直放站工程常见问题及分析

直放站工程常见问题及分析2004年4月深圳国人通信公司主要内容一、直放站工程常见问题及解决办法二、高层建筑信号覆盖问题探讨一、直放站工程常见问题及解决办法直放站常见的问题有自激直放站工作在非线区干扰基站上下行不平衡室内信号泄露系统参数恶化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，强信号通常不会自激，弱信号很容易就会自激。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-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-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-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？主要靠经验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是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）•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）574108615932098251023010535108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）57010761579.5208225843085.53586.8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。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功放饱和频谱-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正常信号谱-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功放饱和输出谱-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增益调测方向增加串入衰减器，降低噪声，提高信号质量-90-80-70-60-50-40-30-20-10010870872874876878880882884886888RefLevel:10.0dBmdB/Div:10.0dBM1M2SpectrumAnalyzerZD420Model:MS2711ASerial#:00125130Date:01/24/2002Time:23:12:02RBW:1MHzVBW:30kHzDetection:Pos.PeakCF:878.5MHzSPAN:20.0MHzAttenuation:20dBdBmFrequency(868.5-888.5MHz)M1:-67.98dBm@868.5MHzM2:-67.98dBm@868.5MHz-90-80-70-60-50-40-30-20-10010870872874876878880882884886888RefLevel:10.0dBmdB/Div:10.0dBM1M2SpectrumAnalyzerZD318Model:MS2711ASerial#:00125130Date:01/24/2002Time:23:02:42RBW:1MHzVBW:30kHzDetection:Pos.PeakCF:878.5MHzSPAN:20.0MHzAttenuation:20dBdBmFrequency(868.5-888.5MHz)M1:-68.62dBm@868.5MHzM2:-68.62dBm@868.5MHz-90-80-70-60-50-40-30-20-10010870872874876878880882884886888RefLevel:10.0dBmdB/Div:10.0dBM1M2SpectrumAnalyzerZD410Model:MS2711ASerial#:00125130Date:01/24/2002Time:23:10:22RBW:1MHzVBW:30kHzDetection:Pos.PeakCF:878.5MHzSPAN:20.0MHzAttenuation:20dBdBmFrequency(868.5-888.5MHz)M1:-69.48dBm@868.5MHzM2:-69.48dBm@868.5MHz增加串入衰减器，降低噪声，提高信号质量加入10dB衰减器加入20dB衰减器加入15dB衰减器调测方向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·