标签: cable

USB Type-C具有全方位连接性、高速数据传输、支持快速充电及反向插头等特性，已成为一种广泛使用的连接标准，普遍应用于各种装置中，如：手机、平板电脑、笔记本电脑、桌面电脑、显示器、外部硬盘、充电器等。USB Type-C的速度也从10/20Gbps提升至现在的40Gbps与即将推出的80Gbps，这都足以显示USB Type-C的应用将越来越广。 因为支持高速、充电及反向插头等特性，越来越多的显示器厂商也将USB Type-C导入成为显示器的接口之一。不过USB Type-C线缆在做高速传输的应用时，必须注意到其高频特性质量是否良好，否则很容易发生无法预期的风险。 两种串扰会造成多严重的潜在风险？ 举例来说，串扰(Crosstalk)是高频特性中一个重要的质量衡量指针项目之一，串扰是由于线路之间的耦合引发的讯号和噪声等的传播，会使得原本的讯号受到干扰而降低其讯号质量。当串扰严重时，有可能会导致误码率上升，这时候在显示器的表现就会出现不定期画面闪烁或噪声的现象，导致用户负面的体验经验。 百佳泰透过长期的经验与实验数据，发现串扰项目有问题的线缆，而 串扰现象分为两种：近端串扰 (Near End Crosstalk /NEXT )、远程串扰 (Far End Crosstalk/FEXT)，这两种串扰严重时都可能会引发上述的潜在风险。

现今信息传输丰沛的时代，许多装置之间都要靠着传输线来做高速传输档案，包含资料传输、图片传输、影音传输等，人手多条传输线已成为常态。 看似结构简单的传输线，其实是由多种零组件进行组装，除了各组件本身的高频特性之外，组件之间的加工及兼容性更是对制造商的一大考验，在确认高频完整性之前，首先必须克服的难题则是在时域测项(Time Domain)的特性阻抗(Characteristic impedance)管控，因为在讯号传输的过程中，传输通道就像是水管，必须保持管道畅通。 潜在风险有哪些？ 特性阻抗对于讯号完整性的影响极大，称Characteristic impedance是高频之母也不为过，因为在传输通道中大部分的设计、加工不良均可以从Characteristic Impedance中看出端倪，在现实中产品常见的问题如下： ★ 连接器端子的接触面积不足，造成讯号反射过大 ★ 裸线的绝缘层包覆不均产生讯号失真 ★ 零组件走线、折弯设计不良影响讯号发散 ★ 产品加工处的虚焊、开路造成讯号传输失败 所有设计、制程不良都可能全面性的影响高频特性，例如：插入损耗(Insertion Loss)、反射损耗(Return Loss)、远近端讯号串扰(NEXT/FEXT Crosstalk)等，而产品的Propagation Delay/ Delay Skew表现若超出了设备芯片解析的能力时，也会造成误码率的提升、数据需重传而让用户感觉速度变慢甚至失效。此时，若缺乏优异的分析能力，则可能造成订单的流失、产能的延宕、大量的客诉，后果不堪设想。 百佳泰立即带您看实际案例 藉由Characteristic Impedance的解析皆可将大部分问题排除，并进一步协助客户规划完善的因应改善方法。以百佳泰过往的真实USB Type-C Cable案例所示，该产品的插入损耗过大，在实际运用上容易造成数据传输失败，透过特性阻抗的检测分析后， 发现样品在组件Paddle Card的阻抗设计过低，并于剥线加工处过高，两者使得特性阻抗的落差(不连续面)过大，进而影响讯号传输时的损失量 。 下图一为传输线阻抗调整前之波形，可看见红色标示不连续面落差约21.41Ω，影响Insertion Loss(下图二)严重超标，讯号大量损失。 经由百佳泰分析后，并提供客户改善建议，样品修正Paddle Card阻抗以及裸线线加工等建议，Impedance不连续面改善为13.29Ω(下图三)， Insertion Loss特性顺利通过标准，其质量改善立竿见影(下图四)。

