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EYE ON FIBER
July 2003
Part 1: Category 1 Testing- Much To Do About Nothing?
Executive Summary
Insertion loss testing in accordance with TIA/EIA-568 B requires a mandrel wrap and a Category 1 light source. We examined the differences in power loss for 62.5 µm fiber links from 2 m to 200 m when tested with different category sources. The test data support the following conclusions.
Mandrel wrapping reduces insertion loss measurements of a category 1 source by 0.13 dB/pair in the link.
With mandrel wrapping, a Category 1 source produces loss values that are 0.03 dB/pair higher than those produced from a Category 2 source. Within the boundaries of CPR tested, Category 2 sources will produce essentially the same losses as Category 1 sources.
Expansion of the range of definition for Category 1 CPR will enable older light sources to be used with no detriment to the reliability of the link.
Mandrel wrapping produces loss measurements below those expected, even if typical attenuation rates and connector losses are used. These low loss measurements can allow conditions of reduced reliability to be accepted during certification by the insertion loss test.
Tests performed with a Category 1 source without a mandrel have better agreement with calculated typical loss values.
Introduction
TIA/EIA-568 B changed the manner in which insertion loss tests are to be made. This revision added two requirements: that the source be a category 1 source and that the launch reference lead be wrapped around a mandrel of a specific diameter, which depends on the fiber core diameter and the jacket diameter. While the madrel is not expensive, a new light source can be.
In order to assess the impact of these two changes, Pearson Technologies conducted comparisons of losses made with category 1 and category 2 sources. In addition, Pearson Technologies conducted tests with and without mandrels.
Test Procedure
The tests were of coils of 62.5 µm tight tube fiber, 2 m patch cords and a 5.44 m premises cable. These length of these cables ranged from 2 m to approximately 200 m. All connectors were SC.
The Category 1 source was from Alcoa Fujikura/Noyes (AFL). This source had an 850 nm CPR of -25.00 and 25.04 dB at, just within the -25.0 dB requirement for a category 1 source.
The 1300 nm CPR was -21.78 to -21.97 dB with multiple tests. These values are within the 1300 nm definition of Category 1, which is -21 dB to -25 dB.
The Category 2 sources were from Fotec, with an 850 nm CPR that ranged from -22.71 to -23.48 dB for serial number 81265 and -22.66 dB to -22.74 dB for serian number 70628. The 1300 nm CPR ranged from -21.45 to -20.96 (S/N 70924). This wavelength is category 1.
Pearson Technologies ran two sets of tests with different source reference leads.
Analysis
We present the results from the two source reference leads in Tables 1 and 2. From basic optics, we would expect the losses to range from high to low as: category 1 without mandrel, category 2 without mandrel, category 1 with mandrel and category 2 with mandrel. The test results show slightly different relationships.
Without a mandrel in both cases, Category 1 losses are generally higher than those of category 2. This relationship is to be expected from the increased core fill and increased NA fill of the category 1 source. The average increase was 0.205 dB (Table 1).
Category 1 losses without a mandrel are generally higher than those with a mandrel. Again, this relationship is as expected. The average increase was 0.21 dB (Table 1).
Table 1: Insertion Loss Data With First Source Reference Lead
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METHOD B INSERTION LOSS DATA |
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Cat. 1 |
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Cat.2 |
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reference |
w/o mandrel |
w mandrel |
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w/o mandrel |
w mandrel |
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typical |
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% of |
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link ID |
length, m |
lead set |
To end A |
To end B |
To end A |
To end B |
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To end A |
To end B |
To end A |
To end B |
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link notes |
loss, dB |
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typical value |
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1 |
100 |
850 nm, 1 |
-0.74 |
-0.62 |
-0.47 |
-0.44 |
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-0.90 |
-0.85 |
-0.48 |
-0.45 |
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38b |
0.90 |
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52% |
49% |
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2 |
100 |
cat. Lead 5 |
-1.08 |
-1.17 |
-0.83 |
-0.89 |
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-0.74 |
-0.75 |
-0.81 |
-0.81 |
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44 |
0.90 |
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92% |
99% |
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3 |
200 |
set 1 SC/SC |
-1.21 |
-1.29 |
-1.04 |
-1.13 |
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-1.01 |
-1.01 |
-0.96 |
-1.03 |
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44+38b |
1.50 |
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69% |
75% |
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4 |
5.44 |
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-0.54 |
-0.70 |
-0.29 |
-0.44 |
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-0.30 |
-0.39 |
-0.35 |
-0.43 |
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blue |
0.62 |
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47% |
71% |
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5 |
5.44 |
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-0.37 |
-0.77 |
-0.42 |
-0.44 |
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-0.37 |
-0.51 |
-0.39 |
-0.43 |
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orange |
0.62 |
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68% |
71% |
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6 |
5.44 |
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-0.48 |
-0.64 |
-0.30 |
-0.51 |
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-0.27 |
-0.47 |
-0.28 |
-0.45 |
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green |
0.62 |
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49% |
83% |
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7 |
5.44 |
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-0.62 |
-0.54 |
-0.43 |
-0.32 |
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-0.39 |
-0.25 |
-0.42 |
-0.28 |
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white |
0.62 |
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70% |
52% |
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8 |
2 |
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-0.76 |
-0.64 |
-0.41 |
-0.36 |
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-0.50 |
-0.29 |
-0.46 |
-0.36 |
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jumper 1 |
0.60 |
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68% |
60% |
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9 |
2 |
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-0.72 |
-0.55 |
-0.44 |
-0.55 |
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-0.49 |
-0.24 |
-0.42 |
-0.25 |
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jumper 2 |
0.60 |
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73% |
92% |
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average= |
65% |
72% |
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DIFFERENCES |
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Cat. 1 |
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Cat. 1-Cat. 2 |
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Cat. 2 |
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Cat. 1-Cat. 2 |
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w/o -w mandrel |
w mandrel |
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w/o -w mandrel |
w/o mandrel |
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1 |
100 |
850 nm, 1 |
-0.27 |
-0.18 |
0.01 |
0.01 |
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-0.42 |
-0.4 |
0.16 |
0.23 |
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2 |
100 |
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-0.25 |
-0.28 |
-0.02 |
-0.08 |
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0.07 |
0.06 |
-0.34 |
-0.42 |
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3 |
200 |
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-0.17 |
-0.16 |
-0.08 |
-0.10 |
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-0.05 |
0.02 |
-0.20 |
-0.28 |
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4 |
5.44 |
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-0.25 |
-0.26 |
0.06 |
-0.01 |
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0.05 |
0.04 |
-0.24 |
-0.31 |
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5 |
5.44 |
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0.05 |
-0.33 |
-0.03 |
-0.01 |
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0.02 |
-0.08 |
0.00 |
-0.26 |
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6 |
5.44 |
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-0.18 |
-0.13 |
-0.02 |
-0.06 |
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0.01 |
-0.02 |
-0.21 |
-0.17 |
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7 |
5.44 |
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-0.19 |
-0.22 |
-0.01 |
-0.04 |
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0.03 |
0.03 |
-0.23 |
-0.29 |
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8 |
2 |
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-0.35 |
-0.28 |
0.05 |
0.00 |
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-0.04 |
0.07 |
-0.26 |
-0.35 |
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9 |
2 |
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-0.28 |
0 |
-0.02 |
-0.30 |
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-0.07 |
0.01 |
-0.23 |
-0.31 |
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