SBE Certified Broadcast Technologist (CBT) — Questions and Answers

Question 1: What is the primary purpose of a playout automation system in a broadcast facility?

To automatically repair corrupted media files before air
To automatically generate closed captions for all content
To automate signal routing between studio and transmitter
To control the scheduling and playback of programming, commercials, and graphics without manual operation (Correct answer)

Correct answer: To control the scheduling and playback of programming, commercials, and graphics without manual operation

Playout automation systems control the sequenced playback of video content, commercials, and graphics according to a programmed schedule, reducing the need for manual operator intervention.

Question 2: What is the significance of the vertical interval in a video signal for broadcast switching?

It contains the color burst reference and must be protected during transmission
It is the blanking period between video frames, the preferred point to perform clean video switches (Correct answer)
It determines the frame rate of the video signal and cannot be altered
It carries closed caption data and cannot be used for switching

Correct answer: It is the blanking period between video frames, the preferred point to perform clean video switches

The vertical interval is the blanking period between frames; switching during this interval avoids visible glitches because no active picture data is being transmitted.

Question 3: What is the time constant of a circuit with a 10kΩ resistor and a 100μF capacitor?

0.1 seconds
1 second (Correct answer)
10 seconds
0.01 seconds

Correct answer: 1 second

The RC time constant τ = R × C = 10,000Ω × 0.0001F = 1 second.

Question 4: Which protocol is used to synchronize clocks in an IP broadcast facility to sub-microsecond accuracy for SMPTE ST 2110?

PTP (Precision Time Protocol) IEEE 1588 (Correct answer)
GPS pulse-per-second only
NTP (Network Time Protocol)
SNTP

Correct answer: PTP (Precision Time Protocol) IEEE 1588

PTP IEEE 1588 provides the sub-microsecond synchronization required for sample-accurate media transport in professional IP broadcast environments.

Question 5: Which of the following items is a broadcast station required by the FCC to maintain in its Public Inspection File?

A log of all music played during the last calendar year
Employee payroll records
Quarterly lists of programs that have provided the most significant treatment of community issues (Correct answer)
Detailed schematics of the main broadcast transmitter

Correct answer: Quarterly lists of programs that have provided the most significant treatment of community issues

The FCC requires all broadcast stations to prepare and file a quarterly list of programs that have addressed issues of importance to their community. This is a key component of the Public Inspection File, which must be accessible to the public. The other options are not required to be in the Public Inspection File.

Question 6: In an ATSC 3.0 broadcast system, what is the role of the bootstrap signal?

It controls transmitter power output
It provides receiver synchronization and system discovery information (Correct answer)
It carries the primary audio essence
It encodes closed-caption data

Correct answer: It provides receiver synchronization and system discovery information

The ATSC 3.0 bootstrap signal allows receivers to synchronize with the OFDM signal and discover system parameters without prior knowledge of the configuration.

Question 7: A technologist measures -10 dBu on an unbalanced consumer audio output but expects +4 dBu on a balanced professional input. What device is needed to interface them correctly?

Noise gate
Equalizer
A/D converter
Active balun or line-level matching transformer (Correct answer)

Correct answer: Active balun or line-level matching transformer

A balun or active matching device converts the unbalanced consumer level to balanced professional level, correcting both impedance and level differences.

Question 8: What is the primary purpose of a transmission line in a broadcast RF system?

To transfer RF energy from the transmitter to the antenna with minimal loss (Correct answer)
To filter out unwanted harmonics in the transmitted signal
To match the antenna impedance to the studio equipment
To amplify the RF signal before it reaches the antenna

Correct answer: To transfer RF energy from the transmitter to the antenna with minimal loss

A transmission line's primary role is to efficiently transfer RF energy from the transmitter output to the antenna while minimizing losses due to reflection and attenuation.

Question 9: A television station's tower is located in a remote area and its monitoring system fails at 10 PM, causing the top beacon to extinguish. According to FCC regulations, what is the most critical immediate action required?

Notify the station's General Manager within one hour.
Report the outage to the Federal Aviation Administration (FAA) if it lasts more than 30 minutes. (Correct answer)
Dispatch a technician to the site as soon as possible.
Log the failure in the station log at the start of the next business day.

Correct answer: Report the outage to the Federal Aviation Administration (FAA) if it lasts more than 30 minutes.

