福祿克Fluke 190-504彩色數(shù)據(jù)示波表
福祿克Fluke 120B 系列 ScopeMeter?工業(yè)用手持式示波表
福祿克Fluke-190-204/S ScopeMeter?彩色數(shù)字示波表
福祿克Fluke-190-502 ScopeMeter?彩色數(shù)字示波表
福祿克Fluke-190-202 ScopeMeter?彩色數(shù)字示波表
福祿克Fluke-190-102 ScopeMeter?彩色數(shù)字示波表
福祿克Fluke-190-104 ScopeMeter?彩色數(shù)字示波表
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福祿克Fluke OptiFiber? Pro?OTDR系列
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福祿克Fluke FI-7000 FiberInspector? Pro光纖顯微攝像機
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福祿克Fluke LinkIQ?線纜+網(wǎng)絡(luò)測試儀
NetAlly LinkSprinter?口袋便攜式網(wǎng)絡(luò)測試儀
福祿克Fluke EtherScope II網(wǎng)絡(luò)通二代
福祿克Fluke 190-504彩色數(shù)據(jù)示波表
泰克Tektronix MDO3000混合域示波器
福祿克Fluke 120B 系列 ScopeMeter?工業(yè)用手持式示波表
福祿克Fluke-190-204/S ScopeMeter?彩色數(shù)字示波表
福祿克Fluke-190-502 ScopeMeter?彩色數(shù)字示波表
福祿克Fluke-190-202 ScopeMeter?彩色數(shù)字示波表
福祿克Fluke-190-102 ScopeMeter?彩色數(shù)字示波表
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In the DSX-5000 CableAnalyzer, this is implemented automatically. If you test to either “ISO11801 Class Ea Channel” or “ISO11801 Class?PL2 Class Ea” and the insertion loss measurement is less than 12 dB at 450 MHz, a relaxed?NEXT limit may be applied. It is not possible to change PASS/FAIL limits in a field tester based on the measured result of a parameter. Compliance with ISO/IEC 11801 Class EA?requirements can be verified using the DTX CableAnalyzer in one of two ways: by obtaining a PASS condition using the regular “ISO11801 Channel Class Ea” or ”ISO11801 PL2 Class Ea” test option, orby obtaining a PASS condition using an alternate “ISO11801 Chan Class Ea Low IL” or “ISO11801 PL2 Class Ea Low IL” option; if a PASS* conditions applies to insertion loss, the true result should be a PASS, as explained in the following.ISO/IEC 11802:2002 Amendment 2 (Published April 2010) – Table A.5 “For Configurations PL1, PL2, and CP1, whenever the class EA?permanent link insertion loss at 450 MHz is less than 12 dB, subtract the term 1,4((f – 450)/50) to the equation stated above for the range of 450 MHz to 500 MHz.” ANSI/TIA-568-C.2 (Published August 2009) There is no such rule/requirement in this North American Standard for Category 6A. Reality check It is very unlikely that implementing the “12 dB rule” is going to turn your failing NEXT and PS NEXT results into a PASS. That’s because the NEXT limit is relaxed between 450 MHz and 500 MHz only, and not by much. Let’s take an example:Tested to “ISO11801 PL2 Class Ea”Tested to “ISO11801 PL2 Class Ea Low IL”It did not change the outcome of the test result, because the failing NEXT was not between 450 MHz and 500 MHz. This may be better explained using an animation:Known issue in previous DTX code The “ISO ClassEa Ch AMD1 Low IL” and “ISO ClassEa PL2 25N1599?Lo IL” test options in the DTX had an insertion loss limit of 12 dB at 450 MHz to prevent the user from incorrectly applying the “12 dB rule” detailed previously. The DTX CableAnalyzer (Version 1.36 limits) had an insertion loss limit that has a step response at 450 MHz as indicated below:This could result in a measurement incorrectly assigning a FAIL for the insertion loss parameter. It’s incorrect because the existing limit for insertion loss still applies; the 12 dB is only used for assessing whether the relaxed NEXT