MT1-2 2022 SCTE

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How many states does the binary numbering system offer?

2

Line power supplies output:

60 VAC or 90 VAC

A modulation scheme that depends on varying amplitude sidebands is called:

Amplitude modulation

The bridge rectifier and filter capacitor convert the AC input voltage to:

An unregulated DC voltage

reliability of an HFC architecture increases ( Choose 2 )

As the number of active devices decreases As the number of customers decreases

A customers installation is not working correctly. Where should the first RF reading be taken?

At the wall plate

What is the problem associated with the donut constellation?

Coherent (discrete) interference

Frames are located at the _ layer of the OSI model.

Data-link

A way of multiplexing several groups of carriers at different frequencies onto a single piece of coaxial cable for transmission in the forward path

FDMA

An analog signal uses AM for video and this type of modulation for audio:

FM

A linear power supply is generally more efficient than a switching power supply

False

In a digital return, if you see activity above the normal upstream band, it must be laser clipping

False

Laser clipping distortion products on the upstream are confined to the normal upstream frequency range in all cases

False

True or false: when coax lines are close together, the signal from the locator is induced onto the parallel conductor making accurate location easy.

False

True or false: when no RF is available at a set top box or cable modem, check levels at the station cabinet or tap plate.

False

The number of waves that pass a fixed point per unit of time defines:

Frequency

A modulation scheme that varies the frequency of a carrier is called:

Frequency modulation

A line power inserter has

Three ports

MPEG specifies different degrees of compression vs. quality by specifying

profiles and levels

What is the common stream type for MPEG - 2 video ?

02

What is the channel bandwidth of a return signal?

1.6 MHz 3.2 MHz 6.4 MHz

1011 is equivalent to a decimal____

11

Which is the TSID for video?

1110 1111

As per the module, how many cable channels fall into the LTE spectrum?

18

Which is NOT an access method used by cable operators in the upstream portion of the network?

Quadrature Phase Shift Keying

The output of a line power supply is a:

Quasi-square wave

Name a way of multiplexing seceral groups of carriers at different slots onto a single piece of coaxial cable for transmission in the return path. (Allows cable modems to communicate with the CMTS)

ATDMA/ TDMA/ SCDMA

Which MPEG - TS field is concerned with the 27MHz program clock reference ?

Adaptation

Which is NOT an issue to consider when preparing a network for new or additional upstream signals ?

RF channels are shared by means of modulation

A signal leakage reading of 5 uV/M at 271 MHz has been detected from 30 feet away. What should you do?

Re-measured from a distance of 10 feet

What is the first step of A / D conversion ?

Sample

What is the first step of A/D conversion?

Sample

A_ is a device that is used to measure the amplitude of a forward path signal

Signal level meter

What statement describes a PMT ?

This entry contains the PID values of each of the elementary streams ( video audio , data ) which make up a program

Which statement describes a PMT?

This entry contains the PID values of each of the elementary streams (video, audio, data) which make up a program

Typical switching power supply switching frequencies are in the:

KHz range

Which of the following is NOT an off air user of the return path RF spectrum?

LTE

Which of the following is NOT a general recommended procedure for making return path measurements on cable systems?

LTE leakage characterization

What is going on with the constellation?

Too much noise, interference, or non-linearity

Output current limit prevents damage due to a failure that draws excessive current from the power supply

True

The 115 VAC power input to a line power supply has a peak voltage higher than 115 volts.

True

The antenna radiation pattern changes based on the antenna type used for leakage detection

True

True or False : BER is defined as the ratio of bits containing errors relative to the number of bits sent and received in a given time interval .

True

True or false: Modulation symbol rate is sometimes called the baud rate

True

True or false: Modulation symbol rate is sometimes called the baud rate.

True

True or false: in upstream modulation, 6 bits per symbol is known as 64 QAM

True

An architecture in which a common signal source is distributed to many municipalities is referred to as :

Point to Multi - point

What is the DOCSIS specified maximum group delay variation?

200 an/MHz

Analog leakage detectors are designed with a very narrow measurement bandwidth making them undabke to measure digital leakage. What is the bandwidth that can be measured by an analog leakage dectector?

25 KHz

The color burst signal is __ MHz above the video carrier

3.58 MHz

The audio carrier in an NTSC channel is located _MHz above the video carrier .

4.5

What is upstream frequency range for a high - split architecture ?

5 to 200 MHz

Whag is the return path spectrum used by a non-EuroDOCSIS sub-split architechture?

5 to 42 MHZ

Digital channels are typically carried___ lower in power than analog channels.

