Viavi HST-3000 Parts list manual

Revision 9.0
March 2012
Technical Assistance: 1-866-228-3762 [e-mail]
© 2012 JDSU. All rights reserved.
HST-3000 VDSL QUICK CARD
WIDEBAND NOISE

Revision 9.0
February 2012
2Technical Assistance: 1-866-228-3762 [e-mail]
© 2012 JDSU. All rights reserved.
VDSL2 QUICK CARD
Wideband Testing - Wideband Noise
Wideband Testing Definitions
Before beginning description of the Wideband test feature found on the HST-3000 it is important the techni-
cian has a basic understanding of two main principles.
• Frequency
• Noise
Frequency: Many technicians are surprised to learn the XDSL signals while on the cable are a series of analog
tones. is is an oversimplication of the technology but a very good explanation from a repair standpoint.
XDSL technologies occupy groups or “spectrums” of frequency according to the technology.
For example, ADSL1 utilizes frequencies between roughly 20 kHz (20000 Hz) to 1.1 MHz (1.1000000 Hz).
ADSL2+ doubles the frequency range to 2.2 MHz and VDSL2 is capable, depending on prole, of going to
30 MHz
Ideally, these spectrums of frequencies would travel from end to end on the circuit all at the same “loudness”
or amplitude. However, in reality, frequency loses amplitude at a linear rate. is means that as frequencies
increase, they lose signal strength faster over the same distance.
Consider the following table, which shows loss per kilometer for three frequencies, 1000 Hz, 300kHz, and
772kHz -- as the frequencies increased their corresponding amplitude decreases.
Table: 1 - Frequency vs Loss per Kilometer
Frequency Loss per Kilometer
1000 Hz 1.27 dB
300,000 Hz 17.87 dB
772,000 Hz 22.56 dB
HST-3000 Test Interface
Connect dual tip & ring + ground leads to the mini-banana connectors on the top of the HST as shown be-
low.
Plug in mini-banana
connectors as shown
n

Revision 9.0
February 2012
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Technical Assistance: 1-866-228-3762 [e-mail]
© 2012 JDSU. All rights reserved.
VDSL2 QUICK CARD
Wideband Testing
Wideband Testing Definitions
Noise: Noise can be considered any unwanted signal in the same spectrum of frequencies used by the XDSL
technology. It is important for the technician to understand every cable pair has some measureable level of
noise. To determine the impact of this noise it must be compared to the level of the XDSL signal.
Noise Margin: Noise margin, simply stated, is the distance or room between the XDSL signal level and the
noise on the cable pair. is distance is expressed in dB rather than inches or feet. Just as it would be better to
have more distance between the noise and signal it is better to have more dB(g 1)
Noise margin is important for two main reasons. 1.) As discussed above, XDSL signals lose strength quickly.
2.) Noise is dynamic, meaning it is uctuating up and down in signal strength. If a proper buer or margin is
not maintained noise could reach a strong enough level to mix into the XDSL signal (g 2).
is problem increases with longer Uverse loops. eir signal strength is rapidly declining and noise accumu-
lates as loop length increases.
XDSL Signal
Level in Blue
XD
XD
XD
S
SL
SL
S
S
S
i
ig
ig
na
na
l
l
l
L
evel in Blu
e
Dynamic Noise Increase
Hits xDSL Signal
D
Dy
Dy
na
na
i
mi
mi
c
c
N
No
No
i
is
is
e
e
I
In
In
cr
cr
ea
ea
se
se
Hits xDSL Si
g
nal
Noise
Margin
Noise
Margin
N
No
No
i
is
is
e
e
M
ar
g
in
XDSL Signal Level
XD
XD
XD
S
SL
SL
S
S
S
i
ig
ig
na
na
l
l
l
Le
Le
ve
ve
l
l
l
N
No
N
N
No
N
N
N
N
N
N
No
No
No
No
No
N
N
NN
N
N
N
o
o
o
o
N
o
N
o
o
N
o
i
i
i
i
i
i
i
is
e
L
L
Le
L
L
L
L
ve
v
v
ve
v
e
e
e
e
ve
e
l
l
Noise Level

Revision 9.0
February 2012
4Technical Assistance: 1-866-228-3762 [e-mail]
© 2012 JDSU. All rights reserved.
VDSL2 QUICK CARD
Wideband Testing
Wideband Testing Definitions
Insertion Loss:
e Insertion Loss test screen that aides in the identication of Bridge-Tap. e technician views the insertion
loss screen looking for non-linear loss characteristic across the range of VDSL frequencies. e result indicates
the presence of bridge-tap by the “dips” in the frequency response curve. e fact that a lower frequency has
lower amplitude then a higher frequency
e Insertion Loss test can be performed using the HST-3000 in-conjunction with the UFED to send and
receive a VDSL2 tone sweep. Because this is a standalone measurement it can be used on the whole circuit
or across portions of the circuit during trouble shooting. Non-linear frequency response is an indication of
bridge-tap or a “wet” section of cable.

Revision 9.0
February 2012
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Technical Assistance: 1-866-228-3762 [e-mail]
© 2012 JDSU. All rights reserved.
VDSL2 QUICK CARD
Wideband Testing - Wideband Noise
Purpose
e purpose of this test is to identify the presence of wideband noise that could interfere or degrade VDSL2
performance. Unacceptable levels of noise could be due to a number of factors including bonding & ground-
ing problems, pair imbalance, interferers within the binder group and other fault conditions.
Excessive levels of wideband noise will interfere with the VDSL signal and can cause degraded performance,
errors and loss of sync. is in turn, can lead to lost IP Video packets and degradation of video performance.
e root cause of excessive levels of noise is typically either pair imbalance or bonding and grounding issues.
It is also important to understand the characteristics of the noise source itself. erefore, if unacceptably high
levels of wideband noise are present, the Spectral Analysis function should be used to isolate the problem.
is test is typically run from the customer premises to cross box.
Procedure
1. Connect the Tip and Ring test leads from the HST-3000 to the desired
pair. Connect the ground lead to a valid earth ground reference (con-
nected to HST-3000 as shown in the gure on Page 4).
2. Press the Home navigation key, press the Copper soft key and then
selected Wideband TIMS from the menu and press OK.
3. Press the Display soft key on the lower left of the display, select WB2
TIMS from the pop-up menu and select Noise from the sub menu.
4. e Wideband Noise measurement starts automatically (Running
indication shown at the top of the screen). To start or stop the measure-
ment, press the Stop / Start soft key at the lower right of the display.
5. For VDSL loops, the Filter should be J-20K8. To change the lter selec-
tion, press the Actions soft key, select Filter from the pop-up menu and
choose J-20K8 from the cascaded (right) menu.
6. For VDSL loops, the Termination should be 100 Ohms. To change the
termination, press the Actions soft key, select Termination from the
pop-up menu and choose 100 Ohms from the cascaded (right) menu.
7. To save results, press the Results soft key and select Save Results
from the pop-up menu.
8. To change the display of the measured noise from reading in dBm to dBrn,
press the Results soft key and select Display Results in dBrn. Follow
the same steps to change back to displaying results in dBm.

Revision 9.0
February 2012
6Technical Assistance: 1-866-228-3762 [e-mail]
© 2012 JDSU. All rights reserved.
VDSL2 QUICK CARD
Wideband Testing - Wideband Noise
Purpose
Wideband noise should be < -50dBm on VDSL loops. at means -90 to -50 dBm.
NOTE1: e YELLOW bridge cable allows for spectral reading across a working VDSL loop and is an optional high impedance
cable.
NOTES: