An autonomous mobile robot needs externals sensors for its own localization and modeling environment. In order to perform the angular precision of ultrasonic sensor and to improve the number of informations for a given time, we developed an ultrasonic sensor network using the multiple receivers mode. In this paper we introduce the ultrasonic network with its hardware architecture and its functioning mode. We also present a method to localize an echo source with the multiple receivers mode and show how to simply model this echo in the robot frame. We then describe the extraction of environment primitives (segment) by the inertia matrix and Hough transform. Finally, we validate the all process by experiments.