AV Knowledge

User Interface

1. A type of system interface referring to the method by which humans interact with the operation of the system. Also known as Human Machine Interface (HMI). 2. The user interface is the only part of the control system that the users need to touch.

stages of image capture for a video camera:

1.Light enters through the camera's lens. 2.In some cameras, the lens focuses the light on a prism, which splits the light into red, blue, and green components. 3.The light travels from the lens or the prism to a light sensitive chip called an imager. 4.The imager transduces the light into a stream of electrons, creating a video signal. This signal is an electronic representation of a frame. 5.Stages 1 through 4 are repeated many times per second. The frames are displayed in sequence, creating the illusion of motion.

Digital Signal Processor (DSP)

A Digital Signal Processor (DSP) combines processor functions like mixers, limiters, and equalizers into a single piece of equipment. Often, multiple processor functions are combined in a single piece of equipment called a digital signal processor (DSP). The operator controls the various processors using specialized DSP software. Then, once the signal has been processed, it is sent to the power amplifier and from there to the loudspeakers.

Boundary Microphone

A boundary microphone relies on reflected sound from a surrounding surface. A boundary microphone sits directly on a table or surface. They are also called "surface mount microphones."

Allied Trade

A business that collaborates with AV professionals to complete a project.

Control System

A control system is a subsystem that enables simplified operation of other complex systems such as an audiovisual and/or lighting systems. A control system is a subsystem that simplifies the operation of an AV system. A control system includes: A user interface A processor or computer Control equipment

Coverage Pattern

A coverage pattern is the predictable pattern of sound energy that every loudspeaker emits. The coverage pattern is based on the frequency of the sounds and the physical size of the loudspeaker.

Digital Signal

A digital signal is a series of fluctuating "on" and "off" states. digital connections: use bi-directional communication. That means that some signals within the cable travel in both directions, sending and receiving information.

sound

A disturbance that travels through a medium as a longitudinal wave

Graphics Card

A graphics card controls the coloring, shape, and level of detail of the computer display signal.

Handheld Microphone

A handheld microphone can be held in the hand or mounted on a lectern or stand for hands-free operation. A microphone specifically designed for the talent or performer to hold during a recording session or live performance.

Limiter

A limiter is an audio signal processor that functions like a compressor except that signals exceeding the threshold level are reduced at ratios of 10:1 or greater. Limiters control the loudness of audio signals, reducing any sounds that exceed an adjustable threshold. Limiters are triggered by spikes in the audio signal, like a dropped microphone. They react quickly to cut these spikes off.

LoudSpeaker Audio Signal Path

A loudspeaker's internal components vary by type, but basically, loudspeakers contain a coiled wire attached to a lightweight cone. The coiled wire is surrounded by a permanent magnet. Sound is reproduced by the following process: 1. The amplifier increases the electrical signal's gain up to a point capable of moving the loudspeaker components. It's important to be sure the power amplifier is sized appropriately to prevent distortion or damage to the loudspeakers. 2. The amplifier sends the boosted electrical signal to the loudspeakers. 3. The electrical signal is applied to the wire coil. 4. The current flowing in the wire coil interacts with the magnetic field from the magnet. That interaction pushes and pulls the cone, producing sound waves. 5. Most loudspeakers are also contained within an enclosure. The enclosure protects the loudspeaker components and gives the audio a richer sound.

Microphone

A microphone is a device that transduces acoustic energy, sound, into electrical energy.

Preamplifier

A microphone preamplifier, also known as a mic pre, amplifies a microphone level signal to line level for routing and processing. Preamplifiers boost the electronic signal captured by the microphone before it is sent to other equipment. Mic signals are very weak; they have to be amplified to a more usable signal level before being routed or sent through other devices. The preamplifier is the first processor an audio signal encounters.

Mixer (Audio)

A mixer is a device for blending multiple audio sources. Audio mixers combine, control, and route audio signals from multiple sources. Mixers are made up of a combination of preamplifiers and signal control devices. They can blend several sources together for the best possible quality and balance. Audio mixers come in both rack mounted and stand alone versions.

Network

A network consists of two or more nodes interconnected so that they can share data.

Power Amplifier

A power amplifier boosts the audio signal so that it has enough energy to move the transducer within a loudspeaker Power amplifiers boost the audio signal enough to move the loudspeakers. Power amps are the last device an electronic audio signal encounters before it is converted back into acoustical energy. The power amplifier is the last processor an audio signal encounters.

Lavalier Microphone

A small microphone designed for hands-free usage. Usually clipped to the clothing.

