There are a lot of useful (and useless) hamradio realted apps for Android. I will list some of the apps I am using. Some of them need a registration and some are only allowed to be used by licensed hamradio operators.
If I am missing any good app or you have any comments on the apps I am using, just leave a comment.
You are in another city, searching for QSO and have no idea, which repeaters are nearby? This app will help you. Depending on your GPS position it shows the next repeaters with callsign, distance and direction. You can filter by band and operation mode for digital modes and there are a couple of other filters that can be applied.
Link: Repeater Book
You had do learn so many country prefixes, but do you remember really all of them? Imagine you are operating a portable HF station and you hear a station with an unknown prefix and you want to know the country the station is calling from. Pocket Prefix knows the answer
Link: Pocket Prefix
You want to search for stations nearby, check your APRS messages or even want to operate APRS without a radio? APRSdroid is the solution. You can run it as pure tcp/ip aprs client but also using a bluetooth TNC or an audio connection to your handheld. You can install the app from the website of the author for free, download the sources and compile yourself or you can buy the app in the playstore and support the author. I did the last option as I think it’s a great app and worth the € 4,50
With this app you can use echolink over ip without using a radio. Great app to play with echolink or run QSOs over echolink if you are not in range of an echolink repeater.
You just switched on your TRX and want to check the band conditions? The NCDXF beacon project will help you a lot with this. A couple of beacons around the world are sending at different times on different bands and different power, so you can get the whole band condition picture after a couple of minutes. The only thing you need to know: Which beacon is sending when on which band. The app NCDXF Beacon answers this question in a perfect way and even shows beacons that are currently out of order.
There is a great article at hamspirit.de (in German) explaining the beacon system.
Link: NCDXF Beacon
You want to operate on satellites like the International Space Station (ISS) and more? The app “ISS-Detektor” shows the next passes in realtime. Some basic satellites like the ISS are free, but it’s worth to buy the updates so that you get all hamradio satellites and also NOAA satellites. The app shows the next pass and has a lot of additional information about the satellite and the frequencies. It also shows the exact direction during the satellite pass, so that it’s easy to point the antenna in the right direction
Link: ISS Detektor pro