[问答]

使用N5241A进行SMC+相位测量的不确定度规格

问答对人有帮助，内容完整，我也想知道答案 0 我的同事和我正在使用带有FCA，IMDx和NFx选项的4端口N5241A来测试变频器; 我们使用SMC +阶段方法进行所有测量。我的任务是为几个状态文件创建和维护校准集; 我们正在测量诸如群延迟，转换增益/损耗，RF / IF端口回波损耗，三阶互调和噪声系数等参数。我正在使用4端口3.5mm E-CAL，18GHz USB功率传感器和346B噪声源来执行所有校准。我使用26.5GHz梳状发生器生成相位参考calset，我已将其应用于群延迟状态文件的calset。我们的客户想要我们所有测量的不确定性规格。当然，我被赋予了获得这些规格的任务......幸运的我！我的第一种方法是使用网络分析仪不确定度计算器; 然而，令我沮丧的是，我发现计算器不包含SMC +相位测量的不确定性！那么，我接着看了N5241A的数据表，发现再次让我感到沮丧的是，那里没有任何SMC +相位测量的不确定性规格！所以，如果有人知道如何计算这些不确定性规格或知道在哪里找到它们，我们将不胜感激！ -担以上来自于谷歌翻译以下为原文 My collegues and I are using a 4-port N5241A with the FCA, IMDx and NFx options to test frequency converters; we're making all of our measurements using the SMC + phase approach. My task is to create and maintain the cal sets for several state files; we're measuring parameters such as group delay, conversion gain/loss, RF/IF port return loss, 3rd order intermods and noise figure. I'm using a 4-port 3.5mm E-CAL, a 18GHz USB power sensor and a 346B noise source to perform all of the calibrations. I used a 26.5GHz comb generator to generate a phase reference calset which I've applied to the group delay state file's calset. Our customer wants the uncertainty specs for all of our measurements. Naturally I was assigned the task of obtaining these specs...lucky me! My first approach was to use the network analyzer uncertainty calculator; however, to my dismay, I found that the calculator does not include uncertainties for SMC + phase measurements! So, I then looked at the data sheet for the N5241A and found, again to my dismay, there weren't any uncertainty specs for SMC + phase measurements in there either! So, if anyone out there knows how to compute these uncertainty specs or knows where to find them, it would be greatly appreciated! -Dan 0
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答案对人有帮助，有参考价值 0 好吧，我有一个不确定性的电子表格，我已准备好进行幅度测量，但它基本上是用于校准SMC的功率计的不确定度的2倍。对于混频器测量，我们没有，也从未有过规范（意味着我们可以追溯到国家标准，在现场验证它们并保证性能）。一个关键原因是混频器的特殊行为极大地影响了不确定性（例如，在IF和RF信号的LO端口上重新转换，从LO源反弹）所以如果想要非常正确，那么你必须知道的事情数量变得非常大。如果你想要一个合理的不确定性估计，那就是功率计在输入频率上的误差（可能是0.15 dB），加上功率计在输出频率上的误差（另一个015 dB），再加上S21误差传递功率从输入到输出的测量（小心校准将其保持为0.03 dB），加上输入电阻误差误差（取决于混频器S11和源匹配）加上混频器剩余输出匹配误差（混频器的S22和负载匹配）。但是由于它们很多，你可以RSS错误; 更正确的是，您可以估算出错误的Sdev，RSS，然后乘以2.77来获得95％的置信区间。这就是振幅。对于相位，您已排除功率计误差，使用匹配项和S21 cal项的幅度误差的6.6倍，然后加回相位参考校准的误差估计。我们对相位精度的描述相当大（在最佳区域+ -6.5度），但我的估计不确定度小于1度，而且我在确定误差方面的经验w.r.t. 群延迟计算，我认为它的顺序约为50-100 psec。而且我们的相位规格是绝对的，但实际上大多数情况下你只关心相对相位误差，而且我认为它从梳齿到梳齿大约为0.25度。所以，如果您需要更多有关估算不确定性的信息，请与我联系。以上来自于谷歌翻译以下为原文 Well, I have an uncertainty spreadsheet that I have prepared for amplitude measurements, but it is essentially 2x the uncertainty of the power meter used for calibrating SMC. We don't have, and never have had, specifications (meaning we can trace them to national standards, verify them in the field, and warrant the performance) for mixer measurements. One key reason is that the particular behavior the mixer greatly effects the uncertainty (for example reconversion on the LO port of IF and RF signals, bouncing off the LO source) so if one wanted to be very correct, the number of things you must know get's very large. If you want a reasonable estimate of uncertainty, it is the error in the power meter at the input frequencies (maybe 0.15 dB), plus the error in the power meter at the output frequencies (another 015 dB), plus S21 error transferrring the power measurement from input to the output (careful cal keeps this to 0.03 dB), plus the input resisudual mismatch error (depends upon the mixer S11 and source match) plus the mixer residual output match error (S22 of the mixer and load match). But since there are a lot of them, you can RSS the errors; to be more correct, you can estimate the Sdev of the errs, RSS them, and multiply by 2.77 to acheive a 95% confidence interval. That's all for amplitude. For phase you have exclude the power meter errors, use the 6.6 times the amplitude errors fro the match terms and S21 cal terms, and then add back in an error estimate for the phase-reference calibration. Our description of phase accuracy is quite large (+-6.5 deg over best region), but my estimated uncertainty is less than 1 degree, and my experience in determining error w.r.t. group delay computations, I think it is on the order about 50-100 psec. And our phase spec is absolute, but really most cases you only care about relative phase error, and I think it is on the order of 0.25 deg from comb to comb tooth. So, let me konw if you need more info on estimating your uncertainty.

2018-12-11 16:01:02 评论举报孔德羲

答案对人有帮助，有参考价值 0 脑洞大赛9 发表于 2018-12-11 19:23 好吧，我有一个不确定性的电子表格，我已准备好进行幅度测量，但它基本上是用于校准SMC的功率计的不确定度的2倍。对于混频器测量，我们没有，也从未有过规范（意味着我们可以追溯到国家标准，在现场验证它们并保证性能）。一个关键原因是混频器的特殊行为极大地影响了不确定性（例如，在IF和RF信号的LO端口上重新转换，从 ... 嗨乔尔博士，我有一些与此主题相关的问题。我们的VNA和DUT之间有一个开关面板。对于群延迟/阶段，去嵌入面板是否会影响你提到的0.25度的不确定性？同样对于SMC，如果我们在我经常问你的频率上进行三角测量，那么功率传感器校准的不确定性是否仍然适用，或者它主要只是VNA误差项仍然存在？是否有一些参考资料来说明夹具如何在不确定性中发挥作用？以上来自于谷歌翻译以下为原文 Hi Dr. Joel, I have some questions related to this topic. We have a switch panel between our VNA and DUT. For group delay/phase, would de-embedding the panel affect the uncertainty considerably over the 0.25 degrees you mentioned? Also for SMC, if we are taking delta measurements across frequencies that I always ask you about, does the uncertainty from the power sensor calibration still apply or would it mainly just be the VNA error terms that remain? Is there some reference material for how fixturing plays a role in uncertainty?

2018-12-11 16:19:49 评论举报陈思远