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六类布线标准内容 |
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The
Specification of Field Test Requirements
for a Balanced Twisted-Pair Cabling System |
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| I.
Cat 6 Installation: field test requirements upon completion
of the installation |
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| A.
General Requirements |
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1.
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Every
cabling link in the installation shall be tested in accordance
with the field test specifications defined in the most recent
draft of the “Transmission Performance Specifications for
4-pair 100 ? Category 6 Cabling” under development by the
Telecommunications Industry Association (TIA). At the time of
this writing, PN-3727 TIA/EIA Draft Standard – Draft 7, dated
August 23, 2000 represents the most recent version. This document
will be referred to as the “TIA Cat 6 Draft Standard.” |
| 2. |
The
installed twisted-pair horizontal links shall be tested from
the IDF in the telecommunications room to the telecommunication
wall outlet in the work area against the “Permanent Link
” performance limits specification as defined in the TIA Cat
6 Draft Standard. |
| 3. |
100%
of the installed cabling links must be tested and must pass
the requirements of the standards mentioned in I.A.2 above and
as further detailed in Section I.B. Any failing link must be
diagnosed and corrected. The corrective action shall be followed
with a new test to prove that the corrected link meets the performance
requirements. The final and passing result of the tests for
all links shall be provided in the test results documentation
in accordance with Section I.C below. |
| 4. |
Trained
technicians who have successfully attended an appropriate training
program and have obtained a certificate as proof thereof shall
execute the tests. Appropriate training programs include but
are not limited to installation certification programs provided
by BiCSi or the ACP (Association of Cabling Professionals). |
| 5. |
The
test equipment (tester) shall comply with the accuracy requirements
for the proposed level III field testers as defined in the TIA
Cat 6 Draft Document. The tester including the appropriate interface
adapter must meet the specified accuracy requirements. The accuracy
requirements for the permanent link test configuration (baseline
accuracy plus adapter contribution) are specified in Table B.2
of Annex B of the TIA Cat 6 Draft Standard. (Table B.3 in this
TIA document specifies the accuracy requirements for the Channel
configuration.) |
| 6. |
The
tester shall be within the calibration period recommended by
the vendor in order to achieve the vendor-specified measurement
accuracy. |
| 7. |
The
tester interface adapters must be of high quality and the cable
shall not show any twisting or kinking resulting from coiling
and storing of the tester interface adapters. In order to deliver
optimum accuracy, preference is given to a permanent link interface
adapter for the tester that can be calibrated to extend the
reference plane of the Return Loss measurement to the permanent
link interface. The contractor shall provide proof that the
interface has been calibrated within the period recommended
by the vendor. To ensure that normal handling on the job does
not cause measurable Return Loss change, the adapter cord cable
shall not be of twisted-pair construction. |
| 8. |
The
Pass or Fail condition for the link-under-test is determined
by the results of the required individual tests (detailed in
Section I.B). Any Fail or Fail* result yields a Fail for the
link-under-test. In order to achieve an overall Pass condition,
the results for each individual test parameter must Pass or
Pass*. |
| 9. |
A
Pass or Fail result for each parameter is determined by comparing
the measured values with the specified test limits for that
parameter. The test result of a parameter shall be marked with
an asterisk (*) when the result is closer to the test limit
than the accuracy of the field tester. The field tester manufacturer
must provide documentation as an aid to interpret results marked
with asterisks. |
|
| Optional
Requirements: |
| 10.
|
A representative
of the end-user shall be invited to witness field testing. The
representative shall be notified of the start date of the testing
phase 5 business days before testing commences. |
| 11. |
A
representative of the end-user will select a random sample of
5% of the installed links. The representative (or his authorized
delegate) shall test these randomly selected links and the results
are to be stored in accordance with the prescriptions in Section
I.C. The results obtained shall be compared to the data provided
by the installation contractor. If more than 2% of the sample
results differ in terms of the pass/fail determination, the
installation contractor under supervision of the end-user representative
shall repeat 100% testing and the cost shall be borne by the
installation contractor. |
| |
| B.
