标签: isolation

随着科技的不断发展，无线功能在电脑产业中的应用已蔚为主流，无线技术的整合应用无疑为使用者带来了极大的便利。然而，在追求便利性的同时自然也伴随着一些潜在风险，特别是在无线效能方面；因此无线技术的可靠性绝对是一个不容忽视的问题。 举例来说，虽然无线连接提供了更灵活的使用场景，但信号稳定性和连接可靠性却容易受到外部干扰而产生影响。不论是电波干扰、无线信号干扰抑或是其他无线设备的竞争都可能导致连接质量上的不稳定，进而影响使用者体验。但是能检测出无线效能是否低落纯粹只是基本功，更重要的是如何找出真正的问题所在，并且针对问题进行改善及排除。接下来百佳泰将透过真实的量测案例，带领大家一步步地了解如何改善电脑无线效能低落的恼人问题 电脑无线效能低落，除错与改善实例分享 在百佳泰曾经合作的案例当中，曾有客户的电脑产品在上市后因为无线效能不佳，遭到大量客诉。客户在面对这样的紧急状况时十分需要像百佳泰这样的专业顾问团队协助问题的定位与厘清，并且希望能够从中给予提供第三方的客观建议，以协助他们及早进行产品修正及调整。 Step.1 Throughput实际量测：天线的VSWR(电压驻波比) 与Isolation(天线隔离度) 针对此次个案，百佳泰顾问团队首先协助客户进行Throughput的基本量测。经量测后确认，baseline的数据确实不佳；为了定位问题，百佳泰进一步进行天线的VSWR与Isolation量测，并得到以下结果。 ◆ VSWR(电压驻波比)，量测频率范围为2GHz~6GHz，红线是Wi-Fi操作频带，蓝线与绿线分别为主天线 (Main Antenna)及副天线(Aux Antenna)。 从VSWR的测试中我们可以看到主、副天线在2.5GHz区间皆超过一般业界标准3。至于在曲线图则可以看到设计的操作频率往低频偏移；而5GHz在之前的验证中因为在throughput没有问题，故我们不会在VSWR这边进行调整。因此，若是未来想让5GHz throughput的数值更好，VSWR仍是一个可以进行调整的部分。 接下来，我们来观察Isolation数据，看看是否有需要修正的问题。 ◆ Antenna Isolation(天线隔离度)，量测频率范围为2GHz~6GHz，红线是Wi-Fi操作频带。 Isolation(隔离度)于2.4GHz与2.5GHz频率分别为-11.23与-14.9dB，两者皆超过一般业界标准 -20~-30 dB，这恐会有隔离度不足而造成throughput性能不好的潜在风险。 综合以上天线的电压驻波比与隔离度测试结果，我们几乎可以断言， 此次实测的电脑产品在天线上存在一些设计疑虑，导致throughput下降 。 Step.2电脑无线性能改善实作：Isolation优化与Throughput验证 经过天线的基本量测后，我们将针对VSWR(电压驻波比)与Isolation(天线隔离度)问题着手进行调整与测试，由于VSWR必须对天线本体结构来进行调整，再加上在该客户表示 基于厂内原物料管控因素，故无法针对天线结构进行变更 ，因此百佳泰顾问团队便建议客户可从Isolation问题进行调整。 在先前的量测结果中，Isolation S21数值为-11.23dB@2.4GHz、-14.9dB@2.5GHz，我们从下图的天线位置中可以看到。两支天线不但都位于产品的正面右侧位置，且两支天线距离间隔不到3公分。因此综合天线实际位置与Isolation数值进行推测，百佳泰顾问团队合理假设， 两支天线有可能因彼此过于接近，造成throughput降低 。 为了验证此假设，我们将两天线中间放置两种隔离材料进行实验，从下图右方的网络分析仪画面中可以看到吸波材与铜箔皆可提高隔离度，2.4GHz Isolation从-12.23dB改善至-14dB；2.5GHz Isolation从-14.9dB改善至-16.5dB。 接下来我们直接用Throughput来验证隔离材料是否能改善效能，从下表可以看出隔离材料Channel 1于20m从23.05Mbps改善至37.52 ~ 47.38Mbps，100m则从6.5Mbps改善至11.24~18.32Mbps，双双验证了改善Isolation确实可提高Throughput性能。 经过以上的Isolation优化与Throughput验证，再次证明「两天线间的距离太近，进而造成Throughput数值低落」的假设是正确的。根据此验证结果，百佳泰建议客户变更天线位置，修改成前墙一支天线、后墙一支天线，此作法不仅可提高天线隔离度，同时也能提升天线可传输的覆盖范围。 待客户变更天线位置，调整成一前一后的天线设计后，百佳泰随即为客户进行Throughput测试确认修改后的效果。量测结果如下表所示。Throughput数据在更改天线位置后明显获得改善，RX(黄色底色) Channel 1，20m从27.73改善至74.07得到Pass结果，其他Channel与距离也都得到Throughput数值提升。 看完了今天的无线效能实测案例分享，相信大家可以发现，不论是天线设计的变更，天线本体与布局设计的好坏，都会直接影响到Throughput的测试结果。

In the recent weeks, I've been considering how to compare and contrast the various printed circuit board (PCB) tools from the different vendors. Now, before we plunge into the fray, let's start with a few "weasel words" (disclaimers). Remember the old saying: "Eagles may soar, but weasels rarely get sucked into jet engines!" I'm sure we can all agree that these words are as true today as they were when first intoned by our ancient ancestors deep in the mists of time. First, what I'm looking to do is consider tools at a high level of abstraction. I'm sure there's a place for a 10,000-line comparison boasting tick marks for every conceivable feature and function. I'm equally certain that I'm not the person who is going to create such a comparison, not the least that features and functions are being added and deleted, and are evolving and mutating on a daily basis. Also, I'm predominantly thinking about core capabilities here—specifically, capturing PCB designs and laying out the boards. At the low-end, this may involve a single engineer or a very small team working in isolation. At the high-end, it may involve multiple multi-person teams from different companies located in different geographical locations around the world, thereby mandating the use of sophisticated library management and data management technology. It may also involve multi-board systems and distributed systems (like the electronics in aircraft), which—in