Document Number: TR-41.9.2-05-02-
Title: Revise TSB31-C Section 14, TRQ.6 DSL Equipment to reference new
DSL clauses for TIA-968-A-3.
Distribution to: TIA TR41.9.2
Meeting Location: Las Vegas, Nevada
February 7, 2005
Submitting
Organization: Cisco Systems, Inc.
Phone: (408) 527-0681
Fax: (408) 526-4184
Email: tlawler@cisco.com
Contact Tim Lawler
Information: Cisco Systems, Inc.
170 West Tasman Dr.
San Jose, CA 95134
Keywords: Part 68, TIA/TSB-31-C, TRQ.6
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1
Table of Contents changes.
14
SHDSL, HDSL2, HDSL4 TERMINAL EQUIPMENT
14.1
Metallic Signals TIA-968-A-3, 4.5.9.2.1
14.2
Longitudinal Output Voltage Limits TIA-968-A-3, 4.5.9.2.3
14.3
Transverse Balance Requirements TIA-968-A-3, 4.6.5
2
14.
SHDSL, HDSL2, HDSL4 TERMINAL EQUIPMENT
14.1
Metallic Signals TIA-968-A-3, 4.5.9.2.1
14.1.1
Background
SHDSL, HDSL2, and HDSL4 terminal equipment transmit significant power in and above
the voiceband and do not support the use of analog splitting technology for coexistence
on the same pair with voiceband services. Therefore, the analog voiceband signal power
limits in TIA-968-A are not applicable to SHDSL, HDSL2, or HDSL4 terminal equipment.
Likewise, SHDSL, HDSL2, and HDSL4 terminal equipment would not ordinarily conform
to the signal power specifications for any of the other services or interfaces defined in
section 4.5 of TIA-968-A.
14.1.2
Purpose
To verify that the PSD is below the mask and to verify total signal power transmitted to
the network is properly limited.
14.1.3
Equipment
(1)
Vector analyzer SEL#62
(2)
Hi-pass filter SEL#63
(3)
Balun transformers SEL#64, #65, #66
(4)
Artificial line SEL#67
NOTE: Refer to Section 5.3 for equipment details.
14.1.4
Equipment States Subject to Test
Transmitting continuously at all line data rates at maximum transmit power.
3
14.1.5
Procedure
Measure the PSD & total power from 1 kHz to 2 MHz:
(1)
Connect the EUT (TU-R) to the companion unit (TU-C) as shown in Figure 14.1-1.
(2)
Using the artificial line, allow the EUT and TU-C to synchronize at maximum
power. When the DSL link has trained up, cause the EUT to continue to transmit
constantly without connection to the TU-C.
(3)
Connect the EUT (TU-R) to the measurement equipment as shown in Figure 14.12.
(4)
Set the vector analyzer frequency range and band power markers at 1 kHz (start)
and 2 MHz (stop). Resolution bandwidth = 10 kHz, Averaging time  10 seconds,
Reference level: -20 dBm/Hz, dB/div: 10 dB and Autorange.
If applicable, load the PSD mask that represents SHDSLM(f) for the appropriate
data rate (R), onto the vector analyzer. Alternatively, comparison with the PSD
mask can be done later, if your vector analyzer lacks this capability.
Note: For HDSL2 and HDSL4 see comment 4 and 5 for PSD mask.
(5)
Measure and record the PSD and total power between 1 kHz and 2 MHz. No filter
is required.
Note: For HDSL2 the band power markers would be set to 1 kHz and 350 kHz for the
total power measurement.
For HDSL4 set the vector analyzer start frequency at 200 Hz (start) and the band
power markers to 200 Hz and 307 kHz for the total power measurement, using the
SEL#65 balun.
Measure the PSD from 500 kHz to 10 MHz:
(6)
Insert a high-pass filter (set to 350 kHz) into the setup as per Figure 14-2, minding
the termination. An external termination (e.g., 50  BNC) is needed for the balun
with most active filters, since they have high input impedance.
(7)
Set the vector analyzer frequency range to 500 kHz (start) and 10 MHz (stop).
There is some overlap with the range covered in steps (3) though (5), but it is often
necessary to “close in” on this part of the signal with a filter to eliminate the pass
band signal, and with a lower range setting.
4
