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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. |
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.” |
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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. |
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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. |
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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). |
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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.) |
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6. |
The tester
shall be within the calibration period recommended by
the vendor in order to achieve the vendor-specified measurement
accuracy. |
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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. |
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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*. |
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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. |
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Optional
Requirements: |
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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. |
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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. |
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B. Performance
Test Parameters |
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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. |
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[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. |
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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. |
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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. |
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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 |
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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. |
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Frequency
Range (MHz) |
Maximum
Step size (MHz) |
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1 –
31.25 |
0.15 |
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31.26
– 100 |
0.25 |
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100 –
250 |
0.50 |
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250 –
350 |
— |
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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. |
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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. |
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7. |
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 |
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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. |
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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. |
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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. |
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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. |
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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. |
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C. Test
Result Documentation |
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1. |
The test results
information for each link shall be recorded in the memory
of the field tester upon completion of the test. |
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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. |
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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. |
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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
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a) |
The identification
of the link in accordance with the naming convention
defined in the overall
system documentation |
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b) |
The overall
Pass/Fail evaluation of the link-under-test including
the NEXT Headroom (overall worst case) number |
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c) |
The date
and time the test results were saved in the memory
of the tester |
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5. |
General Information
to be provided in the electronic data base with the test
results information for each
link:
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a) |
The identification
of the customer site as specified by the end-user |
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b) |
The identification
of the link in accordance with the naming convention
defined in the overall
system documentation |
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c) |
The overall
Pass/Fail evaluation of the link-under-test |
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d) |
The name
of the standard selected to execute the stored test
results |
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e) |
The cable
type and the value of NVP used for length calculations |
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f) |
The date
and time the test results were saved in the memory
of the tester |
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g) |
The brand
name, model and serial number of the tester |
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h) |
The identification
of the tester interface |
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i) |
The revision
of the tester software and the revision of the test
standards database in the tester |
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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. |
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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): |
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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 |
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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. |