turn—requires cables and harnesses to be taken into account. The thing is that I don't want to wander off into the weeds and get sucked into things like thermal analysis and signal integrity analysis and 3D MCAD and suchlike capabilities here—we'll leave those considerations for another day. Last but not least, I'm predominantly thinking about professional-grade PCB offerings, such as those from Altium, Cadence, Mentor, and Zuken. Having said this, I'd also like to include certain tools like DesignSpark PCB and EAGLE PCB in the mix to provide a point of reference. Now, I don't actually want to compare and contrast the various offerings here in this article. The first stage is to choose a framework upon which we can all concur (apart from those who don't agree, but they don't count). For example, one way to describe the PCB tool landscape would be by means of a 2D graph as illustrated below:   The reason I've shown "Enterprise Level" tools as being in the upper-right-hand corner is that we typically wouldn't focus on these tools being used to create simple designs (although they could be), and we certainly wouldn't expect an enterprise-level tool suite being used by a "one-person team." Now, do you agree with the two main categories of "Desktop Level" and "Enterprise Level," or would you prefer different terms? Do you think that we should add another level above "Enterprise," or is that as high as it gets? Also, do you think there should be an additional category between the "Desktop Level" and the "Enterprise Level"—in which case, what should this be called?—or do you think our diagram should reflect a more gradual transition between the two as illustrated below?   Another alternative would be to create a 3D graph, in which the first two dimensions are used to represent "Design Complexity" and "Corporate Complexity" as shown above, while the third dimension is used to reflect additional complexity in both areas, such as multi-board systems and geographically dispersed engineering teams... but you can easily get carried away by this sort of thing. Generally speaking I prefer the KISS Principle ("Keep It Simple, Stupid"). Actually, speaking of the KISS Principle, there are some who might say that even our 2D graphs serve only to confuse the issue. Another representation that finds favour with certain folks would be the dual pyramid approach as illustrated below:   Here, we've divided our tool universe into a "Low-End" and a "High-End." At the lowest of the "Low-End" we have "Basic" offerings (A), from whence we can move up into higher-capacity and higher-speed versions (B). Similarly, in the case of the "High-End," we start with "Mainstream" offerings (C), from whence we can once again move onwards and upwards into higher-capacity and higher-speed versions (D). It's relatively easy to transition from (A) to (B) or from (C) to (D), but migrating from (A) or (B) to (C) or (D) requires an expensive, time-consuming, resource-intensive (learning curve) switch. Once again, do you agree with the terminology used in the above diagram, or would you present this differently in any way. So, our first step is to agree on one of the above diagrams as the basis for our tool comparisons. Do you like the first 2D representation or the second, or do you prefer the dual pyramid representation? Also, do you agree with the terminology I've used, or would you rephrase things in any way? Once we all agree on a basic representation, our next step is going to be to take existing PCB offerings and plot them on our chart, at which point I think the sparks will really begin to fly.