_____ decide where equipment will be positioned in the room.

AV designers

Acoustician

Acousticians are professional experts that advise design teams on acoustics.

Acoustics

Acoustics is the science and technology of sound in all its aspects. Acoustics covers sound production, propagation and control, its interaction with materials, its reception by the ear, and its effects on the hearer.

Subsystem

An AV subsystem is two or more pieces of AV equipment that work together.

AV system

An AV system is two or more pieces of AV equipment that work together to meet a communication need. An AV system's purpose is the communication task it helps accomplish. An AV system is only a tool, used to meet a larger communication goal.

Audio System

An audio system allows users to reproduce, record, and amplify sound.

Equalizer

An equalizer is a piece of electronic equipment that adjusts or corrects the frequency characteristics of a signal. Equalizers (EQs) are frequency control devices that allow you to boost or cut a specific frequency range.

Input

An input is a connection point that receives information from another piece of equipment.

Output

An output is a connection point that sends information to another piece of equipment.

_____ signals are represented as a continuous, varying wave.

Analog

Analog Signal

Analog Signal is represented as a continuous, varying wave. analog signals: usually travel in one direction: output to input.

Arrayed Loudspeaker System

Arrayed loudspeaker system delivers sound from a single point in space. It is also known as a "high-pressure systems." Loudspeakers are grouped together so that all the sound comes from one direction.

Aspect Ratio

Aspect ratio is the ratio of image width to image height. It can be expressed as two whole numbers separated by a colon, e.g. 16:9, or by the decimal equivalent of the implied division, e.g. 1.77. Common video aspect ratios include the following: 4:3 (1.33) for Standard-Definition (SD) video very common in late 20th century 16:9 (1.78) for High-Definition (HD) video Some computer and video production displays added space below the 16:9 aspect ratio of HD video and made a 16:10 (1.6) aspect ratio.

_____ allows groups to communicate by voice only.

Audio conferencing

_____ operate equipment during live events.

Audio, video, and lighting technicians

Audioconferencing

Audioconferencing, or teleconferencing, allows multiple groups to communicate by audio over long distances. Audioconferencing is often used in conjunction with videoconferencing. Audioconference data may travel over ISDN, IP or POTS.

Analog Standard: PAL

Australia, China, Western Europe, parts of South America and Africa Computer graphics signals, as well as PAL and SECAM analog signals, are progressive. People stare at computer screens for long periods of time, and interlace artifacts can stress viewers' eyes. The number of lines in a computer display signal depends on the resolution sent out by the graphics card.

Brightness

Brightness is the amount of light reflected or emitted from a display. look at the black areas of the image. If the brightness level is too low, then areas with subtle differences in levels of black will all be represented as one shade. If the brightness level is too high, the intended black areas of the image will appear gray.

vertical market

Concentrates on a specific industry or market. A vertical market is a group of similar businesses or customers.

Contrast

Contrast is the range of difference between the lightest and darkest areas of the display. range of difference between the lightest and darkest areas of the display. When adjusting contrast, look at the white areas of the image.

Which of the following best describes the function of a microphone?

Converting sound waves into electrical signals

DVI-D Connector

Digital Visual Interface digital only, single link or dual link

Distributed Systems

Distributed loudspeaker systems are suspended overhead, often in the ceiling, at regular intervals. Due to their even placement, they can provide even coverage throughout the listening area.

Emissive Technology

Emissive Technology is any display device that emits light to create an image.

Ergonomics

Ergonomics, also known as Human Factors or Human Factors Engineering, is the scientific study of the way people interact with a system. It focuses on effectiveness, efficiency, reducing errors, increasing productivity, improving safety, reducing fatigue and stress, increasing comfort, increasing user acceptance, increasing job satisfaction and improving quality of life. Ergonomics is different than a time and motion study, which focuses solely on productivity and efficiency.

Frame Rate

Frame rate is the number of frames sent from a display source per second.

Analog Standard: SECAM

France, parts of Asia and Africa Computer graphics signals, as well as PAL and SECAM analog signals, are progressive. People stare at computer screens for long periods of time, and interlace artifacts can stress viewers' eyes. The number of lines in a computer display signal depends on the resolution sent out by the graphics card.

Full Bandwidth Signal

Full Bandwidth Signal is the highest quality analog video signal. This is because each signal l - R, G, B, H, and V - has its own cable. Full Bandwidth Signal is also known as an "unencoded signal."

