1. Plant Hardening
August 2008

2. Architecture

3. Service Deployments Issues / Concerns Current Plant Performance
“There will be operational challenges.”
Costs
Current Plant Performance
Connections
Operating Signal Levels
Plant quality
Technology changes and the effect on plant performance
Line conditioning tools

4. Operational Costs $135,000 fixing the plant Example:
15,000 subscribers
4,500 annual service calls (30%)
$337,500 per call)
1,800 related to the drop plant (40%)
$135,000 fixing the plant
Kajola-Kristada

5. Changing Modulation Schemes
Service Calls
Changing Modulation Schemes
Increasing the modulation scheme will carry more data in the same bandwidth
QPSK to 16 QAM to 32 QAM
64 QAM to 256 QAM and beyond….
Increasing the modulation scheme demands improved performance in the system to obtain similar results
From QPSK to 16QAM theoretically demands an additional 4-6dB noise improvement
Signal levels can be adjusted to overcome the CNR but this may have significant negative effects on the distortion parameters.

6. Why does performance need to improve?
Increasing subscriber penetration for 2 way digital services decreases C/N and increases MER
Less BW per subscriber requires advanced modulation techniques to deliver more
Network requires better performance to deliver the same quality
BER
50%
40%
30%
20%
CNR
Kajola-Kristada

7. Increasing the modulation scheme requires additional headroom above the threshold.
Strong / Good
Good Video (forward path)
BAD High Speed Data
NO VoIP
Functional
Operating Level
Carrier to Noise
BER
Service Threshold with 16 QAM
Intermittent
Service Threshold with QPSK
No Service
Weak / Poor
5 MHz Return Band Frequency 42 MHz

8. Why it may be a challenge
Strong / Good
Ingress – Typically limits the
upstream of the 5-15 MHz range
Functional
Operating Level
Intermittent
Service Threshold
No Service
Weak / Poor
5 MHz Return Band Frequency 42 MHz

9. Plant RF Impairments Micro-Reflections; Ingress Noise;Group delay; CPD
Good Video
Slower High Speed Data
Functioning VoIP
Strong / Good
Functional
Operating Level
VoIP / HSD
Carrier
Intermittent
VoIP / HSD
Carrier
Service Threshold
No Service
Weak / Poor
5 MHz Return Band Frequency 42 MHz

10. Slow or No High Speed Data
Plant Issue’s Water Migration, Poor Installation Practice, Connection Issue’s
Strong / Good
Corrected
Functional
Operating Level
Good Video Possible
Slow High Speed Data or..
Intermittent VoIP
Connector Issue
VoIP / HSD
Carrier
Good Video Possible
Slow or No High Speed Data
No VoIP
Intermittent
Service Threshold
No Service
Weak / Poor
5 MHz Return Band Frequency 42 MHz

11. Ingress degrades quality lowering threshold.
Significantly effects forward error correction which results in packet loss and loss of connection for VoIP (high speed data as well)
It is caused by
Craft errors
Damaged cable / connectors
Un-terminated ports
Poor RF shielding on components
Moisture penetration
Strong / Good
Functional
Operating Level
Service Threshold
Service Threshold
No Service
Weak / Poor
5 MHz Return Band Frequency 42 MHz

12. Ways to improve performance.
Segment the node by adding additional forward and return optics.
Improves Noise and Distortion
Increases BW per sub
CMTS and DOCSIS technology that lower the threshold
Use Line Conditioning Tools
Step Attenuators
Filters
Clean up (or harden) the plant
Add additional Return Bandwidth beyond 42 MHz and / or increase upper limit to 1GHz.
Kajola-Kristada

13. * Step 1 Functional Intermittent No Service Operating Level
Low value Tap, a step attenuator has been installed lowering the entire return band Noise / Ingress and Data Carrier(s)1
Strong / Good
Hub or Head end
Network
Docsis Modem – Fwd Receiver and Return Data Carrier
Functional
CMTS
Operating Level
Carrier to Noise
BER
Example:
12 dB Step Attn
Intermittent
Service Threshold
No Service
Weak / Poor
5 MHz Return Band Frequency 42 MHz

