The Design Of Multiplepath Two-way Audio And Ethernet Signal Transmitting System Based On CPLD

Following the swift and violent developing of technology,a revolution in communication area has ansen once again.Being the mainstay of modern communication,Communication Technique of Optical Fiber bears the brunt in the revolution.To be regarded as a new technique,the whirl away and extensive use of Communication Technique of Optical Fiber are very rare.Communication Technique of Optical Fiber is not only the important symbol of the new technology revolution in the world but also the main device for transporting various information in the unborn-society.Optical fiber is the abbreviation of light guide fiber and the media of fiber-optic communication.Fiber-optic communication is such a method of communication which uses light-wave to be the carrier of information and which uses optical fiber to be the media of information transmission.The matter constituent of fiber-optic communication includes optical fiber,light source and optical detector. The means of classification depends on craftwork,material,optical character,and so on.In using,we usually classify fiber-optic depend on its application.In this way,it can be classified into communicate optical fiber and transduce optical fiber.Transmission medium optical fiber can be divided into two kinds-the popular type and the tailored type.The swift and violent developing of fiber-optic communication owes to its prominent superiors such as the high capacity,the long distance of transmission,the small signal-to-crosstatk ratio,the fine security,and so on. The substance of fiber-optic communication is the method using light-wave to transmit information in optical fiber.Among so many light-waves,laser turns into the first choice for its remarkable superiors such as powerful directivity,cohence,monochromaticity,and so on.Therefore,a new statement which is called laser-optical fiber communication turns out.At the sending end,the primed information is changed into electrical signal,then modutated onto the laser bean which sent out from the optical maser and transmit in the optical fiber; At the receiving end,the optical detector receives the optical signal and transforms it into electrical signal,then to reinstate original information by means of demodulate.The above-mentioned is the theory of fiber-optic communication.To be regarded as a device using in fiber-optic communication, optical transmitter and receiver is equipment that change electrical signal into optical signal,and change optical signal into electrical signal in essential.According to transmission mode,it can be divided into two kinds-analog optical transmitter and receiver and digital optical transmitter and receiver.Digital optical transmitter and receiver treats the primed information with digital processing,then multiple the signal to merge the multiplexed signal into one high-speed digital signal brush and change it to optical signal.At the receiving end,it changes optical signal to electrical signal,then through the process of decompose to obtain primary signal such as video signal,audio signal,data-signal,and so on.Analog optical transmitter and receiver is the equipment that uses manner of frequency modulation,amplitude modulation and phase modulation to modulate video signal,audio signal and data-signal into a certain carrier frequency,then via the optical fiber to transmit.At the receiving end,demodulate the information so to obtain the baseband video signal,audio signal,data signal,and so on.The research is derived from traffic and safe guarding object of construction production,in addition,the product also can use in area intelligent monitored control system.Its applications are very extensive.According to the idiographic demand of this construction object,the product should not only support the transmission of multipath audio signal and multipath Ethernet signal but also can expand multipath video signal and multipath data signal.In designing the project,in the first place,I set about this job from humanization design and intelligent management,and then determined the flashboard unique architecture.The optical transmitter as well as the optical receiver constitute of a motherboard and four isostructure sonboards which stick on the motherboard.Every sonboard is responsible for transmitting two path of audio signal and one path of Ethernet signal,while receiving two path of audio signal and one path of Ethernet signal.So,in total,the transmitting and receiving of eight path of audio signal and four path of Ethernet signal is achieved.The architecture of this design is very flexible;the error of each sonboard won't influence the transmission of other sonboards in the system. Moreover,because the ostructuralism of the sonboards,it is convenient for product development and maintenance.Once determined the structure,I set about from details to design each functional module such as audio analog-to-digital conversion,audio digital-to-analog conversion and Ethernet module.In sonboard,we first merge the various path of signal into EPM570,then via EPM570 to transport the signal to the motherboard.In this process,EPM570 has played a role of relay station.When we think of it in terms of function extend in the future,the important rote of EPM570 witt show itself. The design of motherboard is the focal point of hardware design;the motherboard is responsible for signal multiplexing,tapping, photo-electric conversion and electric-photo conversion.During the process of multiplexing and tapping,the secondary multiplexing of audio signal and Ethernet signal is accomplished by HDMP1032,the primary tapping of audio signal and Ethernet signal is accomplished by HDMP 1034,the primary multiplexing and the secondary tapping of audio signal and Ethernet signal is accomplished by EPM2210.Based on the train of thought mentioned above,we give preference to the aspects such as economical efficiency,practicability,working atmosphere in considering accomplishing the chosen of functional chip, then drew the circuit diagram.Such is the main process of hardware design.Based on the accomplish of hardware design,I test the system in two ways-simulation software test and system parameter test.In addition,I carried out the communicating effect test with the help of my classmate.The objective that software test mainly direct at is the VHDL code embedded EPM2210.For the process of opposite direction transport is the same as positive direction transport,to avoid repetition work,I only emulate positive direction transport.In the process of emulation,the train of thought has been confirmed:At the sending end,the mutiplex data stream coming from audio analog-to-digital conversion module and Ethernet module enter EPM2210 to accomplish the primary multiple connection,then the data stream enter HDMP1032 and be introduced into HDMP1034;At the receiving end,the signal coming from HDMP1034 was read into the output buffer of each channel according to relevant time slot,then the data stream in the output buffer is sent into the corresponding delivery outlet of audio and Ethernet at the corresponding valid clock edge(The multipling and tapping process of the reverse signal is the same as it of the positive direction signal We definite the direction from the sending ends to the receiving end as positive direction.Otherwise, definite it as opposite direction).The detailed process of speaking test and the data received from parameter testing will be showed in Section2,Chapter4.In the designing,I received a series of minute circuit diagram,and then verified the feasibility of system via software emulation.At last,I manufactured the motherboard and sonboard that can transport eight path of audio signal and four path of Ethernet signal,besides,did hardware test to the syste.