limit should be applied. As a result, we have changed the limit for insertion loss in the DTX CableAnalyzer and LinkWare software. The above result will now look like:The change indicated was incorporated into the DTX CableAnalyzer Software Version 2.22 and LinkWare 6.0 releases. If the AUTOTEST fails now, it’s because it failed to meet the 12 dB insertion loss requirement at 450 MHz, indicating that this test option cannot be used to achieve a PASS result for the Class EA?channel. It is possible for the DTX CableAnalyzer to report a PASS* for insertion loss @ 450 MHz if the measured insertion loss at 450 MHz is closer to 12 dB than the specified accuracy of the DTX CableAnalyzer. This PASS* for insertion loss?indicates that the DTX CableAnalyzer cannot determine within its measurement accuracy whether the relaxed NEXT and PS NEXT limits are applicable. It does not necessarily indicate that the measured insertion loss is within the measurement uncertainty of the limits for insertion loss that is applicable to ISO/IEC 11801 Class EA?cabling. If necessary, the true insertion loss performance of the cabling can be verified using the regular “ISO11801 Channel Class Ea” and “ISO11801 PL2 ClassEa”?test options, and observing the test result for insertion loss. If this result does not contain a PASS* result for insertion loss, the PASS* for insertion loss of the ISO11801 Chan ClassEa?Low IL test, technically speaking, should be a PASS and not PASS*. This is a limitation of the code in the DTX CableAnalyzer. In conclusion: The overall result of an ISO/IEC 11801 Class EA?test should be as follows:If either the “ISO11801Channel Class Ea” or “ISO11801Chan Class Ea Low IL” test shows a pass, the result is a PASS.If either the?”ISO11801 PL2?ClassEa” or “ISO11801 PL2 ClassEa Low IL”?test shows a pass, the result is a PASS.If the “ISO11801Chan Class Ea Low IL” or “ISO11801 PL2 ClassEa Low IL”?test shows a PASS* that is caused by the result for insertion loss only, the result of the “ISO11801Chan Class Ea Low IL” or “ISO11801 PL2 ClassEa Low IL”?should be reviewed for insertion loss only; if this result is a PASS, the result of the “ISO11801Chan Class Ea Low IL” or “ISO11801 PL2 ClassEa Low IL” test can be considered to be PASS (the ‘*” is not applicable)....
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....
FLUKE DTX系列測試報告中為什么會出現(xiàn)*號?以及同樣的線材在不同的測試平臺上的結(jié)果為什么會有不一致的現(xiàn)象? 請看下面文章:通常如果測試的最差余量不幸落在了儀器的測試精度范圍之外,在設(shè)備的測試界面上我們就會發(fā)現(xiàn)會多出(*).號標(biāo)志 。 這恰好是基于ANSI/TIA/EIA-568-BandIEC61935-1的標(biāo)準(zhǔn)要求來做的. 讓我們來看看在什么頻率點出現(xiàn)1.9db的余量值為了更好的便于理解,在下附圖中我們將標(biāo)準(zhǔn)極限值的用紅色線條標(biāo)識出來.用兩條黑色的線條來標(biāo)識出儀器的精度判別范圍,其中黃色區(qū)域?qū)⑹蔷葻o法識別的區(qū)間.在所有的測試結(jié)果結(jié)果當(dāng)中,如果不幸有測試的最差余量值落在了這個區(qū)間,那么將會有(*)予以明確標(biāo)示.這對于理解在頻率域范圍內(nèi)的波形幅度變化是非常重要的。我們選擇線對Pair3,6-4,5繪制出下圖:剛好在這個無法判別的精度區(qū)間,因此*會出現(xiàn)在最終的測試結(jié)果當(dāng)中??偨Y(jié):通常如果出現(xiàn)*號的標(biāo)示,不論是通過或者不通過,我們認(rèn)為當(dāng)前的測試結(jié)果都是超出了機器的判別精度范圍之外,因此我們需要就相同的線材進行多次測試,驗證經(jīng)過多次測試結(jié)果是否一致?或者換一下接頭,把線材調(diào)一個頭測試一下。另外,為什么不同儀器會有不同值。以DTX-1800為例:有的插入損耗0.1的結(jié)果上面是標(biāo)注有*號的,標(biāo)有*號的意味著是在精度范圍之外,機器已經(jīng)無法判斷出測試結(jié)果究竟是不是通過,有些它就會以“失敗”來判斷出此次測試結(jié)果;同樣,另外一臺DTX-1800的機器上,測試結(jié)果是以通過來標(biāo)識的,它的插入損耗為0.9也是標(biāo)注有*號的,也就是說DTX-1800這臺機器它的某些測試指標(biāo)上下容許有正負1+1%的上下浮動誤差。...
