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THE HOBBYIST’S GUIDE TO RTL-SDR:
REALLY CHEAP SOFTWARE DEFINED
A GUIDE TO RTL-SDR AND CHEAP
SOFTWARE DEFINED RADIO BY THE
AUTHORS OF THE RTL-SDR.COM BLOG
TABLE OF CONTENTS
The Hobbyists Guide to RTL-SDR
What is Software Defined Radio (SDR)?
What is The RTL-SDR?
What Equipment do I need to get into RTL-SDR?
RTL-SDR Technical Specifications RTL-SDR ADC RTL-SDR Bandwidth Input Impedance RTL-SDR Current Usage RTL-SDR Minimum PC Specifications RTL-SDR Compatible Dongles Tips for Buying RTL-SDR Dongles R820T Packages Other SDRs worth mentioning Software Defined Radio Basic Theory Setting up and using your RTL-SDR SDR# Setup Guide (Tested on Windows Vista/7 + XP) Troubleshooting Guide SDR Sharp Users Guide Main Settings Other Settings Setting the RF Gain Setting the PPM Correction SDR Sharp Plugins SDRSHarp Minoutput Sample rate Compiling SDR# On Linux with Mono Other General Purpose Scanning Software HDSDR Setup Guide SDR-RADIO.COM V2 Setup Guide GQRX
1) Direct Sampling Mode
2) Upconverters Positioning your RTL-SDR Dongle
1) Use an active USB repeater cable or hub
2) Use a mini embedded or Remote computer to transmit the signal wirelessly to your PC Dongle Shielding and Noise Reduction Common Sources of Noise Dongle USB Cable Grounding Improvement USB Cable Ferrites Preselector Filters Coax Stub Filter Improving the Stock Antenna Calibrating the RTL-SDR Audio Piping General Frequency Guide ACARS Receiving Guide Introduction to ACARS ACARS Tutorial (Windows) ADS-B Receiving Guide ADS-B Introduction ADS-B Tutorial Feeding Data to flightradar24.com NOAA Weather Satellite (APT) Guide Introduction to NOAA Weather Satellites NOAA Weather Satellite Receive Tutorial Weather Balloon (Radiosonde) Guide Radiosonde Receiving Tutorial Marine Automatic Identification System (AIS) Guide AIS Tutorial AIS Antenna Guide Software Tutorials Decoding VHF Data Link Mode 2 (VDL2) Introduction to VDL2 Decoding VDL2 with MultiPSK KG-VDL Air Traffic Control Scanner Guide SDR# Frequency Scanner DAB Radio Guide DAB Receive Tutorial Receiving Analogue TV (PAL/NTSC) Guide Guide to Listening to Trunked Radio: Analogue and Digital P25 Unitrunker Voice Trunking Following Tutorial Decoding Digital Voice (P25/DMR/Mototrbo/NXDN/ProVoice) Tuning DSD+ CTCSS Trunked Radio Pager Decoding Guide Tutorial Other Decoders Radio Astronomy Guide Observing the Hydrogen Line and Galactic Plane Meteor Scatter Detection HF Modes Decoding Guide Shortwave Broadcast Radio CW (Morse Code) RTTY STANAG 4285 SSTV Digital SSTV WSPR Marine HF Modes Differential GPS (DGPS) Digital Radio Mondiale (DRM) Guide HFDL Decoding Guide D-STAR RTL-SDR for Android SDR Touch Wavesink USB ADSB RTL-SDR SDR Weather Receiving 10 GHz Beacons GNU Radio Introduction GNU Radio Program: FFT Display GNU Radio Program: WBFM Receiver GNU Radio Program: Compiling a WBFM-RDS Receiver Compiling RTL-SDR Drivers from Source on Windows Compiling with MingW Compiling using Visual C++ 2010 Panadapter Guide RDS Receiving Guide APRS Guide APRSISCE/32 AGW Packet Engine and Tracker MDT Decoding Guide
More Information and References:
Using multimonNG on Linux and Windows Using RTL_TCP Streaming MP3 FM With Linux: RTL_FM Heat Map Band Scan RTL_POWER Flags RTLSDR Scanner Train Telemetry Data Decoding Decoding Funcube Satellite Telemetry Decoding Orbcomm Satellites ISS Satellite Reception Weather/Temperature Sensor Decoding Guide Decoding Smart Power Meters NRF24L01+ Decoding Analyzing Unknown Signals Audacity MiniModem Receiving and Tracking GPS with the RTL-SDR Active GPS Antennas and Bias-T’s Projects For the Future and Better SDR’s HRPT Software DVB-T Decoding DECT Cordless Phones Other Interesting Projects People Have Done with the RTL-SDR DVB-T HDTV on Linux Drivers DVB-T TV Watching Software DVB-T on Windows Quick Way to Change between DVB-T and SDR Drivers on Windows Vista/7/8 Antenna Guide Antenna ESD Safety Antenna Adapter Guide Coaxial Cable Guide Antenna Gain/Directivity Radiation Patterns Antenna