HDMI connector

HDMI connector is also available in "mini" and "micro" versions.

direct view display

Houses the light-producing elements and screen in one piece of equipment. In pro AV systems, the most common direct view displays are monitors There are limits on the size of direct view displays. Larger direct view displays can also be very expensive. When an application calls for a larger display, and the lighting in the environment can be controlled, AV pros often use projection systems.

block diagram

In AV documentation, a block diagram is an illustration of the signal path through a given system. It maps the path of a signal from source to destination. It is also known as a signal flow schematic or an AV system flow diagram.

Feedback

In the context of audio, feedback is unwanted noise caused by the loop of an audio system's output back to its input. In the context of control systems, feedback is data supplied to give an indication of status, i.e., on or off. A CPU sends out an instruction to a device, which executes the instruction and then replies back to the CPU.

Interlaced Scanning

Interlaced scanning is the scanning process that combines odd and even lines of pixels in a video image to produce a full frame of video signal.

Ambient Light

Lighting throughout an area that produces general illumination. REF

Mono Playback

Mono playback is a type of playback that uses a single channel of sound. In mono systems, every loudspeaker plays an identical sound. You would probably use mono for speech reinforcement or background music in a retail paging system.

Multi-Channel Playback

Multi-channel playback, or surround sound, can have five or more channels. Loudspeakers positioned all around a room each play a different channel, so that different sounds seem to be coming from all sides. Surround sound creates a realistic, immersive experience for movie or performance playback.

Analog Standard: NTSC

North America, parts of South America, Japan NTSC analog video signals are interlaced. The number of lines in an analog video signal depends on its regional broadcast standard.

Pixel

Pixel is an acronym for picture element. The small element used to build a digital image.

Programmers

Programmers write computer code and design the user interface.

_____ draw(s) all the lines in an image in order from top to bottom.

Progressive scanning

Reflective Technology

Reflective Technology is any display device that reflects light to create an image.

Refresh Rate

Refresh rate is the number of times per second a display—a monitor, television, or projector— will draw the image sent to it.

Reverberation

Reverberation is the combination of many acoustic reflections that are dense enough in time so as to not be audible as reflections but instead to act as a statistical sonic decay "tail" to sounds in the room.

Room Configuration

Room configuration is the overall shape of a space, especially in relation to furniture positions and wall locations.

Serial Digital Interface (SDI)

SDI is an uncompressed, unencrypted, standardized digital video signal. SDI was designed by the Society of Motion Picture and Television Engineers (SMPTE) for use in professional video equipment. You won't usually see SDI connection points on consumer equipment like BluRay players, and it isn't used for computer graphics output. Instead, SDI appears on professional equipment used for video conferencing, broadcast, etc. SDI signals are typically transported using BNC connectors.

Progressive Scanning

Scanning that traces the image's scan lines sequentially, such as in an analog computer monitor.

common formats of digital display connections:

Serial Digital Interface (SDI) Digital Video Interface (DVI) High Definition Multimedia Interface (HDMI) DisplayPort Thunderbolt USB 3 Mobile High-Definition Link Digital formats are capable of carrying a lot more than just one signal type at a time. Some digital connections can carry video, audio, control, internet, and even standard power. DVI, HDMI, and DisplayPort are all licensed technologies and belong to different organizations. HDMI is most often used for home entertainment equipment, while DisplayPort is more commonly used for computer displays. DVI was frequently used in computers, but it has been largely replaced by HDMI. You could potentially see any of the three on just about any piece of digital display equipment.

_____ are responsible for checking, cleaning and repairing installed AV equipment.

Service providers

_____ includes the design, integration, operation and service of temporary systems.

Staging

Stereo Playback

Stereo playback is a type of playback that has two separate channels (left and right). Playing distinct sounds on the left and right creates a more realistic listening experience when playing back music or other performances.

Sync

Sync preserves the time relationship between video frames and correctly positions the image horizontally and vertically.

_____ are responsible for AV system installation, setup, and user training.

Systems integrators

Closest Viewer

The closest viewer should sit no closer than 1X the screen's width.

Farthest Viewer

The farthest viewer depends on the system's purpose, but in general should sit no farther than 8X the screen's height.

Frequency

The number of complete waves that pass a given point in a certain amount of time

Transmissive Technology

Transmissive technology is any display device that creates images by allowing or preventing light to pass through it.

types of loudspeakers

Tweeters reproduce high frequency sounds. Mid-range loudspeakers reproduce mid-range sounds. Woofers reproduce low frequency sounds. Loudspeakers that handle extremely low frequency sounds are called "subwoofers."

Video

Video is electronically captured, transported, and displayed images.

