摘要
电能表作为用电量的测量工具广泛的应用于各种场合。在电能表校表系统中,需要的最基本的输入信号源是高精度双路正弦信号源,并要求可对其频率、相位、幅值进行调节,来对电能表进行校准。
基于单片机的程控信号源设计，运用数字调相、数字调幅和数字调频等技术，要求实现相位、幅度、频率的高精度程控调节。本文设计了一种利用锁相环频率合成技术和数字波形合成技术组成的程控低频正弦波信号发生器，并给出了调幅、调频、调相的实用电路，频率调节通过改变8253计数器的分频系数来实现；相位调节由51单片机预置计数器的计数初值来完成，幅度的调整通过改变DAC1210II的参考电压来实现，使频率分辨率达0.01Hz,相位调节精度达0.1°，并介绍电路中的主要芯的功能及使用。输出正弦波频率和幅值的精度高，稳定性好，失真度低，电路简单、可靠、便于程控。
关键词：数字合成信号源；程控；调幅；调频；移相；
Abstract
Meter consumption as the size of the measurement tool is widely used in various occasions. In single-phase power meter verify system, the most basic needs of the input signal is the source of two-way high-precision sine signal source, and may request its frequency, phase, amplitude in a certain step to adjust to the imitate of the actual electricity load with a right meter calibration.
Design of the programmable signal supply controlled source，which based on the MCU，including digital phase adjustment，distal amplitude adjustment，digital frequency adjustment etc．The system should achieve high quality digital adjustment of phase, amplitude and frequency. This paper describes the use of a PLL frequency synthesizer technology, and digital wave form synthesis technology consisting of program-controlled low-frequency sine wave signal issued devices, and applies the amplitude， frequency， phase of practical circuit. Frequency can be adjusted through a change in the 8253 counter-frequ (2010-06-05, C/C++, 373KB, 下载32次)
摘要
温度测量仪表是工业生产中常用的一种测量装置。对于配用热电偶的二次测温仪表,传统的检定方法是采用逐盘转动电位差计进行平衡读数, 然后查热电偶分度表求出误差,检定过程比较复杂。为了简化检定操作,方便现场检定,我们设计了新型的适用于mV 型测温仪表的检定仪。该检定仪利用AT89C51单片机, 将各种常用热电偶分度表固化在检定仪的EPROM 中,将毫伏发生器、调节器、显示器等组成一体, 具有操作简便、读数准确、功能强、重量轻、体积小等优点, 操作人员不必再查找热电偶分度表。该检定仪设有电势正负转换开关, 为具有零位补偿的测温仪表的零位检定与修理提供了方便，通过不同的按键，该仪表可以选择不同的热电偶分度号，进行校零和进入不同的工作状态。所以该型检定仪是一种非常适宜于现场使用的仪器。
关键词：检定仪；单片机；热电偶；线性化
Abstract
The temperature meter is one of the commonly used measuring devices in the industrial production. The traditional calibration method for going with the thermocouple’s temperature meter is looking up the thermocouple indexing table to extract the error after a balance reading through the plate rotation potentiometer. Obviously, the process of calibrating is too complex. In order to simplify the operations of the calibration and make the scene calibration more convenient, we have designed a new calibrator which is suitable for the mV temperature meter’s calibration. Such calibrator uses a AT89C51 single-chip computer to solidify each kind of commonly used thermocouple indexing table in the calibrator s EPROM, then the millivolt generator, the regulator, the monitor and so on will compose a body, which has the advantage of simple operation, accurate reading, strong function, light weight, small volume and so on. And the operators do not need to look up the thermocouple indexing (2010-06-05, C/C++, 218KB, 下载32次)
DUT系列数据采集模块将温度传感器（热电阻，热电偶等）的输出信号或电流、电压直接转换成数字量，通过RS-485总线及标准通信协议将数据传送给主机。在模块上由89C51单片机管理模块自动工作，通道转换、ADC启动、采集数据、参比端补偿（热电偶）、引线电阻补偿（热电阻）、数字校零、非线性校正和数据处理等，均由单片机完成，主机仅在需要数据时，发送读取数据命令，模块给出已经线性化了的温度的数字量。通讯协议兼容台湾研华ADAM4000系列和松下PLC的通讯协议，可以与大多数组态软件直接连接，不需要额外的驱动程序，技术人员不需要有温度检测专门知识和编程能力即可使用。本产品主要用于各种现场的数据采集和控制系统。
DUT Series data acquisition module temperature sensor (RTD, thermocouples) De Shuchuxinhao or the current, voltage directly into Shuzi amount, via RS-485 bus, and data transfer standard communication agreement Ji Zhu Ji. 89C51 microcontroller in the module by the management module automatically, channel conversion, ADC start, collecting data, reference junction compensation (TC), lead resistance compensation (thermal resistance), digital calibration, linear calibration and data processing by the MCU to complete, the host only needs the data to send read data command, the module has been given a linear temperature of the digital. Communication protocol compatible with Advantech ADAM4000 series and the Panasonic PLC s communication protocol, can be directly connected with most of the configuration software, no additional drivers, technicians do not have temperature sensing capabilities and programming expertise to use. This product is mainly used for a variety of field data acquisition a (2010-05-10, C/C++, 3463KB, 下载106次)