福祿克DSX-5000關(guān)于線纜類型的說明,如果您手里頭剛好有福祿克DSX-5000 Cableanalyzer 線纜分析儀,那么您可以很明顯的看到它與福祿克DTX1800的區(qū)別,那就是前面有S和U的區(qū)別,那他們是什么意思呢?U-FTP,SF-UTP,S-FTP,U-UTP,F-UTP,福祿克DSX5000線纜類型詳細介紹技術(shù)資料:U-FTP雙絞線:沒有總屏蔽層,線對屏蔽為鋁箔屏蔽的屏蔽雙絞線;SF-UTP雙絞線:總屏蔽層為絲網(wǎng)+鋁箔的雙重屏蔽,線對沒有屏蔽的雙重屏蔽雙絞線;S-FTP雙絞線:總屏蔽層為絲網(wǎng),線對屏蔽為鋁箔屏蔽的雙重屏蔽雙絞線。U-UTP雙絞線:即通常所說的UTP雙絞線,非屏蔽雙絞線;F-UTP雙絞線:總屏蔽層為鋁箔屏蔽,沒有線對屏蔽層的屏蔽雙絞線;UTP Unshielded Twisted Paired 非屏蔽雙絞線,除某些特殊場合(如受電磁輻射嚴(yán)重、對傳輸質(zhì)量要求較高等)在布線中使用。...
安裝一個PC LinkWare 9.3軟件。下載頁面:www.faxytech.com/Linkware, 下載版本4.2 固件,以及記住保存的固件文件!確保您的電池電量充足;如果有疑問,電源連接到你的DSX-5000儀器。打開電腦LinkWare軟件9.3 。在Versiv/ TFS主框架連接到使用隨附單元的微型USB線的電腦。點擊 Utilities > DSX-CableAnalyzer > Software Update 加載 update_4_2_Build_6.cic 文件。...
在使用福祿克FLuke DSX-5000的過程中,有些人會有這樣的疑問,為什么同材質(zhì)不一樣會顯示不一樣的長度呢?下面連訊達工程師叫您如果校準(zhǔn)您的DSX-5000線纜認(rèn)證分析儀。你只需要做以下簡單幾步就能完成操作。輸入數(shù)字(使用供應(yīng)商的數(shù)據(jù)表格)。選擇對應(yīng)的線纜類型。利用已知長度的線纜校準(zhǔn)NVP。校準(zhǔn)NVP的時候,至少需要30M-100M的線材,線材測試的實際長度,然后通過NVP變化,使線材的長度和校準(zhǔn)長度一樣。圖文介紹:選擇測試設(shè)置界面,選擇NVP:選擇Measure (測量)調(diào)整NVP使得長度等于你已知線纜的長度。 ...