Performance Test Parameters |
| |
The
test parameters for Cat 6 are defined in TIA Cat 6 Draft standard,
which refers to the TIA/EIA-568-B.2
standard. The test of each link shall contain all of the following
parameters as detailed below. In order to pass the test all
measurements (at each frequency in the range from 1 MHz through
250 MHz) must meet or exceed the limit value determined in the
above-mentioned draft standard. |
| [Optional
Requirement – can only be combined with option (a) in Section
I.C.6.] Each parameter shall be measured from 1 through
350 MHz and all of these measurement points are to recorded
in the test results information as detailed in Section I.C.6. |
| 1.
|
Wire
Map
Wire Map shall report Pass if the wiring of each wire-pair from
end to end is determined to be correct.
The Wire Map results shall include the continuity of the shield
connection if present. |
| 2.
|
Length
The field tester shall be capable of measuring length of all
pairs of a basic link or channel based on the propagation delay
measurement and the average value for NVP ( 1 ). The physical
length of the link shall be calculated using the pair with the
shortest electrical delay. This length figure shall be reported
and shall be used for making the Pass/Fail decision. The Pass/Fail
criteria are based on the maximum length allowed for the Permanent
Link configuration (90 meters – 295 feet) plus 10% to allow
for the variation and uncertainty of NVP. |
| 3.
|
Insertion
Loss (Attenuation)
Insertion Loss is a measure of signal loss in the permanent
link or channel. The term “Attenuation” has
been used to designate “Insertion Loss.” Insertion Loss shall
be tested from 1 MHz through 250 MHz in
maximum step size of 1 MHz. It is preferred to measure insertion
loss at the same frequency intervals as NEXT Loss in order to
provide a more accurate calculation of the Attenuation-to-Crosstalk
ratio (ACR) parameter.
Minimum test results documentation (summary results): Identify
the worst wire pair (1 of 4 possible).
The test results for the worst wire pair must show the highest
attenuation value measured (worst case), the frequency at which
this worst case value occurs, and the test limit value at this
frequency |
| 4. |
NEXT Loss
Pair-to-pair near-end crosstalk loss (abbreviated as NEXT Loss)
shall be tested for each wire pair combination from each end
of the link (a total of 12 pair combinations). This parameter
is to be measured from 1 through 250 MHz. NEXT Loss measures
the crosstalk disturbance on a wire pair at the end from which
the disturbance signal is transmitted (near-end) on the disturbing
pair. The maximum step size for NEXT Loss measurements shall
not exceed the maximum step size defined in the draft standard
as shown in Table 1, column 2.
Minimum test results documentation (summary results): Identify
the wire pair combination that exhibits the worst case NEXT
margin ( 2 ) and the wire pair combination that exhibits the
worst value of NEXT (worst case). NEXT is to be measured from
each end of the link-under-test. These wire pair combinations
must be identified for the tests performed from each end. Each
reported case shall include the frequency at which it occurs
as well as the test limit value at this frequency. |
| Frequency
Range (MHz) |
Maximum Step
size (MHz) |
| 1 – 31.25 |
0.15 |
| 31.26 – 100 |
0.25 |
| 100 – 250 |
0.50 |
| 250 – 350 |
— |
|
5.
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PSNEXT
Loss
Power Sum NEXT Loss
shall be evaluated and reported for each wire pair from both
ends of the link-under- test (a total of 8 results). PSNEXT
Loss captures the combined near-end crosstalk effect (statistical)
on a wire pair when all other pairs actively transmit signals.
Like NEXT this test parameter must be evaluated from 1 through
250 MHz and the step size may not exceed the maximum step size
defined in the draft standard as shown in Table 1, column 2.
Minimum test results documentation (summary results): Identify
the wire pair that exhibits the worst case margin and the wire
pair that exhibits the worst value for PSNEXT. These wire pairs
must be identified for the tests performed from each end. Each
reported case shall include the frequency at which it occurs
as well as the test limit value at this frequency. |
| 6. |
ELFEXT
Loss, pair-to-pair
Pair-to-pair FEXT Loss shall be measured for each wire-pair
combination from both ends of the link-under-test. FEXT Loss
measures the crosstalk disturbance on a wire pair at the opposite
end (far-end) from which the transmitter emits the disturbing
signal on the disturbing pair. FEXT is measured to compute ELFEXT
Loss that must be evaluated and reported in the test results.
