Term
| Name the 3 parts of a fiber optic cable. |
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Definition
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Term
| What is the difference between multi-mode and single mode fiber? |
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Definition
Single- higher bandwidth longer distance
Multi- lower band width shorter distance |
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Term
| Name 4 wavelengths where low loss transmission windows occur in a fiber cable. |
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Definition
Multi Single
859nm 1310
1300nm 1550 |
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Term
| What is the difference betwen tight and loose buffer cable? |
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Definition
Tight buffer- indoors- yellow jacket- single-orange- multi
Loose- out door- black jacket- more durable |
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Term
| Name 4 advantages of using fiber optic over copper cables. |
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Definition
-low attenuation -Difficult to tap
-high bandwidth
-Immune to EMI and RFI |
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Term
| Name two methods used to splice fiber cables. |
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Definition
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Term
| Name 3 fiber optic light source used in fiber optics. |
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Definition
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Term
| What does VCSEL stand for? |
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Definition
| Vertical Cavity Surface Emitting Laser |
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Term
| What is another common name for a constant voltage system? |
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Definition
-High Impedance -70 volts
-Distributed |
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Term
| Where are constant voltage audio systems commonly used? |
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Definition
| Commercial Establishments |
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Term
| Why is a transformer required at each speaker in a distributed system? |
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Definition
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Term
| What three voltages are commonly used for constant voltage audio systems? |
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Definition
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Term
| How are speakers rated in distributed systems? |
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Definition
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Term
| How many speakers can be connected to an amplifier in a constant voltage system? |
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Definition
| As many of few as you wish as long as you do not exceed amplifier capacity. |
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Term
| Besides the power used by the speaker, what are two other factors to consider when concerning power loss? |
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Definition
-Transformer insertion loss
-Loss due to cable |
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Term
| What is the industry rule of thumb used when figuring required amplifier output wattage for a constant voltage system? |
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Definition
-Total tap wattage +20%= amp wattage
-Total tap wattage -1.2= amp wattage |
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Term
| What are the two field components that make up a radio wave. |
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Definition
Electric field (e-field)
Magnetic field (h-field) |
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Term
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Definition
| Base unmodulated radio wave that the tx and rx lock onto. |
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Term
| Name two types of modulation |
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Definition
-Amplitude Modulation
-Frequency Modulation |
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Term
| What type of modulation is used for wireless microphone and IEM systems? |
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Definition
| Frequency modulation- has a wider frequency response and a better dynamic range. |
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Term
| What two types of audio processing are used in transmitting and receiving? |
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Definition
-Pre/ Post emphasis EQ
-Companding |
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Term
| What does the term "true diversity" mean? |
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Definition
| The ability to sample the radio field from two or more locations. And the ability to select or combine the resulting signal. |
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Term
| What diversity design is most commonly used? |
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Definition
| receiver switching diversity |
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Term
| What is the minimum antenna size for transmitting and receiving? |
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Definition
| -1/4 the size of the wavelength you are transmitting or receiving. |
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Term
| Name 4 types of antenna designs. |
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Definition
-Ground Plane
-Log periodic dipole array
-Yagi
-Helical
-Whip
-Circularly polarized |
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Term
| What is the best way to maintain maximum efficiency between a transmitting and receiving antenna? |
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Definition
| -Line of sight between tx and rx |
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Term
| Name two types of antenna distribution. |
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Definition
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Term
| What causes "Drop Out", "Noise Up", and "Hits". |
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Definition
-Obstructions
-Dead or dying batteries
-Multi-path efects |
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Term
| What is the purpose of the squelch circuit? |
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Definition
| To mute the audio output of the receiver when RF signal level falls below a set threshold. |
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Term
| Which frequency band has it's transmitter power limited to 50mW |
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Definition
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Term
| Which frequency band has it's transmitter power limited to 250mW? |
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Definition
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Term
| Why should you turn on amplifiers after you turn on all other electronic equipment in a sound system? |
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Definition
| So you don't pop your speakers |
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Term
| Why should you turn on amplifiers after you turn on all other electronic equipment in a sound system? |
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Definition
| So you don't pop your speakers |
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Term
| Name and explain some methods used to test a driver. |
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Definition
-Battery
-Sine wave sweep
-DMM |
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Term
| Name 3 benefits of using ferrofluid. |
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Definition
-Heat dissipation
-Coil centering
-Extra damping |
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Term
| Name 3 type of material used to make compression driver diaphragms. |
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Definition
-Aluminum
-Titanium
-Beryllium |
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Term
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Definition
| Peak level minus noise floor. |
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Term
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Definition
The result of atoms bumping into each other electric.
-Electric Noise |
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Term
| What is the benefit of graphing out a system gain structure? |
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Definition
| -Helps in making design and purchase decisions |
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Term
| How many volts does 0 dBu equal? |
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Definition
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Term
| What devices are used to adjust attenuation when setting a systems gain structure? |
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Definition
-External pads
-Onboard input/outputs controls provided they are "post" pre-amps. |
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Term
| How must we approach aligning the crossover's outputs with each of it's associated amplifier inputs? |
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Definition
-Treat them as individual gain structure "branches"
-Start by adjusting the largest segment of the system. |
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Term
| What is the purpose of a system limiter? |
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Definition
| To act as an early warning device that allows you to take measures to protect the system. |
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Term
| What ratio setting is best for a system limiter |
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Definition
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Term
| What 3 methods are used to determine clip points in a system? |
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Definition
-piezo magic
-onboard indicators
-o-scope |
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Term
| What 3 methods are used to determine clip points in a system? |
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Definition
-piezo magic
-onboard indicators
-o-scope |
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Term
| When using an oscilliscope to find clip points, how do you connect the positive and negative leads of the scope to the device under test? |
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Definition
-tie low (pin 3) to ground
-this allows you to read accurate voltage. |
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Term
| Before physically setting gain structure, why do you first run signal through the system? |
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Definition
-To chech the integrity of the system
-You must fix ground/ power/ driver issues before attempting to calibrate a systmes's gain structure |
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Term
| Why would we zero out an EQ before attempting to set gain structure? |
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Definition
| Any cuts or boosts will affect the EQ output during calibration. |
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Term
| In a typical audio circuit, it is beneficial to have the load impedance ___ times the source impedance to insure efficient ____ transfer from device to device. |
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Definition
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Term
| In a typical audio circuit, it is beneficial to have the load impedance ___ times the source impedance to insure efficient ____ transfer from device to device |
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Definition
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Term
| What is amplifier input sensitivity? |
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Definition
| The amount of voltage required at the input to produce full rated output. |
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Term
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Definition
-The difference between peak and average signal.
-Crest factor in dB= 10log(peak/average) |
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