A universal software defined wireless platform and a specific method for its application is proposed here to perform field test measurements for performance evaluation of communications system. The platform implements every application, starting from the transmitter and receiver of wireless link, the virtual measurement instruments for the baseband signals and the performance evaluation algorithm, purely in software which solution offers high level of flexibility, and it provides an easy and cheap solution for performance testing. Since a PXI-based HW platform is also included in the solution proposed here, every physical RF analog signals generated or processed in software can be recovered. Both the analog RF output and input of the transceiver are available, therefore real field tests can be performed, even more, the performance of a communications system can be evaluated in a real operating network. In this paper the performance of FM-DCSK wireless communications system, operated in the 2.4-GHz ISM band, is evaluated based on real field tests using PXI platform. A systematic method for validation of system implemented on the PXI HW is provided.