Design Of Speech Interface Based On AMBE Algorithm

As the information technology continues to change rapidly, the new means ofcommunication are constantly emerging. Therefore, it is very important to efficientlyand fast process the signal. Transmission and switching of voice signals in any form ofcommunication system occupies a very important position. The transmission of voicesignals is no longer confined to the traditional phone system, you can also use thenetwork for transmission. In terms of the transmission of voice signals, the bandwidthresources are its greatest constraints. Therefore, the study of a low-rate coding, and canconvert voice signals into voice interface ethernet signal is very necessary. This cansave the storage and conservation of bandwidth for transmission of low-rate signals andethernet.This Thesis mainly analyzes and studies the following contents. Firstly, it analyzesthe domestic and foreign development of speech coding, understands the meaning anddevelopment direction of the low bit rate speech coding. The digital communicationsystem has a lot of advantages, such as, storage and processing convenience, very goodvoice effect, strong anti-interference ability, easy encryption operation, but points outthat in the sampling rate and quantization standard conditions of ideal range, butrequiring higher data bit rate to obtain a high quality speech signal, problems broughtby the transmission channel bandwidth and the requirements of the increase in theamount of storage. At the same time, the PCM waveform coding, parametric coding,hybrid coding are deeply studied, comparing the advantages and disadvantages ofdifferent algorithm, finally AMBE (Advanced multi-band excitation) algorithmbelonging to mixed coding algorithm is chosed as the design of coding theory. Then,this thesis involves the working principles and characteristics of AMBE-2000, voiceband codec chip, chip micro controller, user interface circuit module and ethernetmodule IPort-1used in the system design, paves the way for the design of hardwarecircuit and software code. The overall design and system principle of work system arealso analyzed in it. Finally, it talks about hardware circuit design and software codewriting. Hardware is mainly designed based on modularization, choosing theAMBE-2000chip as the core to design the circuit, including the control module design,coding and decoding module design, user interface circuit design, ethernet module and power supply module design; the software design deeply studies the data format andtiming diagram of AMBE-2000, writes the main program design, procedures, acceptingthe program codes using C language. In addition, based on the integration of hardwareand software, it carries out functional test of the system. The system is tested and theexperimental study on the function, the system reaches the design objectives and targets,in the rate of2.4Kbps,4.8Kbps,9.6Kbps, complete voice on the network.The system based on AMBE algorithm theory, uses a more representativeimproved multi-band excitation coding algorithm, AMBE encoding chips to compressthe encoded digital voice signal. The voice data is compressed by IPort-1multifunctionembedded module, using its internal hardware embedded TCP/IP network protocolconversion from RS-232serial port into an ethernet port for transmission over theInternet, to achieve high-quality voice calls. The use of existing network resources,improves their use value, you can save a lot of construction and maintenance costs, theinterface design can be applied to satellite communications, defense communicationsand VOIP and other communication systems, which has an extremely wide range ofapplications and practical value, while the Internet voice transmission provides somereferences.