HDMI协会针对HDMI Cable认证测试规范， 分别于4月7日及4月15日公告两大重要更新 ，百佳泰在第一时间即与协会确认相关信息，以下为重点整理。 1.新增HDMI Passive Adapter认证测试计划 HDMI为目前最普及的影音传输接口，广泛被使用在各类影音产品，也发展出各式HDMI接头(Standard, Mini, Micro Connector等)，其中市面上已衍生多种HDMI Adapter (如公头转母头, Standard转Micro Connector)，然而过往这类产品未被定义在HDMI规格书内，因此无法有效规范其功能性及兼容性，进而在使用端上衍生出相关问题。 HDMI协会近年来注意到此现象，为了确保HDMI Adapter与HDMI相关产品间的兼容性，正式推出HDMI Passive Adapter认证计划。依据使用需求HDMI Passive Adapter可分成三种类型：不同接头转换的Pig Tail Type或Small Attachment Type，或是用于特殊用途的Adjustable Cable Type，如壁嵌式HDMI插座。 通过HDMI Passive Adapter认证测试，即可确保您的产品HDMI 1.4b功能使用无虞 。 图片来自HDMI官网 2.Premium High Speed HDMI Cable开放Converter Type Cable认证 Premium High Speed HDMI Cable可支持TMDS传输模式下最高18G带宽，但是以往受限于测试方法，只能针对Wire或Active Type Cable执行认证测试。近期HDMI协会改良Converter Type Cable测试方法，使用示波器和讯号产生器测试眼图，克服以往无法使用ENA测试眼图的难题， 即日起针对Converter Type Cable亦可执行认证测试 。 随着此次规格更新，作为Converter Type Cable之一的全光纤AOC Cable直接受惠，过往在Ultra High Speed HDMI Cable测试规范下，除了必须支持HEAC功能，用来传输HEAC的线缆仍需使用铜线才能认证，若是使用全光纤的话则无法取证，而Premium High Speed HDMI Cable规范下的HEAC功能为选择性支持，在此规格更新后成为现阶段全光纤AOC Cable的测试方案首选。

In the fast-paced world of active devices and the very tangible area of test equipment, the lowly cable and associated connectors sometimes seem to be almost invisible, in both the prototyping and production cycles. That's not only unfair to their self-esteem (to use the trendy parlance), but unwise. Sure, we hear that "everything is going wireless," but the reality is that hard-wired signal interconnects are an indispensable and irreplaceable part of nearly all systems.   It gets more challenging: as more design engineers work on projects that extend into the gigaHertz and higher range, they'll have to learn to give more consideration to the cable assembly as a critical and even dynamic part of the design. If you look at RF/microwave-centric publications and web sites, about one-third of the ads and content are devoted to the subject. It's a world where second- and third-order parameters such as phase matching between two nominally identical assemblies (such as used for phased-array radar) become critical; even the temperature coefficient of a cable's specifications can be a concern. The assemblies are carefully engineered, modeled, tested, and fabricated energy waveguides with precise dimensions, special internal and external insulating materials, and more.   Fortunately, cable assemblies are getting some attention from diverse perspectives, as shown by these unrelated features I have seen in the past few months:   We hear a lot about counterfeit components—mostly ICs and passives—but we don't see much about the situation with cabling. Yet, it seems to be a serious problem, especially as the cable may work to some extent if not full spec. According to Cabling Installer, their 2011 article on the subject Counterfeit cable exposed was among their top 10 articles in 2014, three years after publication! (Also see Counterfeit cable is getting ugly .) The result is a cable assembly that doesn't fully meet the operating spec and may sort-of work but only support lower data rates, or a PoE (Power over Ethernet) installation unable to provide the specification's power.   It's not just electrical performance, either. On the safety side, a cable’s insulation in most installations must be fire-rated to not support combustion, yet these fakes fall far short— and it's an issue that you won't know about until a fire breaks out. Would you have even imagined presumed copper cable that was really brittle aluminum, but with a copper cladding? Think of the installation and performance surprises on that one!   The thing about cable is that it is so easy to make a fake, and put almost any rating you want on it. After all, who "tests and verifies" the cable's performance when data rates go down and BER goes up? Who checks the insulation? You may take it as a "given" that if it says Cat5/UL rated, it actually is, but that's naive. Note that this is not a new concern. Even in audio, non-RF applications, I often wondered about the super (aka "monster") audio cables that were sold as OFHC (oxygen free, high conductivity) ostensibly because of their superior performance potential. How do you really know the vendor isn't shipping plain copper slapped with an OFHC label?   Problems with RF/microwave cables in complex installations. I saw an ad (yes, a print ad!) from W.L. Gore stating that "a recent study for the aerospace industry showed that more than 29 percent of microwave cable assemblies fail during installation , and aircraft manufacturers have accepted the practice of simply replacing them." Wow, I thought, that has to be costly and time-consuming, in so many ways! Gore's solution is to provide a simulator to evaluate the stress of installation, with features which replicate bend radius, routing guides that induce torque, and abrasion bars to simulate routing across sharp edges of access holes in the airframe structure.   Finally, there's the world beyond extending to 100 GHz, well beyond modest 1 to 10 GHz, where spectrum is available and new components make reachable. What sort of cables and connectors can you use there? It's a brave new world of tiny, tinier, and tiniest, with hair-thin cables and corresponding matchhead-sized connectors.   This V Connector (male and female) from Anritsu provides coaxial coverage to 65 GHz, with a 1.85-mm geometry endorsed by IEC (International Electrotechnical Commission); it mates with standard available 2.4-mm connectors.   Cabling seems to be one of those things with which engineers have both love/hate and ignore/fear relationships, it often seems to me. For example, my cable modem and wireless router sit next to each other, but they are connected with a 20-ft. (7-m) Ethernet cable, because that's what I had handy on the day of installation. Yet when recently I found a 2-ft. (0.7-m) cable in my spare-cable collection, I wasn't sure if I should swap the shorter one in for the longer one. On one hand, the shorter one is more elegant and appropriate, and wouldn't need to be coiled up and tied back; on the other hand, everything is in place and working, so why take a chance and upset things?   While basic cable-assembly connectivity and continuity is very easy to verify with an ohmmeter, the actual performance to specifications of the assembly is not—especially for non-electrical parameters. What's your relationship with cables, connectors, and assemblies? Have you ever overlooked something that came back later to cause you design, debug, or production aggravation?

