Anga 2013 v2

Brady Volpe

Massive Traffic Growth

The “terabyte club” will reach 6 million by 2015

There will be over 20 million households generating half a terabyte per month in 2015

-‐Cisco Visual Networking Index: Forecast and Methodology, 2010-‐2015

• Need: 1 Gbps bi-‐direcHon pipe in five years • Need more digital – Less Analog :: No Analog!

© The Volpe Firm ConfidenHal

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Digital vs. Analog


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Simple Headend Best PracHces •  Separate amplificaHon for analog & digital •  No amplificaHon for DOCSIS •  No amplificaHon for AGC pilot signals !! ▫  Lose pilot – lose plant & DOCSIS

•  Minimize combining & cable runs ▫  eQAMs & dense CMTSs will have low output power •  Do use forward path monitoring on QAMs


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Analog Impairments •  For each 1 dB increase in system carrier levels:

•  CTB raHo degrades by 2 dB •  CSO raHo degrades by 1 dB •  CNR improves by 1 dB


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CTB CSO

Noise Floor

Visual carriers Aural carriers

Digital DistorHons – CIN & CCN •  For each 1 dB increase in system carrier levels: ▫  CNR behaves as before with all-‐analog operaHon ▫  CIN raHo degrades by 1 to 2 dB (mix of 2nd & 3rd order) ▫  CCN raHo degradaHon depends on CIN and CNR values ▫  See ANSI/SCTE 17 2007


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Thermal noise

CCN

CIN

Visual carrier

Aural carrier

QAM Channels

Sweep


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Standing Waves

Roll off at band edges

Misalignment

Space Between QAM Channels Small


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No Sweep Points 8 MHz BW

No Sweep Points 8 MHz BW

• One sweep point every 8 MHz • No sweep points under QAM

•  A lot can happen between QAM channels!

Some Examples


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Loose seizure screw on amplifier

Corrosion on seizure screw in amplifier causes standing wave

•  Suckouts, standing waves, LTE, and other impairments more difficult with standard sweep

Sweepless Sweep – How it Works •  Compares headend levels to outside plant levels

• No sweep injecHon signals (non-‐interfering)

•  Less expensive, no headend unit, just meter


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Sweepless Sweep


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Sweepless Sweep System Problems


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Digital Levels •  Cable Modem or Set Top Box ▫  Ideal Downstream RF Input: 60 dBuV (0 dBmV) ▫  Recommended RF Input: 55 – 65 dBuV (±5 dBmV) ▫  Worse Case RF Input: 50 – 70 dBuV (±10 dBmV) ▫  Never exceed total power: 90 dBuV (30 dBmV) •  Too high or too low causes receiver demod issues

•  Recommended Tx levels for opHmum CNR: ▫  100 – 110 dBuV (40 – 50 dBmV)


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Summary •  Cable networks are moving from analog to digital •  CTB, CSO, etc. turn into noise (CIN) •  Sweep systems may need to be upgraded •  Correct digital levels at end devices are criHcal ▫ May require new test equipment

•  It’s a great Hme to be in cable!


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Brady Volpe [email protected]

Anga 2013 v2

Business

Transcript of Anga 2013 v2