色妇精东麻豆国产一区二区三区

400-996-0787

色妇精东麻豆国产一区二区三区 新闻中心 技术文章

返回

新闻中心

联系我们

全国统一服务热线：

134 1039 1245
400-996-0787
0755-8399 9818
联系邮箱：

sales@faxytech.com
联系地址：

深圳市福田区华强北路华联发大厦602室

3dB原则(法则) – DTX-1800/DSX2-8000 CableAnalyzer

A YouTube video explaining how this this works is also?available from here.

This is applicable to ALL test limits in the DTX CableAnalyzer where a Return Loss measurement is made.

When?the Insertion Loss is less than 3.0 dB at the frequency point where the measurement is made, then the Return Loss measurement is ignored and not uated against the selected Test Limit/Cabling Standard in the DTX CableAnalyzer.This is often referred to as the?3 dB rule.It applies to ALL cabling standards/test limits in the DTX CableAnalyzer.

On a short?link,the Insertion Loss may never reach 3.0 dB.If that were to happen, then the entire measurement would be?ignored, or as the cabling standards phrase it; “recorded for information only”.If this were to happen with your DTX CableAnalyzer, you would see an “i” appear next to the summary result for that test parameter.In LinkWare software, the result would be recorded with “N/A’.An example is shown below:

Concern is normally caused when the result has a negative margin.In this example we see the Return Loss margin was -2.2. A?negative margin is normally associated with a FAIL, but because the entire link never exceeded 3.0 dB Insertion Loss, it is not a FAIL.

Let’s review in detail how this works by looking at another example test result.

A TIA Cat 5e Perm.Link AUTOTEST was run on a 29.0 m installed link, giving the following result:

Looks normal – very nice margins.Let’s take a look at the Return Loss result in a little more detail:

You will observe that?the limit line has two colors, black and red.The cabling standards do not require the cable tester manufacturer to display where the?3 dB rule is implemented to the user, only that it is implemented.However, the DTX CableAnalyzer will indicate where the 3 dB rule has been implemented by changing the color of the limit line.If the?limit line is black, it?indicates that the Insertion Loss was less than 3.0 dB.If the?limit line is red, the Insertion Loss was 3.0 dB or greater.So for this Pair 3,6 the Return Loss?is not uated below 29.3 MHz. Let’s take a quick look at the Insertion Loss for Pair 3,6:

As you can see, the Insertion Loss reached 3.0 dB at 29.3 MHz, as previously indicated in the Return Loss Pair 3,6 graph above.

It’s an interesting rule, because if it were not in place, our margin for the above result would reduce from 10.2 dB to 9.0 dB:

As previously mentioned, if the link is particularly short, then the Insertion Loss may never reach 3.0 dB and the entire Return Loss?result is “ignored”.Let’s take a closer look at the first example where the test result was:

Looking at the worst case Return Loss result, we see the entire limit line is black, suggesting that the Insertion Loss for Pair?3,6 never reached 3.0 dB:

Looking at the Insertion Loss for Pair 3,6:

We see that the Insertion did indeed never reach 3.0 dB, so the entire measurement is not uated against the limit line (ignored) and recorded as “i” Information Only.If this result was downloaded to LinkWare Software, the report would show N/A against this measurement:

No further action is required by the installer.This is a valid standards compliant result.

色妇精东麻豆国产一区二区三区

目录

色妇精东麻豆国产一区二区三区

销售品牌+

贵濒耻办别/福禄克工业仪器+

红外热像仪+

测温仪+

数字万用表+

数字钳形表+

绝缘电阻测试仪+

接地电阻测试仪+

示波器+

蓄电池电阻分析仪+

电能质量分析仪+

安规测试仪+

过程校准器+

回路校验仪+

压力校验仪+

温度校验仪+

测距仪+

粒子计数器+

多功能环境测试仪+

照度计+

空气质量检测仪+

风速仪+

安装测试仪+

激光对中仪+

测振仪+

数据采集器+

医疗测试+

配件/工具+

狈别迟础濒濒测（原狈别迟厂肠辞耻迟）+

有线色妇精东麻豆国产一区二区三区+

无线色妇精东麻豆国产一区二区三区+

有线+无线色妇精东麻豆国产一区二区三区+

Fluke Networks/福禄克网络仪器+

网线测试仪+

色妇精东麻豆国产一区二区三区+

光纤测试仪+

配件/工具+

贵尝滨搁/菲力尔+

红外热像仪+

搁补测迟别办/雷泰仪器+

红外测温仪+

在线式红外测温仪+

碍贰驰厂滨骋贬罢/是德（原础驳颈濒别苍迟/安捷伦）+

数字万用表+

电源+

示波器+

痴滨础痴滨（原闯顿厂鲍）+

光时域反射仪（翱罢顿搁）+

光功率计+

光源+

贰齿贵翱（加拿大贰齿贵翱）+

光时域反射仪（翱罢顿搁）+

光功率计+

光源+

罢别办迟谤辞苍颈虫/泰克+

数字万用表+

示波器+

数据采集器+

信号发生器+

图形源表厂惭鲍仪器+

配件+

惭别驳驳别谤/梅凯（梅格）+

绝缘电阻测试仪+

继电保护测试仪+

低电阻测试仪+

接触电阻测试仪+

接地电阻测试仪+

贵翱罢搁滨颁/飞础科+

红外热像仪+

配件+

碍驰翱搁滨罢厂鲍/共立（克列茨）+

绝缘电阻测试仪+

厂鲍惭滨罢翱惭翱/住友+

光纤熔接机+

贵耻箩颈办耻谤补/藤仓+

光纤熔接机+

驰翱碍翱骋础奥础/横河+