福祿克DSX-5000：溫度對應福祿克插入損耗（衰減）測試的影響
在ANSI/TIA、ISO/IEC和IEEE中發現的插入損耗限製是基於在20℃（68μF）下運行的鏈路。隨著溫度的升高，你可以預期你的鏈接的插入損耗也會增加。在設計中冇有考慮到這一點可能會導致傳輸錯誤。在某些情況下，預期的應用可能不起作用。
布線標準為這一主題提供了極好的指導。
ANSI/TIA568C.2附錄G
電纜可以安裝在天花板空氣空間、提升管軸和非空調建築如倉庫和製造工廠中，其中溫度可以顯著高於20℃，以確保符合CLAU規定的通道插入損耗。SE 62.7，根據電纜長度上的環境平均溫度、安裝電纜的插入損耗裕度和電纜的插入損耗溫度係數，水平電纜距離可能需要降低到90米以下。
ISO/IEC 11801:2011表32——水平溝道長度方程
對於高於20℃的工作溫度，對於屏蔽電纜，H應減少0.2%，每C C減少0.4%，每C C（20℃至40℃），未屏蔽電纜的0%，6%C（＞40℃～60℃）。其中H是長度。
該ANSI/TIA568C.2標準繼續以表格的形式提供額外的指導：
The Insertion Loss limits found in ANSI/TIA, ISO/IEC and IEEE are based on the link operating at 20 ºC (68 ºF). As temperature increases, you can expect the Insertion Loss of your link to increase too. Failing to take this into account in your design may result in transmission errors. In some cases, the intended application may not work.
The cabling standards provide excellent guidance on this subject. You are encouraged to purchase these online at either https://global.ihs.com or http://www.iso.org.
ANSI/TIA-568-C.2 Annex G
Cables may be installed in return air plenums, in ceiling spaces, riser shafts and non air-conditioned buildings such as warehouses and manufacturing plants where the temperature can be significantly higher than 20 ºC. In order to ensure compliance with the channel insertion loss specified in clause 6.2.7, the horizontal cable distance may need to be reduced below 90 meters depending upon the average temperature of the environment over the length of the cable, the insertion loss margin of the installed cabling, and the insertion loss temperature coefficient of the cable.
ISO/IEC 11801:2011 Table 32 – Horizontal channel length equations
For operating temperatures above 20 ºC, H should be reduced by 0,2 % per ºC for screened cables; 0,4 % per ºC (20 ºC to 40 ºC) and 0,6 % per ºC (>40 ºC to 60 ºC) for unscreened cables. Where H is length.
This ANSI/TIA-568-C.2 standard goes on to provide additional guidance in the form of a table:
|
Temperature (ºC (ºF)) |
Maximum
horizontal unscreened cable length (m) |
Maximum
horizontal screened cablelength (m) |
Length de-rating (m) (unscreened) |
Length de-rating (m)(screened) |
|
20 (68)
25 (77) 30 (86) 35 (95) 40 (104) 45 (113) 50 (122) 55 (131) 60 (140) |
90.0
89.0 87.0 85.5 84.0 81.7 79.5 77.2 75.0 |
90.0
89.5 88.5 87.7 87.0 86.5 85.5 84.7 83.0 |
0.0
1.0 3.0 4.5 6.0 8.3 10.5 12.8 15.0 |
0.0
0.5 1.5 2.3 3.0 3.5 4.5 5.3 6.0 |
Some field testers allow you to adjust the insertion loss PASS/FAIL line based on temperature. This is not permitted per ANSI/TIA, ISO/IEC and IEEE. If your cable is to be subjected to an elevated temperature, your design must take this into account by reducing the length of the link, not by relaxing the Insertion Loss limit.
Fluke Networks DSX-5000或者DSX-5000 does not allow you to adjust the Insertion Loss in any of its field testers based on temperature.