ELFEXT measures the relative strength of the far-end crosstalk
disturbance relative to the attenuated signal that arrives at
the end of the link. This test yields 24 wire pair combinations.
ELFEXT is to be measured from 1 through 250 MHz and the maximum
step size for FEXT Loss measurements shall not exceed the maximum
step size defined in the draft standard as in Table 1, column
2.
Minimum test results documentation (summary results): Identify
the wire pair combination that exhibits the worst case margin
and the wire pair combination that exhibits the worst value
for ELFEXT. These wire pairs must be identified for the tests
performed from each end. Each reported case shall include the
frequency at which it occurs as well as the test limit value
at this frequency. |
| 7.
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PSELFEXT
Loss
Power Sum ELFEXT is a calculated parameter that combines the
effect of the FEXT disturbance from three wire pairs on the
fourth one. This test yields 8 wire-pair combinations. Each
wire-pair is evaluated from 1 through 250 MHz in frequency increments
that do not exceed the maximum step size defined in the draft
standard as shown in Table 1, column 2.
Minimum test results documentation (summary results): Identify
the wire pair that exhibits the worst case margin and the wire
pair that exhibits the worst value for PSELFEXT. These wire
pairs must be identified for the tests performed from each end.
Each reported case shall include the frequency at which it occurs
as well as the test limit value at this frequency |
| 8. |
Return
Loss
Return Loss (RL) measures the total energy reflected on each
wire pair. Return Loss is to be measured from both ends of the
link-under-test for each wire pair. This parameter is also to
be measured form 1 through 250 MHz in frequency increments that
do not exceed the maximum step size defined in the draft standard
as shown in Table 1, column 2.
Minimum test results documentation (summary results): Identify
the wire pair that exhibits the worst case margin and the wire
pair that exhibits the worst value for Return Loss. These wire
pairs must be identified for the tests performed from each end.
Each reported case shall include the frequency at which it occurs
as well as the test limit value at this frequency. |
| 9.
|
ACR
(Attenuation to crosstalk ratio) [This parameter is not demanded
by the draft standard but may be
required in order to obtain the premise wiring manufacturer’s
warranty]
ACR provides an indication of bandwidth for the two wire-pair
network applications. ACR is a computed parameter that is analogous
to ELFEXT and expresses the signal to noise ratio for a two
wire-pair system. This calculation yields 12 combinations –
six from each end of the link.
Minimum test results documentation (summary results): Identify
the wire pair combination that exhibits the worst case margin
and the wire pair combination that exhibits the worst value
for ACR. These wire pair ombinations must be identified for
the tests performed from each end. Each reported case shall
include the frequency at which it occurs as well as the test
limit value at this frequency. |
| 10.
|
PSACR
[This parameter is not required by the draft standard but
may be required in order to obtain the
premise wiring vendor's warranty]
The Power Sum version of ACR is based on PSNEXT and takes into
account the combined NEXT disturbance of all adjacent wire pairs
on each individual pair. This calculation yields 8 combinations
- one for each wire pair from both ends of the link.
Minimum test results documentation (summary results): Identify
the wire pair that exhibits the worst case margin and the wire
pair that exhibits the worst value for PSACR. These wire pairs
must be identified for the tests performed from each end. Each
reported case shall include the frequency at which it occurs
as well as the test limit value at this frequency. |
| 11. |
Propagation Delay
Propagation delay is the time required for the signal to travel
from one of the link to the other. This
measurement is to be performed for each of the four wire pairs.
Minimum test results documentation (summary results): Identify
the wire pair with the worst case
propagation delay. The report shall include the propagation
delay value measured as well as the test
limit value. |
| 12.
|
Delay
Skew [as defined in TIA/EIA-568-B.1; Section 11.2.4.11]
This parameter shows the difference in propagation delay between
the four wire pairs. The pair with the shortest propagation
delay is the reference pair with a delay skew value of zero.
