General Flashcards
(36 cards)
Explain the Needs Analysis Pyramid
End User Needs determine Applications, which determines the Tasks required to address the need, which then defines the Functions and Features.
How far above the ambient noise floor should the SPL of the AV system be for good intelligibility?
25 dB SPL
Explain the dB Weights
dB A-weighted = Used at lower listening levels. Better represents how humans perceive sound at lower levels
db C-weighted = More accurate at high levels, such as concert venues (above 85 dB SPL)
What is the typical conference room target for sound pressure level and how is it weighted?
70 dB SPL A-Weighted (not including headroom)
Assumes 45 db SPL of background noise
What is uniformity in terms of audio and how is it acheived?
Uniformity is an equal sound level across all listeners. It is achieved by proper speaker selection and placement.
True or False, in speech systems sound should emanate from the direction of the speaker to create a visual connection.
True
What is intelligibility?
Can the audio be understood
What is harmonic distortion?
Signal distortion that arises when harmonics of an input signal are produced during processing and end up on the output signal
THD stands for?
Total Harmonic Distortion
What does a vectorscope measure?
Measures amplitude, hue, and phase of video signals
What does a waveform monitor measure?
Measures amplitude and timing of luminance and color signals.
What does an Oscilloscope do?
Plots signal amplitude and timing
What is the formula for calculating projector throw?
Screen Width x Lens Zoom Ratio
What is the newly recognized terminology for commissioning and what does it entail?
System Performance Verification = Process for testing all elements of an AV system to verify that they function as intended, and identifying any issues that need to be resolved prior to hand-off
What is the permissible amount of space that can be occupied in a conduit based on 1, 2, or 3 cables?
1 Cable = 53 percent
2 Cables = 31 percent
3 Cables = 40 percent
What is bend radius and what is the typical allowance for a cable?
The amount that a cable is allowed to be bent. Usually 4X the cable diameter
What is the minimum safety load for mounting AV equipment? (Safe Working Load: SWL or WLL)
5X the weight; 5=”Safety Factor”
Name the 3 common cooling methods used in AV racks?
Convection = hot air rises out of vents at top (only works for racks with low amount of heat)
Evacuation = Fans at top draw air up and out
Forced Air = Fans at bottom draw in cool air, forcing it upward, vents at top
Name 2 types of boxes you might encounter when pulling cable through conduit?
Junction Box (J-Box) = At the end of the conduit run Pull Box = At an intermediate position (Should be placed every 100 ft of conduit or after a 180 degree bend)
What is insertion loss?
Energy lost in the form of heat when energy is transferred from one side of a transformer to another.
What are the typical types of commercial speaker setups?
Direct-Coupled = Low impedance loudpspeakers (16, 8, 4 ohm) connected directly to amp
Constant Voltage = chained or “distributed” speakers when direct connection is impractical. Uses a 25V, 70V, or 100V transformer.
Name the 3 types of transformers
1:1 = Same # of windings on primary and secondary side Step-Up = More secondary windings, voltage and impedance increases, current decreases Step-Down = Fewer windings on secondary, Current increases, voltage and impedance decrease
What is included in a program report?
1 - Executive Summary = Overview of programming process, systems, special issues, and budget
2 - Space Planning (special design considerations)
3 - System Descriptions (non-technical)
4 = Infrastructure Considerations
5 - AV Budgets
Which phase comes directly after the program phase and is based on the program report?
The Design Phase
