BDS RF Technology and Spectrum Management 2

Question 1

What is the mid-split upstream frequency range proposed for DOCSIS 3.1 Extended Spectrum?

Accepted Answer

5–85 MHz

Answer

Mid-split architecture extends the upstream return path from the traditional 5–42 MHz sub-split to 5–85 MHz, providing additional upstream capacity for operators upgrading their plants.

Question 2

A cable technician measures excessive composite triple beat (CTB) distortion. What is the most likely cause?

Accepted Answer

Amplifiers being driven beyond their linear operating range

Answer

CTB distortion is caused by third-order nonlinearities in amplifiers that are over-driven; reducing the output level or increasing the amplifier's operating headroom will reduce CTB products.

Question 3

What is the function of an equalizer in a cable amplifier?

Accepted Answer

To pre-emphasize higher frequencies to compensate for the frequency-dependent attenuation of coaxial cable

Answer

Cable attenuation increases with frequency, so equalizers pre-tilt the frequency response at the amplifier input to compensate, ensuring a flat response at the amplifier output.

Question 4

What is the DOCSIS 3.1 maximum downstream channel width for an OFDM channel?

Accepted Answer

192 MHz

Answer

DOCSIS 3.1 OFDM downstream channels can be up to 192 MHz wide, dramatically increasing capacity compared to the 6 MHz QAM channels used in earlier DOCSIS versions.

Question 5

What is PNM (Proactive Network Maintenance) in a DOCSIS 3.1 cable system?

Accepted Answer

Tools and techniques that use built-in DOCSIS measurement capabilities to detect impairments before subscribers are affected

Answer

PNM leverages DOCSIS 3.1 wideband spectrum analysis and pre-equalization data from cable modems to proactively identify and locate network impairments before they cause service outages.

BDS - Broadband Distribution Specialist Practice Test

BDS - Broadband Distribution Specialist Practice Test

BDS RF Technology and Spectrum Management 2