Resolution bandwidth = 10 kHz, Averaging time  10 seconds, Reference level: 50 dBm/Hz, dB/div: 10 dB and Autorange.
If applicable, load the PSD mask that represents SHDSLM(f) for the appropriate
data rate (R), onto the vector analyzer. Alternatively, comparison with the PSD
mask can be done later, if your vector analyzer lacks this capability.
(8)
Measure and record the PSD between 500 kHz and 10 MHz.
Note: If the line rate is greater than 2 Mbps, this process is modified slightly. Adjust the
start frequency on the vector analyzer to 700 kHz instead of 500 kHz. Also, use
590 kHz on the high-pass filter instead of 350 kHz, and adjust the mask,
respectively. This adjustment may be necessary because of “bleed-over” from the
passband, which is more likely at the higher rates. The start frequency on the
analyzer and the cut-off frequency on the filter can be adjusted as necessary,
keeping in mind that the effects of the filter must not be within the window of
measurement.
Measure sliding 1 MHz window (WS) power criteria in the 1.1 MHz-10 MHz band:
(9)
Without changing the setup from step (7), use the band power markers to
measure the total power in the window from 1.1 MHz to 10 MHz. If the reading is
less than -50 dBm, stop and record. If the reading is greater than -50 dBm, break
into smaller windows of 1MHz, and record the highest reading from all windows.
Note: For HDSL2 the sliding 1 MHz window (WS) starts at 3.1 MHz.
Measure the PSD from 10 MHz to 30 MHz:
(10)
Use balun SEL#66 and filter settings as appropriate (see note (4) of Figure 14-1).
(11)
Set the vector analyzer frequency range and band power markers at 10 MHz
(start) and 30 MHz (stop). Resolution bandwidth = 100 kHz, Averaging time  10
seconds, Reference level: -50 dBm/Hz, dB/div: 10 dB and Autorange.
If applicable, load the PSD mask that represents SHDSLM(f) for the appropriate
data rate (R), onto the vector analyzer. Alternatively, comparison with the PSD
mask can be done later, if your vector analyzer lacks this capability.
Note: It may be necessary to break this band up further, depending on the instruments
selected.
(12)
Measure and record the PSD between 10 MHz and 30 MHz.
Measure sliding 1 MHz window (WS) power criteria in the 10 MHz-30 MHz band:
5
(13)
14.1.6
Without changing the setup from step (11), use the band power markers to
measure the total power in the window from 10 MHz to 30 MHz . If the reading is
less than -50 dBm, stop and record. If the reading is greater than -50 dBm, break
into smaller windows of 1 MHz, and record the highest reading from all windows.
Alternative Method
A spectrum analyzer (SEL #57) may be used instead of the Vector Analyzer. A high pass
filter is preferred for measurements above the operating band. The signal power may be
calculated by integrating the PSD over the operating band. The PSD may be compared
against the limit by using a spreadsheet or other software applications. The spreadsheet
may also be used to calculate the total power over a 1 MHz sliding window.
14.1.7
Suggested Test Data
(1)
Plots of the PSD for each line rate with the limit line shown on each graph.
(2)
Total Signal Power Level.
(3)
Line Data Rate and Baud Rate if applicable.
14.1.8
Comments
(1)
Watch the dynamic range on each measurement. Make sure proper dynamic
range is selected for each measurement.
(2)
Filter type should ideally yield a 0dB gain, flat, in all areas of measurement. The
filter is present only to prevent the strong passband signal from overloading the
front end of the analyzer, and reducing its ability to range down.
(3)
Equipment that is classified as G.SHDSL according to clauses 5.4.2 and 6.3.2 of
T1.417-2003, the PSD mask (SHDSLM(f)) can be calculated from the following:
2

