Acoustic Transmitter

Передача сигнала, модулированного с акустическим несущей частоты.

The acoustic transmitter app is designed for use with hands-on guided learning explorations in digital communication and signal processing. The app provides a digital communication transmission signal modulated to an acoustic carrier frequency.

The acoustic transmitter app can be operated in two modes: carrier tone and text transmission. In carrier tone mode, the app simply transmits the waveform cos(2πfct) for a 500 millisecond duration at a user-specified carrier frequency, fc < 22.05 kHz. In the text transmission mode, the app provides a digital communication transmission modulated to a programmable acoustic carrier frequency. The transmitter implements quadrature amplitude modulation, a 13-symbol Barker code or a 51-symbol pseudo-random sequence for timing and frequency recovery, and a data payload fixed at 50 ASCII characters.