已翻译+RFTRAININGdnew1.ppt
《已翻译+RFTRAININGdnew1.ppt》由会员分享,可在线阅读,更多相关《已翻译+RFTRAININGdnew1.ppt(58页珍藏版)》请在三一文库上搜索。
1、天线增益和方向,dBi是用来描述天线的增益。它以100%效率的各向同性辐射器或者超于基准的各向同性分贝数作为参考。,一个100%有效的各向同性辐射器由一个平均高效点源(全部经过天线的能量都被辐射出去)组成。,当能量集中在一个单位面积, 能量密度会变得更加高, 这就代表了增益。,天线效率和增益,-天线的效率是指有多少能量进入天线而没有被辐射出去。,PowerBridgeM3 Antenna Array,-例如: 一副增益为-3dBi的天线是怎样可以成为一个各向同性天线呢?,天线系统,输入功率,输出功率(只有1/2),一个各向同性辐射器的最好效率是0dBi, 如果这个各向同性辐射器的增益是-3dB
2、i, 这意味着这个天线的效率只有50%(只有1/2的输入能量被辐射出去)。,反射能量是输入功率的1/2(-3dB),各向同性辐射天线,一个效率为70%的复杂天线, 它必定是一个优良的设计。,效率损耗通常来自于高增益天线里的功率分配网络输送数组元素的电阻插损。,Ubiquiti 设备使用高TX 输出功率,-输出功率将有助于增加链接的距离和可靠性。 不过它必须 是“光洁”的能量(后面有更多的介绍),-一般地说, Ubiquiti 无线设备的输出功率范围为+26dBm到+28dBm。,-10dBm,+13dBm,+28dBm,无线车锁,手提电脑,AirMax 无线设备,dBm的认知,-分贝(dB)是
3、一个比值。dBm 是一个真实的数值, 这个数值是以1毫瓦特作为参考基准。,-dBm遵照跟dB相同的对数映射到域的规则。,问题:500mW是多少dBm?0.002mW的时候是多少 dBm?,跟dB做法一样,应用相同的规则。加倍将增加+3dB. 到10的时候,将会增加+10dB. 然而, 现在是以1mW作为参考(一个真实的数值), 所以“dBm“代表的是一个真实的数值。,Ubiquiti 设备拥有令人满意的RX灵敏度,-Ubiquiti AirMax 能够在窄频段里运行, 并且能够提高灵敏度(5Mhz频段的灵敏度有-103dBm),-Ubiquiti 无线设备使用优化的RF设计去实现接收器最大灵敏
4、度。,-85dBm,-103dBm,传统的 WIFI 设备,AirMax无线设备,Radio Sensitivity Improves with Narrow Channel 缩短路径改善无线电的的灵敏度,40MHz,20MHz,10MHz,5MHz,-Power can remain constant as channel size is varied 由于路径大小的变化,功率可以保持不变,-Thermal noise decreases as channel size decreases 由于路径大小的减少,热噪声也减少,NOISE FLOOR,-Result is an increase
5、 in Signal/Noise seen by receiver 从接收器可以看出在信号/噪音方面的显著效果,For 5MHz Channel, signal area remains the same, but noise area is now 1/8th the amount as 40MHz case,PtP Long Distance Performance Review 点对点长距离绩效评估,TX Power,RX Sensitivity,+28dBm,-103dBm,Antenna Gain,+34dbi,Antenna Gain,+34dbi,A Link Budget sh
6、ows the maximum path loss the link can sustain (this will determine the distance of the link)一个连接预算显示可以支撑的最大路径损耗(这决定了一个连接的距离) Link Budget = Antenna Gains + TX Power - RX Sensitivity 连接预算=天线增益+输出功率-接收灵敏度 = 34dBi + 34dBi + 28dBm + 103dBm “Link Budget” = 199dB,On the transmit side, TX Power and Antenna
7、 Gain define the “intensity” of the signal 在发送方面,输出功率和天线增益决定信号的“强度”,On the receive side, RX Sensitivity and Antenna Gain define the “listening ability” of the radio 在接收方面,接收灵敏度和天线增益决定无线电的“听力”,Using AirLink Simulator 使用AirLink模拟器,http:/ Equipment, Deployment Variables, and Location of Point to Point
8、Link 确定设备,安装变量和点对点连接位置,Using AirLink Simulator 使用AirLink模拟器,http:/ graph shows the terrain profile of the link and Fresnel Zone Clearance (more on this later) 这图表显示连接的地形轮廓和菲涅耳区间隙,These are the simulated results which will appear in AirOS 这些模拟结果会出现在AirOS里,Using AirLink Simulator 使用AirLink模拟器,http:/ c
9、an be simulated! Above are results of actual deployment compared to AirLink simulation 性能可以被模拟!以上实际安装结果比作为AirLink模拟,Link Performance Indicators 链路性能指示,Combined Signal Strength Receiver Hears 收听到的联结的信号强度,Signal Strength corresponding to MIMO Chains for each Antenna Polarity 信号强度相当于MIMO信道,为天线各个极化性,Noi
10、se Floor represents the environmental noise (from interference) the receiver hears on the operating frequency 本底噪声代表环境噪声(来自干扰) 接收器从工作频率中收听,AirMax Quality calculates the airtime efficiency for the client. Higher AMQ is important for hi-performance links. AirMax 特性为用户计算通话效率。 高AMQ对高性能链接很重要,AirMax Capac
11、ity takes into account AMQ AirMax 性能把AMQ考虑在内,TX/RX Rates are the Wireless Data Rates. Rates achievable depend largely on Signal Strength (next page) 发射接收比率是无线数据比率,可达到的比率很大程度取决于信号强度(下页),Transmit CCQ is calculated 计算出传播CCQ,Signal Strength (SNR) and Data Rates,-Achievable data rates depend on signal st
12、rength. Higher Signal strength allows for faster data rates -Increasing MIMO chains to 2, effectively doubles data rates 可达到的数据比率取决于信号强度,高信号强度就高数据比率 增加MIMO信道到2,数据比率就加倍,All Rates in table are based on HT40 mode (40MHz Channel) 表格中的所有数值是基于HT40模型(40MHz信道),Important! Real acheivable TCP/IP rates are app