Videoconferencing

Videoconferencing is the live communication of two or more parties via video and audio.

Display size

Viewer distance is an important consideration in display size. The onscreen image must be large enough to enable the farthest viewers to understand it. Display size is also based on the type of information the user needs to view. If the user needs to be able to discern small details, the image will have to be bigger in order to show them clearly. If the user just needs to see a general picture, a smaller image will do. explanation: Think of the massive displays found in large spaces like stadiums. They have to be big for the crowd to see the images. Bigger is not always better, however. It is possible to have a screen that is too large for a space. Those sitting closest to the screen then have to turn their heads from side to side to see the whole display. The display should be the right size for everyone to view it comfortably.

Wavelength

Wavelength is the physical distance between two corresponding points of two consecutive cycles.

Webconferencing

Webconferencing combines audioconferencing with computer graphics for sharing over the Internet.

In rooms of the same size, a user who needs to show detailed spreadsheets probably needs _____ compared to a user who needs to show videos.

a bigger display

In the AV industry, a vertical market is ____.

a group of potential customers with similar needs and business requirements

DisplayPort

a port that transmits digital video and audio (not analog transmissions) and is slowly replacing VGa and DVI ports on personal computers.

Which of the following best defines "video" in the terms of the AV industry?

a sequence of still images that are electronically captured, transported, and displayed and perceived as moving images

decibel

a unit that compares the intensities of different sounds

Customer service is of high importance for _____ in the AV industry.

all job roles

Businesses that collaborate with one another to complete a project are known as _____.

allied trades

Octave

an eight-line stanza

Local Area Network (LAN)

connects devices within a small geographical area, such as a building or campus. LANs are generally owned and/or operated by the end user. A computer network limited to the immediate area, usually the same building or floor of a building. A LAN connects devices within a small geographical area, such as a building or campus.

Virtual Local Area Network (VLAN)

connects separate LANs to form a logical group. For instance, the LANs at each branch of a large company could be combined into one company-wide VLAN. A virtual local area network (VLAN) is created when network devices on separate LAN Segments are joined together to form a logical group that can communicate via switching. Devices on a VLAN form a single, isolated broadcast domain.

Wide Area Network (WAN)

covers a large geographical area, such as a state or country. The Internet, which covers the entire world, is one large WAN. A wide area network (WAN) is a network that spans large geographical distances, connecting several LANs (local area networks) via leased line, packet switching, virtual private network (VPN), or other means. LANs are connected to a WAN through use of a router.

The main role of manufacturers in the AV industry is ____.

creating and producing AV products

The quality of a(n) _____ recording never changes, regardless of how many times it is copied or played.

digital

primary display technology categories

emissive, reflective, and transmissive.

Box sales firms focus their business solely on _____.

equipment sales

If the contrast of an image is too low, the intended white areas of the image will appear _____.

gray

The _____ department handles employee paychecks, insurance, benefits, and taxes.

human resources

Aspect ratio is a numerical value comparing _____.

image width to image height

An organization's website, logo, social networking presence, and newsletter can all be considered aspects of _____.

marketing

In the professional AV industry, the most common direct view displays are _____.

monitors

most common audio playback modes

monophonic (mono), stereophonic (stereo) and multi-channel.

Logarithm

multiples of ten For example, the log of 10,000 is 4 and the log of 0.0001 is -4.

A graphics card outputs signals measured in _____.

pixels

A room with a flat floor may need displays that are _____ than a room with a sloped floor.

positioned higher

the most common signal processors

preamplifiers, power amplifiers, mixers, limiters, and equalizers.

Independent sales representatives are paid through____.

sales commissions

AV dealers are shifting their sales from equipment to _____.

services

An AV system's purpose can be defined as _____.

the communication task it helps accomplish

Amplitude

the height of a wave's crest/ the intensity of a wave

Frequency

the number of complete wavelengths that pass a point in a given time the number of complete cycles per unit of time. Frequency is measured in cycles per second, or hertz (Hz). The more cycles per second, the higher the frequency. The frequency of a sound controls its tone frequency does not control sound pressure (volume)

Furniture positions in an AV space affect _____.

the size and positions of the displays

The higher a sound's frequency is, the higher its _____ will be.

tone

After light is focused on an imager, the imager _____.

transduces the light into a stream of electrons

Overhead projectors are a simple type of _____ display.

transmissive

Computers are used as visual system sources whenever _____.

users need to share information using a software program

Distributors can reduce costs for manufacturers by ____.

warehousing, selling and shipping their products

Harmonics

whole number multiples of the fundamental frequency