Design And Implementation Of DSP-based Embedded Wireless Oriented Electronic Whiteboard System

This dissertation focused on the mathematical model of the ultrasonic signal andthe ultrasonic endpoint detection algorithms. The hardware circuit of DSP-basedembedded wireless oriented electronic whiteboard was designed and realized,and the ultrasonic endpoint algorithm based on the characteristics of theultrasonic waveform was implemented with DSP. The test results show that thissystem fulfills the writing function.Up to now, the blackboard is the primary teaching tool for the university, highschool and elementary school. With the progress of the science and technology,so many teachers and students are not satisfied with the traditional teachingtools, for example, the blackboard, the chalk, and the blackboard eraser. Moreand more schools are keen on building the multimedia room, and attempt toboost the activity by using the projection and screen. However, the screen cannot meet the teachers' writing requirement, on the other hand, the teachers,familiar with chalk writing, are not comfortable with the mouse operation.Meanwhile, a number of schools have laid the campus networks connecting withInternet. Although it solves the pollution of the mill dust and time-consumingproblem, face-to-face teaching model is also primary and teachers are still thekernel in the classroom. Although the computers are used in the multimediaroom, it restricts the convenient communications between the teachers and thestudents. Visualization and non-keyboard are the remained problems to besolved in the modern teaching. To be pleased, the electronic whiteboard canovercome the disadvantages of the traditional means, and is the best choice ofthe Computer Aided Education.Nowadays, there are the scanning electronic whiteboard, the touchingelectronic whiteboard, and the laser electronic whiteboard in domestic market.The scanning electronic whiteboard scans the pictures and words on thewhiteboard with the image sensors, such as CCD, into the PC system. Becausethe scanning is performed after the whole whiteboard was written, the scanningelectronic whiteboard is not able to track the handwriting in real time.Furthermore the scanning whiteboard is large and expensive. The touchingelectronic whiteboard captures the handwriting according to the pressure of thepen on the whiteboard. Compared with the scanning electronic whiteboard, itcan track the handwriting in real time. However, it is also large and expensive.The laser electronic whiteboard possesses the high resolution characteristicscompared to the two electronic whiteboard mentioned previously. But it is thesame expensive a whiteboard. Thewireless oriented electronic whiteboard overcomes the disadvantages mentionedT lized with Digital Signalr (DSP), and the analog r the receiving andplifying of the ultrasonicdecr analog circuit to some extent, meanwhileTheA/DwhiTelecembe fIn chapter two, the wireless positioning algorithms in the mobileunication are introduced firstly, and several positioning methods forelectronic whiteboard are explained. We emphasize the positioning algorithmused by DSP-based embedded wireless oriented electronic whiteboard.Chapter three discusses the designing and implementation of the hardwaresystem of DSP-based embedded wireless oriented electronic whiteboard.Chapter four puts the emphases on the mathematical model of the ultrasonicsignal and the endpoint detection algorithms for the ultrasonic. The algorithmswe mentioned include the classical threshold-comparison algorithm, thewavelet-based endpoint detection algorithm and the endpoint detection methodbased on the ultrasonic waveform characteristic.In chapter five, the endpoint detection algorithm based on the ultrasonicwaveform characteristic is discussed in detail. Then the implementation withDSP of this method is explained, and the flow charts of the correspondingprocedures are shown in this chapter.nd large as the other two type electronicbefore, and it is not only high resolution but also small, portable, and cheap.he ultrasonic time-delay extraction algorithm is reaProcesso circuit only is responsible foam signal and infrared signal. This designing structureeases the dependency on theincreases the reliability and consistency of the electronic whiteboard system.amplified ultrasonic signal is firstly transformed into the digital signal bydevice, and then it is transmitted into DSP and stored. The receivedultrasonic is analyzed with DSP, and the steady point of the ultrasonic waveformis found in order to extract the precise time-delay and achieve the location of theteboard pen.his dissertation composes of seven chapters.Chapter one reviews the development history and the current state of thetronic white board, and expatiates the significance of exploiting DSP-basededded wireless oriented electronic whiteboard. Moreover the framework,thunction and the performance of this system are also shown.commChapter six shows the test results of DSP-based embedded wireless orientedelectronic whiteboard, include the he symmetry, the resolution, thetracking rate and the writing performance.Chobile communication andelectronic whiteboard are summarized respectively.ed and realized.ical threshold-comparison algorithm, theethod based on the ultrasonic waveformcharacteristic is implemented with DSP, and it is applied in thed embedded wirelessorienfectronic whiteboard.Increasing the electronic whiteboard area, and accomplishing writingfluently in the larger area (2.4m×1.2m).Investigating the influence of the different environment on the system.linearity, tapter seven summarizes the contribution and deficiency of DSP-basedembedded wireless oriented electronic whiteboard.The main contribution of this dissertation is listed as following:The positioning algorithms used for mThe hardware system of DSP-based embedded wireless orientedelectronic whiteboard is designThe mathematical model of the ultrasonic signal is concluded, and theresearches on three ultrasonic endpoint detection methods are conducted,including the classwavelet-based endpoint detection algorithm and the endpoint detectionmethod based on the ultrasonic waveform characteristic.The endpoint detection mDSP-based embedded wireless oriented electronic whiteboard system.There are three problems to be solved on the DSP-baseted electronic whiteboard.Optimizing the PCB designing, and enhancing the running stability othe DSP-based embedded wireless oriented el...