  f 


sin 

K
f

sym
1


 SHDSL 


2
SHDSL M ( f )   135
f sym
 f 




1  
f 


 sym 

4
1.5
0.5683  10  f ,

MaskedOffsetdB(f) is defined as:
6


MaskedOffsetdB( f )

1
10


10
,
f

f
int
12


f


f 3db 


f int  f  1.1MHz

f f

1  0.4  3dB
MaskedOffsetdB( f )  
f 3dB

1

,
f  f 3dB
,
f  f 3dB
fint is the frequency where the two functions governing SHDSLM(f) intersect in the
range 0 to fsym. KSHDSL, fsym, f3dB, and the line bit rate LBR are defined in Table 15
of T1.417-2003. The G.SHDSL PSD and total average power is measured with a
termination of 135 Ohms.
(4)
Equipment that is classified as HDSL2 (SMC 4) according to clause 5.3.4 and
6.2.4 of T1.417-2003, the PSD mask can be determined from Table 6 and Figure
5 of T1.417-2003. The HDSL2 PSD and total average power is measured with a
termination of 135 Ohms.
(5)
Equipment that is classified as HDSL4 according to clause 5.4.3 and 6.3.3 of
T1.417-2003, the PSD mask can be determined from Table 18 and Figure 15 of
T1.417-2003. The HDSL2 PSD and total average power is measured with a
termination of 135 Ohms.
7
TU-R
(EUT)
Artificial line
(9kft 26 AWG)
Companion
(TU-C)
Figure 14.1-1 Test Configuration to Establish Data Mode
TU-R
(EUT)
Balun
Transformer
High Pass
Filter
Vector
Analyzer
NOTES:
(1)
In practice, two transformers are typically used. One for 1kHz < f < 10 MHz, and
another for 5 MHz < f < 30MHz. (There is some overlap in measurements).
(2)
In practice, two settings are used. The filter is set to high-pass, 350 kHz for
measurements in the 500 kHz < f < 10 MHz band, for data rates below 2Mbps.
The filter is set to high-pass, 590 kHz for measurements in the 700 kHz < f < 10
MHz band, for data rates above 2Mbps.
(3)
No high-pass filter is used for 1 kHz < f < 500 kHz because this is in the passband.
(4)
A high-pass filter may or may not be needed for 10 MHz < f < 30 MHz, depending
on the dynamic range of your instrument for these frequencies. If a filter is
needed, use the same settings as for the 500 kHz/700 kHz < f < 10MHz band.
Figure 14.1-2 Test Configuration to Measure PSD and Total Power
8
14.2
14.2.1
Longitudinal Output Voltage Limits TIA-968-A-3, 4.5.9.2.3
Background
Longitudinal output voltage (LOV) limits complement PSD limits by restricting the
amplitude of common mode signals much like the PSD limits restrict the amplitude of the
equipment’s differential mode signals. LOV limits are necessary, as common mode
signals tend to couple more readily than differential mode signals in multi-line, twisted
pair cable plant. In other words, LOV limits are necessary to limit crosstalk.
14.2.2
Purpose
To verify that the longitudinal output voltage is below the limit.
14.2.3
(1)
Equipment
Vector analyzer SEL#62
NOTE: Refer to Section 5.3 for equipment details.
14.2.4
Equipment States Subject to Test
Transmitting continuously at its highest signal power and upstream line data rate.
14.2.5
Procedure
(1)
Condition the EUT to transmit at it highest upstream signal power level and line
rate as described in 14.1.5 steps (1) and (2).
(2)
Connect the EUT to the test circuit of Figure 14.2-1.
(3)
Set the vector analyzer frequency range at 1 kHz (start) and 2.5 MHz (stop) and
set the band power markers to 1 kHz and the upper -30 dB frequency, relative to
peak PSD (“Operating Band”). For SHDSL at its highest data rate, this would be
565.5 kHz. Resolution bandwidth = 3 kHz, Averaging time  1 second, Reference
level: -30 dBV, dB/div: 10 dB and Autorange.
For HDSL2 refer to Table 6 of T1.417-2003 to determine the frequency range of
the “Operating Band”.
For HDSL4 refer to Table 18 of T1.417-2003 to determine the frequency range of
the “Operating Band”.
9
(4)
If reading is less than -50 dBV between band power markers, stop and record. If
