This document describes a software-defined radio system called Longear that was developed by Wavenetix over 3 years for high dynamic range signal collection and processing of OFDMA signals. The system uses joint detection and iterative interference cancellation algorithms to distinguish signals that are only a few dB apart. It processes signals in both acquisition and post-processing modes using a multithreaded software architecture. Field tests showed the system could detect signals separated by as little as 5-9 dB without interference cancellation, and up to 30 dB with serial interference cancellation enabled. Wavenetix offers this and other wireless testing technologies and services to equipment manufacturers and wireless operators.