微弱信號檢測裝置
四川理工學院 劉鵬飛、梁天德、曾學明
摘要：
本設計以TI的Launch Pad為核心板，采用鎖相放大技術設計并制作了一套微弱信號檢測裝置，用以檢測在強噪聲背景下已知頻率微弱正弦波信號的幅度值，并在液晶屏上數字顯示出所測信號相應的幅度值。實驗結果顯示其抗干擾能力強，測量精度高。
關鍵詞：強噪聲；微弱信號；鎖相放大；Launch Pad
Abstract:
This design is based on the Launch Pad of TI core board, using a lock-in amplifier technique designed and produced a weak signal detection device, to measure the known frequency Sine wave signal amplitude values of the weak in the high noise background, and shows the measured signal amplitude of the corresponding value in the liquid crystal screen. Test results showed that it has high accuracy and strong anti-jamming capability.
Keywords: weak signal detection; lock-in-amplifier; Launch Pad
1、引言
隨著現代科學技術的發展，在科研與生產過程中人們越來越需要從復雜高強度的噪聲中檢測出有用的微弱信號，因此對微弱信號的檢測成為當前科研的熱點。微弱信號并不意味著信號幅度小，而是指被噪聲淹沒的信號，“微弱”也僅是相對于噪聲而言的。只有在有效抑制噪聲的條件下有選擇的放大微弱信號的幅度，才能提取出有用信號。微弱信號檢測技術的應用相當廣泛，在生物醫學、光學、電學、材料科學等相關領域顯得愈發重要。
2、方案論證
針對微弱信號的檢測的方法有很多，比如濾波法、取樣積分器、鎖相放大器等。下面就針對這幾種方法做一簡要說明。
方案一：濾波法。
在大部分的檢測儀器中都要用到濾波方法對模擬信號進行一定的處理，例如隔離直流分量，改善信號波形，防止離散化時的波形混疊，克服噪聲的不利影響，提高信噪比等。常用的噪聲濾波器有：帶通、帶阻、高通、低通等。但是濾波方法檢測信號不能用于信號頻譜與噪聲頻譜重疊的情況，有其局限性。雖然可以對濾波器的通頻帶進行調節，但其噪聲抑制能力有限，同時其準確性與穩定性將大打折扣。
設計了水聲信號發生系統中的功率放大電路，可將前級電路產生的方波信號轉換為正弦信號，同時進行濾波、功率放大，使其滿足換能器對輸入信號的要求。該電路以單片機AT89C52，集成6階巴特沃思低通濾波芯片MF6以及大功率運算放大器LM12為核心，通過標準RS232接口與PC進行通信，實現信號增益的程控調節，對干擾信號具有良好的抑制作用。經調試該電路工作穩定正常，輸出波形無失真，在輸出功率以及放大增益、波紋系數等方面均滿足設計要求。
This paper presented a design and implementation of underwater acoustic power amplifer. This circuit converted the rectangle signal generated by frontend circuit into the Sine signal， then filtered and power amplification， it meets the requirements of the transducer.Included AT89C52， 6th order Butterworth filter MF6， hipower amplififier LM12.Communication with PC through the RS232 port. The signal gain is adjustable and could be remote controlled. It has a good inhibitory effect on the interference signal. After debugged， this circuit works stable， the output waveform has no distortion， it meets the design requirement in outprt power， amplifier gain and ripple factor.
介紹了采用ATmega48單片機實現三相無刷直流電機控制器的方法。利用Atmega48獲得帶死區的脈寬調制（PWM）、霍爾傳感器的換相處理、正弦驅動信號的產生和電機轉速的控制等功能。采用該方法的優點是所需的外圍器件少，成本低。
Abstract:
The method of 3-phase brushless DC motor control based on ATmega48 is presented in this paper.The system uses ATmega48 to generate PWM signals with dead-time, hall sensors signals commutation，Sine driving signal and rotational speed of motor.Using this method，the needed external devices are few, the cost is low.
用戶程序示例教程
The Blinky project is a simple program for the LPC2138using Keil MCB2130 Microcontroller Board.
It blinks the LEDs at speed according to the Potentiometer setting and prints the current seting to the Serial Port 1.In addition it generates a Sine wave with an adjustable frequency on the speaker of the board.
This project is created using the Keil ARM CA Compiler.
The Logic Analyzer built into the simulator may be used to monitor and display any variable or peripheral I/O register. It is already configured to show the PWM output signal on PORT3.0 and PORT3.1
This ARM Example may be debugged using only the uVision Simulator and your PC--no additional hardware or evaluation boards are required. The Simulator provides cycle-accurate simulation of all on-chip peripherals of the ADuC7000 device series.
