Software Defined Radio Advisors: Prof. Chih-Chun Wang Prof. J. V. Krogmeier Graduate Mentor: A. W. Layton Members: Shannon Sremac, Kevin Choi, Zi Jin Lu, Jack O’Reilly Software Defined Radio Department of Electrical and Computer Engineering System Diagram (GNURadio) Differential Phase Shift Keying (DBPSK) Software Defined Radio Software-defined radio (SDR) is a radio communication technology that is based on software defined wireless communication protocols instead of hardwired implementations. We aimed to continue the work from last semester’ team and develop a walkie-talkie system implemented with software defined radios. Simplified waveform utilizing DBPSK Information is carried in a change in phase. Demodulation consists on comparing the previous wave with the current wave. Signal Processing Overview: Encode audio data Package data into bytes Transmit data over free space from one computer Receive data from free space to second computer Decode data, convert to audio signal Components in a Typical Packet Packet Encoder/Decoder Conversion of Audio: CVSD Discussion & Future Work Preamble (Default = 2 Bytes) Access Code (Default = 8 Bytes) Whitener Offset (4 bits) Payload Length (12 bits) 512 Bytes payload (512 Bytes) CRC (4 Bytes) Padding (Making the packet multiple of 512 Bytes) Continuously variable slope delta modulation Encoder reads input sample and compares to reference value. Will output 1/0 bit and change step size of bit accordingly. “Compromise between simplicity, low bitrate, and quality” Similar methods: Pulse Code Modulation (PCM), etc. Continue testing and implementing the system. Research ways to improve upon system performance. 1. Preamble and Access code are important in identifying the data as a packet by the receiver. Receiver will check for Preamble and Access code before processing the packet. 2. The whitener offset is important for the receiver to dewhiten the packet. It takes 4 bits in packet space. 3. Payload length records how much bytes of actual data occupies the packet. By default it is 512 bytes. 4. The CRC32(4 Bytes) will check for the correctness of the packet. 5. If we open the option “Pad for USRP”, the packet encoder will automatically pad the data to be a multiple of 512 bytes. Design and develop model to compete in DARPA Spectrum challenge. Relevant Experience Experience with communication systems and digital signal processing is preferred. ECE 264, ECE301, ECE438, and ECE440 are all used in this SDR project. Skilled in Linux operation.