Design Frequency Standing Wave Ratio (SWR) Antenna Polarization Antenna Positioning VHF/UHF Example Antennas Discone (Broadband Antenna) Scantenna (Broadband Antenna) ¼ Wave Monopole ground plane Whip Dipole J-Pole / Slim Jim Collinear Spiral Turnstile / Cross Dipole Quadrifilar Helix (QFH) Active GPS Patch Yagi Uda PCB ADS-B Antenna HF Antennas Long Wire/Random Wire Magnetic Loop Appendix A: Audio Piping Stereo Mix VB Cable Virtual Audio Cable Setting the Sample Rate Appendix B: Radio Basics Propagation Bandwidth Modes Decibels (dB) to Times Appendix C: Multimode Decoders List Last Words Where to Get More Help Errata Updates Legal Stuff PREFACE In February 2012 the first FM radio signal was received with an RTL2832U RTL-SDR dongle using custom SDR drivers. Since then tens of thousands of hams, security researchers, hackers, makers, tinkerers, students and electronics enthusiasts have purchased RTL-SDR dongles to use as a very cheap software defined radio.
This book is intended to be a comprehensive guide for hobbyists on the use of the RTL-SDR dongle.
The book consists mainly of tips to get the best out of your RTL-SDR and tutorials for the various interesting projects that can be done using the dongle.
The information and tutorials in this book are up to date at the time of writing. Because SDR technology and its supporting software is evolving at such a fast pace, we cannot guarantee that they will work without the need for some tweaking in the future. We will do our best to keep this book updated.
If you discover any mistakes, missing information or just have any feedback on the book please feel free to contact me at email@example.com.
Tips for reading on Kindle: Be sure to adjust the font size settings to your preference as the default font size can be very large. All Kindle readers have this setting in their options or toolbars. The free Calibre software is another good alternative for reading this book.
WHAT IS SOFTWARE DEFINED RADIO (SDR)?
In traditional hardware radios, the mathematical operations required to decode and process radio signals are performed using analogue circuitry.
Recently, computers have become powerful enough to perform the required mathematical calculations in software, hence the term software defined radio.
This has led to advanced radios that previously required complicated analogue hardware now being able to be implemented easily in software. This has reduced the cost of advanced radio capabilities such as wideband tuning and waterfall displays.
WHAT IS THE RTL-SDR?
The RTL-SDR is an extremely cheap software defined radio which is based on DVB-T TV (Digital HD TV) USB receiver dongles that have the RTL2832U chip in them. It was discovered by hardware hacker Eric Fry, Linux driver developer Antti Palosaari and the Osmocom team who were developing their own SDR that the RTL2832U chip had a mode which enabled SDR.
Today, by using custom software drivers, a commonly used cheap TV dongle (under $30 USD) can then be turned into a sophisticated SDR with features that would have until recently cost in the hundreds to thousands of dollars.
Of course, the performance of these dongles will not match a dedicated SDR, but they perform extremely well for the price, and almost all hobbyist projects that can be done with expensive radios or SDRs can also be done with the rtl-sdr.
A wideband SDR opens up many interesting possible projects and avenues to explore. Some applications of the RTL-SDR include the following, some of which will be discussed in more depth in the project tutorials chapter.
Listening to unencrypted Police/Ambulance/Fire/EMS conversations.
Listening to aircraft traffic control conversations.
Tracking aircraft positions like a radar with ADS-B decoding.
Decoding aircraft ACARS short messages.
Scanning trunking radio conversations.
Decoding unencrypted digital voice transmissions.
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 and the ISS.
Listening to unencrypted military communications.
Monitoring meteor scatter.
