Saturday, May 30, 2015

Using RTLSDR with an Android Smartphone

Been away for a while (sorry to my few readers!).  I'm busy a lot so please understand, hopefully good things coming.

This one was very fun, I would like to see more digital modes supported which may happen in the future.

Hardware required:
--Android phone with Android 4.4 or higher
--USB-OTG cable
--RTLSDR dongle and its antenna


I was able to get the USB-OTG cable for ~$4 from Fry's, not hard to get.  Software-wise, you need the RTL2832U driver made by Martin Marinov off Google Play (search those terms on Google Play, the driver is free).  You can pay $10 for an SDR Touch app that does what RF Analyzer (the app we use) does, probably more as I haven't tried it yet; however getting a free app is more fun right?--At least for your wallet. :)

 The app (Github site pictured above), which *can* be free if you just install the .apk off Github ( https://github.com/demantz/RFAnalyzer ), but is now available as well for $1.01 on Google Play (don't ask me about the pricing, maybe he likes pennies :p )  If you want the free route, download the zip file.  Now I did this in Windows so it may be slightly different for Linux/BSD.  On your phone, set the "Developer Options" on and enable "USB Debugging" and allow "Installing apps from unverified places".  It was fairly straight forward from there, I just copied over the "RFAnalyzer.apk" to my phone and it installed and put an icon on my phone.

To use it, first be sure to charge your phone up (I looked for a while for ways to charge the phone while using the USB port, there were some ways to do it but they looked a little risky to me and I don't want to break my phone.  Watch out for the "Y-splitters", that apparently doesn't work so be careful if you find products that say they can charge and have a device plugged in.  So you're limited to your battery-life unless you find another way.).  Oh and note that it's recommended to plug the RTLSDR dongle into a powered USB-hub so it draws power to operate from AC instead of your phone.  Plug in the hardware first, then open up the app and go to settings and set the source type as RTL-SDR.

Other than that, it should do the rest.  Hit the triangle-looking button to "start sampling" and you should start seeing a spectral display.  You can scroll with your fingers through the spectrum.  Now go to the FM-radio bands of 87.5MHz - 108MHz and seek out your favorite radio station.  You may have to set modulation to FM.  If you hear it, it works!  You're actually receiving the waves, not listening through the internet.

Sorry I don't have nice pictures of my setup, I use my phone for most all my pictures now.  Also I did this a while ago and when my phone updated to Android 5.0 the app was slightly broken, so just a warning for that.