无中心多路对讲机设计方案

In this paper a perfect resolution of No-center Multiplexer-interphone is given. Through taking use of FDMA (frequency division multiple access), the resolution finds a way to transport speech signal to several stations at the same time respectively and to broadcast. SCM works as the controller and employs VCO (Voltage Control Oscillator) and PLL (Phase Lock Loop) to modulate FM. A radio chip demodulates FM to reform speech and FSK, cooperating with a D/A converter controlling the local oscillation circuit to switch communication channels. The communication linked by the 2FSK signal. The system is stable and the man-machine interface is friendly.