直放站工程常见问题

1用户服务部2•一、移动通信系统的发展•二、直放站概述•三、直放站系统原理、应用模式介绍•四、直放站主要技术参数•五、各类直放站的安装、调试（重点）•六、直放站网管系统（重点）•七、直放站工程常见问题（重点）交流内容3直放站常见的问题有●自激●直放站工作在非线性区●干扰基站●上下行不平衡●室内信号泄露●系统参数恶化4自激自激产生的原因：隔离度不够一般要求系统的隔离度大于直放站增益15dBm弱信号同样站点隔离距离，弱信号要比强信号更容易发生自激。5自激判断方法GSM系统：用手机直观判断用频谱测试CDMA系统：用频谱仪测试基站查询6-60-50-40-30-20-10829830831832833834835836837838RefLevel:-0.1dBmdB/Div:6.86dBM1SpectrumAnalyzerCH28Model:MS2711ASerial#:00139017Date:01/04/2002Time:16:40:08RBW:1MHzVBW:30kHzDetection:Neg.PeakCF:833.5MHzSPAN:10.0MHzAttenuation:30dBdBmFrequency(828.5-838.5MHz)M1:-6.43dBm@833.011MHzCDMA上行自激信号特点：能量集中边沿清晰幅度较大信号带内7-110-100-90-80-70-60-50-40-30-20-10829830831832833834835836837838RefLevel:-10.0dBmdB/Div:10.0dBM1SpectrumAnalyzerZNN112Model:MS2711ASerial#:00125130Date:01/26/2002Time:00:42:27RBW:1MHzVBW:30kHzDetection:Pos.PeakCF:833.5MHzSPAN:10.0MHzAttenuation:0dBdBmFrequency(828.5-838.5MHz)M1:-35.40dBm@833.513MHz环境不好引起的自激8-90-80-70-60-50829830831832833834835836837838RefLevel:-46.0dBmdB/Div:4.5dBM1SpectrumAnalyzerCH3Model:MS2711ASerial#:00139017Date:01/05/2002Time:11:01:38RBW:1MHzVBW:30kHzDetection:Neg.PeakCF:833.5MHzSPAN:10.0MHzAttenuation:0dBdBmFrequency(828.5-838.5MHz)M1:-62.17dBm@833.337MHz临界自激信号9如何避免自激1、在工程设计要考虑施主天线与重发天线的隔离2、弱信号时与强信号时的天线间的隔离的差别，系统要求的增益不一样，在工程方案设计时容易忽视3、调试：调试要认真确认调试时要留一定余量室内分布系统也要注意自激产生隔离度的计算参考公式水平隔离度：Ih=22.0+20log10(d/λ)-(Gd+Gr)+(Xd+Xr)＋C（公式1）垂直隔离度：Iv＝28.0+40log10(d/λ)＋C（公式2）d为两天线水平距离（单位：米）λ为天线工作波长（单位：米）Gd、Gr分别为施主和重发天线的增益（单位：dB）Xd、Xr分别为施主和重发天线的前后比（单位：dB）C为阻挡物体损耗，11●天线的安装方式及隔离度值范围●垂直安装方式施主天线重发天线15～25米5米距离（米）隔离度（dB）57410861593209825102301053510812●天线的安装方式及隔离度值范围●水平安装方式重发天线施主天线25米距离（米）隔离度（dB）57010761579.5208225843085.53586.813直放站工作在非线区主要原因有：输入信号太大，LNA饱和增益太大，功放饱和14如何确认输入信号设计或调到多少较合适？输入信号=设备的标称输出功率-设备的增益如：标称输出功率为40dBm，增益为90dB的机器，则输入信号电平为-50dBm左右。15功放饱和的频谱现象•LNA饱和表现在频谱的根部扩张•功放饱和表现在频谱的顶部失真16-90-80-70-60-50-40-30-20-10010870872874876878880882884886888RefLevel:10.0dBmdB/Div:10.0dBM1SpectrumAnalyzerZXS825Model:MS2711ASerial#:00125130Date:01/24/2002Time:20:02:31RBW:1MHzVBW:30kHzDetection:Pos.PeakCF:878.5MHzSPAN:20.0MHzAttenuation:10dBdBmFrequency(868.5-888.5MHz)M1:-9.34dBm@878.525MHz-100-90-80-70-60-50-40-30-20-100870872874876878880882884886888RefLevel:0.0dBmdB/Div:10.0dBM1SpectrumAnalyzerZXS8Model:MS2711ASerial#:00125130Date:01/24/2002Time:19:37:02RBW:1MHzVBW:30kHzDetection:Pos.PeakCF:878.5MHzSPAN:20.0MHzAttenuation:0dBdBmFrequency(868.5-888.5MHz)M1:-18.22dBm@878.525MHz正常信号谱功放饱和输出谱17-90-80-70-60-50-40-30-20-10010870872874876878880882884886888RefLevel:10.0dBmdB/Div:10.0dBM1SpectrumAnalyzerZXS825Model:MS2711ASerial#:00125130Date:01/24/2002Time:20:02:31RBW:1MHzVBW:30kHzDetection:Pos.PeakCF:878.5MHzSPAN:20.0MHzAttenuation:10dBdBmFrequency(868.5-888.5MHz)M1:-9.34dBm@878.525MHz正常信号-100-90-80-70-60-50-40-30-20-100870872874876878880882884886888RefLevel:0.0dBmdB/Div:10.0dBM1SpectrumAnalyzerVVXModel:MS2711ASerial#:00139005Date:01/17/2002Time:20:21:48RBW:1MHzVBW:30kHzDetection:Pos.PeakCF:878.5MHzSPAN:20.0MHzAttenuation:0dBdBmFrequency(868.5-888.5MHz)M1:-20.53dBm@878.575MHz前端饱和顶部失真前端饱和信号频谱18功放饱和的调试方法LNA饱和减小输入信号在前端加衰减器功放饱和降低设备增益19降低设备内部增益，减少非线形噪声，提高信号质量-90-80-70-60-50-40-30-20-10010870872874876878880882884886888RefLevel:10.0dBmdB/Div:10.0dBM1M2SpectrumAnalyzerZXS830Model:MS2711ASerial#:00125130Date:01/24/2002Time:20:03:26RBW:1MHzVBW:30kHzDetection:Pos.PeakCF:878.5MHzSPAN:20.0MHzAttenuation:10dBdBmFrequency(868.5-888.5MHz)M1:-78.07dBm@868.55MHzM2:-78.07dBm@868.55MHz-90-80-70-60-50-40-30-20-10010870872874876878880882884886888RefLevel:10.0dBmdB/Div:10.0dBM1SpectrumAnalyzerZXS825Model:MS2711ASerial#:00125130Date:01/24/2002Time:20:02:31RBW:1MHzVBW:30kHzDetection:Pos.PeakCF:878.5MHzSPAN:20.0MHzAttenuation:10dBdBmFrequency(868.5-888.5MHz)M1:-9.34dBm@878.525MHz-90-80-70-60-50-40-30-20-10010870872874876878880882884886888RefLevel:10.0dBmdB/Div:10.0dBM1M2SpectrumAnalyzerZXS820Model:MS2711ASerial#:00125130Date:01/24/2002Time:20:02:57RBW:1MHzVBW:30kHzDetection:Pos.PeakCF:878.5MHzSPAN:20.0MHzAttenuation:10dBdBmFrequency(868.5-888.5MHz)M1:-77.17dBm@868.55MHzM2:-77.17dBm@868.55MHz降低设备内部增益，减少非线形噪声，提高信号质量降低20dB增益降低30dB增益降低25dB增益调测方向20干扰基站干扰源的来源：自激上行底噪过大基站带直放站过多其它系统的干扰21静态噪声及计算输入端：Pin=K·T0·B式中:K为波尔兹曼常数：1.38╳10-23·W/Hz·KT0为绝对温度2900KB为设备带宽输出端：Pout=Pin+Gr+F噪声功率输入Pin直放站增益Gr直放站噪声系数F底部噪声=静态噪声+动态噪声动态噪声外部的环境噪声自然噪声人为噪声自然噪声大气、太阳、银河噪声等人为噪声电力线、汽车发动机、工业设备等22测算有效路径损耗：基站机顶到直放站施主口见的有效路径损耗LLINK=PBTS-PDONORGSM系统计算时要考虑载频数和双工合路单元的插损cdma系统计算时不但要考虑载频数和双工合路单元的插损还要考虑分配导频功率所占基站输出功率的比例和用户水平。23底噪的计算方法一般要求基站接受到直放站的噪声电平小于-120dBm，那么要求直放站的输出底噪电平小于[-120dBm-LLINK]24CDMA室内机（宽带）底噪图-130-120-110-100-90-80-70-60-50-40-30810815820825830835840845850855RefLevel:-30.0dBmdB/Div:10.0dBM1SpectrumAnalyzerJX-DZModel:MS2711BSerial#:00209018Date:04/24/2002Time:14:36:33RBW:1MHzDetection:Pos.PeakdBmFrequency(808.49-858.49MHz)M1:-52.02dBm@830.169MHzCDMA室内机（宽带）底噪图本机设备底噪功放噪声白噪声25无线直放站施主天线端口无线直放站重发天线端口使用便携式频谱仪-130-120-110-100-90-80-70-60-50-403-0810815820825830835840845850855:-M1SpectrumAnalyzer频谱测量图无线射频直放站底部噪声的测量26无线直放站施主天线端口底部噪声：PL无线直放站重发天线端口底部噪声Gr+PL使用便携式频谱仪干线放大器施主天线端口底部噪声Gr+PL+LGr=直放站增益L=分布线缆有效路径损耗无线射频直放站+分布系统底部噪声的测量27移频直