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nachotrull
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What activity must occur to produce an EMP?
Nuclear explosion
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What two elements produce the EMP effects?
- Gamma rays
- Secondary neutron radiation
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What are the electromagnetic pulse forms produced by the derived environment?
- High altitude EMP (HEMP)
- System generated EMP (SGEMP)
- Source region EMP (SREMP)
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Why is high altitude electromagnetic pulse environment protection important for critical, time urgent mission systems?
It can affect many systems simultaneously
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Why is system-generated electromagnetic pulse a problem for satellites and reentry vehicles?
They are directly exposed to nuclear radiation from a high altitude burst.
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What are the two distinct regions of importance for SREMP?
Source and radiated
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What effects on communications are there after a nuclear detonation?
- Comms blackout
- Scintillation effects
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What capabilities can be employed by MILSTAR to mitigate communications loss within a contaminated area?
Crosslink
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Describe the difference between long-line and local effect of EMP on facilities?
- Longline- Long power lines, comm cable links, pipelines
- Local- Facility shield, building structure, wiring, equipment cabinets
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How can a facility be survivable against EMP?
Shielded facility. All openings filtered and protected.
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What happens in an EMP induced event?
Causes a magnetic or electric field to be induced in an electrical circuit that can cause an error in the response of the circuit.
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Why is bonding important in EMP protection?
To make sure a mechanically strong, low impedance interconnection between metal objects.
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Where should all metallic penetrations entering the protected area be located?
A common location.
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To reduce coupling into susceptible circuits, what element is installed on both signal and power lines?
Filters
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_____ is any electromagnetic disturbance that interrupts, obstructs, or otherwise degrades or limits the effective performance of electronics and electrical equipment.
Electromagnetic Interference
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How do you differentiate between an unintentional interference and interference from jamming signal?
- Unintentional interference normally travels a short distance; a search of the immediate area may reveal source. Moving RX antenna may cause noticeable variations.
- Intentional has little to no variation and indicates enemy jamming.
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What type of EMI occurs when an unwanted carrier frequency follows the normal signal path through the effected receiver?
Co-channel
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How can you eliminate broadband transmitter noise?
Placing a band-pass filter on the offending transmitter.
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When do spurious responses occur?
When a receiver responds to off-frequency signals.
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What type of equipment often generates many spurious emissions?
Rapid tuning methods.
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What intermodulation frequency components can cause EMI in the receiver/transmitter?
Sum and difference
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What type of intermodulation can have a very large bandwidth and cause more severe interference problems than intermodulation products created in either transmitters or receivers?
"Rusty Bolt" intermodulation
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What type of EMI occurs when high level radiated signals penetrate and induce a radio frequency voltage in the internal circuits of a system or equipment?
Brute Force interference
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What AM receivers are particularly susceptible to power line noise?
HF, VHF
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Relays may cause interference inside receivers because of broadband radiated noise originating from what?
The opening and closing of the contacts
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How would you normally eliminate EMI caused by sodium and mercury vapor lights?
Installing new bulbs
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What is the purpose of the AFSIR program?
To document and resolve spectrum interference problems.
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Under the AFSIR program, what organizational level must begin an investigation to identify the source of EMI?
The lowest unit level affected.
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Why must you ensure maintenance personnel responsible for the affected equipment check it before submitting an EMI report?
Make sure equipment isn't the problem.
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How do you confirm an EMI problem?
Check with other users of the same frequency and determine whether they receive the EMI.
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If your EMI sounds like noise, what are the possible sources of these interferences?
- Power lines
- Welding equipment
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Who is responsible for recording specific information concerning EMI?
You, the operator
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What types of EMIs are exempt from AFSIR reporting?
- Transient EMI from natural sources (rain/lightning)
- Space weather
- Aboard ISR aircraft
- Or if only affecting frequencies assigned on a non-interference basis for training purposes
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How should an AFSIR report be submitted?
Through chain of command, then to their MAJCOM, and then to the AFSMO.
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What document contains guidelines for classifying EMI reports?
CJCSI 3320.02B, Joint Spectrum Interference Resolution (JSIR)
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What service provided by the 85 EIS analyzes and recommends corrective actions for reported EMI problems?
Quick fix interference reduction capability (QFIRC)
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What is the objective of the JSIR program?
Report and assist with the resolution of EW and recurring EMI.
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Who maintains a central database of EMI cases, resolutions, and lessons-learned for all DOD EMI?
Joint Spectrum Center
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