NICET ITWBS Level III key terms

An in-building device that receives radio signals from a donor site and retransmits them inside a building while also carrying portable radio transmissions back out to the donor. It amplifies both paths at once.

A general category of amplifier system that improves coverage inside a structure by taking an existing outdoor signal and repeating it indoors. It includes channelized and broadband designs and must meet code and licensing rules.

A network of remote antennas fed from a common head-end so that radio coverage is spread evenly across a building. It serves one or more frequency bands and may be fed by a BDA or a base station.

A DAS in which the head-end converts radio signals to optical signals and sends them over fiber to remote units, then back to radio at each remote. Fiber allows long cable runs with low loss.

The central equipment location of a DAS or BDA system where donor signals are received, conditioned, and distributed. It typically houses the master unit, power supplies, and monitoring or alarm equipment.

The main electronics chassis in a BDA or DAS head-end that filters, amplifies, and splits signals between the donor side and the distribution side. It often includes control and alarm reporting functions.

A device located out in the building that converts the signal from the head-end back to radio frequency and feeds local service antennas. It may also amplify uplink signals returning to the head-end.

The antenna that points at an outdoor cell site or public safety radio site and links the in-building system to that outside network. Its aim and isolation strongly affect system performance.

An antenna inside the building that radiates amplified signals to and receives signals from portable radios used by occupants and responders. Multiple service antennas are usually needed for even coverage.

The amount of signal path loss between the donor antenna and the service antennas. Too little isolation lets amplified output feed back into the input, causing oscillation or self-interference.

A runaway feedback condition in which a booster's amplified output is picked up by its own input and re-amplified repeatedly. It can shut the system down or interfere with the donor network.

Circuitry that automatically reduces amplifier gain when input signals are strong, preventing overload and distortion. It helps the system adapt to changing signal levels at the donor site.

The radio spectrum reserved for emergency responders, such as VHF, UHF, 700 MHz, and 800 MHz land mobile allocations. In-building systems must support the specific bands used by local agencies.

Terrestrial two-way radio systems used by public safety agencies, typically operating in VHF, UHF, 700 MHz, or 800 MHz bands. LMR is the primary voice communications technology for most responders.

A family of digital LMR standards that lets equipment from different manufacturers interoperate. Many public safety in-building systems must pass P25 digital signals without distortion.

A nationwide public safety broadband network built on LTE technology and dedicated to first responders. In-building designs sometimes must accommodate its frequencies alongside traditional LMR bands.

A defined range of radio frequencies used for a particular service or system. In-building designs are usually band-specific because antennas, amplifiers, and filters are tuned to those ranges.

The range of frequencies a filter or amplifier lets through with little loss. Signals outside the passband are attenuated, which helps reject unwanted interference.

A component that passes desired frequencies while blocking others. In public safety boosters, filters keep the system from amplifying unauthorized or interfering signals outside its assigned band.

A signal booster that amplifies only specific narrow channels rather than a whole band. It reduces interference and is often required where band-wide amplification could disrupt nearby systems.

A booster that amplifies an entire frequency band at once rather than individual channels. It is simpler but can amplify unwanted signals and cause more interference if not well isolated.

The radio signal strength and quality available inside a structure for portable and mobile radios. Designers verify it so responders can communicate reliably in stairwells, basements, and remote rooms.

The physical space within a building where the communications system must provide acceptable signal. It is usually defined on floor plans and drives antenna placement and power budgets.

A numeric scale describing how intelligible received voice audio is, ranging from unusable to clear. Acceptance testing often requires a minimum DAQ score across the coverage area.

A method of verifying in-building coverage by measuring signal at points on a planned grid of the floor plan. Results are compared against the design criteria and pass/fail thresholds.

The formal measurement process used to show that an installed system meets the design and code requirements. It is typically witnessed by the authority having jurisdiction before the system is approved.

The official or agency responsible for enforcing code requirements and approving the installed system. AHJs may be fire marshals, building officials, or radio system managers.

A mandatory rule adopted by a jurisdiction, such as a building or fire code that mandates public safety radio coverage in certain structures. It defines performance, testing, and documentation obligations.

A consensus standard covering emergency communications systems and radio coverage for responders, including requirements for in-building two-way radio systems. Designers and AHJs often reference it in local code.

Formal authorization from a jurisdiction to install a communications system. Permit applications usually require design drawings, calculations, and equipment specifications before work begins.

A drawing updated to show the system as actually installed, including final device locations and cable routes. It is commonly required for closeout and future maintenance.

The process of verifying and adjusting a newly installed system so it performs as designed before handover. It includes functional checks, gain settings, alarm testing, and documentation.

Supervision of a booster or DAS for faults such as loss of power, low output, or oscillation. Alarms may report locally or remotely so failures are corrected quickly.

The reduction in signal strength as radio frequency travels along a coaxial cable, increasing with length and frequency. Designers account for it when planning antenna runs and power budgets.

A calculation that adds gains and subtracts losses along a signal path to predict received power. It helps designers confirm that coverage targets will be met before installation.

Unwanted radio energy emitted outside the intended operating band. Boosters must limit it to avoid interfering with other radio services and to comply with licensing conditions.

Unwanted radio energy that degrades reception or transmission. In-building systems can both suffer from and cause interference, so isolation and filtering are critical.

The fraction of transmitted digital bits received incorrectly. For P25 systems it is a key measure of signal quality and is often tested alongside voice intelligibility.

A measure of how cleanly a digital radio signal is received, reflecting errors and distortion. It matters for P25 voice and data because low quality can cause dropped or garbled calls.