SignalID is a free Android app developed by Tortillum that recognizes radio signals. With over 20 recognized signals, it can help you identify signals that you may not know. The app requires only 5 seconds of recording time to recognize the signal. All you need to do is set the frequency and bandwidth properly, select the frequency range, and place the microphone of the phone near the loudspeaker. Then press the big button and wait for 5 seconds. The algorithm is based on frequency, so it is important to tune your radio/SDR correctly to avoid errors. If you notice any bugs or have suggestions, you can leave a comment. The app is also open source and can be found on Github.