FCC Part 17 rules, which incorporate FAA standards, require that any failure of a top light or flashing obstruction light lasting more than 30 minutes must be reported to the FAA. This allows for a Notice to Airmen (NOTAM) to be issued, ensuring aviation safety. While logging the event and dispatching a technician are also necessary, the immediate safety-critical step is notifying the FAA.

Question 10: Which system must broadcasters test regularly for national safety compliance?

Weather radio service
Transmitter power control
Emergency Alert System (EAS) (Correct answer)
Building PA system

Correct answer: Emergency Alert System (EAS)

The Emergency Alert System (EAS) is a national public warning system that requires broadcasters to disseminate critical public safety information during emergencies. Broadcasters are legally mandated by the FCC to regularly test their EAS equipment and procedures to ensure its readiness and compliance, guaranteeing that vital alerts can be transmitted effectively to the public when needed.

Question 11: What is the impedance of a series RLC circuit at resonance?

Equal to the capacitive reactance
Equal to the inductive reactance
Zero
Equal to the resistance only (Correct answer)

Correct answer: Equal to the resistance only

At resonance, inductive and capacitive reactances cancel, leaving only the resistance as the circuit impedance.

Question 12: Which of the following electronic components is primarily used to amplify signals or act as an electronic switch?

Transistor (Correct answer)
Capacitor
Inductor
Resistor

Correct answer: Transistor

A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is a fundamental building block of modern electronics used in applications like amplifiers and digital circuits.

Question 13: A technician must work on equipment near the base of a high-power broadcast tower on a winter day. Besides being aware of RF fields, what is a critical physical hazard for which the technician must wear a hard hat?

Falling ice or equipment from the tower structure. (Correct answer)
Exposure to ultraviolet radiation.
Static discharge from the tower.
Loud noise from cooling fans.

Correct answer: Falling ice or equipment from the tower structure.

Broadcast towers can accumulate significant amounts of ice in winter, which can break off and fall, posing a serious impact hazard to anyone below. Similarly, tools or hardware could be accidentally dropped by climbers. Therefore, wearing a hard hat is a critical safety measure for protecting ground personnel from falling objects.

Question 14: Which network switch feature is most critical for efficiently managing multicast traffic in a media-over-IP environment by preventing streams from being sent to all network ports unnecessarily?

IGMP Snooping (Correct answer)
Spanning Tree Protocol (STP)
Link Aggregation (LACP)
Power over Ethernet (PoE)

Correct answer: IGMP Snooping

By default, a standard switch floods multicast traffic to all ports, which can overwhelm the network and connected devices. IGMP (Internet Group Management Protocol) Snooping allows the switch to 'listen' to the IGMP messages between devices and the router. The switch builds a table of which ports have devices that have requested a specific multicast stream and then forwards that stream only to those ports, drastically reducing unnecessary traffic.

Question 15: In broadcast engineering, what does ERP stand for and what does it represent?

Effective Resonant Power — power reflected by the transmission line
Equivalent Resonant Power — power at resonance frequency of the antenna
Effective Radiated Power — transmitter power multiplied by antenna gain relative to a dipole (Correct answer)
Effective Radiated Power — the actual power delivered to the antenna terminals

Correct answer: Effective Radiated Power — transmitter power multiplied by antenna gain relative to a dipole

ERP (Effective Radiated Power) is the product of the transmitter power fed to the antenna and the antenna's gain referenced to a half-wave dipole, representing the apparent power radiated in the maximum direction.

Question 16: Which component resists the flow of current in a circuit?

Transistor
Diode
Resistor (Correct answer)
Capacitor

Correct answer: Resistor

A resistor is a passive two-terminal electrical component specifically designed to resist the flow of electric current in a circuit. It introduces a controlled amount of electrical resistance, converting electrical energy into heat. Resistors are used to limit current, divide voltage, and terminate transmission lines, among other functions.

Question 17: Which unit is used to measure electrical resistance?

Volt
Ohm (Correct answer)
Ampere
Watt

Correct answer: Ohm

The Ohm (Ω) is the SI derived unit of electrical resistance, named after German physicist Georg Ohm. Resistance is a measure of the opposition to the flow of electric current in an electrical circuit. A higher resistance means less current will flow for a given voltage.

Question 18: What is the significance of the 'fence line' in RF safety planning around an AM broadcast antenna?