Listening to FM radio, and decoding RDS information.
Listening to DAB broadcast radio.
Use rtl-sdr as a panadapter for your traditional hardware radio.
Decoding taxi mobile data terminal signals.
Use rtl-sdr as a true random number generator.
Listening to amateur radio hams on SSB with LSB/USB modulation.
Decoding digital amateur radio ham communications such as CW/PSK/RTTY/SSTV.
Receiving HF weatherfax.
Receiving digital radio monodiale shortwave radio (DRM).
Listening to international shortwave radio.
Looking for RADAR signals like over the horizon (OTH) radar, and HAARP signals.
WHAT EQUIPMENT DO I NEED TO GET INTO RTLSDR?
All one really needs is the following
RTL-SDR software (most of which is free) Furthermore, you can get more advanced with some extras An upconverter to receive the HF bands (0 - 30 MHz) A low noise amplifier (LNA) to improve reception.
Preselector filters to filter noise.
Places to buy these products can be found at http://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/.
RTL-SDR TECHNICAL SPECIFICATIONS22-2200 MHz Tunable Range (Approx. depends on tuner model)
3.2 MHz max bandwidth (~2.8 MHz stable) 8-bit ADC giving ~50 dB dynamic range
4.5dB noise figure LNA
RTL-SDR ADC ADC is an acronym for “Analogue to Digital Converter”. It is a microchip that reads in an analogue signal and then digitizes it. The more bits an ADC has, the more accurate the digitization can be. For example an 8-bit ADC can scale the analogue input into values between -127 and +127, whereas a 12 bit ADC can scale values from -2047 to +2047.
So with a low bit ADC certain small details in the analogue input, such as weak signals may be lost during digitization. The RTL-SDR has an 8-bit ADC, which is fairly low, but large enough to give
decent performance. The dynamic range of an ADC can be calculated approximately with:
number_of_bits * 6 dB. This gives the RTL-SDR approximately 50 dB of dynamic range. However, the dynamic range is usually slightly larger (~60 dB) due to the oversampling trick that can be performed in software.
Dynamic range is the range between the largest and smallest possible values.
RTL-SDR BANDWIDTH The maximum bandwidth of the RTL-SDR is 3.2 MHz, though the largest stable bandwidth is either
2.4 MHz or 2.8 MHz depending on your PC. Setting the bandwidth too large can cause samples to be lost on slow PCs giving choppy audio.
Most RTL-SDR compatible software will let you choose your bandwidth which is sometimes referred to as sample rate as well. Although sample rate and bandwidth are not the same thing, in the RTL-SDR setting the sample rate to 2 Msps (Mega Samples per second) will give you 2 MHz of bandwidth.
Setting it to 2.8 Msps will give you 2.8 MHz of bandwidth. (If you are familiar with Nyquist you might wonder how 2 Msps can give 2 MHz, this is because the RTL-SDR uses I/Q sampling with two ADCs).
The bandwidth is the size of the frequency spectrum that you can see at any one time.
INPUT IMPEDANCEAs RTL2832U dongles are intended for use with TV, they all have an input impedance of 75 Ohms.
Most amateur and professional radio equipment runs on 50 Ohm cabling, connectors and adapters.
You might think this mismatch will be a problem, however the loss due to the mismatch is minimal, equating to less than 0.2 dB.
RTL-SDR CURRENT USAGEThe R820T uses approximately 300 mA of current whilst the E4000 needs approximately 170 mA.
RTL-SDR MINIMUM PC SPECIFICATIONSFor SDR# any modern PC with a dual core processor, at least 1 GB of memory and Windows XP or newer should be sufficient. The PC must also have a USB 2.0 or newer port.
Slower PCs and embedded microcontroller based computers like the Raspberry Pi can be used with efficient command line software.
RTL-SDR COMPATIBLE DONGLESAlmost any DVB-T dongle with the RTL2832U chip can be used with the RTL-SDR drivers. However, one must pay attention to the tuner chip used in the dongle. The tuner chip defines the frequency range of the dongle.
The R820T is the most commonly purchased RTL-SDR. The E4000 used to be more popular but Elonics, the manufacturer has closed down making these chips rare and expensive. Other tuners are less commonly found.
For these reasons, currently RTL-SDR.com recommends the R820T tuner, unless you require the higher frequencies that the E4000 tuner gives.