Over the past several weeks, I've been mulling the problem of how to compare and contrast the various printed circuit board (PCB) tools from the different vendors. Now, before we plunge into the fray, let's start with a few "weasel words" (disclaimers). Remember the old saying: "Eagles may soar, but weasels rarely get sucked into jet engines!" I'm sure we can all agree that these words are as true today as they were when first intoned by our ancient ancestors deep in the mists of time. First, what I'm looking to do is consider tools at a high level of abstraction. I'm sure there's a place for a 10,000-line comparison boasting tick marks for every conceivable feature and function. I'm equally certain that I'm not the person who is going to create such a comparison, not the least that features and functions are being added and deleted, and are evolving and mutating on a daily basis. Also, I'm predominantly thinking about core capabilities here—specifically, capturing PCB designs and laying out the boards. At the low-end, this may involve a single engineer or a very small team working in isolation. At the high-end, it may involve multiple multi-person teams from different companies located in different geographical locations around the world, thereby mandating the use of sophisticated library management and data management technology. It may also involve multi-board systems and distributed systems (like the electronics in aircraft), which—in turn—requires cables and harnesses to be taken into account. The thing is that I don't want to wander off into the weeds and get sucked into things like thermal analysis and signal integrity analysis and 3D MCAD and suchlike capabilities here—we'll leave those considerations for another day. Last but not least, I'm predominantly thinking about professional-grade PCB offerings, such as those from Altium, Cadence, Mentor, and Zuken. Having said this, I'd also like to include certain tools like DesignSpark PCB and EAGLE PCB in the mix to provide a point of reference. Now, I don't actually want to compare and contrast the various offerings here in this article. The first stage is to choose a framework upon which we can all concur (apart from those who don't agree, but they don't count). For example, one way to describe the PCB tool landscape would be by means of a 2D graph as illustrated below:   The reason I've shown "Enterprise Level" tools as being in the upper-right-hand corner is that we typically wouldn't focus on these tools being used to create simple designs (although they could be), and we certainly wouldn't expect an enterprise-level tool suite being used by a "one-person team." Now, do you agree with the two main categories of "Desktop Level" and "Enterprise Level," or would you prefer different terms? Do you think that we should add another level above "Enterprise," or is that as high as it gets? Also, do you think there should be an additional category between the "Desktop Level" and the "Enterprise Level"—in which case, what should this be called?—or do you think our diagram should reflect a more gradual transition between the two as illustrated below?   Another alternative would be to create a 3D graph, in which the first two dimensions are used to represent "Design Complexity" and "Corporate Complexity" as shown above, while the third dimension is used to reflect additional complexity in both areas, such as multi-board systems and geographically dispersed engineering teams... but you can easily get carried away by this sort of thing. Generally speaking I prefer the KISS Principle ("Keep It Simple, Stupid"). Actually, speaking of the KISS Principle, there are some who might say that even our 2D graphs serve only to confuse the issue. Another representation that finds favour with certain folks would be the dual pyramid approach as illustrated below:   Here, we've divided our tool universe into a "Low-End" and a "High-End." At the lowest of the "Low-End" we have "Basic" offerings (A), from whence we can move up into higher-capacity and higher-speed versions (B). Similarly, in the case of the "High-End," we start with "Mainstream" offerings (C), from whence we can once again move onwards and upwards into higher-capacity and higher-speed versions (D). It's relatively easy to transition from (A) to (B) or from (C) to (D), but migrating from (A) or (B) to (C) or (D) requires an expensive, time-consuming, resource-intensive (learning curve) switch. Once again, do you agree with the terminology used in the above diagram, or would you present this differently in any way. So, our first step is to agree on one of the above diagrams as the basis for our tool comparisons. Do you like the first 2D representation or the second, or do you prefer the dual pyramid representation? Also, do you agree with the terminology I've used, or would you rephrase things in any way? Once we all agree on a basic representation, our next step is going to be to take existing PCB offerings and plot them on our chart, at which point I think the sparks will really begin to fly.