Electrical Engineering Department
BS in Electrical Engineering
Software defined radios (SDRs) are versatile systems that integrate hardware and software to create a reprogrammable wireless system. Due to the versatility and hardware requirements of a SDR, they are typically expensive and not always affordable for educational institutions. GNU Radio is a free software package that allows users to do signal processing on any computer using python and C++. Using the Universal Software Radio Peripheral (USRP) board in conjunction with a standard personal computer (PC), a RF daughterboard, and the GNU Radio software, we can create a software defined radio that can transmit, receive, and process signals. Because the USRP a personal computer to perform symbol generation, less specialized hardware is needed for the implementation of a software radio, thus reducing the overall system cost. The low cost of a USRP-based SDR enables the implementation of SDRs in laboratory courses, allowing students to learn about digital signal processing along with wireless communication systems.
The objective of this senior project is to develop a low-cost SDR that can be used to support student learning of digital wireless communications in a laboratory setting. To demonstrate the capabilities of the SDR, example modulations using BFSK and BASK were developed. In addition, supporting documents like a “quick-start guide” were created to assist in the implementation of SDRs in a digital communications lab. The RFX400 daughterboard was used as a front end with the USRP to test if a college level student could use this hardware with GNU Radio to transmit a modulated signal. The carrier frequencies of these modulated signals were increased to within the bandwidth of the RFX400, 400 to 500 MHz, then these signals were transmitted and successfully received but not with the same clarity as the signal before transmission. Transmitting signals through the air always causes signal degradation, but the number of samples that the USRP uses during reception also affects the quality of the received signal. The USRP and GNU Radio are the ideal hardware and software combination to use by students due to the affordability, versatility, and ease of use.