This document provides an introduction to software defined radio (SDR). It discusses the various wireless signals that can be received, explains what SDR is and how it works, lists common SDR hardware and software options for getting started, and offers tips on tuning signals, identifying unknown transmissions, and potential next steps like decoding pager or garage door signals. Legal considerations around reception are also briefly mentioned.

1. Software Defined Radio 101
Mike Saunders @hardwaterhacker

2. About Mike
• Started IT in 1998
• Security since 2007
• Avid ice fisherman

4. Signals Around Us
• Cell phones (900/1,800/1,900 MHz)
• Wifi (2.4 & 5 GHz)
• Bluetooth & Zigbee (2.4 GHz)
• Broadcast TV (54 - 900 MHz)
• Pagers
(35/43/152/157/163/454/462/929
MHz)
• ADSB (978/1090 MHz)
• AIS (162 MHz)
• Police & military comms (varied)
• HAM radio (varied)
• Satellite comms (varied)
• Cordless phones (1.7/27/43-50/900
MHz, 1.9/2.4/5.8 GHz)
• Radar (varied)
• Car remotes (315 / 433 MHz)
• Garage door openers (310/315/390
MHz)
• TV & presenter remotes (varied)
• Etc. etc. etc.

7. What is SDR?
• Radios used to be implemented in hardware
• Software Defined Radio - software tunes receiver
hardware to desired frequency
• Additional software can decode transmission to reveal
data
• Signals can be transmitted with certain hardware

8. What You Need
• Hardware
• rtl, HackRF One, Ubertooth One, Yardstick, Funcube,
etc.
• Antenna
• Software
• GNU Radio, SDR#, GQRX, etc.

9. Getting Started - Hardware
• Generic RTL2832U / R820T
• ≈ $15
• 25 - 1700 MHz
• RX only

10. Getting Started - Hardware
• Generic RTL2832U / R820T
• Aluminum case limits noise
• ≈ $25
• 25 - 1700 MHz
• RX only

11. Getting Started - Hardware
• HackRF One
• ≈ $330
• 10 MHz - 6GHz
• TX & RX
• 20M samples/second

12. Getting Started - Software
• Windows
• SDR#, HDSDR, SDR-RADIO.COM
• Mac & Linux
• GNU Radio, GQRX, Linrad
• Android
• SDR Touch, Wavesink Plus, RFAnalyzer

13. Getting Started - SDR#
• SDR# - www.airspy.com
• Quick start guide - http://www.rtl-sdr.com/rtl-sdr-
quick-start-guide/

14. Getting Started - Tuning
• http://www.nws.noaa.gov/nwr/coverage/
station_listing.html
• https://www.youtube.com/watch?v=gFXMbr1dgng

15. Getting Started - FM Radio

16. Common Problems
• Don’t forget to install Zadig driver with generic RTL
• Some USB 3.0 ports don’t work well
• Issues with USB passthrough in VMs
• Frequency drift due to temperature differences (non-
TCXO chipset)

17. SDR# Common Problems
• Slower processors = dropped samples, choppy audio
• Even an issue in VMs on more powerful hardware
• HDSDR is harder to use, but less overhead

18. SDR# Common Problems

19. ID an unknown signal
• Spend time sweeping through frequencies
• Search for known frequencies at radioreference.com
• Look up signal waterfall on sigidwiki.com

20. • Signal @ 152.480 Mhz

21. radioreference.com

22. FCC License Search

23. Search Results

24. Review Frequencies

25. Review Registration

26. Check SigIDWiki
Captured sample waterfall SigIDWiki Reference

27. Legal Disclaimer
• I am not a lawyer, this may or may not be illegal
• Research and decide for yourself
• 18 U.S.C § 2511
• 18 U.S.C § 2510

28. Decoding Pages
• Walk through:
• http://www.rtl-sdr.com/rtl-sdr-tutorial-pocsag-pager-decoding/
• You need:
• SDR#
• VBCable
• http://vb-audio.pagesperso-orange.fr/Cable/index.htm
• PDW
• http://www.discriminator.nl/pdw/index-en.html

29. More Common Problems

30. More Common Problems

31. Next Steps
• Garage door hacking - http://samy.pl/opensesame/
• Ding Dong Ditch - http://samy.pl/dingdong/
• Decode a signal using GNU Radio

32. Wrap Up
• Get started cheap
• All kinds of signals to listen to and analyze
• Be responsible with what you find
• Report issues

33. Resources
• http://www.rtl-sdr.com/rtl-sdr-quick-start-guide/
• http://www.radioreference.com/apps/db/
• http://www.sigidwiki.com/wiki/Database
• http://wireless2.fcc.gov/UlsApp/UlsSearch/
searchAdvanced.jsp
• Noise Floor - @0xabad1dea - https://
www.youtube.com/watch?v=5N1C3WB8c0o

34. Questions?
• mike@hardwatersecurity.com
• https://hardwatersec.blogspot.com
• @hardwaterhacker