IMDx源功率校准问题

我正在使用带有两个内部源和组合器的N5241A PNA-X进行IMDx测量;
端口1是输入，端口2是输出。
我在DUT输出端测量相对于载波的IM3，在音调功率对话框中输出音调功率设置为-5dBm;
我还将功率调平设置为“设置输出功率，接收器调平”并选中“耦合音功率”和“ALC开启”。
当我在通道1上执行源校准时，我一直将功率电平设置为大约-35dBm，因为DUT具有大约40dB的增益。
内部源扫描感兴趣的频率范围-35dBm，没有错误。
然后，根据测量窗口开始第二次扫描，其为-5dBm。
此时校准失败（35-40dB），并在屏幕上弹出几个“Src1 Unlevel”和“Src2 Unlevel”错误消息。
如上所述，我将两个信号源的输出功率配置为由音调功率对话框中端口2上产生的-5dBm信号控制;
为什么分析仪会尝试在端口1上测量此功率？
我假设显着的校准失败是由于端口2上没有任何信号，因此没有电源到达B接收器;
为什么校准向导没有提示我将电缆从端口1连接到端口2？
另外，如果有一种方法可以使用校准向导使用-5dBm信号校准B接收器，我可以使用这两个内部信号源吗？
很明显，这两个光源不能产生-5dBm的两个音调。
帮帮我！
-担

以上来自于谷歌翻译

   以下为原文

  I am performing a IMDx measurement using a N5241A PNA-X with two internal sources and combiner; port 1 is the input and port 2 is the output.  I'm measuring IM3 relative to carrier at the output of the DUT with the output tone powers set to -5dBm in the tone power dialog box; I've also set power leveling to "Set Output Power, Receiver Leveling" and checked "Coupled Tone Powers" and "ALC On".

When I'm performing the source calibration on channel 1, I've been setting the power level to approximately -35dBm since the DUT has approximately 40dB of gain.  The internal sources sweep across the frequency range of interest at -35dBm with no errors.  Then, a second sweep begins that according to the measurement window is at -5dBm.  The calibration fails significantly at this point (by 35-40dB) and several "Src1 Unlevel" and "Src2 Unlevel" error messages pop up on the screen.

I configured the two sources' output power to be controlled by the resulting -5dBm signal present on port 2 in the tone power dialog box as I described above; why does the analyzer try to measure this power on Port 1?

I'm assuming the significant calibration failure is due to there not being any signal on Port 2 and so there is no power getting to the B receiver; why didn't the calibration wizard prompt me to connect a cable from Port 1 to Port 2?  Plus, if there is a way to calibrate the B receiver with a -5dBm signal using the calibration wizard, can I use the two internal sources?  It's apparent that the two sources are not capable of producing two tones at -5dBm.

Help!
-Dan

刘华湘

2018-12-13 17:10:28

嗨Dan，我实际上刚刚把这个问题（在阅读你的帖子之前）提请我们的软件团队注意，我们已经指派了一个工程师来找到一种方法来更好地处理打开输出均衡的IMD校准案例。
处理这个实际上并不是很简单。
当您在测量期间打开输出水平时，您依靠DUT的增益将音调放大到您指定在输出接收器上测量的水平。
PNA-X的源ALC电路仅用于提供微小的调整，以克服电缆损耗并纠正轻微的频率响应。
当您使用DUT进行测量时，这一切都能正常工作。
然而，在校准期间，DUT没有连接，也不知道DUT在校准过程中的增益是多少，我们不知道如何将通道中的输出功率水平转换为适当的输入功率水平我们
需要音调电平校准（总是相对于输入参考接收器完成）。
简而言之，现在您正确校准的唯一选择是在启动校准向导之前将通道设置更改为“设置输入功率”或“设置输入功率，接收器调平”（并相应调整音调功率）
。
校准完成后，您可以切换回输出均衡。
一旦我们在固件中设计了一种更自动的方式来处理这个用例，我会在这里发布一个更新;
所以请继续关注。

