-
便攜式信號采集在機器健康診斷系統(tǒng)中有較高的應(yīng)用價值。機器健康診斷的信號特點是包括低頻信號。本文研究是為了實現(xiàn)簡易而且低成本的低頻便攜式信號采集。以Microchip公司單片機PIC18F1320為核心設(shè)計信號采集電路，實現(xiàn)了信號的采集和保存。系統(tǒng)采用串行電可擦除芯片24LC32A保存數(shù)據(jù)，經(jīng)過有線通信，信號數(shù)據(jù)由串行口通過MAX232芯片輸送到微型計算機接收和保存，最后繪制出信號波形。 微型計算機程序采用Visual Basic編程。研究成功采樣頻率為3 kHz的復(fù)雜信號，證明該方案符合設(shè)計要求。
Abstract:
Portable signal acquisition is useful in machine health monitoring systems. The signal characteristics of machine health monitoring includes low frequency signals. The goal of this study is to realize simple, inexpensive and portable low frequency signal sampling. This paper provides the project of signal acquisition system design based on PIC18F1320 microcontroller manufactured by the Microchip Technology Incorporation to achieve signal sampling and storage. The system adopted EEPROM 24LC32A to store the signal data. The microcomputer received data via wired link with the MAX232 IC through the serial port. The microcomputer program, programmed in Visual Basic, received the data, stored it and plotted the signal. The study successfully samples 3kHz complicated signals and thus meets the design requirement.
標(biāo)簽：
F1320
1320
PIC
18F
上傳時間：
2013-11-19
上傳用戶：moerwang
-
All inputs of the C16x family have Schmitt-Trigger input characteristics. These Schmitt-Triggers are intended to always provide proper internal low and high levels, even if anundefined voltage level (between TTL-VIL and TTL-VIH) is externally applied to the pin.The hysteresis of these inputs, however, is very small, and can not be properly used in anapplication to suppress signal noise, and to shape slow rising/falling input transitions.Thus, it must be taken care that rising/falling input signals pass the undefined area of theTTL-specification between VIL and VIH with a sufficient rise/fall time, as generally usualand specified for TTL components (e.g. 74LS series: gates 1V/us, clock inputs 20V/us).The effect of the implemented Schmitt-Trigger is that even if the input signal remains inthe undefined area, well defined low/high levels are generated internally. Note that allinput signals are evaluated at specific sample points (depending on the input and theperipheral function connected to it), at that signal transitions are detected if twoconsecutive samples show different levels. Thus, only the current level of an input signalat these sample points is relevant, that means, the necessary rise/fall times of the inputsignal is only dependant on the sample rate, that is the distance in time between twoconsecutive evaluation time points. If an input signal, for instance, is sampled throughsoftware every 10us, it is irrelevant, which input level would be seen between thesamples. Thus, it would be allowable for the signal to take 10us to pass through theundefined area. Due to the sample rate of 10us, it is assured that only one sample canoccur while the signal is within the undefined area, and no incorrect transition will bedetected. For inputs which are connected to a peripheral function, e.g. capture inputs, thesample rate is determined by the clock cycle of the peripheral unit. In the case of theCAPCOM unit this means a sample rate of 400ns @ 20MHz CPU clock. This requiresinput signals to pass through the undefined area within these 400ns in order to avoidmultiple capture events.For input signals, which do not provide the required rise/fall times, external circuitry mustbe used to shape the signal transitions.In the attached diagram, the effect of the sample rate is shown. The numbers 1 to 5 in thediagram represent possible sample points. Waveform a) shows the result if the inputsignal transition time through the undefined TTL-level area is less than the time distancebetween the sample points (sampling at 1, 2, 3, and 4). Waveform b) can be the result ifthe sampling is performed more than once within the undefined area (sampling at 1, 2, 5,3, and 4).Sample points:1. Evaluation of the signal clearly results in a low level2. Either a low or a high level can be sampled here. If low is sampled, no transition willbe detected. If the sample results in a high level, a transition is detected, and anappropriate action (e.g. capture) might take place.3. Evaluation here clearly results in a high level. If the previous sample 2) had alreadydetected a high, there is no change. If the previous sample 2) showed a low, atransition from low to high is detected now.
標(biāo)簽：
Signal
Input
Fall
Rise
上傳時間：
2013-10-23
上傳用戶：copu
-
All inputs of the C16x family have Schmitt-Trigger input characteristics. These Schmitt-Triggers are intended to always provide proper internal low and high levels, even if anundefined voltage level (between TTL-VIL and TTL-VIH) is externally applied to the pin.The hysteresis of these inputs, however, is very small, and can not be properly used in anapplication to suppress signal noise, and to shape slow rising/falling input transitions.Thus, it must be taken care that rising/falling input signals pass the undefined area of theTTL-specification between VIL and VIH with a sufficient rise/fall time, as generally usualand specified for TTL components (e.g. 74LS series: gates 1V/us, clock inputs 20V/us).The effect of the implemented Schmitt-Trigger is that even if the input signal remains inthe undefined area, well defined low/high levels are generated internally. Note that allinput signals are evaluated at specific sample points (depending on the input and theperipheral function connected to it), at that signal transitions are detected if twoconsecutive samples show different levels. Thus, only the current level of an input signalat these sample points is relevant, that means, the necessary rise/fall times of the inputsignal is only dependant on the sample rate, that is the distance in time between twoconsecutive evaluation time points. If an input signal, for instance, is sampled throughsoftware every 10us, it is irrelevant, which input level would be seen between thesamples. Thus, it would be allowable for the signal to take 10us to pass through theundefined area. Due to the sample rate of 10us, it is assured that only one sample canoccur while the signal is within the undefined area, and no incorrect transition will bedetected. For inputs which are connected to a peripheral function, e.g. capture inputs, thesample rate is determined by the clock cycle of the peripheral unit. In the case of theCAPCOM unit this means a sample rate of 400ns @ 20MHz CPU clock. This requiresinput signals to pass through the undefined area within these 400ns in order to avoidmultiple capture events.