什么是福祿克DSX-5000通道測試和永久鏈路測試?通常我們再測試過程中提到用什么測試標(biāo)準(zhǔn),現(xiàn)在工程中大部分使用的是通道測試,也就是用跳線加通道然后選擇對應(yīng)的Channel標(biāo)準(zhǔn),一般不用永久鏈路的原因是因為永久鏈路損耗,購買就太貴了。所以選擇經(jīng)濟的跳線形勢。除去這些因素,我們來看看他們到底有什么區(qū)別?我們?nèi)绾芜x擇爭取的DSX-5000測試模式。第一:永久鏈路測試方法。為了獲得有意義的測試結(jié)果,有必要福祿克DSX-5000選擇適當(dāng)?shù)逆溌纺P??!坝谰面溌贰钡男阅芏x為:一條通過了測試的永久鏈路在添加了合格的跳線之后,所構(gòu)成的“信道”其性能將自動滿足標(biāo)準(zhǔn)規(guī)定的參數(shù)要求?!昂细瘛钡奶€是指按照跳線標(biāo)準(zhǔn)已通過了測試的跳線。 建議DSX-5000使用永久鏈路的測試模型和測試標(biāo)準(zhǔn)進行新安裝電纜鏈路的認(rèn)證。在永久鏈路的生命周期中,用戶跳線和設(shè)備跳線可能會多次更換,而永久鏈路(及質(zhì)量)是不變的。 永久鏈路測試模型要求“測試跳線”對于測量過程是完全透明的。在實際操作中,這意味著參數(shù)測量時,測試工具必須更加復(fù)雜,以便消除測試跳線的影響。 然而,實際的情況卻是,永久鏈路模型包含了“末端連接”的特性 – 也就是說包含了測試適配器末端的8針插頭(RJ45)和鏈路末端的插座的參數(shù)。對于近端串?dāng)_(NEXT)和回波損耗等重要參數(shù),“插頭-插座”的不同組合會帶來各種不穩(wěn)定的測試結(jié)果。為了正確評估鏈路末端的插座(在TO或配線架中)以及這些插座中線對終端的性能,永久鏈路測試適配器末端的插頭應(yīng)該是標(biāo)準(zhǔn)的測試插頭,它對所有頻率測試參數(shù)能夠在所允許的窄帶公差范圍內(nèi)提供元器件參數(shù)的“中心”性能,穩(wěn)定且基本不偏離此中心。這就要求所有這些測試插頭之間的差別不會很大,最重要的是:能夠提供可重復(fù)的穩(wěn)定測試結(jié)果。第二:通道測試方法。在幫助恢復(fù)服務(wù)或在應(yīng)用支持活動中需要檢測電纜時, 通常要進行通道(信道)測量, 而在一項新的安裝結(jié)束時通常不進行道(信道)測試( 因為此時每條鏈路的跳線大多都還沒安裝)。正確的信道測量必須扣除測試儀的信道適配器(DSX-PC5ES,DSX-PC6S)與跳線連接(水晶頭)的匹配影響。...
解讀您網(wǎng)線Fluke測試報告。您的網(wǎng)線測試報告由我們的Fluke DTX-1800網(wǎng)線測試儀和相關(guān)的Fluke LinkWare軟件生成。為了解釋如何生成此測試報告,以及它上面顯示的值和圖形的含義,我們首先需要稍微觸及一下這些規(guī)范。Fluke測試儀支持Cat 5e和6個跳線的兩套規(guī)格:TIA和ISO規(guī)格。ISO規(guī)范比TIA更嚴(yán)格。對于Cat6a跳線,測試儀僅支持ISO規(guī)格。我們將銷售符合TIA或ISO規(guī)格的網(wǎng)線; 在絕大多數(shù)情況下,我們的網(wǎng)線符合更嚴(yán)格的ISO規(guī)范?;夭〒p耗的規(guī)格限制與網(wǎng)線長度無關(guān); 相同的通過/失敗限制適用于任何長度的網(wǎng)線。然而,串?dāng)_(NEXT)并非如此。串?dāng)_的規(guī)格限制隨長度而變化,對于較長的網(wǎng)線而言變得更加寬松。