以上来自于谷歌翻译

以下为原文

Hi Dan,

I've actually just brought this issue (before reading your post) to the attention of our software team and we've assigned an engineer to figure out a way to better deal with IMD calibration cases where output leveling is turned on. dealing with this is actually not very simple. when you have output leveling turned on during the measurement, you are relying on the gain of the DUT to amplify the tones to the level you have specified to be measured on the output receiver. the PNA-X's source ALC circuits are only used to provide minor adjustments to overcome cable losses and correct for slight frequency response. this all works fine when you make the measurement with the DUT in place. during the calibration however, the DUT is not connected and not knowing what the gain of the DUT is during the calibration process, we don't know exactly how to translate the output power level you have in the channel to the proper input power level we need for tone level calibration (which is always done relative to the input reference receiver). To make a long story short, right now your only option for proper calibration is to change the channel setting to either "Set Input Power" or "Set Input Power, receiver leveling" (and adjust the tone powers accordingly) before starting the calibration wizard. after calibration is completed, you can switch back to output leveling.

once we devise a more automatic way in the firmware to deal with this use case, I will post an update here; so stay tuned.

嗨Dan，我实际上刚刚把这个问题（在阅读你的帖子之前）提请我们的软件团队注意，我们已经指派了一个工程师来找到一种方法来更好地处理打开输出均衡的IMD校准案例。
处理这个实际上并不是很简单。
当您在测量期间打开输出水平时，您依靠DUT的增益将音调放大到您指定在输出接收器上测量的水平。
PNA-X的源ALC电路仅用于提供微小的调整，以克服电缆损耗并纠正轻微的频率响应。
当您使用DUT进行测量时，这一切都能正常工作。
然而，在校准期间，DUT没有连接，也不知道DUT在校准过程中的增益是多少，我们不知道如何将通道中的输出功率水平转换为适当的输入功率水平我们
需要音调电平校准（总是相对于输入参考接收器完成）。
简而言之，现在您正确校准的唯一选择是在启动校准向导之前将通道设置更改为“设置输入功率”或“设置输入功率，接收器调平”（并相应调整音调功率）
。
校准完成后，您可以切换回输出均衡。
一旦我们在固件中设计了一种更自动的方式来处理这个用例，我会在这里发布一个更新;
所以请继续关注。

以上来自于谷歌翻译

以下为原文

Hi Dan,

I've actually just brought this issue (before reading your post) to the attention of our software team and we've assigned an engineer to figure out a way to better deal with IMD calibration cases where output leveling is turned on. dealing with this is actually not very simple. when you have output leveling turned on during the measurement, you are relying on the gain of the DUT to amplify the tones to the level you have specified to be measured on the output receiver. the PNA-X's source ALC circuits are only used to provide minor adjustments to overcome cable losses and correct for slight frequency response. this all works fine when you make the measurement with the DUT in place. during the calibration however, the DUT is not connected and not knowing what the gain of the DUT is during the calibration process, we don't know exactly how to translate the output power level you have in the channel to the proper input power level we need for tone level calibration (which is always done relative to the input reference receiver). To make a long story short, right now your only option for proper calibration is to change the channel setting to either "Set Input Power" or "Set Input Power, receiver leveling" (and adjust the tone powers accordingly) before starting the calibration wizard. after calibration is completed, you can switch back to output leveling.

once we devise a more automatic way in the firmware to deal with this use case, I will post an update here; so stay tuned.

孔德羲

2018-12-13 17:22:52

引用: Topcbpcba 发表于 2018-12-13 17:53
嗨Dan，我实际上刚刚把这个问题（在阅读你的帖子之前）提请我们的软件团队注意，我们已经指派了一个工程师来找到一种方法来更好地处理打开输出均衡的IMD校准案例。
处理这个实际上并不是很简单。
当您在测量期间打开输出水平时，您依靠DUT的增益将音调放大到您指定在输出接收器上测量的水平。

实际上，校准的最佳方法是更改为“设置输入功率”（无rx调平）并在衰减器设置范围内的功率电平下进行校准（对于大多数盒子，这是衰减器损耗加5到
-30，因此10 dB衰减器将允许-5到-40 dBm）。
因为你在测量中使用rx调平，所以没有使用源功率校准。
仅使用rx cal，因此事实上，除了rx调平开始其对源功率校准设置的猜测之外，源功率校准设置无关紧要。
因此，为了获得最佳和最快的rx均衡，请将通道的源功率电平设置为hwihc接近驱动放大器所需电平所需的电平。
修复，如果它来了，将是我上面所说的;
Cal将在输出端自动转动Rx水平，在源范围内找到中间值，并从中计算源平衡。

以上来自于谷歌翻译

以下为原文

In fact, the best way to calibrate is to change to "set input power" (No rx leveling) and do the calibration at a power level which is between within the attenuator setting (for most boxes, this is the attenuator loss plus 5 to -30, so a 10 dB attenuator will allow -5 to -40 dBm).