5 to 6 dBmV

What is the symbol rate of 256 QAM ?

5.36 MS / s @ 6MHz and 6.95 MS / d @ 8MHz

Analog PAL uses a channel bandwidth of 8 MHz and analog NTSC uses a channel bandwidth of__ MHz

6

What is the bandwidth of a signal with an upper frequency limit of 275MHz and lower frequency limit of 267MHz ?

8 MHz

How many symbol bits are in a 256 QAM ?

8 bits / symbol

How many symbol bits are in a 256 QAM?

8 bits/symbol

What are the components of an MPEG - 2 macroblock ?

8 x 8 blocks

When using the divide and conquer (or half split method) troubleshooting method, if the signal level at a tap indicates a signal level below minimum, the next place to check would be:

The output of the amplifier upstream

What type of filter blocks a band of frequencies?

Band rejection filter

Which MPEG frame type offers the best compression ratio ?

Bi - directional frame

Which of the following would best indicate that excessive upstream attenuation is present?

Cable modem transmit power at the maximum

When using a VOM on a feeder/distribution coax, the amount of resistance measured in ohms across the center conductor and outer metal shield when a short circuit is present will likely be:

Close to zero

What is the optical form of FDM in the return path?

WDM

When using a handheld digital signal analyzer (H-DSA) or signal level meter (SLM) the difference between an analogs video and audio carrier levels are expressed as a ratio of dB called the:

Delta

What is one of the primary reasons why LTE cellular service is impacted by digital leakage?

Digital leakage looks like boise that effectively covers the entire LTE spectrum

Why is digital leakage hard to measure?

Digital leakage looks like white noise Loss of measurement sensitivity at 6MHz bandwidth

Wht type of antenna has a gain of 2.14 dB?

Dipole

An HFC network is typically designed with :

Fewer active devces as compared to a tremand branch system architecture .

The HFC access network is similar to the coaxial tree and branch topology except that long coaxial trunk runs are replaced by ___links .

Fiber

The technique of varying the ___of a carrier based on the characteristics of the baseband signal by referencing two carriers .

Phase

Contains the optical reciever which recieves the light from the outside plant optical return transmitter.

Headend

Which return / forward split offers the most amount of upstream bandwidth ?

High

Which interference type is more likely to lead to upstream laser clipping if the laser has insufficient margin for interference?

Impulse and/or burst noise

Which of the following is NOT a stationary impairment on the return path?

Impulse/ burst noise

The resistance of a short piece of coax cable will read approximately ___ on an ohm-meter.

Infinity

The technique of varying the of a carrier based on the characteristics of the baseband signal by referencing two carriers .

Phase

How might you observe laser clipping with a spectrum analyzer on a fully loded upstream network?

Look for activity out of band above the upstream maximum frequency

Which ATSC PSIP base table extensions provides version , size and carries PIDs for all other tables ?

MGT

One million Hz is

MHz

Which of the following is the best way to prevent aliasing of measurements with digital oscilloscopes?

Make sure the sample rate is at least twice the maximum bandwidth of the input signal

What are two aspects of a dipole antenna that can be used for directional information?

Maximum gain portion of the radiation pattern and the null point

Which 2 way RF configuration uses 104 MHZ up to 1000 MHZ for the downstream?

Mid-split

Audio and video information are superimposed on an RF carrier by a process called:

Modulation

What is the name of the headend or hub device that produces 6 MHZ QAM signals ?

Modulator

What is the name of the headend or hun device that produces 6MHz QAM signals?

Modultor

Layer 3 of the OSI model is called __

Network

Layer 3 of the OSI model is called__

Network

What is the table that has a PID value of Ox1FFF ?

Null

A crowbar circuit monitors

Output voltage

Which MPEG frame type uses data from the previous frames to reconstruct the MPEG video ?

P - frame

What does the controller in a switching power supply vary in order to control the output voltage?

Switching frequency and duration

What is the designation used by cable operators for a digital signal frequency (e.g., QAM)?

The center frequency

What is the initial indicator used by LTE service providers to determine that a cell site has interference?

The uplink recieved strength signal indicator (RSSI)

Which of the following measurments is not provided by proactive network maintenance technology?

They are all provided by PNM technology

How could you determine if a raised noise floor on the lower upstream frequencies is there continuously or only intermittently?

Use a sampling oscilloscope and do an FFT on the samples between strong impulses.

Impulse noise is caused by:

Vehicle ignitions, neon signs, static from lightning, power line switching transients, household appliances.

After connecting the drop to the set top box, no digital picture appears on the TV. What course of action should be down next?

Verify hookup- component, HDMI, composite, etc


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