Here’s an app which purports to turn your radio equipped Android device into a SDR. It called SDR Touch and is available for free download from the developer’s website. According to the developers, its designed to work with the familiar RTL-SDR dongles, and Android 3.1 and up. According to the developer Martin Marinov the app:
Turns your mobile phone or tablet into an affordable and portable software defined radio scanner. Allows you to listen to live on air FM radio stations, weather reports, police, fire department and emergency stations, taxi traffic, airplane communications, audio of analogue TV broadcasts, HAM radio amateurs, digital broadcasts and many more! Depending on the hardware used, its radio frequency coverage could span between 50 MHz and 2.2 GHz. It currently demodulates WFM, AM, NFM, USB, LSB, DSB, CWU and CLW signals. You can get a compatible USB receiver for under $20 online from eBay. Just plug in your rtl-sdr compatible USB DVB-T tuner into your Android device using a USB OTG Cable and turn on SDR Touch. For list of supported Realtek RTL2832U based dongles, please see the end of the description. Those features are supported via a driver that you will need to download from Google Play.”
REVIEW: we downloaded the free version of the app and installed on a cheap Craig CMP741E tablet running Android 4.0.3. We started up the app and plugged in our RTL2832U dongle via a USB female to mini-USB male adapter. The app started with the standard FM broadcast band view shown in the video. We could find no instructions on the website or with the app, but after pushing a few buttons it prompted us to download a driver from Google play. We OKd this, but no driver was found. Turns out our Craig table is not an “accepted Google device” so it cannot access Google apps for the driver needed. This temporarily prevented further evaluation of the app, until we learned that Martin has made the driver available for the “rest of us” with non-Google approved devices! You can download the .apk from his GitHub page.
Once the RTL2832U driver .apk was downloaded and installed it “saw” our USB device and SDR Touch began working, receiving nearby FM broadcast stations. We were not, however, able to receive an aero weather beacon on 118.375 MHz AM located two miles away. So your mileage may vary, which is true with any RTL-SDR dongle endeavor. Nevertheless this is an interesting app, and is in ongoing development. We suggest you try the free version first, and if it works on your device you may want to purchase Martin’s Pro version (which unlocks a number of expanded features for around 5.99 British Pounds.)