13、rox. 50% of wireless air rates due to radio overhead,Fade Margin and Recommended Signal Strength,-Signal “Fading” is caused by environmental changes caused by weather or terrain movement 信号“Fading”是由天气和地质变动引起的环境变化而产生的。 -It is good practice to design in approximately 15dB of “Fade Margin” to a PtP li
14、nk 一个好的做法是设计大约15dB的“衰落边际”到一个PtP联结 -Example: If you are designing to achieve a minimum wireless date rate of 180MBps (-70dBm), then the link should be designed such that its installed signal strength is -55dBm 例如:如果你想达到一个无线数据比率的最小值180MBps(-70dBm),那么联结的信号强度就应设置到-55dBm,DAY 1,DAY 2,DAY 3,8dB signal fluc
15、tuation,Deployment and Fresnel Zones,-Portions of the transmitting signal can reflect off of obstructions and arrive at the receiver out of phase with the direct signal. 一部分传播信号能通过障碍物反射回来,异相的接收者能收到直接的信号。 -Because the path lengths are different, the out of phase signals can cancel each other out and
16、reduce the received signal power 因为路径长度是不一样的,异相的信号能互相抵消和减小收到的信号的强度 The Fresnel Zones defines the region which must be free of obstructions to ensure no significant signal reflections arrive at the receiver. Only the first Fresnel Zone is typically of concern for AirMax PtP Links. 菲涅耳波带解释为没有障碍物的区域确保重
17、要信号能反馈给接收者。只有第一个捏菲耳波带是AirMax PtP 联结的典型有利环境。,Fresnel Zone Obstruction,The “reflected signal” can add out of phase with the direct signal reducing received signal power,direct signal,reflected signal,Equation for Calculating Fresnel Zone depth at any point in line of direct link,Fn=The nth Fresnel Zon
18、e d1 = distance of P from one end in meters d2 = Distance of P from other end in meters 1 = Wavelength of the transmitted signal in meters,The Fresnel Zone required clearance becomes greater as the wavelength increases. Therefor, lower frequencies correspond to a larger Fresnel Zone clearance.,Fresn
19、el Zone example for 2.4GHz deployment. Maximum clearance is approximately 8 meters.,Installers can use AirLink to ensure their deployment has First Fresnel Zone clearance,Spectrum Analyzer 波谱分析器,-AirView is standard utility available in AirOS. It runs on all M Series AirMax products from Ubiquiti Ai
20、rView是标准效用可用在AirOS,它可运行在所有M系列来自Ubiquiti的AirView产品 -The application allows the installer to analyze the noise environment and intelligently select the optimum frequency to install a PtP AirMax link 它的应用可以让安装者去分析噪声环境和精明地选择最有利的频率去安装一个PtP AirMax 联结,In the unlicensed bands, interference can significantly
21、 impact link performance. Using AirView, we can see exactly where the interference is and what channels to select to avoid it. 用没有许可的品牌产品,干扰会明显地影响联接的性能。用AirView产品,我们可以明确地看到干扰信号在哪里和调到哪个信道可以消除它。,Spectrum Analyzer 光谱分析仪,This shows the frames per second (FPS) and total RF frames recorded. The FPS can be
22、 increased (giving a more “live” feel”) by reducing the frequency span 这表示每秒帧数(FPS)和所记录的RF总帧数。 FPS值随频率周期的降低而增加。,The Waterfall view shows frequency and RF energy as a function of time. In this case, there is a running 1 minute time window 瀑布形图像表示频率和RF能量的时间函数。此图表示1分钟间隔的情况。,This view gives the RF signa
23、ture of the noise environment. Over time, energy that appears most frequently will be filled into the graph 这是在噪声环境下RF的标识。长时间产生的大部分能量会显示在图标里。,The real-time view is similar to a RF Spectrum Analyzer screen. It shows real-time RF energy vs. frequency. It records maximum energy, average energy ,and cur
24、rent energy 实时图像与RF光谱分析仪的显示图相似,它表示RF能量与频率的实时关系,记录下最大能量,平均能量和现行能量,Channel Operation 路径的运行,Channel Flexing 路径弯曲,Noise 噪声,Signal 信号,Narrowing Channel Width increases sensitivity and improves interference immunity 缩短路径宽度可以增强敏感度和防干扰能力。,5MHz channel size is minimum supported filtering in AirMax radios; no
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 翻译 RFTRAININGdnew1
链接地址:https://www.31doc.com/p-2993356.html