Now that you have your shiny new Raspberry Pi, you may be asking yourself “what can I do with this thing?” Jonathan last spoke about making an emulation box to play all of your favorite classic games from yesteryear, but now he is back with a new project. Welcome to the Software-Defined Radio, one of the coolest devices to hit the market this decade. These often cheap USB gumsticks can pluck precious information right out of the frequencies floating around us for analysis. Join us for an adventure of pairing the amazing Raspberry Pi and the versatile Software-Defined Radio to ride the airwaves and decode data as if it came out of thin air. Products Used: RTL-SDR - https://amzn.to/2FYo3yh HackRF One - https://amzn.to/32Xcyjv PortaPack - https://amzn.to/3kCrSYG Raspberry Pi 3B+ - https://amzn.to/33V4zTd Video: https://www.youtube.com/watch?v=27_2RhtCKdA

1. SDR Base Station with
Raspberry Pi
Jonathan Singer
Source: radioforeveryone.com

2. Agenda
• #whoami
• Basics of Radio & History
• What is SDR?
• Radio Hardware and Software
• First Project – Freq Show
• Second Project – ADSB Receiver
• Third Project – APRS Adventures
• Legalities and Learning

3. #whoami
• Masters of The Cybers from USF
• BS of IT from UCF
• DEF CON Security Goon
• OWASP Tampa Co-leader
• BSides Orlando Co-founder
• GuidePoint Security Splunk Dude
• SANS Certs and Stuff
• Undercroft Guild Master

4. Basics of Radio & History
Because we all need to learn where we came from

5. Radio Transceivers
• RX
• Receiving
• Listen only
• Passive
• TX
• Sending
• Adding to the airwaves
• Active
• May be illegal
Source: oscarliang.com

6. Modulation Basics
AM involves the alteration of the amplitude of the carrier wave, whereas FM
involves changes in the frequency of the carrier wave

7. Software-Defined Radio
A radio communication system where components that
have been traditionally implemented in hardware are
instead implemented by means of software on a personal
computer or embedded system.
Source: en.wikipedia.org

8. History
• Digital receiver was first coined in 1970 by a research in DoD
• Software radio was introduced in 1984 by E-Systems (now Raytheon)
• This led to research to be published in IEEE in 1992
• Software Defined Radio was coined in 1995 as part of a military effort

9. The Speakeasy Program
• One of the first public software radio initiatives was the U.S. DARPA-
Air Force military project named SpeakEasy.
• The primary goal of the SpeakEasy project was to use programmable
processing to emulate more than 10 existing military radios, operating
in frequency bands between 2 and 2000 MHz.
• Another SpeakEasy design goal was to be able to easily incorporate
new coding and modulation standards in the future, so that military
communications can keep pace with advances in coding and
modulation techniques.

10. SDR Hardware
Analog to Digital Converters (ADC)

11. HackRF One
• Half-duplex transceiver
• Can only send or receive, but not at the
same time
• 1 MHz – 6 GHz
• Up to 20 million samples per second
• Software-configurable RX and TX gain
and baseband filter
• Software-controlled antenna port
power (50 mA at 3.3 V)
• USB-powered
• Open source hardware
• ~$330 (or $100 for a clone)
Source: greatscottgadgets.com

12. Honorable Mention:
PortaPack for HackRF One Source: hackmod.de

13. LimeSDR
• Full-duplex
• Can send and receive at the same time
• 100 kHz – 3.8 GHz
• Examples:
• Radio astronomy
• RADAR
• 2G to 4G cellular basestation
• Media streaming
• IoT gateway
• HAM radio
• Wireless keyboard and mice emulation and detection
• Tire pressure monitoring systems
• Aviation transponders
• Utility meters
• Drone command and control
• ~$300
Source: limemicro.com

14. RTL-SDR
• RTL – REALTEK RTL2832U
• The RTL2832U is a high-
performance DVB-T COFDM
demodulator that supports a USB
2.0 interface.
• 24 MHz – 1766 MHz
• Receive Only
• ~$25
Source: rtl-sdr.com

15. KerberosSDR
• 4 RTL-SDR in one case
• Built-in USB hub
• Coherent RTL-SDR with 4x
channels perfect for:
• Direction finding
• Passive radar
• Beam forming
• Raspberry Pi header!
Source: hackerwarehouse.com

16. What can you do with an RTL-SDR?
• Use as a police radio scanner.
• Listening to EMS/Ambulance/Fire
communications.
• Listening to aircraft traffic control
conversations.
• Tracking aircraft positions like a radar
with ADSB decoding.
• Decoding aircraft ACARS short messages.
• Scanning trunking radio conversations.
• Decoding unencrypted digital
voice transmissions such as P25/DMR/D-STAR.
• Tracking maritime boat positions like a radar
with AIS decoding.
• Decoding POCSAG/FLEX pager traffic.
• Scanning for cordless phones and baby
monitors.
• Tracking and receiving meteorological agency
launched weather balloon data.
• Tracking your own self launched high altitude
balloon for payload recovery.
• Receiving wireless temperature sensors and
wireless power meter sensors.
• Listening to VHF amateur radio.
• Decoding ham radio APRS packets.
• Watching analogue broadcast TV.
• Sniffing GSM signals.
• Using rtl-sdr on your Android device as a
portable radio scanner.
• Receiving GPS signals and decoding them.
• Using rtl-sdr as a spectrum analyzer.
• Receiving NOAA weather satellite images.
• Listening to satellites.
• Radio astronomy.
• Monitoring meteor scatter.
• Listening to FM radio, and decoding RDS
information.
• Listening to DAB broadcast radio.
• Listening to and decoding HD-Radio (NRSC5).
• Use rtl-sdr as a panadapter for your traditional
hardware radio.
• Decoding taxi mobile data terminal signals.
• Use rtl-sdr as a high quality entropy source
for random number generation.
• Use rtl-sdr as a noise figure indicator.
• Reverse engineering unknown protocols.
• Triangulating the source of a signal.
• Searching for RF noise sources.
• Characterizing RF filters and measuring antenna
SWR.
• Decoding Inmarsat STD-C EGC geosynchronous
satellites.
• Listening to the ISS (International Space
Station).
Source: hamradioscience.com

17. SDR Software
You can explore this part on your own

18. Windows and Linux Tools
• GNU Radio
• Very manual and verbose
• GQRX
• Great for Linux and Mac
• SDR Sharp #
• Super powerful Windows tool
• SDRUno
• From the SRDPlay team

19. First Build Project
Bring on the Freq Show
Source: learn.adafruit.com

20. Freq Show: Raspberry Pi RTL-SDR Scanner
• Frequency Analyzer
• Raspberry Pi with touchscreen
• Runs Raspberry Pi OS
• Formally Raspbian
• Supports any hardware
compatible with RST-SDL drivers
• With a battery pack, super
portable
Source: learn.adafruit.com

21. Assembly
• Cheap Pi Touchscreen with Case
• Any Raspberry Pi Hardware
• Case may change per model
• RTL-SDR
• Antenna
• Can use one included
• Stylus
• Not necessary, but found its easier
with touchscreen.
Source: amazon.com

22. Software Setup
• Install OS (Raspberry Pi OS)
• Install Screen Drivers
• Install Software
• https://github.com/adafruit/FreqShow
• sudo python freqshow.py
• Optional:
• Make it autostart
Source: learn.adafruit.com

23. Prebuilt Tool Stack
One OS to Rule the Airwaves
Source: balena.io

24. pisrd-image: The SDR Linux Distro for
Raspberry Pi
• Modified Raspbian image with
the latest SDR software pre-
installed and ready to go.
• Compatible with every
Raspberry Pi.
Pre-installed Tools:
• GNURadio
• GQRX
• LimeSuite
• LimeVNA
• SDRAngel
• Soapy Remote
• LeanSDR
• VIRGO
• CygnusRFI
• rpitx
• rtl_433
• acarsdec
• Gpredict
• multimon-ng

25. Second Build Project
Plane spotting for the rest of us
Source: mprnews.org

27. FlightAware PiAware ADS-B Ground Station
• Live data on flightaware.com (subject to standard data processing
delay of up to two minutes)
• Access to up-to-the-second live data received by the local device
(accessible from the stats page with a local network connection)
• Data from local device highlighted on FlightAware track logs
• Detailed statistics on site performance
• A free Enterprise Account (USD89.95/mo value)
• I use this all the time when traveling for accurate inbound and outbound
flight data, and historicals

28. ADS-B – 1090 Mhz + 978 Mhz
• Airplane Communications
• PiAware Image (Debian)
• Dump1090
• 1090 MHz extended squitter
decoder
• Commercial Aviation
• Dump978
• Universal Access Transceiver (UAT)
decoder
• Bi-directional data
Source: amazon.com

29. Assembly
• Cheap Pi Case
• Screen (optional)
• Any Raspberry Pi Hardware
• Case may change per model
• RTL-SDR
• Antenna
• Can use one included, but tuned are better
• Clear view of the sky and elevated
• Remember that the signals from aircraft are
not designed to penetrate objects, so the
antenna should be located "line of sight" to
the sky with no obstructions.
• The most optimal installations, which are
installed outdoors and on a roof, have a
range of over 250mi / 400km.
Source: samkear.com

30. Software Setup
• Install OS (Raspberry Pi OS)
• Install PiAware from repository
OR
• Install PiAwareOS
• https://flightaware.com/adsb/piaware/build
• Claim your device on FlightAware
• View Stats!
Source: flightaware.com

