Handling audio signals

摘要

At a transmitting end of the system, an electrical signal having baseband audio content is input 11. The audio signal may for example be produced by a guitar or another audio sound source. The audio signal is converted to a pulse width modulation (PWM) 13, 15 or pulse density modulation signal (33, 35 Fig. 3) and is transmitted optically over an optical fibre 16. At a receiving end of the system (Fig. 2) the optical signal is demodulated to an analogue electrical audio signal and forwarded to an audio receiving device such as a mixing desk or an amplifier. The demodulation may be performed using a low pass filter (23, Fig. 2). Pulse density modulation may be performed using a sigma-delta modulator. A signal conditioning circuit 12, such as an impedance matching circuit, may be provided at the transmitting end between the audio input and the modulation means. The audio signals lie in the frequency range of human hearing (20Hz- 20kHz).