Be cause you are using rx leveling in the measuerment, the source power cal is not used AT ALL. Only the rx cal is used, so in fact, it doesn't matter what the source power cal settings are, other than the rx leveling starts its guess at the source power cal setting. So, for best and fastest rx leveling, set the source power level for the channel at the level hwihc is near the level that will be needed to drive your amplifier to the final desired level.

The fix, if it comes, will be just what I said above; Cal will automatically turn of Rx leveling at the outptut, find a middle value in the source range and and compute the source leveling from that.

引用: Topcbpcba 发表于 2018-12-13 17:53
嗨Dan，我实际上刚刚把这个问题（在阅读你的帖子之前）提请我们的软件团队注意，我们已经指派了一个工程师来找到一种方法来更好地处理打开输出均衡的IMD校准案例。
处理这个实际上并不是很简单。
当您在测量期间打开输出水平时，您依靠DUT的增益将音调放大到您指定在输出接收器上测量的水平。

实际上，校准的最佳方法是更改为“设置输入功率”（无rx调平）并在衰减器设置范围内的功率电平下进行校准（对于大多数盒子，这是衰减器损耗加5到
-30，因此10 dB衰减器将允许-5到-40 dBm）。
因为你在测量中使用rx调平，所以没有使用源功率校准。
仅使用rx cal，因此事实上，除了rx调平开始其对源功率校准设置的猜测之外，源功率校准设置无关紧要。
因此，为了获得最佳和最快的rx均衡，请将通道的源功率电平设置为hwihc接近驱动放大器所需电平所需的电平。
修复，如果它来了，将是我上面所说的;
Cal将在输出端自动转动Rx水平，在源范围内找到中间值，并从中计算源平衡。

以上来自于谷歌翻译

以下为原文

In fact, the best way to calibrate is to change to "set input power" (No rx leveling) and do the calibration at a power level which is between within the attenuator setting (for most boxes, this is the attenuator loss plus 5 to -30, so a 10 dB attenuator will allow -5 to -40 dBm).

Be cause you are using rx leveling in the measuerment, the source power cal is not used AT ALL. Only the rx cal is used, so in fact, it doesn't matter what the source power cal settings are, other than the rx leveling starts its guess at the source power cal setting. So, for best and fastest rx leveling, set the source power level for the channel at the level hwihc is near the level that will be needed to drive your amplifier to the final desired level.

The fix, if it comes, will be just what I said above; Cal will automatically turn of Rx leveling at the outptut, find a middle value in the source range and and compute the source leveling from that.

陈晓露

2018-12-13 17:30:47

引用: 脑洞大赛9 发表于 2018-12-13 18:05
实际上，校准的最佳方法是更改为“设置输入功率”（无rx调平）并在衰减器设置范围内的功率电平下进行校准（对于大多数盒子，这是衰减器损耗加5到
-30，因此10 dB衰减器将允许-5到-40 dBm）。
因为你在测量中使用rx调平，所以没有使用源功率校准。

我尝试了你的建议，没有校准错误。
我们随后在网络分析仪上进行的测量与我们的“控制”非常吻合，即我们使用两个发生器，组合器和频谱分析仪进行的可比测量。
谢谢你的帮助！
-担

以上来自于谷歌翻译

以下为原文

I tried what you suggested and had no calibration errors. The measurements we then took on the network analyzer lined up quite well with our "control", i.e. a comparable measurement we performed using two generators, a combiner and a spectrum analyzer. Thanks for your help!
-Dan

陈晓露

回帖（3）

刘华湘

孔德羲

陈晓露

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