The Design Based On Voip Network Telephone Terminal And The Realization Of The System Function Module

With the development of the computer and the wideband technology, the information network with multimedia correspondences as the subject has become the focus in the world. As the telephone service in the Internet, the IP telephone has been regarded as the new times which the telephone develops, and becomes one of targets of the next generation network (NGN) .Although the IP telephone has the multitudinous superiority, it has the very big problem, some technical need to be improved urgently.This article inspected in the domain correlated in domestic and foreign at this moment, in the foundation of actual project, we designed hardware frame and the software frame based on the VoIP network telephone terminal. In view of the insufficiency of VoIP technology, this article has done the following work:(1) According to actual demand, construction entire VoIP network telephone terminal hardware frame and software frame.In hardware frame aspect, this article dissects the chip's shaping and it's merit, constructs entire hardware system; In the software frame aspect, this article elaborated the software design proposal in detail, and has done the detailed research on the software modulation design.(2) Researched and improved two algorithms. One kind is the echo counterbalance algorithm, another one is the telephone condition examination algorithm. In the echo counterbalance algorithm aspect, this article has conducted the massive research and the analysis in view of the current mainstream echo counterbalance algorithm, we discovered it has many deficiencies. Because use traditional Geigel algorithm has a bad accuracy, extremely high in time the existence of near-end pronunciation or the bidirectional telephone conversation rate of false alarm, it causes so long as has appeared the near-end pronunciation, the filter coefficient can disperse and appear the echo, needs to vanish period of time after the near-end pronunciation the filter coefficient to be able to restrain, this cannot solute echo question very well. This article proposed one kind of improvement algorithm in this foundation, this algorithm has defined a filter balance factor formula, according to this formula, we readjustment filter balance factor value appropriately, through controlsling the LMS filter coefficient's freezing and the restoration, we solute echo puzzle perfectly; In the telephone condition examination algorithm aspect, in view of the busy signal examination algorithm which has has only been able to examine the busy signal, but cannot examine the dial tone, hang the staccato the deficiency, this article improves its algorithm to enable it to apply these aspects, make it can be better used in the actual system application.(3) Designed and realized partial functions of the system. Mainly includes the ringing module, the telephone condition examination module, the echo counterbalance module, the DTMF code gathering module designing and the realization. And this article applies the algorithm realization in these actual modules, it causes the fundamental research and the practical application unifies.Finally, the paper reviewed the entire research situation based on the change of Voip network telephone terminal technical and the realization of system function module research, summarized the system's insufficient payment, and proposed the question that the system should be further improved.