在距離的短暫變化范圍內(nèi),極限的變化很小,F(xiàn)luke建議我們測試一個比測試網(wǎng)線稍長但不短的限制。然而,任何實際失敗的網(wǎng)線“通過”的可能性都被Fluke建立在這些極限集中的誤差參數(shù)范圍,并將提醒測試操作員(并在測試報告中顯示)測試是在測試者的統(tǒng)計誤差范圍內(nèi)(因此不是鐵的某些通過)。我們不會出售網(wǎng)線,除非它產(chǎn)生的誤差范圍之外的測試結(jié)果遠遠大于相鄰極限集之間的差異。如果Cat 6或6a跳線超過20米,我們將針對20米標(biāo)準(zhǔn)進行測試,因為我們沒有為更長的網(wǎng)線編寫“限制設(shè)置”。這是一個示例測試報告,其中一些最重要的項目用于解釋。1、測試限制:這是以米為單位的長度,計算了測試中使用的規(guī)格限制。它應(yīng)始終等于或超過網(wǎng)線的實際長度,并代表Fluke測試儀具有一組編程限制的下一個更長的網(wǎng)線長度。2、長度,延遲,偏斜和阻力表:該表顯示了測試儀對網(wǎng)線長度的估計(可能與實際長度不同 - 這個數(shù)字是通過測量電延遲來估算的),傳播延遲(即信號從信號中獲取的時間長度)網(wǎng)線的一端到另一端),以納秒為單位,延遲偏斜以納秒為單位(傳播延遲從一對到另一對的最大差異),以及一對以歐姆為單位的電阻(不要與網(wǎng)線的特性阻抗相混淆,它始終處于或接近100歐姆)。3、串?dāng)_(NEXT)表:該表確定了網(wǎng)線中最差的近端串?dāng)_(NEXT)結(jié)果。串?dāng)_是其中一個數(shù)據(jù)對上的信號在另一個數(shù)據(jù)對上引發(fā)信號的趨勢 - 這種現(xiàn)象在模擬世界中有時會導(dǎo)致您在使用電話時在后臺隱約聽到另一個對話。在網(wǎng)線中的每個可能的對/對組合之間測試串?dāng)_,并且從“主”和“遠程”測試器單元測試串?dāng)_,每個的結(jié)果分別在“MAIN”和“SR”列下報告。右側(cè)的“最壞情況值”表在跳線測試中始終為空白?!白钤愀獾囊粚Α?- 該線顯示,參考連接器引腳分配,哪組對表現(xiàn)出最差的串?dāng)_。這里經(jīng)常(盡管不總是),將是36對和45對,因為36對必須被分開,因為它被端接到非相鄰的引腳,并且位于連接器中的45對的正上方或下方,使這兩對更容易相互串?dāng)_。以下三行將顯示網(wǎng)線規(guī)格的凈空高度,以及凈空最窄的位置。 “NEXT(分貝)” - 該行未顯示實際的NEXT(近端串?dāng)_)值; 相反,它顯示了以dB為單位的最小余量,測得的NEXT值超過了測試極限。在這種情況下,最差的結(jié)果比所需的規(guī)格好3.2 dB。串?dāng)_隨頻率而變化,可接受的串?dāng)_限制也隨頻率而變化,并且該最小值可以在測試范圍內(nèi)的任何頻率下發(fā)生。在測試范圍內(nèi)的其他地方的串?dāng)_性能總是至少同樣好,并且在許多點上將比這個值好得多。注意,NEXT表示為正值,并且該值越高,串?dāng)_水平越低; 該值表示預(yù)期信號電平超過串?dāng)_電平的dB數(shù)。這導(dǎo)致看起來像“ “Freq。(MHz)” - 該行顯示以兆赫為單位的頻率,其中出現(xiàn)上面一行所示的最差NEXT余量。主要和遠程單元獲得了類似的結(jié)果,最差頻率在一個方向上為239.5 MHz,在另一個方向上為241.0 MHz。 “Limit(dB)” - 此行顯示所示頻率下NEXT的限制(以dB為單位)。