Tuesday, August 19, 2014

Lady Ada - adafruit.com RTL-SDR

Overview

Author Gravatar Image LADY ADA
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Software-defined radio (SDR) is a technique for turning a computer into a radio. But not just an AM/FM radio - by using the computing power on your desktop you can listen and decode a wide variety of broadcasts. SDR can turn your computer into a weather-band receiver, a police/fire report scanner, a music listening station, and more! Instead of manually tuning inductors, its all done in software by chips fast enough to pick up and decode radio waves on the fly
If you've ever been curious about software defined radio (SDR), this USB stick is the easiest way possible to have fun with a powerful, configurable receiver. Packed with the powerful RTL2832U and R820T tuner, it can tune into signals from 24MHz to 1850MHz. That means you can use a computer (with Windows, Mac, or Linux) to tune into: FM Radio, AM signals (but not AM radio), CW (morse code!), unencrypted radio signals (such as those used by many police and fire departments), POCSAG pagers, and more.

In this tutorial we'll show how to get your very first listening adventure underway - listening to FM radio and decoding the RDS/RBDS data signal that is sent along with many FM radio stations as well.
This tutorial is for Windows users only at this time! There's hundreds of tutorials, posts and projects for a variety of operating systems over at http://www.rtl-sdr.com/

Download & Install Software

Author Gravatar Image LADY ADA
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We'll be using the awesome SDR# software for windows, which is really easy to use and very powerful as well! Visit http://sdrsharp.com/ to download - we're using Rev 1243
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If for some reason the site is down, we have a mirror of the install folder from 5/19/2014

We suggest downloading the latest version as there will be minor bug fixes, etc!
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Save and uncompress the zip file
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Double-click on install.bat
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This will download the latest build and extract it into the current folder. SDR# does not install into the toolbar or start menu!
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Driver Fix

Author Gravatar Image LADY ADA
Before we continue, we'll have to install the Windows driver for the RTL USB stick and then swap it for a 'low level access' driver. The default driver assumes you'll just be using the RTL-SDR for watching TV or radio but we want to be able to control it to do much more.

Plug in the stick, Windows should automatically install the REALTEK 2832U driver
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Now from inside the SDR# directory, run Zadig which will do the driver swapping for us
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From the Options menu, select List All Devices
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Then from the devices drop-down, find one that says Bulk-In, Interface (interface 0). If there's more then one, select one at a time, and verify below to get the right one.

Check that you get USB ID 0x0BDA (vid) and 0x2838 (pid) and the RTL2832UUSB driver
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Click Replace Driver
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That's it!

SDR# FM Radio

Author Gravatar Image LADY ADA
Lets start by just listening to every-day FM radio. Open up SDRsharp.exe (you can close Zadig)
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Begin by selecting the RTL-USB dongle instead of audio card
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Select WFM (wide-band FM radio) under the Radio signal type
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Click on Configure
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And set the gain about half-way up
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You can set your favorite frequency (FM station) by clicking on the large numbers up top
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Click Play/Start and set the volume starting from low to high so you don't hurt your ears!
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You can 'seek' for radio stations by looking for peaks. Click on them to tune in
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With the latest versions of SDR-Sharp it will automatically detect and decode RBDS/RDS data that is sent along with FM radio
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Chances are your radio station is also playing Donna Summer!

SDR# SAME (Weather) Radio

Author Gravatar Image LADY ADA
Most every-day AM/FM radios can't tune into the SAME weather network but with RTL-SDR we can! SAME is the national weather alert system, which broadcasts weather data as well as emergency alerts.

Lets tune into the closest weather station to Adafruit which is in New York City. You'll want to tune into whatever station is closest to you.

To begin, visit the NOAA weather station frequencies-by-county index here
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The frequency is 162.550 MHz, type that into the SDR# frequency window
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You can see a little peak, its much smaller signal than the FM radio stations. It's also much thinnerwhich makes it a narrow-band FM rather than wideband. Since its voice, not stereo music, they use less of the frequency band, so select NFM as the decoding type
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The station is marked as degraded, but by amplifying the gain on the RTL-SDR we were able to tune in
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You should be able to hear a computer-generated voice speaking out the weather forcast. It's not terribly exciting but it is very thorough, often giving very detailed reports. The signal continuously transmits so you can tune in at any time!

Going forward

now that you have some basic functionality working, try tuning into other frequencies, and trying the different kind of decoding (e.g. CW/AM/NFM) to tune into AM radio!

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