Research Of 900MHz Digital Interphone Based On Vocoder

With the increasing demand for mobile communication, interphone becomes more and more popular since it is instant, convenient and economical. At present, the Interphone available mainly works at 150MHz, 400MHz and 450MHz. The traditional analogue interphone will gradually withdraw from the market because of its inherent disadvantages such as poor speech quality, lower efficiency of bandwidth usage and lower security. With the current reality that the resource of frequency bandwidth is tensional and the extent of interphone digitization is low in mind, this paper presents a new 900MHz digital interphone on the basis of the technology of Vocoder. The advanced Vocoder technology is used in interphone to implement the low-rate speech signal coding, of which the digital modulation and demodulation is performed with the help of wireless digital transceiver chip. And on the basis of that, this paper introduces the TDD (Time Division Duplex), discusses the frame structure of the TDD protocol, and gives the way of realizing TDD. The 900 MHz full-duplex Digital Interphone invented has a promising prospect for broad application.