Telecommunications Industry Association
TR41.9-16-02-XXX
Document Cover Sheet
Project Number
TIA-PN-31-D-4
Document Title
Power Spectral Density test procedures for FAST DSL
Source
Cisco Systems
Contact
Tim Lawler
170 West Tasman Dr.
San Jose, CA 95134
Distribution
TR-41.9
Intended Purpose
of Document
(Select one)
X
Phone: (408) 527-0681
Fax: (408) 853-3288
Email: tlawler@cisco.com
For Incorporation Into TIA Publication
For Information
Other (describe) -
The document to which this cover statement is attached is submitted to a Formulating Group or sub-element
thereof of the Telecommunications Industry Association (TIA) in accordance with the provisions of
Sections 3.3.2.2 through 3.3.2.4 inclusive of the TIA Engineering Committee Operating Procedures dated
May 2014, all of which provisions are hereby incorporated by reference.
Abstract
This contribution is a proposal for adding Power Spectral Density test procedures for FAST DSL to TSB31-D-4.
V2.1 – 20141205
Telecommunications Industry Association
9.42
564B
TR41.9-16-02-XXX
Power Spectral Density, FAST Terminal Equipment TIA-968-B-3, 5.3.10.1.2
9.42.1
Background
As is the case for the FAST modem’s total power, its PSD must be limited to minimize
crosstalk. PSD is limited by the imposition of a PSD mask, which specifies a limit as a
function of frequency. The mask permits a reasonable level in the operating bands
while restricting the FAST modem’s PSD below the operating bands to protect POTS
and above the operating bands both to minimize interference both with the downstream
spectrum as well as other DSL systems potentially affected by crosstalk. The mask
presents measurement challenges because it specifies such a broad range of signal
levels and resolution bandwidths, which can’t practically be made in a single sweep due
to limitations in the spectrum analyzer’s dynamic range and bandwidth. For this reason
and resolution bandwidth considerations, the mask is broken into segments.
565B
9.42.2
Purpose
The purpose of this test is to verify that the transmitted PSD is below the PSD mask
limits.
566B
9.42.3
Equipment
(1)
Spectrum analyzer SEL#57.
(2)
Spectrum analyzer SEL#81.
(3)
100:50 ohm BALUN transformer SEL#71
(4)
100:50 ohm BALUN transformer SEL#59.
(5)
100:50 ohm BALUN transformer SEL#82
Note: Refer to subclause 5.5 for equipment details.
567B
9.42.4
Equipment States Subject to Test
The equipment under test should be transmitting continuously at its highest obtainable
signal power.
568B
9.42.5
Procedure
In this procedure the frequency range is divided into six segments. The number of
segments chosen depends on the capabilities of the test equipment.
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Telecommunications Industry Association
TR41.9-16-02-XXX
Each frequency point in the operating bands (corresponding to a measurement in a
single resolution bandwidth) of a PSD should be measured by averaging the power in
the resolution bandwidth of that frequency point for a time period of at least 10 seconds.
798B
9.42.5.1 Procedure for Segment 1
(1)
Condition the EUT to transmit its upstream signals continuously.
(2)
Connect the EUT to the test circuit of Figure 9.42-1 using BALUN transformer
SEL#71.
(3)
Set the spectrum analyzer as follows:
Resolution bandwidth (RBW): 100 Hz
Attenuation: Set for minimum without overload
Reference level: (-20) dBm
dB/div: 10 dB
Marker function: Noise dBm/Hz
Start frequency: 200 Hz
Stop frequency: 4 kHz
(4)
799B
Measure and record the PSD over the frequency range 200 Hz to 4 kHz.
9.42.5.2 Procedure for Segment 2
(1)
Condition the EUT to transmit its upstream signals continuously.
(2)
Connect the EUT to the test circuit of Figure 9.42-1 using BALUN transformer
SEL#59.
