The Design Of Speech Playing System Based On Optical Transmission

In the traditional speech playing system, the transmission and broadcast of the speech signal depend on all kinds of cables in many cases,which made the transmission of the spech signal between the sender and receiver end through a lot of cables;this creates lots of problems, such as cable transmission which needs to have some special interface make transmission attachment of the cable become troublesome,especially the messy cables spreading throughout the room(e.g.,classroom,office or home), which not only make the speech playing system inconvenient to move,but affect the beauty of the environment.With the development of radio communication technology,especially the emergence of short-distance radio communication technology,the transmission of sound no longer only rely on cable.Infrared wireless signal transmission is a kind of short-distance wireless transmission technology which transmit signal using infrared ray as transmission carrier which has advantages of high confidentiality,high safety,low power consumption and cost.The main content of this paper is to design a kind of speech playing system based on optical transmission,which mainly includes two parts:infrared sending and receiving.The paper mainly expounds the principles of infrared wireless communication, the overall design of the system,and the hardware design and software programming process of the system also made a detailed analysis.The design adopts STM32F103 issued from STMicroelectronics company as the main control chip of the infrared transceiver module.Design scheme of each part of the hardware and its concrete principle of work are discussed in detail and then the fthe module are illustrated in system software part and the program flow diagram and part of source program are given.In the system design,firstly a speech signal acquired by using the phonetic acquisition circuit or the audio line input passes through amplification and filter processing and transmits real-time speech signal and temperature signal in orientation without distortion controlled by infrared devices through single-chip microcomputer and relays and then give to a single-chip microcomputer which control infrared device to receive useful analog voice signal demodulate by the speech signal and the temperature signal, passes through audio power amplifier circuit, and plays the voice through the speaker.After system debugging and performance test, the system performance is stable, whichhas realized the real-time transmission of speech signals and temperature digital signal,and its communication distance reach up to 2 m, 80 kbit/s of transmission rate,without speech distortion in the transmission process and barcode missing of the temperature data.The system has many features such as clear to play, easy to carry, low cost, which realize the design and achieve the expected requirements on the overall requirements and performance indicators,which can be conveniently used in home, office, classroom and other indoor places.