標(biāo)簽：
C16x
微控制器
輸入信號
時序圖
上傳時間：
2014-04-02
上傳用戶：han_zh
-
在偉福集成環(huán)境下使用PICC.講述在偉福集成環(huán)境如可設(shè)置PICC, 簡單的調(diào)試步驟. 更詳細(xì)的說明請參閱偉福仿真器使用手冊.關(guān)于如何在MPLAB 下使用PICC C 語言, 請參閱Microchip 相應(yīng)的手冊.
2-1 安裝PICC將CD-ROM 裝入光驅(qū), 自動運行程序?qū)⒆詣訂? 如果你已禁止自動運行功能, 可以直接運行: cd_drive:\compiler\install.exe安裝程序?qū)⒅笇?dǎo)你完成PICC 的安裝.2-2 設(shè)置偉福集成環(huán)境在偉福集成環(huán)境中, 將編譯器路徑指向PICC 所在目錄將Ｃ命令行設(shè)置為: -16F877 –G –O –Zg -c將連接命令行設(shè)置為: -16F877 –G –O -Zg其中: -16F877 為芯片型號–G –O -c 為源程序調(diào)試設(shè)置項, 不可修改–Zg 為打開優(yōu)化你可以在命令行中加入其它控制項2-3 調(diào)試Ｃ語言在WAVE\SAMPLES 目錄下有一個PIC C 語言的例子程序: PIC_C.PRJ.１. 打開PIC_C 項目.２. 編譯該項目(F9)３. 用F7,F8 單步調(diào)試?yán)映绦颍? 打開觀察窗口觀察變量
標(biāo)簽：
PICC
集成環(huán)境
上傳時間：
2013-10-16
上傳用戶：lili123
-
jbuzzer is an application written in Java that allows mapping your comuter keyboard to sounds. It supports short samples as well as streaming format. The GUI allows dynamically adding and removing new slots for samples.
標(biāo)簽：
application
keyboard
jbuzzer
comuter
上傳時間：
2014-12-07
上傳用戶：qoovoop
-
《SQL查詢報表源碼生成器V1.1》是專為ASP/JSP網(wǎng)絡(luò)程序員開發(fā)的一個小工具軟件，目的是為了程序員能快速完成開發(fā)的網(wǎng)站SQL查詢報表程序。 本程序特點： 1)使用非常方便，能在1－2分鐘之間完成復(fù)雜的ASP/JSP查詢功能； 2)功能強大，能生成支持返回HTML代碼或者XML代碼結(jié)果。 3)可生成ASP/JSP源碼或者支持生成VB組件（COM＋）的源代碼。 4)提供WINDOWS操作系統(tǒng)下Preview效果。
標(biāo)簽：
SQL
1.1
ASP
JSP
上傳時間：
2015-01-14
上傳用戶：caozhizhi
-
minigui 開發(fā)軟件附帶實例源碼，mg-samples-1.6.2.tar.gz。
標(biāo)簽：
minigui
開發(fā)軟件
源碼
上傳時間：
2015-03-27
上傳用戶：youmo81
-
This a Bayesian ICA algorithm for the linear instantaneous mixing model with additive Gaussian noise [1]. The inference problem is solved by ML-II, i.e. the sources are found by integration over the source posterior and the noise covariance and mixing matrix are found by maximization of the marginal likelihood [1]. The sufficient statistics are estimated by either variational mean field theory with the linear response correction or by adaptive TAP mean field theory [2,3]. The mean field equations are solved by a belief propagation method [4] or sequential iteration. The computational complexity is N M^3, where N is the number of time samples and M the number of sources.
標(biāo)簽：
instantaneous
algorithm
Bayesian
Gaussian
上傳時間：
2013-12-19
上傳用戶：jjj0202
-
報表源碼 FastReport 3 is new generation of the report generators components. It consists of report engine, designer and preview. FastReport 3 can be installed in Delphi 4-7 and C++Builder 4-6.
標(biāo)簽：
report
FastReport
generation
components
上傳時間：
2015-04-04
上傳用戶：qiaoyue
-
linux 的引導(dǎo)程序源碼The Microsoft® Windows® Software Development Kit (SDK) provides the documentation, samples, header files, libraries, and tools you need to develop applications that run on Windows. The applications you develop with this edition of the SDK can run on the x86, x64 and Itanium-based versions of Windows Server 2003 SP1, Windows XP SP2, Windows XP x64 Pro Edition, and Windows 2000. A new custom install allows you to select components you wish to install on a more granular level.
標(biāo)簽：
documentation
Development
Microsoft
reg
上傳時間：
2013-12-20
上傳用戶：我們的船長
