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黄剑屏

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[问答]

失真信号怎么测量

您好,问题描述使用PSA E4440A进行IP3测试。
测量互调信号时,SA设置:RBW:10Hz,量程:0Hz,输入衰减器:20dB Int前置放大器:使用以下命令读取数据。
init:cont off init:imm; * opc?
read返回1 freq:cent f1 mhz calc:mark1:y?
读imdlvl了。
我的问题是,使用该程序,我可以获得大约-80dBm的IMD水平,但是,当程序运行完毕后,我按“单”,我发现IMD水平从-80到-120dBm。
这是-120dBm级别也通过手动测量确认。
我尝试通过设置init:imm来解决问题;
* OPC?
读取两次返回1,仍存在问题。
非常感谢您的帮助!
你的,伊柳

以上来自于谷歌翻译


     以下为原文

  Hello,  

problem description

using PSA E4440A doing IP3 test.

when measuring the intermodulation signal, SA setting:
RBW: 10Hz,  
span: 0Hz,
Input attenuator: 20dB
Int Preamp: ON
using the following command to read the data.
init:cont off
init:imm;*opc?
read returned 1
freq:cent f1 mhz
calc:mark1:y?
read imdlvl out.

My problem is,
use the program, I could get IMD level of around -80dBm,
however, when the program finished running, I press "single",
I found the IMD level going from -80 to -120dBm. This is -120dBm
level is also confirmed by manual measurement.

I tried to solve the problem by setting the  
init:imm; *opc?
read returned 1
for twice, still problem exists.

Your help would be highly appreciated!

Yours,
Yiliu  

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黄剑屏

2019-1-30 10:38:17
欢迎任何评论

以上来自于谷歌翻译


     以下为原文

  any comment is welcome
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李欢

2019-1-30 10:50:02
引用: dkhwakd 发表于 2019-1-30 10:38
欢迎任何评论

以上来自于谷歌翻译

嗨Yiliu - 看看提供的程序代码,有一些事情是显而易见的......首先,我没有看到标记打开的位置(calc:mark1:stat on)。
此外,当使用如此小的带宽时,扫描时间可能很长,如果源和分析仪之间的时间参考没有被锁定,这可能导致信号在频率上漂移一些,并且标记不再在Intermod失真上
产品。
我还注意到列出的代码是SCPI命令,除了“read imdlvl out”列出的最后一个命令,它不是SCPI命令。
了解用于阅读IMD产品的实际SCPI命令是有帮助的。
分析仪的其他设置包括扫描时间?
对于使用的CW音调,它们的间距和幅度是多少?
为什么测量是在零跨度内完成的?
问候 -

以上来自于谷歌翻译


     以下为原文

  Hi Yiliu -

Looking at the program code provided, a few things are noticeable...

Firstly, I don’t see where the marker is turned on (calc:mark1:stat on).  

Also, when using such a small bandwidth, the sweep time could be long, and if the time references between the source and analyzer are not locked, this can result in the signal drifting some in frequency and the marker no longer being on the Intermod distortion product.  

I also noticed that the code listed is SCPI commands, except for the last command listed of “read imdlvl out”, which is not a SCPI command.  It would be helpful to know what the actual SCPI commands were for reading the IMD products.  

What are the other settings of the analyzer including sweep time?  

For the CW tones used, what are their spacing and amplitude?  

Why is the measurement being done in zero span?

Regards -
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