Zero Frequency is a tone generator (sine wave and square wave) and minimal signal analyzer with fancy user interface for android. The main purpose of Zero Frequency is to search and play resonance frequencies. This app is not intended for professional use. Zero frequency cannot generate frequencies in infrasound range or ultrasonic range due to device hardware limitations. Tone generator: setup frequency,time and waveform. Make sure frequency is less then half samplerate. The maximum time depends on device memory. Frequency analyzer: click R or use app menu to open frequency analyzer. The app is free and have no ads or annoying banners.