本系統(tǒng)分電壓測量和信號產(chǎn)生輸出兩大部分，電壓測量部分以模擬電路為主，配合放大模塊、A/D轉(zhuǎn)化模塊、顯示模塊；通過凌陽單片機進(jìn)行數(shù)據(jù)處理，在誤差允許范圍內(nèi)顯示測量電壓值。信號產(chǎn)生以直接數(shù)字式頻率合成器(Direct Digital Frequency Synthesis,簡稱DDS或DDFS)為核心，經(jīng)過AT89S52對DDS芯片內(nèi)部進(jìn)行控制，使之輸出標(biāo)準(zhǔn)正弦波形，利用編程實現(xiàn)頻率預(yù)置、步進(jìn)，達(dá)到電壓輸出頻率的可調(diào)節(jié)步進(jìn)。通過調(diào)試與測量完成了題目的基本部分和全部發(fā)揮部分的要求并有自己的創(chuàng)新
While faster processors, larger memory, and powerful graphics are fundamental requirements for workstations, users
are also demanding a low-cost, solution-based approach wrapped around a standards-based technology. The Sun UltraTM
20 Workstation, which leverages the AMD OpteronTM processor with Direct Connect Architecture based on AMD64
technology, provides multiple operating system choices and leading nVidia graphics, delivers a platform that offers
flexibility and performance in a cost-effective package with solutions to benefit customers across the board.
AVR single-chip developed by a very low threshold, as long as the computer will be able to study the development of AVR microcontroller. Only a single-chip ISP download beginners line, the editing, debugging of software programs through a direct line into the AVR microcontroller, which can develop AVR Series Single-chip package of a variety of devices. AVR single-chip microcomputer in the industry known as "front-line struggle to seize state power."
AVR single-chip developed by a very low threshold, as long as the computer will be able to study the development of AVR microcontroller. Only a single-chip ISP download beginners line, the editing, debugging of software programs through a direct line into the AVR microcontroller, which can develop AVR Series Single-chip package of a variety of devices. AVR single-chip microcomputer in the industry known as "front-line struggle to seize state power."
This is a comparison foundation construction of data example code, the function is quite complete, was myself debugs the successful procedure, might again on Visual c++ the direct movement
頻率合成技術(shù)在現(xiàn)代電子技術(shù)中具有重要的地位。在通信、雷達(dá)和導(dǎo)航等設(shè)備中，它可以作為干擾信號發(fā)生器；在測試設(shè)備中，可作為標(biāo)準(zhǔn)信號源，因此頻率合成器被人們稱為許多電子系統(tǒng)的“心臟”。直接數(shù)字頻率合成（DDS——Digital Direct Frequency Synthesis）技術(shù)是一種全新的頻率合成方法，是頻率合成技術(shù)的一次革命。本文主要分析了DDS的基本原理及其輸出頻譜特點，并采用VHDL語言在FPGA上實現(xiàn)。對于DDS的輸出頻譜，一個較大的缺點是：輸出雜散較大。針對這一缺點本文使用了兩個方法加以解決。首先是壓縮ROM查找表，
Matlab 畫三維立體圖形
The aim of geom3d library is to handle and visualize 3D geometric primitives
such as points, lines, planes, polyhedra... It provides low-level functions
for manipulating 3D geometric primitives, making easier the development of more
complex geometric algorithms.
Some features of the library are:
- creation of various shapes (3D points, 3D lines, planes, polyhedra...)
through an intuitive syntax.
Ex: createPlane(p1, p2, p3) to create a plane through 3 points.
- derivation of new shapes: intersection between 2 planes, intersection between
a plane and a line, between a sphere and a line...
- functions for 3D polygons and polyhedra. Polyhedra use classical vertex-faces
arrays (face array contain indices of vertices), and support faces with any
number of vertices. Some basic models are provided (createOctaedron,
createCubeoctaedron...), as well as some computation (like faceNormal or
centroid)
- manipulation of planar transformation. Ex.:
ROT = createRotationOx(THETA);
P2 = transformPoint3d(P1, ROT);
- direct drawing of shapes with specialized functions. Clipping is performed
automatically for infinite shapes such as lines or rays. Ex:
drawPoint3d([50 50 25; 20 70 10], 'ro'); % draw some points
drawLine3d([X0 Y0 Z0 DX DY DZ]); % clip and draw straight line
Some functions require the geom2d package.
Additional help is provided in geom3d/Contents.m file, as well as summary files
like 'points3d.m' or 'lines3d.m'.
We introduce a sub-cell WENO reconstruction method to evaluate spatial derivatives in the high-order ADER scheme. The basic idea in our reconstruction is to use only r stencils to reconstruct the point-wise values of solutions and spatial derivatives for the 2r-1 th order
ADER scheme in one dimension, while in two dimensions, the dimension-by-dimension sub-cell reconstruction approach for spatial derivatives is employed. Compared with the original ADER scheme of Toro and Titarev (2002) [2] that uses the direct derivatives of reconstructed polynomials for solutions to evaluate spatial derivatives, our method not only reduces greatly the computational costs of the ADER scheme on a given mesh,
but also avoids possible numerical oscillations near discontinuities, as demonstrated by a number of one- and two-dimensional numerical tests. All these tests show that the 5th-order ADER scheme based on our sub-cell reconstruction method achieves the desired accuracy, and is essentially non-oscillatory and computationally cheaper for problems with discontinuities.