31. I’m on a Boat!
It’s not just planes, but vessels too!
Super Bonus Points

32. Source: sdfjkl.org

33. AIS – 162 Mhz
• Ship Tracking
• rPiAIS Image
• https://www.aishub.net/rpiais
• AIS Dispatcher
• AIS Decoder
Source: uputronics.com

34. Third Build Project
Going global with your packets…
Jam out with your HAM out?
Source: aprs.fi

35. APRS – Automated Packet Reporting System
• Digital real time communications system
• Share tactical information and messages
• Plot location of moving objects using GPS
• Weather station telemetry
• Short messages (think SMS for HAMS)
• Fun fact: originally called Automated Position Reporting System back
in the 80’s

36. APRS I-Gate and Digipeater - Base Station
• Digipeater listens for digital radio packets, receives them, then
“repeats” them over its own system
• I-Gate listens for digital radio packets, then forwards them to the
Internet to be forwarded to other I-Gates
• Can sent packets to the proper recipient, or upload online to services such as
APRS.FI
• Packets can also come from the Internet and be transmitted to station in your
area

37. Passive I-Gate
• Listen for digital broadcasts and collect them with your Pi and SDR
• Share online for rebroadcast or other APRS services
• No transmission, which means no license needed
• Still fun to participate and listen in

38. Assembly
• Cheap Pi Case
• Any Raspberry Pi Hardware
• Case may change per model
• RTL-SDR
• Handheld radio can do both RX/TX
if using
• Antenna
• Can use one included, but tuned
are better
• Transmitting radio if operating as
a digipeater (repeater)
Source: samkear.com

39. Software Setup
• Install OS (Raspberry Pi OS)
• Install Direwolf
• https://github.com/wb2osz/direwolf
• A bit more configuration for the
HAMs
• Enjoy being part of an awesome
HAM community (get your license)
Source: flightaware.com

40. Other Fun Projects
Yes, there is more, much more…

41. NOAA ! and METEOR " Weather Data
Source: happysat.nl

42. SSTV from the International Space Station
• Slow scan television from the
Russian module of the ISS
Source: nasa.gov & spaceflightsoftware.com

43. Radiosonde aka Weather Balloons
Source: sdrplay.com

44. Good Ol’ FM Radio
• RDS – Radio Data System
• Small embedded data like genre, track
and station info
• HD Radio (NRSC-5-C)
• Development goal of NRSC-5-C was
digital terrestial radio using the already
allocated FM bandwidth
• Result was an IBOC (in-band on-channel)
system that supports both analog and
digital signals within the existing FM
allocations
• This hybrid scheme is flexible and the
station can choose to allocate more or
less of the spectrum to analog or digital,
or the entire spectrum allocation could
be used for a pure digital signal.
Source: rtl-sdr.com

45. Important Questions
The more you know… keep you out of trouble

46. Do I need a HAM License?
• No, if you only want to listen
• It’s already in the air
• But it’s not always that simple
with some laws
• Yes, if you want to broadcast
• Different levels of license for
broader frequencies and
strengths
• May be fun to get and explore

47. Electronic Communications Privacy Act
of 1986 (ECPA)
• 18 U.S. Code § 2510.Definitions
• (16)“readily accessible to the general public” means, with respect to a
radio communication, that such communication is not—
• (A)scrambled or encrypted;
• (B)transmitted using modulation techniques whose essential parameters have been
withheld from the public with the intention of preserving the privacy of such
communication;
• (C)carried on a subcarrier or other signal subsidiary to a radio transmission;
• (D)transmitted over a communication system provided by a common carrier, unless
the communication is a tone only paging system communication; or
• (E)transmitted on frequencies allocated under part 25, subpart D, E, or F of part 74,
or part 94 of the Rules of the Federal Communications Commission, unless, in the
case of a communication transmitted on a frequency allocated under part 74 that is
not exclusively allocated to broadcast auxiliary services, the communication is a two-
way voice communication by radio;

48. Illegal Stuff
• Decrypting Encrypted Traffic
• Commercial Pager Data, POCSAG, Flex
• Transmitting without a license
• Pirate Radio
• Emergency Services
• Airplanes (ADSB)
• Exceptions:
Super low power close range
FM Transmitter in your car
Wi-Fi and Bluetooth (and similar like ZigBee & ZWave)

49. Simply Don’t Do It
You will kill it for the rest of us, don’t be that person

50. Source: brannon.online
Holypager is a system that
intercepts all POCSAG pager
messages in the city it resides
and forwards them to one
(holy) pager. The installation
anonymizes all messages and
forwards them randomly to
one of three pagers on display.
Each message is also printed on
a contiguous role of receipt
paper amassing a large pile of
captured pages for gallery
goers to peruse.

51. YouTube
• Andreas Spiess – Amazing hobbyist with fun educational videos
• Tech Minds – Great tutorials and breakdowns for SDR
• ModermHam – Very cool intro level stuff from a hobbiest

52. Questions?