Use an OTG (on-the-go) USB cable to connect your HackRF/RTL-SDR to an Android phone/tablet and this app will show you the RF spectrum (frequency magnitude and waterfall plot). You can browse through the frequency spectrum just by using scroll and zoom touch gestures. Additional features as of today are:- select FFT size- activate optional averaging and peak holding- select color schema for the waterfall plot- select drawing types for the FFT: line or bars- read samples from a file (generated by Michael Ossmann's hackrf_transfer tool or by rtl_sdr) - AM/FM/SSB audio demodulation- adjust squelch and channel width- RTL-SDR support- Record to a raw IQ file compatible with hackrf_transfer, GNU Radio,. This app is in active development and I'm currently working on the following features:- Optimizing the signal processing to lower CPU usage and increase filter performance- Bookmarks- Scanner (scan a specific range for the strongest signal) I also try to keep the app stable and as bug-free as possible. Bugreports are always welcome and I promise to work hard to resolve every one of them. Note that there is a loggingfeature in the settings which helps a lot with trouble shooting any errors. PERMISSIONS:This app uses the INTERNET permission only to connect to the local rtl_tcp instance used by the RTL2832U driver. The WRITE_EXTERNAL STORAGE permission is only used to write log files to the SD card (disabled by default). WHAT YOU NEED:In order to use this app you will need:- A HackRF or an RTL-SDR dongle (this is obvious xD) - An Android device that either supports USB OTG (please google if your device supports OTG) or has an USB host port- An USB OTG cable (costs about 3$) to connect the HackRF/RTL-SDR to your Android device (not needed if your device has a full size USB host port) - Only for RTL-SDR: The free RTL2832U driver from Martin Marinov (https://play. google.com/store/apps/details? id=marto. rtl_tcp_andro) IMPORTANT:The HackRF/RTL-SDR is powered by the Android phone/tablet. Some phones or tablets might not deliver enough power on their USB port to power the HackRF/RTL-SDR (power issues are often caused by low quality USB cables or OTG adapters). Also notice that doing the necessary digital signal processing is very CPU intensive and though I did my best to optimize the algorithms the app still needs a decent device (I recommend 2 CPU cores or more) to run fluently. Please use the 2-hour refund period provided for every Google Play app to test functionality and refund the app if it does not work for your device. Here is a list of already tested and working devices (may be incomplete) :- Nexus 7 2012- Nexus 7 2013- Nexus 5- Moto G- Moto G 4G- Acer A500- Samsung S3 LTE- Samsung S4- Samsung S4 LTE- Samsung S5- Samsung Note 3- Samsung Galaxy Tap S 8. 4 & 10. 5- HTC M7- HTC M8- LG G2- LG G3- Motorola Xoom M601- Dragon Touch A1XIf the app is working for you and your device is not in this list, please include your phone type in a short ratingand share the good news with other users ;) Here is a list of devices that were reported NOT to work with this app (may be incomplete) :- Sony Xperia Pro + HackRF (because USB output power is too low -) - Nexus 4 (works only with Y cable and custom ROM to enable OTG support) - Nexus 9 (Not a power issue, I am still investigating on this) LICENSE:This application is released under the GNU General Public License v2. It is free software and the source code is available on GitHub: https://github.com/demantz/RFAnalyzerYou might wonder why you have to pay for a free app: You don't have to. The APK package is also available in thegit repository and you can download and install it from there. But keep in mind: by buying the app you will get automaticupdates and you will support my work. LEGAL ISSUESPlease note that I am not responsible for any legal issues caused by the usage of this application. Be responsible and comply with your local law.