You may create various input signals like digital pulses, Sine waves, sawtooth waves, and square waves using signal functions which you write in C. Signal functions run in the background in the simulator within timing constraints you configure. In this example, several signal functions are defined in the included Startup_SIM.INI file.
This example program shows how to configure and use the A/D Converter of the following microcontroller:
STMicroelectronics ST10F166
After configuring the A/D, the program reads the A/D result and outputs the converted value using the serial port.
To run this program...
Build the project (Project Menu, Build Target)
Start the debugger (Debug Menu, Start/Stop Debug Session)
View the Serial Window (View Menu, Serial Window #1)
View the A/D converter peripheral (Peripheral Menu, A/D Converter)
Run the program (Debug Menu, Go)
A debug script (debug.ini) creates buttons that set different analog values in A/D channels. As the program runs, you will see the A/D input and output change.
Other buttons create signals that generate Sine wave or sawtooth patterns as analog inputs. µ Vision3 users may enable the built-in Logic Analyzer to view, measure and compare these input signals graphically.
Verilog HDL: Magnitude
For a vector (a,b), the magnitude representation is the following:
A common approach to implementing these arithmetic functions is to use the Coordinate Rotation Digital Computer (CORDIC) algorithm. The CORDIC algorithm calculates the trigonometric functions of Sine, coSine, magnitude, and phase using an iterative process. It is made up of a series of micro-rotations of the vector by a set of predetermined constants, which are powers of two. Using binary arithmetic, this algorithm essentially replaces multipliers with shift and add operations. In a Stratix™ device, it is possible to calculate some of these arithmetic functions directly, without having to implement the CORDIC algorithm.
基于TMS320F2812 光伏并網發電模擬裝置PROTEL設計原理圖+PCB+軟件源碼+WORD論文文檔,硬件采用2層板設計，PROTEL99SE 設計的工程文件，包括完整的原理圖和PCB文件，可以做為你的學習設計參考。 摘要：本文實現了一個基于TMS320F2812 DSP芯片的光伏并網發電模擬裝置，采用直流穩壓源和滑動變阻器來模擬光伏電池。通過TMS320F2812 DSP芯片ADC模塊實時采樣模擬電網電壓的正弦參考信號、光伏電池輸出電壓、負載電壓電流反饋信號等。經過數據處理后，用PWM模塊產生實時的SPWM 波，控制MOSFET逆變全橋輸出正弦波。本文用PI控制算法實現了輸出信號對給定模擬電網電壓的正弦參考信號的頻率和相位跟蹤，用恒定電壓法實現了光伏電池最大功率點跟蹤（MPPT），從而達到模擬并網的效果。另外本裝置還實現了光伏電池輸出欠壓、負載過流保護功能以及光伏電池輸出欠壓、過流保護自恢復功能、聲光報警功能、孤島效應的檢測、保護與自恢復功能。系統測試結果表明本設計完全滿定設計要求。關鍵詞：光伏并網，MPPT，DSP Photovoltaic Grid-connected generation simulator Zhangyuxin，Tantiancheng，Xiewuyang(College of Electrical Engineering, Chongqing University)Abstract: This paper presents a photovoltaic grid-connected generation simulator which is based on TMS320F2812 DSP, with a DC voltage source and a variable resistor to simulate the characteristic of photovoltaic cells. We use the internal AD converter to real-time sampling the referenced grid voltage signal, outputting voltage of photovoltaic, feedback outputting voltage and current signal. The PWM module generates SVPWM according to the calculation of the real-time sampling data, to control the full MOSFET inverter bridge output Sine wave. We realized that the output voltage of the simulator can track the frequency and phase of the referenced grid voltage with PI regulation, and the maximum photovoltaic power tracking with constant voltage regulation, thereby achieved the purpose of grid-connected simulation. Additionally, this device has the over-voltage and over-current protection, audible and visual alarm, islanding detecting and protection, and it can recover automatically. The testing shows that our design is feasible.Keywords: Photovoltaic Grid-connected，MPPT，DSP 目錄引言 11. 方案論證 11.1. 總體介紹 11.2. 光伏電池模擬裝置 11.3. DC-AC逆變橋 11.4. MOSFET驅動電路方案 21.5. 逆變電路的變頻控制方案 22. 理論分析與計算 22.1. SPWM產生 22.1.1. 規則采樣法 22.1.2. SPWM 脈沖的計算公式 32.1.3. SPWM 脈沖計算公式中的參數計算 32.1.4. TMS320F2812 DSP控制器的事件管理單元 42.1.5. 軟件設計方法 62.2. MPPT的控制方法與參數計算 72.3. 同頻、同相的控制方法和參數計算 8