It marks the boundary beyond which the general population MPE limit must be met (Correct answer)
It defines the licensed coverage area of the station
It marks the point where grounding electrodes must be installed
It is only required for directional antenna systems

Correct answer: It marks the boundary beyond which the general population MPE limit must be met

The fence line around an AM antenna defines the boundary where uncontrolled (general population) RF exposure limits must be satisfied to protect the public.

Question 19: Which logic gate produces a HIGH output only when all inputs are HIGH?

NOR gate
AND gate (Correct answer)
NAND gate
OR gate

Correct answer: AND gate

An AND gate outputs HIGH (logic 1) only when all of its inputs are simultaneously HIGH.

Question 20: A broadcast facility is implementing a new IP-based video system to distribute a single live camera feed to 25 separate monitoring destinations within the plant. Which IP transmission method is the MOST efficient for this purpose?

Anycast
Multicast (Correct answer)
Broadcast
Unicast

Correct answer: Multicast

Multicast is the most efficient method because the source sends a single packet stream to a specific multicast group address. Network switches then intelligently replicate the stream only to the ports connected to devices that have requested to join that group, saving significant bandwidth compared to other methods.

Question 21: What phenomenon occurs when a signal in one conductor induces a signal in an adjacent conductor?

Skin effect
Crosstalk (electromagnetic coupling) (Correct answer)
Common-mode rejection
Impedance mismatch

Correct answer: Crosstalk (electromagnetic coupling)

Crosstalk is the undesired inductive or capacitive coupling of a signal from one conductor into an adjacent conductor.

Question 22: Which of the following statements best describes the fundamental principle of the SMPTE ST 2110 suite of standards for professional media over IP networks?

It separates video, audio, and ancillary data into individual, independently-timed essence streams over IP. (Correct answer)
It is primarily designed for transmitting compressed video over the public internet to consumers.
It uses a proprietary compression algorithm to transmit 4K video over standard 1 Gigabit Ethernet networks.
It encapsulates the entire SDI signal, including video, audio, and data, into a single IP stream for simplified transport.

Correct answer: It separates video, audio, and ancillary data into individual, independently-timed essence streams over IP.

The core concept of SMPTE ST 2110 is the separation of video, audio, and ancillary data into individual 'essence' streams. Each stream is independently packetized and timed using Precision Time Protocol (PTP), which provides immense flexibility in routing and processing signals within a production environment.

Question 23: In a parallel RC circuit, what happens to total impedance as frequency increases?

Impedance increases
Impedance remains constant
Impedance decreases (Correct answer)
Impedance becomes purely resistive

Correct answer: Impedance decreases

As frequency rises, capacitive reactance decreases, reducing the overall parallel impedance of the RC circuit.

Question 24: What does the term 'group delay' refer to in the context of broadcast transmission equipment?

The startup delay of a backup transmitter
The latency added by a frame synchronizer
The variation in propagation delay across different frequencies through a filter or circuit (Correct answer)
The delay introduced by a buffer in an IP stream

Correct answer: The variation in propagation delay across different frequencies through a filter or circuit

Group delay is the rate of change of phase with frequency; non-constant group delay causes different frequency components to arrive at different times, distorting the signal.

Question 25: According to Kirchhoff's Current Law (KCL), what is the relationship of currents at a junction (or node) in a circuit?

The total current leaving a junction is equal to the total current entering it. (Correct answer)
The current is the same through all components in any circuit configuration.
The total current entering a junction is greater than the total current leaving it.
The algebraic sum of all voltages around a closed loop is zero.

Correct answer: The total current leaving a junction is equal to the total current entering it.

Kirchhoff's Current Law (KCL) is based on the conservation of charge and states that the algebraic sum of currents entering a junction must equal the algebraic sum of currents leaving that junction.

Question 26: Which law states that the algebraic sum of currents at any node in a circuit equals zero?

Kirchhoff's Current Law (Correct answer)
Kirchhoff's Voltage Law
Ohm's Law
Faraday's Law

Correct answer: Kirchhoff's Current Law

Kirchhoff's Current Law (KCL) states that the sum of currents entering a node equals the sum of currents leaving it.

SBE Certified Broadcast Technologist (CBT)

The CBT exam, administered by the Society of Broadcast Engineers, certifies technicians on the technical knowledge required to operate and maintain broadcast equipment across AM/FM and TV systems. It covers broadcast systems, RF transmission, digital standards, FCC regulations, and safety.

Questions

45 min

Time Limit

70%

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