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[讨论] Noise in Receiver

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发表于 2005-10-11 18:37:00 | 显示全部楼层 |阅读模式
I am measuring a receiver operating at around 1 Ghz. I have a Spectrum Analyzer at the output and a RF Generator at the Input. I  decreses the RF level at the Input up to a level that is almost not observable in the Spectrum Analyzer. Surprisingly, the level is below the Noise level predicted as   =-174 + 10 log BW . Any idea about what is wrong?
发表于 2005-10-11 22:13:00 | 显示全部楼层
你用中文描述一下吧
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发表于 2005-10-12 12:20:00 | 显示全部楼层
<P>会不会是接收机有较大的增益,将输入信号放大,导致实际输入到频谱分析仪的信号功率接近或者超过噪底了?</P>[br]<p align=right><font color=red>+3 RD币</font></p>
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发表于 2005-10-12 19:12:00 | 显示全部楼层
<P>Can you give more details?</P><P>Confusion in receiver BW vs. SA BW? Using noise marker that already compensates BW? Generator level higher than expected due to attenuator leakage?</P>[br]<p align=right><font color=red>+3 RD币</font></p>
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发表于 2005-10-19 14:41:00 | 显示全部楼层
I didn't understand your question
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发表于 2005-10-20 11:02:00 | 显示全部楼层
请问Receiver BW和SA BW 概念有什么不同?
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发表于 2005-10-23 07:51:00 | 显示全部楼层
<P>Hi,</P><P>First you may need to check your target IQ setpoint power seen as S.A, and maybe the output already be smaller than your target when your input approaching to -174+BWLog.</P><P>I believe you already correct RBW/VBW, and maybe your receiver really good!</P><P>You can try to calculate S/N ratio an thus get your receiver NF number.</P><P>Regards,</P><P>wilson</P>[br]<p align=right><font color=red>+5 RD币</font></p>
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发表于 2005-10-31 23:59:00 | 显示全部楼层
<P>如果你的signal 不是wideband的,那么很明显你的测试将是有问题的。只有宽带信号才有可能在噪声里被接受和解调(它有个扩频增益)。如果是窄带信号,那么就是你的SP的setup有问题,或者是你的SP的noisefloor太高。我想你应把详细的测试环境告诉大家,这样才有可能知道是何原因。</P>[br]<p align=right><font color=red>+5 RD币</font></p>
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