One of the prerequisites for the development of telecommunication services is the understanding of the propagation of the waves, either acoustic, electromagnetic, radio or light waves, which are used for the transmission of information. In this work, we shall limit ourselves to the study of radio waves: this term apply to the electromagnetic waves used in radio communications. Their frequency spectrum is very broad, and is divided into the following frequency bands : ELF waves (f < 3 kHz), VLF (3-30 kHz), LF waves (30-300 kHz), MF waves (300-3000 kHz), HF (3-30 MHz), VHF waves (30-300 MHz), UHF waves (300-3000 MHz), SHF waves (3-30 GHz), EHF waves (30-300 GHz) and sub- EHF waves (300-3000 GHz).
标签： Propagation Radio Wave
上传时间： 2020-06-01
上传用户：shancjb
The unguided transmission of information using electromagnetic waves at radio frequency (RF) is often referred to as wireless communications, the first demonstration of which took place at the end of the 19th cen- tury and is attributed to Hertz. The technology was, shortly thereafter, commercialised by, amongst others, Marconi in one of the first wire- less communication systems, i.e., wireless telegraphy. In the first half of the 20th century the technology was developed further to enable more than the mere transmission of Morse code. This first resulted in uni- directional radio broadcasting and several years later also in television broadcasting.
标签： Imperfections RF
上传时间： 2020-06-01
上传用户：shancjb
There is an unprecedented enthusiasm for radio frequency identification (RFID) technologies today. RFID is based on the exchange of information carried by electromagnetic waves between a label, or tag, and a reader. This technology is currently in full economic expansion, which has manifested itself in widely backed research activities, some of which will be examined in this book.
标签： Identification Frequency Sensors Radio and
上传时间： 2020-06-08
上传用户：shancjb
基于TMS320F28035芯片为控制核心的空间矢量异步电机变频器 我们设计的异步电机变频调速器以TMS320F28035芯片为控制核心，通过输出三相PWM波控制智能功率模块IPM驱动三相异步电机。我们使用空间矢量SVPWM算法，并对其进行了优化。采用检测反电势的方法省去了昂贵的光电编码器，大大节省了成本。同时开创性的研发了自动根据运行环境调节的自适应变频算法，使我们的变频调速器可以在电网条件恶劣的乡村山区工作，由此该变频器已被一家民用水泵生产企业预订。关键字 变频器 TMS320f28035 IPM SVPWM In our design, the asynchronous machine inverter based on the chip of TMS320F28035 drives the three-Phase asynchronous machine by sending three-phase PWM waves to the IPM, which is short for the Intelligent-Power-Module. The SVPWM (space vector pulse width modulation) strategy is applied to our control algorithm and we optimize it mainly in two aspects. Firstly the inverter detects the speed by measuring the Back EMF instead of installing an expensive photoelectric encoder for costs reduction.
标签： tms320f28035 芯片
上传时间： 2022-05-08
上传用户：zhanglei193
VIP专区-嵌入式/单片机编程源码精选合集系列（76）资源包含以下内容：1. stc12c的AD处理.2. 这是keil公司的mcm2300开发板上的.3. 一些关于SOPC,NIOS设计的论文,可以作毕业设计参考.4. 远程数据访问RDA等.5. 基于lpc2148的按键扫描程序.6. spce061a实现的键盘扫描程序.7. SPCE061A实现的LED拉幕显示效果.8. SPCE061A中位操作头文件.9. SPCE061A+SPCL051液晶显示汉字程序.10. keil.11. 采用LPC935控制的一个项目.12. 采用MPS430控制的项目.13. mm36sb020的spi的接口,已经调试过的 /* 定义命令 *//* #define ERSC 0x90f6 // 檫除整个芯片 // #define SRC 0xfffffffe //.14. LCD6963模块的驱动,可以显示汉字和图形. 线路图 89C51 T6963C -------- | 8 P1.0-1.7|=========== D0-7 | P3.0|--.15. ATmega16上面的ADC测试.16. 小液晶1602驱动程序.17. 基於C51的智能毫秒計, 精準到1ms, 含原理圖.18. NXP2103开发版图.19. 软件红外线接收程序 采用24MHz晶振.20. 串行口通信程序.21. 投票系统.22. 一担挑游戏.23. 组数游戏.24. 歌星大奖赛.25. VHDL mif file generator, which can generate several waves.26. uboot.27. 该程序是一个tffs文件系统的源码.28. 这是一个测试液晶显示的程序,测试LCD的亮灭.硬件连接如下: 3脚接偏置电阻,接个10K的可调,.RS4,RW5,E6脚接P3^3,P3^2,P3^1,程序头部有定义可根据实际修改.29. uart5/atmega8515/led 时钟显示.30. 逆变器原理图.31. 基于LPC2210的FFT程序.32. 这是我读研的时候用VB开发的一个与基于CAN-PCI5121的通讯小程序.33. 这是基于CAN-PCI5121开发的通讯程序.34. 将每一个声源加到混音缓冲器,经过处理后返回.35. 处理声源,时间,做好各类资源的调整工作,为声音的输入输出做准备..36. NiosII培训资料,主要讲述如何操作NIOS,对初学者帮助较大..37. 当前流行的802.15.4ZIGBEE协议的应用开发流程.38. Zigbee应用开发介绍说明.39. 完整的空调控制程序.40. VMMforSystemVerilog的源码资料 学习SystemVerilog的好东西.
上传时间： 2013-05-19
上传用户：eeworm