14. Line Conditioning Step Attenuators * Step 2
The CMTS “Auto Level” will turn up the Data Carrier to the original level no longer impaired by the ingress.
Strong / Good
CMTS
Network
Docsis Modem – Fwd Receiver and Return Data Carrier
Functional
Operating Level
Carrier to Noise
BER
Example:
12 dB Step Attn
Intermittent
Service Threshold
No Service
Weak / Poor
5 MHz Return Band Frequency 42 MHz
Kajola-Kristada

15. Plant Hardening Plant Hardening Hardline Drop General Comments
Impedance, Micro-Reflections
CPD
Hardline
Drop
General Comments

16. Customer Experience

17. Customer Experience

18. Operating Condition
Snug It Up
Kajola-Kristada

21. Signal reflections occur throughout the cable plant and are called micro-reflections.
They are caused by the individual slight errors in impedance match.
The severity of the mismatch is measured by the magnitude of the return-loss ratio.
The larger the return loss, the better, perfection is infinite.
Mismatches may include connectors, mis-installed products, poor construction and damaged cable.
For example - If a lousy splice block is installed approximately 150 feet past an amplifier.
The splice, which may only have a 12 dB return loss, reflects signals back upstream that has been attenuated by 13.5 dB (1.5 dB in cable attenuation plus the return loss of the splice).
The reflected signals then arrive back at the output of the amplifier attenuated by a total of 15 dB (1.5 dB additional cable loss for the upstream trip plus the previous 13.5 dB).
The signals are now reflected by the amplifiers output mismatch, A return loss of 16 dB is common.
At this point, the reflected signal has an amplitude that is 31 dB below the primary signal and delayed by the round-trip propagation through 300 feet of cable, which takes about 350 ns.
The signal is horizontally delayed approximately 1/7 inch on a 27-inch television set.
This is not enough to become a visible ghost or second image.
However, depending on the relative phases of the RF carriers of the primary and reflected signal,
the visual effect may be enough to cause a softening of a previously well-defined luminance
level transition.
With repeated mismatches, the crispness of the pictures may be noticeably
reduced.
This softening effect is easily seen on displays of character-generated text pages.
Kajola-Kristada

22. CPD Common Path Distortion, also known as PIM: Passive InterModulation
Only occurs where downstream and upstream share the same path
Amplifier, Tap, and Passive ports
It is a diode effect that creates intermod products usually at 6 MHz intervals
Accentuated with higher signals

23. What causes CPD? Contact problems cause non-linear effects:
Oxidized contact surfaces
Contaminated contact surfaces
Too low contact pressure
Loose components

24. Ref. Level
500 kHz
15 MHz
25 MHz
12/05/2004

25. Plant Trouble Calls
Kajola-Kristada

26. Hardline Cable is defined Connector to equipment interface is defined
Connector to cable interface defined

27. Hardline Cable Prep
“A” – Center Conductor
“B” – Core Depth
“X” and “Y” – No Burrs or Rough Edges

28. Typical Hardline Connector Retention Forces
Cable Size
Center Conductor Force (lbs)
Outer Conductor Force (lbs)
Combined Force (lbs)
100
250
400
150
350
500
.565
175
575
.625
200
600
.700
225
425
650
.715
.750
450
700
.840
275
475
750
.860
315
480
795
.875
300
800
1.000 – 1.125
950
1.160
375
1025
Typical Hardline Connector Retention Forces

30. Drop The cable is defined The connector male and female is defined
Established test procedures for electrical, mechanical and environmental performance.

32. Architecture In-House
Modem Fwd
and Ret Levels
Ground block to code
Old TV
Appliance Noise
Off Air signals
Architecture In-House
DC Motor Noise
AC Unit
Florescent Lights
Cordless Phone
Video Games
Fan Motor Noise
Cable Damage
Hardening

33. Summary Improving the Network
Tighten the plant
Line Conditioning
Reducing Node Sizes
CMTS / DOCSIS advancements
The Drop Plant may very well still be the weakest link.
Connections (Moisture and Loose connectors) cost $$
F-Connectors, F-81’s, Terminators

34. Thanks