將此值添加到NEXT(dB)線上顯示的邊距將告訴您在測試網(wǎng)線中該頻率下NEXT的實際值(以dB為單位)。4、回損表:該表確定了網(wǎng)線中用于回波損耗性能的最差對,并顯示該對的最差通過裕量與規(guī)格的回波損耗限值?;夭〒p耗是由于線路阻抗變化導(dǎo)致的網(wǎng)線中的信號引起的損耗。 - “最差對” - 再次參考連接器引腳分配,顯示哪一對具有相對于規(guī)格限制的最小回波損耗裕度。 “RL(dB)” - 與上面相應(yīng)的NEXT表一樣,該值不顯示回波損耗值,但顯示了最壞的一對在最差頻率下超過測試極限的dB數(shù)。在這種情況下,根據(jù)是使用主數(shù)據(jù)還是遠程數(shù)據(jù),最小邊距為7.5(主)或10。 “頻率(MHz)” - 回波損耗隨頻率變化很大,這表示測得的回波損耗最接近允許極限的頻率。正如您所看到的,在這種特殊情況下,最小的余量發(fā)生在非常不同的頻率(11.5和250 MHz),具體取決于是否咨詢了主要或遠程測試單元,但在這兩種情況下,保證金都非常出色。 “限制(dB)” - 該行顯示了相關(guān)頻率下回波損耗的允許限值。此數(shù)字加上“RL(dB)”行中顯示的余量,為您提供“Freq。(MHz)”行頻率下網(wǎng)線的測試回波損耗值。再次,就像串?dāng)_一樣,數(shù)字可能看起來是向后的:如果限制為20 dB,這意味著測試值應(yīng)超過20 dB以通過規(guī)范,而不是更少,因為更高的dB值意味著更少的回波損耗,不多。為了使事情稍微有點混亂,有些人用負dB表示這些RL數(shù)字,這意味著它們與正dB表示完全相同 - 如果您遇到需要RL負值的規(guī)范,請牢記這一點。這些限制和測量完全相同,但符號相反。在里面 ”5、長度估計這里,如左邊的表格,是基于信號通過它的時間估計的網(wǎng)線長度。這些估計通常相當(dāng)接近但可能與測量的物理網(wǎng)線長度不同。6和7、 NEXT和RL圖:這些圖表顯示了NEXT和回波損耗值,以dB為單位,因為它們隨頻率變化。水平軸是頻率(Cat 5e將達到100 MHz,Cat 6將達到250 MHz,Cat 6a將達到500 MHz),垂直軸為dB。在每種情況下,相對平滑,較低的紅色跡線顯示測試極限,并且上面的不均勻,凹凸不平的彩色跡線顯示六對組合(對于NEXT)或四對(對于RL),每個具有不同的顏色。只要配對和配對組合的跡線保持在適用的限制線以上,網(wǎng)線就會通過規(guī)范。你可能會懷疑,在看這些時,有一件事就是為什么它們?nèi)绱吮恐?。除了像限制?biāo)記那樣平滑,均勻的曲線,顯示網(wǎng)線實際NEXT和RL的跡線往往具有峰和谷,在大多數(shù)情況下,在圖中以規(guī)則的間隔重復(fù)。造成這種情況的原因可能有很多,但主要原因是信號通過網(wǎng)線傳播時最大的“事件”是阻抗凸點,并伴隨著導(dǎo)體在連接器處的重新定向(導(dǎo)致串?dāng)_增加)每一端。因為在這些點處存在反射,所以網(wǎng)線傾向于以與網(wǎng)線的物理波長相對應(yīng)的頻率“振鈴”,這意味著不僅在該頻率處將存在回波損耗尖峰,但是在它的所有諧波倍數(shù)。在較長的網(wǎng)線中,這些尖釘往往不如較短的網(wǎng)線那么突出; 只要它們不會導(dǎo)致網(wǎng)線超過NEXT或RL的規(guī)定限制,它們就不會引起關(guān)注。...
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