數(shù)字頻率的設(shè)計與制作

電子信息工程論文編號:DZXX166  論文字數(shù):14734,頁數(shù):47

目  錄

摘  要 I
Abstract II
第一章  引  言 1
1.1 國內(nèi)外研制狀況 1
1.2 課題的目的意義 1
1.3 預(yù)期達到的目標 2
1.4 設(shè)計所需要的儀器設(shè)備、器件 3
第二章 設(shè)計方案提出與論證 4
第三章  系統(tǒng)硬件設(shè)計 6
3.1 系統(tǒng)硬件總述 6
3.2 復(fù)位電路 6
3.3 時鐘電路 8
3.4 分頻電路 9
3.5  8051經(jīng)8255與鍵盤顯示器接口電路 11
3.5.1 鍵盤工作原理 11
3.5.2 LED顯示器工作原理 12
3.5.3 其它主要功能器件 16
3.5.3.1 驅(qū)動LED顯示器集成芯片7407 16
3.5.3.2  8051單片機芯片 17
3.5.3.3  8255微機并行接口芯片 18
3.5.4 鍵盤顯示器接口整體電路圖 20
3.6 整形放大電路 20
3.7 看門狗電路 22
第四章  系統(tǒng)軟件系統(tǒng)設(shè)計 24
4.1 軟件系統(tǒng)總述 24
4.2 系統(tǒng)初始化設(shè)計 24
4.3 鍵盤程序設(shè)計 24
4.4 測試程序設(shè)計 25
4.4.1 T0和T1工作方式確定 25
4.4.2 測試程序 26
4.5 數(shù)據(jù)處理程序設(shè)計 27
4.6本章小結(jié) 29
第五章  結(jié)論 30
致謝 31
附錄1：數(shù)據(jù)處理程序 33
附錄2：鍵輸入原程序 41
附錄3：顯示程序 43
附錄4：系統(tǒng)總硬件圖 44

摘  要
傳統(tǒng)數(shù)字頻率計的測頻誤差主要包含兩項σ=σ1+σ2。σ1為閘門時間的相對誤差，在數(shù)值上等于頻標信號的準確度，σ1=—ΔFs/Fs，F(xiàn)s為頻標信號頻率；σ2位對測頻技術(shù)的相對量化誤差，σ2=±Tx/T，Tx為被測信號周期，T為閘門時間。σ1與所用石英晶體的頻率穩(wěn)定度有關(guān)，為減少σ1，常采用高穩(wěn)定度的石英晶振；σ2是一變量，在同一閘門內(nèi)低頻段和高頻段相差幾個數(shù)量級，它對測頻精度的影響最為嚴重。為減小σ2常采用下列方法：頻率較低時改用測周期；多周期測量法；模擬內(nèi)插法；頻率倍增法等。采用這些方法對測頻誤差有一定的改善，但并未解決根本問題，且增加了軟硬件成本。
本文介紹一種利用單片機實現(xiàn)的高精度測頻儀，其特點是：
(1) 測量精度高，且在同一閘門內(nèi)，各被測頻率的測量精度相等，當(dāng)閘門的時間為10s時，σ2≈10﹣7；
(2) 閘門時間在0.01s--10s間任意設(shè)置；
(3) 測頻范圍寬，F(xiàn)x=0.1Hz—100M Hz；
(4) 預(yù)算速度高，通過特殊的定點數(shù)運算代替浮點數(shù)運算，運算中保留4字節(jié)有效數(shù)字；
(5) 顯示軟件中通過浮動小數(shù)點的位置顯示8位十進制有效數(shù)字；
(6) 具有連續(xù)顯示功能。
關(guān)鍵詞：頻率計、等精度測量、單片機

Abstract
For the traditional numeral frequency meter the frequency measurement error mainly contains two itemsσ=σ1+σ2. σ1 is the relative error of strobe time which in value is equal to the accuracy of standard frequency signal, σ1=-ΔFs/Fs, Fs is the standard frequency of the standard signal; σ2 is the relative quantification error to the frequency measurement technology, σ2=±Tx/T, Tx is the period of the measured signal, T is the strobe time. σ1 is related with the uses the frequency stability of the quartz crystal. σ1 often can be reduced by using high stability quartz crystal oscillator; σ2 is a variable, the value of which the differs several magnitudes between the low frequency band and the high frequency band in the identical strobe, so the influence to the frequency measurement precision of σ2 is the most serious. In order to reduceσ2 the following method is often used: chang to cycle measure when the frequency is low; multi-cycles measure; Analog interpolation; ampify the frequency and so on. By using these methods the frequency measurement error can be reduced for a little, but the basic problem can not be solved, and also increased the software and hardware cost.
In this article, we introduced a cymometer with high accuracy which realizes by using the monolithic integrated circuit, its characteristics are:
High Measuring accuracy, and the precision of all of the measured frequency is equal in the identical strobe, when the strobe time is 10s, σ2≈10 -7;
(2) The strobe time can be random setting in the rang of 0.01s--10s;
(3) The frequency measurement scope is wide, Fx=0.1Hz --100M Hz;
(4) The operation rate is high. By using special given points operation to replace the floating number operation, 4 byte significant digit is retains in the operation;
(5) In the software for display 8-bit decimal bases significant digits are displayed through the fluctuation decimal point position;
(7) It has the continuously demonstration function.
Key words:  Cymometer,  Measurements with the same precision,  Single-chip Machine