Communications engineering. The pulse position modulation uses a pulsed carrier with a constant frequency and an analogue modulation signal with constant amplitude. The carrier's pulse position is changed by the modulation signal, which contains the information to be transmitted. A positive modulation signal causes the modulated signal to advance the carrier the more the more positive the modulation signal is. With a negative modulation signal the modulated signal runs after the carrier the more the more negative the modulation signal is. Pulse position modulation is used for ultra-wideband applications like digital radio transmission over short distances or motion detectors.