1. Matt Schurmann Erik Thompson Jon Pirog Scott Curtis

2. Overview  Introduction  Functional Description  Technical Description  Performance Objectives  Implementation Alternatives  Toward Senior Design  Conclusion  References

3. SDR? Amateur Radio? Say What?  Traditional radio implementations use fixed-function hardware to implement protocol stacks  Today an estimated 16,000 amateur hardware-based radio repeaters exist in the USA A Repeater

4. What is Software Defined Radio?  SDR is a radio architecture that seeks to implement as much of its functionality as possible in digital baseband software  Ideally, SDR is 100% re-configurable. Flexible RF hardware receives, transmits and performs A/D conversion. Software does everything else

5. Functional Description Hardware-Based Radio Software Defined Radio Images: Bruce McNair, EE585WS, Spring 2011, Stevens Institute of Technology

6. Functional Description (cont’d)  Two fundamental sections:  RF Frontend – Interface between air and baseband processing  Baseband Processing – perform modulation (FM for amateur radio), demodulation, coding, error correction, waveform synthesis, RF hardware tuning. Interface with user, internet, data link layer

7. Functional Description (cont’d)

8. Implementation Issues  Current ADC technology doesn’t allow high-rate, high precision frequency.  Remember the Nyquist Frequency? Digitizing a 1.3 GHz signal, means sampling over 2.6 GHz!  Work-around: superheterodyning

9. Superheterodyning

10. Wideband Hardware  The amateur radio bands in the USA range from about 1 MHz to 1.3 GHz  Amplifiers are limited by gain- bandwidth product. High gain = low bandwidth  Similar concerns exist for mixers, filters

11. Baseband Hardware  Baseband hardware design pits Power vs. Re-configurability  Compromise: Hybrid FPGA and Microcontroller hardware design  Which programming language to use? C for Microcontroller, VHDL for FPGA

12. Baseband Software  Baseband software for waveform synthesis and modulation will require intense digital signal processing (DSP)  Saving Grace: GNU Radio – an open- source software radio library using C and Python!

13. Performance Objective  To implement an SDR-based amateur radio repeater prototype  It must have competitive performance, even if it is more expensive Range SNR User Interface

14. Toward Implementation  Software Design: GNU Radio  Two Hardware Possibilities: Hardware Design – see our various reports USRP – “Universal Software Radio Peripheral.” Available through Stevens SDR Lab Tradeoff – Cost, Time, Complexity vs. Learning Opportunity, Impressiveness of Project

15. USRP

16. Custom Design RF Receiver Schematic Altera Cyclone FPGA Demo Board

17. Conclusion  SDR-based Amateur Radio Repeater  Many design tradeoffs, and constraints due to cost, time, current technology  More information: http://mjsch.org/d6http://mjsch.org/d6  Questions?

18. Selected References Huseyin Arslan and Hasari Celebi, "Software Defined Radio Architectures for Cognitive Radios," in Cognitive Radio, Software Defined Radio, and Adaptive Wireless Systems.: Springer, 2007, ch. 4, pp. 109-144. Tom Wada. (2005) All Digital FM Receiver. [Online]. http://www.ie.u- ryukyu.ac.jp/~wada/design05/spec_e.htmlhttp://www.ie.u- ryukyu.ac.jp/~wada/design05/spec_e.html Mahababul Hansan, Md Khan, and Farzana Akhter, "Design and Implementation of a QPSK Demodulator," BRAC University, Bangladesh, 2010. Behzad Ravazi, RF Microelectronics. Upper Saddle River: Prentice, 1998. Technologies, Wipro. "Software Defined Radio Whitepaper." 2002. http://www.broadcastpapers.com/whitepapers/WiproSDRadio.pdf (accessed February 25, 2011). E. Blossom, "Exploring GNU Radio," http://www.gnu.org/software/gnuradio/doc/exploring- gnuradio.html, November 2004. http://www.arrl.org/files/file/Hambands_color.pdf McNair, Bruce. “EE585WS Class Notes.” Stevens Institute of Technology, Spring 2011