USB is typically used to carry digitized audio. After all, even USB 1.1 has the bandwidth. You may have USB speakers or you may stream audio from a hard drive that's connected to your computer through a USB cable. Can you hear the distortion that the USB link adds to your music? Some people think they can. I recently received a link that, as connections go, is absolutely hilarious. The Absolute Sound, a site for audiophiles, posted its 2013 TAS Editors' Choice Awards: Digital Interconnects . Let's start with the first one. Here goes, and I quote: AudioQuest Diamond 0.75m, $549; 1.5m, $695 audioquest.com This über-expensive USB cable is simply revelatory in its combination of ease and refinement on one hand, and resolution and transparency on the other. Although capable of resolving the finest detail, Diamond USB has a relaxed quality that fosters deep musical involvement. Deep musical involvement? We're talking a digital cable here. Audiophiles, please get your ears out of the sand and listen to me. USB is a digital bus. As long as the receiver can properly receive the bits and tell the difference between a logic 1 and a logic 0, the digital representation of the audio at the receiver's output will be a perfect replica of that which was transmitted. You claim that you can hear the difference between an inexpensive and expensive USB cable? I'm sorry, but you have been deceived. On average, digital links deliver one bit error for every 10 12 bits sent. You can't possibly hear that. Next, you'll tell me that you can hear the difference in clock jitter produced by that inexpensive cable. Again, as long as the bits are properly interpreted, there is no difference in signal as a result of a cable. If there is any distortion in the entire audio chain, it's on the analogue side. Any time you convert a digital representation of audio into an analogue signal, there is some distortion added. I refuse to believe that anyone can hear that distortion in any good audio system. A top notch audio analyser might detect a difference, but not your ears. Now, I can understand not buying the cheapest of USB cables, but I'd do that for reliability, not audio quality. Don't fool yourself. Paying $695 for a USB cable will not get you better audio. You will get the same audio quality from a $6.95 cable. The audio quality is a function of the original encoding, the decoding, the analogue signal processing and amplifier, and the speaker. Go ahead, prove me wrong. Get yourself a top-of-the-line audio analyser and show me the difference in audio quality between cables that carry digital signals. Take a look at the linked page above. Be sure to read the comments over there as well, and then tell us what you think. This article was originally published on The Connecting Edge. Martin Rowe Senior Technical Editor EE Times