请教ＧＳＭ的问题

seeyouseeme

小弟在系统调试中，遇到下面问题，希望高手指点：
１．Ｉ／Ｑ解调器输出的Ｉ，Ｑ路之间的交流电平幅度不平衡应该小于多少才不至于影响基带解调？
２．在接近灵敏度附近时，中频星座图偶尔不收敛．

li_lzw

<P>可以从EVM指标入手，具体我也不是很清楚，我只知道直流不平衡体现在OOS指标上，请参考</P><P 0cm 0cm 9pt"><B normal"><U><FONT size=2><FONT face="Times New Roman">8-PSK modulation<p></p></FONT></FONT></U></B></P><P 0cm 0cm 9pt"><FONT face="Times New Roman" size=2>The RMS EVM values, measured after any active element and excluding the effect of passive combining equipment, shall not exceed:</FONT></P><P 0cm 0cm 9pt 42.55pt"><FONT face="Times New Roman" size=2>Under normal conditions 7.0 %</FONT></P><P 0cm 0cm 9pt 42.55pt"><FONT face="Times New Roman" size=2>Under extreme conditions 8.0 %</FONT></P><P 0cm 0cm 9pt"><FONT face="Times New Roman" size=2>The RMS EVM values, measured after any active element and including the effect of passive combining equipment, shall not exceed:</FONT></P><P 0cm 0cm 9pt 42.55pt"><FONT face="Times New Roman" size=2>Under normal conditions 8.0 %</FONT></P><P 0cm 0cm 9pt 42.55pt"><FONT face="Times New Roman" size=2>Under extreme conditions 9.0 %</FONT></P><P 0cm 0cm 9pt"><FONT face="Times New Roman" size=2>The origin offset suppression shall exceed:</FONT></P><P 0cm 0cm 9pt 42.55pt; mso-outline-level: 1"><FONT face="Times New Roman" size=2>35 dB</FONT></P><P 0cm 0cm 9pt"><FONT face="Times New Roman" size=2>For normal and micro BTSs the frequency offset shall not exceed:</FONT></P><P 0cm 0cm 9pt 42.55pt; mso-outline-level: 1"><FONT face="Times New Roman" size=2>0,05 ppm </FONT></P><P 0cm 0cm 9pt"><FONT face="Times New Roman" size=2>For pico BTSs the frequency offset  shall not exceed:</FONT></P><P 0cm 0cm 9pt 42.55pt; mso-outline-level: 1"><FONT face="Times New Roman" size=2>0,1 ppm </FONT></P><P 0cm 0cm 9pt"><FONT face="Times New Roman" size=2>The peak EVM values, excluding the effect of passive combining equipment, shall not exceed:</FONT></P><P 0cm 0cm 9pt 42.55pt; mso-outline-level: 1"><FONT face="Times New Roman" size=2>22 %</FONT></P><P 0cm 0cm 9pt; TEXT-INDENT: 0cm"><FONT face="Times New Roman" size=2>The 95:th percentile EVM value, excluding the effect of passive combining equipment, shall not exceed:</FONT></P><P 0cm 0cm 9pt 42.55pt; mso-outline-level: 1"><FONT face="Times New Roman" size=2>11 %</FONT></P><P 0cm 0cm 9pt 42.55pt; mso-outline-level: 1"><FONT face="Times New Roman" size=2></FONT> </P><P 0cm 0cm 9pt 42.55pt; mso-outline-level: 1"> </P>[br]<p align=right><font color=red>+3 RD币</font></p>

335375882

请教高手 ，通信中所说的三阶交调是什么，怎么产生的

happylin

相干解调时产生的

zhixinluo

电路非线性造成的。比如，有f1，f2信号，三届交调产物有2f1-f2等等