systems.