(3)
Set the spectrum analyzer as follows:
Resolution bandwidth: 1 kHz
Attenuation: Set for minimum without overload
Reference level: (-20) dBm
dB/div: 10 dB
Marker Function: Noise dBm/Hz
Start frequency: 4 kHz
Stop frequency: 20 kHz
(4)
Measure and record the PSD over the frequency range 4 kHz to 20 kHz.
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Telecommunications Industry Association
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TR41.9-16-02-XXX
9.42.5.3 Procedure for Segment 3
(1)
Condition the EUT to transmit its upstream signals continuously.
(2)
Connect the EUT to the test circuit of Figure 9.42-1 using BALUN transformer
SEL#59.
(3)
Set the spectrum analyzer as follows:
Resolution bandwidth: 10 kHz
Attenuation: Set for minimum without overload
Reference level: (-20) dBm
dB/div: 10 dB
Marker Function: Noise dBm/Hz
Start frequency: 20 kHz
Stop frequency: 2 MHz
(4)
799B
Measure and record the PSD over the frequency range 20 kHz to 2 MHz.
9.42.5.4 Procedure for Segment 4
(1)
Condition the EUT to transmit its upstream signals continuously.
(2)
Connect the EUT to the test circuit of Figure 9.42-1 using BALUN transformer
SEL#59.
(3)
Set the spectrum analyzer as follows:
Resolution bandwidth: 1 MHz
Attenuation: Set for minimum without overload
Reference level: (0) dBm
dB/div: 10 dB
Marker Function: Noise dBm/Hz
Start frequency: 2 MHz
Stop frequency: 30 MHz
(4)
Measure and record the PSD over the frequency range 2 MHz to 30 MHz.
(5)
The mask value to be compared against is the maximum value the mask takes within
a window [f − ½ × RBW, f + ½ × RBW].
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Telecommunications Industry Association
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TR41.9-16-02-XXX
9.42.5.5 Procedure for Segment 5
(1)
Condition the EUT to transmit its upstream signals continuously.
(2)
Connect the EUT to the test circuit of Figure 9.42-1 using BALUN transformer
SEL#82.
(3)
Set the spectrum analyzer as follows:
Resolution bandwidth: 1 MHz
Attenuation: Set for minimum without overload
Reference level: (0) dBm
dB/div: 10 dB
Marker Function: Noise dBm/Hz
Start frequency: 30 MHz
Stop frequency: 106 MHz
(4)
Measure and record the PSD over the frequency range 30 MHz to 106 MHz.
(5)
The mask value to be compared against is the maximum value the mask takes within
a window [f − ½ × RBW, f + ½ × RBW].
799B
9.42.5.6 Procedure for Segment 6
(1)
Condition the EUT to transmit its upstream signals continuously.
(2)
Connect the EUT to the test circuit of Figure 9.42-1 using BALUN transformer
SEL#82.
(3)
Set the spectrum analyzer as follows:
Resolution bandwidth: 100 kHz
Attenuation: Set for minimum without overload
Reference level: (-10) dBm
dB/div: 10 dB
Marker Function: Noise dBm/Hz
Start frequency: 106 MHz
Stop frequency: 300 MHz
(4)
Measure and record the PSD over the frequency range 30 MHz to 300 MHz.
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Telecommunications Industry Association
569B
9.42.6
TR41.9-16-02-XXX
Alternative Method
None
570B
9.42.7
Suggested Test Data
(1)
Measured PSD for each frequency range with the associated PSD limit line.
(2)
Loop characteristics or test mode via software used to obtain the PSD measurement.
571B
9.42.8
(1)
Comments
Care must be taken to ensure that measurement errors are kept to a minimum.
Sources of error may include:
Impedance deviations from the ideal 100 ohm termination
BALUN loss
Spectrum analyzer input clipping
PSD measurement errors caused by excessively fast sweep times or not averaging
enough samples when making a swept average measurement.
(2)
Some spectrum analyzers may need a low-pass filter set to cut off frequency of 30
kHz for the Segments 1 and 2 measurement.
FIGURE 9.42-1 PSD CONNECTION DIAGRAM FOR SEGMENTS
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