the reading is greater than -50 dBV, break into smaller windows of 3 kHz, and
record the highest reading from all windows. A correction factor of -1.3 dB must
be applied to discrete readings obtained with a 3 kHz bandwidth for comparison
against the LOV limit as specified over a 4 kHz bandwidth.
(5)
Set the vector analyzer band power markers from the upper -30 dB (relative to
peak PSD) frequency to 4  the upper -30 dB frequency. For SHDSL at its highest
data rate, this would be 565.5 kHz to 2262 kHz.
(6)
If reading is less than -80 dBV between band power markers, stop and record. If
the reading is greater than -80 dBV, break into smaller windows of 3 kHz, and
record the highest reading from all windows. A correction factor of –1.3 dB must
be applied to discrete readings obtained with a 3 kHz bandwidth for comparison
against the LOV limit as specified over a 4 kHz bandwidth.
(7)
Repeat steps (3) though (6) for each of the data rates that the EUT can support.
14.2.6
Alternative Method
A spectrum analyzer (e.g. SEL #57) may be used instead of the Vector Analyzer. If the
spectrum analyzer does not have a 1 Mohm input then an impedance adapter must be
used. A correction factor for the adapter may be necessary.
14.2.7
Suggested Test Data
(1)
Plot of the LOV with the limit line shown.
(2)
Line Data Rate and Baud Rate if applicable.
14.1.8
Comments
(1)
For this requirement, the operating band is the range of frequencies between the
lower and upper -30 dB points (relative to peak PSD) of the signal passband as
determined from the PSD masks.
(2)
Care must be taken in the construction of the LOV test fixture. Resistor values
must be matched previously. Test leads from the fixture to the EUT should be
kept as short as possible to minimize RF ingress.
10
NOTES:
(1)
The resistor values in Figure 14.2-1 are in ohms.
(2)
If the EUT does not have a ground connection or exposed grounded surface, it
shall be placed upon a ground plane that is also connected to earth ground (the
same ground shared by the vector analyzer).
FIGURE 14.2-1 LOV TEST FIXTURE & CONNECTION DIAGRAM
11
14.3
Transverse Balance Requirements TIA-968-A-3, 4.6.5
14.3.1
Background
See Section 10.1.1
14.3.2
Purpose
To determine transverse balance of SHDSL, HDSL2 and HDSL4 EUTs.
14.3.3
Equipment
(1)
Spectrum analyzer SEL# 34
(2)
Tracking generator SEL# 39.
NOTE: Refer to Section 5.3 for equipment details.
14.3.4
Equipment States Subject to Test
Active state with appropriate grounding applied and the EUT transmitter turned off.
14.3.5
Procedure
(1)
Connect the EUT to the test circuit of Figure 10.2-1 with the 135 ohm calibration test
resistor in place.
(2)
Set the spectrum analyzer and tracking generator to the appropriate frequency
ranges: (see comment 1 and 2)
(2)
SHDSL EUT - 200 Hz to 490 kHz
(b)
HDSL2 EUT - 200 Hz to 422.1 kHz
(c)
HDSL4 EUT - 200 Hz to 493.6 kHz
Follow steps (3) through (13) in section 10.2.5.
14.3.6
(1)
(a)
Comments
For the purposes of this requirement, the applicable operating range is defined as
the entire range of frequencies between the highest and lowest frequencies having
12
PSD values within 20 dB of the peak PSD. Thus, the applicable frequency range
for transverse balance testing varies depending upon the supported PSD masks.
(2)
Alternatively, a narrower frequency range may be used for SHDSL EUT that is
defined by the points at which the measured power spectral density (PSD) is 20
dB down from the maximum level associated with both the maximum data rate of
the upstream and downstream signals.
(3)
The longitudinal termination is defined in TIA-968-A-3, clause 4.6.5. Metallic
source impedance and metallic voltage to be used for transverse balance
measurements of SHDSL, HDSL2 and HDSL4 terminal equipment is 135 ohms
(ZM) and 0.367 V (VM) for each of the supported PSD masks.
13