Distribution System Passive Devices

The RF signal level at the input to a tap plate is 30dBmV. You measure 15dBmV at the tap port of a tap plate. What is the dB loss value of this tap plate?

15

For a four-way splitter, what percentage of the original input power is available at output port?

25%

Levels attenuate by about ____ dB at each split of a tap plate or splitter bank.

3.5 db

What is the typical loss for a two-way splitter?

3.5 db

What is the typical loss for a four-way splitter?

7 db

what is a passive device?

A passive device does not need electricity to perform its functions.

Hybrid Fiber Coax (HFC)

Hybrid fiber-coax (HFC) is a common cable network that allows customers to access cable operator networks using a combination of optical fiber and coaxial cable.

Insertion loss

Insertion loss is the RF loss from the input port to the output port of an RF device.

power inserters

Power inserters are used to inject AC power onto the coaxial cable.

Name a gasket that is designed to prevent RF signals from entering (ingress) or leaving (egress) a closed housing such as a power insert or amplifier.

RF integrity

splitter isolation

The amount of attenuation between the two output ports

What device passes AC signals and block DC sources?

capacitor

tap back housing

contains the seizure mechanisms that connect to the feeder hardline coax

tap faceplate

contains the tap electronics and tap ports for connection to sub drops

addressable taps

devices that allow a system operator to remotely connect or disconnect signals from individual tap ports. The tap is controlled by means of an RF data carrier that is sent through the HFC network. An RF receiver inside the addressable tap receives and decodes this signal. Each addressable tap port is given a unique numerical address that allows the operator to command them individually.

Name a passive uneven or unbalanced RF splitting device, with low loss from input to output port (insertion loss).

directional coupler

What passive devices are combined to create a tap?

directional coupler and splitter

True or False: Feed-through and addressable are two types of directional taps used in one type of HFC architecture.

false

rfi gasket

help prevent leakage of RF signals, into and out of the tap

weatherproofing gasket

help to seal the tap from water and other contaminants

What device is used to compensate for down-tilt?

in-line equalizer

What is the loss of signal between the input and output port of a directional coupler called?

insertion loss

power passing taps

pass ac power between the input, output and tap ports. sometimes done to power electronics at the cx premises, like telephone interfaces or powering wifi hotspots. routing plugs or jumpers permit the selection of which ports pass the aca power. also called telephony taps.

What is the name of the isolation between the tap plate ports, designed to prevent interfering RF signals from neighboring customer signals to move between ports?

port to port isolation

This device facilitates adding AC power from a line power supply (LPS) onto coax cable while also allowing RF signals to pass along the same cable.

power inserter

Active devices such as amplifiers in an HFC contain devices to:

separate an AC signal from an RF signal

conditioner

similar in function to an equalizer but offers the ability to individually equalize downstream and upstream signals

in-line equalizer

standalone passive device that contains equalization without gain. adjust signal level across the hfc frequency band.

isolation loss

the loss between the output port and the coupled port, or equivalently the loss between the coupled port and the output port. Typical isolation values are 25 dB or greater. Most directional couplers designed for outdoor use in HFC networks will pass AC power between two or more of the ports. The maximum rated AC current is specified for such couplers. Isolation prevents interference produced by one subscriber's terminal from affecting another subscriber's service.

coupled loss

the loss from the input port to the coupled port or from the coupled port to the input port. Directional couplers are categorized by the coupled loss. For example there are 9 dB directional coupler, 12 dB directional couplers and so fourth. Note that as the coupled loss decreases, the insertion loss increases.

An RF splitter is an electrical circuit that takes a radio frequency signal that is applied to the input port and splits it between the two output ports. Since the power levels of the split RF signals at the two outputs are equal in amplitude, the splitter is said to be a balanced device.

true

General rule #1, capacitors pass AC signals and block DC sources. General rule #2, inductors pass DC signals and block AC sources.

true

In the early days of CATV and HFC systems, all electronics at the subscriber premises were powered by the subscriber. This is changing with the advent of power passing taps.

true

bypass bar

used to keep services downstream functioning during a face plate swap. electrically connects the tap input and output ports when the faceplate is removed. disconnected when the faceplate is installed.