Minimum test results documentation (summary results): Identify
the wire pair with the worst case propagation delay (the longest
propagation delay). The report shall include the delay skew
value measured as well as the test limit value. |
| |
| C.
Test Result Documentation |
| 1. |
The
test results information for each link shall be recorded in
the memory of the field tester upon completion of the test. |
| 2. |
The
test results records saved by the tester shall be transferred
into a Windows-based database utility that allows for the maintenance,
inspection and archiving of these test records. A guarantee
must be made that the measurement results are transferred to
the PC unaltered, i.e., “as saved in the tester”at the end of
each test and that these results cannot be modified at a later
time. Superior protection in this regard is offered by testers
that transfer the numeric measurement data from the tester to
the PC in a non-printable format. |
| 3. |
The
database for the completed job shall be stored and delivered
on CD-ROM including the software tools required to view, inspect,
and print any selection of test reports. |
| 4. |
A
paper copy of the test results shall be provided that lists
all the links that have been tested with the
following summary information
| a)
|
The
identification of the link in accordance with the naming
convention defined in the overall system
documentation |
| b)
|
The
overall Pass/Fail evaluation of the link-under-test including
the NEXT Headroom (overall worst case) number |
| c) |
The date and time the test results were saved in the memory
of the tester |
|
| 5. |
General
Information to be provided in the electronic data base with
the test results information for each
link:
| a) |
The
identification of the customer site as specified by the
end-user |
| b) |
The
identification of the link in accordance with the naming
convention defined in the overall
system documentation |
| c) |
The overall Pass/Fail evaluation of the link-under-test |
| d) |
The
name of the standard selected to execute the stored test
results |
| e) |
The
cable type and the value of NVP used for length calculations |
| f) |
The
date and time the test results were saved in the memory
of the tester |
| g) |
The
brand name, model and serial number of the tester |
| h) |
The
identification of the tester interface |
| i) |
The
revision of the tester software and the revision of the
test standards database in the tester |
| j)
|
The
test results information must contain information on each
of the required test parameters that
are listed in Section I.B and as further detailed below
under paragraph I.C.6. |
|
| 6.
|
The
detailed test results data to be provided in the electronic
database for each tested link must contain
the following information (only one
of these two formats must be specified): |
| a) |
For
each of the frequency-dependent test parameters, the value measured
at every frequency during the test is stored. In this case,
the PC-resident database program must be able to process the
stored results to display and print a color graph of the measured
parameters. The PC-resident software must also provide a summary
numeric format in which some critical information is provided
numerically as defined by the summary results (minimum numeric
test results documentation) as outlined above for each of the
test parameters.
Length: Identify the wire-pair with the shortest electrical
length, the value of the length rounded to the nearest 0.5 m
[optional: foot] and the test limit value
Propagation delay: Identify the pair with the shortest
propagation delay, the value measured in nanoseconds (ns) and
the test limit value
Delay Skew: Identify the pair with the largest value
for delay skew, the value calculated in
nanoseconds (ns) and the test limit value
Attenuation: Minimum test results documentation as explained
in Section I.B for the worst pair
Return Loss: Minimum test results documentation as explained
in Section I.B for the worst pair as measured from each end
of the link
NEXT, ELFEXT, ACR: Minimum test results documentation
as explained in Section I.B for the worst pair combination as
measured from each end of the link
PSNEXT, PSELFEXT, and PSACR: Minimum test results documentation
as explained in Section I.B for the worst pair as measured from
each end of the link |
| b) |
For
each of the frequency-dependent test parameters, the minimum
test results documentation shall be stored for each wire-pair
or wire-pair combination as observed from each end of the link.
The minimum test results documentation for each test parameter
shall be in compliance with the information in Section I.B.
Link length, propagation delay, and delay skew shall be reported
for each wire pair as well as the test limit for each of these
parameters. |
