The Low Noise Circuit Design And Realization Of Subminiature Wireless Localization Electronic Whiteboard

Subminiature wireless localization electronic whiteboard is the newest real time handwriting input equipment of computer which can use resistor velamen,electromagnetism induction,infrared,CCD,ultrasonic to locate. This paper has balanced the advantages and disadvantages of each localization technology, considered the advantaged predominance like high localization precise,cheapness,long time of usageand so on of the ultrasonic localization technology, adopts the ultrasonic localization technology. Currently there are many products in the markets which use the ultrasonic localization technology, the ones which are representative are Yutongbi which is produced by North Control Jietong electronic Limited Liability Company and the Xiandao electronic whiteboard which is produced by Shenzhen Xiandao electronic Limited Liability Company and so on. Subminiature wireless localization electronic whiteboard mainly completes the basic functions of real-time handwriting input,the computer screen handwriting and operating the computer screen.The main tasks and contributions of this paper are as follows:Firstly, this paper has fully researched the basic theory of low noise circuit design, and on the basis of the low noise principle of the class link amplifier, this paper has decreased the noise factor of the first class amplifier of the Subminiature wireless localization electronic whiteboard, and adopted the non-noise bias circuit, at the same time ,increased the the first amplifier index;Secondly, this paper has adopted sound screen and grounding technology to decrease the inner and outer noise interfere, practice has proved that using the screen technology has taken importance in improving the performance of Subminiature wireless localization electronic whiteboard. On the basis of the hardware design, this paper has completed the software design of the time delay gaining and the data transferring based on USB 1.1 protocol, has gotten the product sample associating the software with the hardware, achieved the whole design of the Subminiature wireless localization electronic whiteboard through combining the sample with the crust;Thirdly, this paper has tested the performance of Subminiature wireless localization electronic whiteboard and has compared the Subminiature wireless localization electronic whiteboard with the congener products. The real test results prove that the complex capability index like localization precise,real time capability,writing range,writing effect of the Subminiature wireless localization electronic whiteboard are better than the congener products on the market, Subminiature wireless localization electronic whiteboard has wider market foreground. Because the writing range of the Subminiature wireless localization electronic whiteboard is more than A4 and is about 80×80cm on the clean surface, this paper has brought forward the idea of using the Subminiature wireless localization electronic whiteboard in the 42 inches screen which will be improved in the future.The main contents of this paper are as follows:In the first chapter the current research conditions have been summarized, the problems of the Subminiature wireless localization electronic whiteboard and the research contents of this paper are introduced;In the second chapter the basic concept and basic model of the low noise circuit design has been introduced in detail which has lain the foundation for the component selection and the noise capability analysis of the Subminiature wireless localization electronic whiteboard.In the third chapter, on the basis of the localization theory and low noise circuit design theory, the hardware has been designed, at the same time, the software program has been compiled;The fourth chapter is the importance of this paper, in this paper, the class link amplifier design principle and the non-noise bias circuit has been introduced in detail, at the same time, the grounding and screening technology of the PCB in the Subminiature wireless localization electronic whiteboard has been analysed, at last this chapter has selected low noise components to complete the product;In the fifth chapter, the general capability index like localization precise,real time capability,writing range,writing effect of the Subminiature wireless localization electronic whiteboard has been tested in detail, at the same time, this chapter has completed the performance comparison between Subminiature wireless localization electronic whiteboard and the congener products on the basis o which this chapter has brought forward the innovation points and the next research direction;The sixth chapter is the summarization and expectation of this paper.The research significance of the Subminiature wireless localization electronic whiteboard lies in: Subminiature wireless localization electronic whiteboard by working together with the DM4601,DM4602,vote instrument,discussion board,U-disc notepad and so on can implements the basic equipments and platforms construction of the complete digital education which provide advantageous conditions for the long-distance teaching, long-distance answering, long-distance homework submitting and stop the phenomena of copying the homework each other when submitting the homework through network. This platform has improved 　some disadvantages of the traditional education style on the basis of inheriting the soul of traditional education theory and has increased the teaching quality enormously. It is proved by practice that Subminiature wireless localization electronic whiteboard has conformed the current of network education in the "Eleven Five" plan and has prodigious market value.The innovations of this paper are as follows:1,his paper has fully researched the basic theory of low noise circuit design, and brought the low noise circuit design into the hardware design of the Subminiature wireless localization electronic whiteboard, which has improved the noise performance of the Subminiature wireless localization electronic whiteboard, increased the complex performance like localization precise ^ real time capability,writing range,writing effect;2,This paper has resolved the problem of unshapely handwriting,chaos localization data,handwriting unable to identify nearly the ultrasonic sensors which has been embodied in the congener products based on the ultrasonic localization technology and has affected the natural writing;3,The rate between capability and price is quite high;4,The writing range.is much big, and can reach 80×80cm on the clean surface and has the space that can be enlarged.Be restricted by time and the author ability of this paper there are the following problems that needed be settled as soon as possible:1,Subminiature wireless localization electronic whiteboard can not correctly and practically display the tip of a writing brush;2,The second grade amplifier of Subminiature wireless localization electronic whiteboard has adopted DS1868 to accommodate the gain automatically which make　 the price of research high and the circuit complex;3,Subminiature wireless localization electronic whiteboard does not apply the special temperature sensor, so the product ability is accessible to temperature.