Volume 1 Unit 2
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What activity must occur to produce an EMP?
What two elements produce the EMP effects?
- Gamma rays
- Secondary neutron radiation
What are the electromagnetic pulse forms produced by the derived environment?
- High altitude EMP (HEMP)
- System generated EMP (SGEMP)
- Source region EMP (SREMP)
Why is high altitude electromagnetic pulse environment protection important for critical, time urgent mission systems?
It can affect many systems simultaneously
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.
What are the two distinct regions of importance for SREMP?
Source and radiated
What effects on communications are there after a nuclear detonation?
- Comms blackout
- Scintillation effects
What capabilities can be employed by MILSTAR to mitigate communications loss within a contaminated area?
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
How can a facility be survivable against EMP?
Shielded facility. All openings filtered and protected.
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.
Why is bonding important in EMP protection?
To make sure a mechanically strong, low impedance interconnection between metal objects.
Where should all metallic penetrations entering the protected area be located?
A common location.
To reduce coupling into susceptible circuits, what element is installed on both signal and power lines?
_____ is any electromagnetic disturbance that interrupts, obstructs, or otherwise degrades or limits the effective performance of electronics and electrical equipment.
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.
What type of EMI occurs when an unwanted carrier frequency follows the normal signal path through the effected receiver?
How can you eliminate broadband transmitter noise?
Placing a band-pass filter on the offending transmitter.
When do spurious responses occur?
When a receiver responds to off-frequency signals.
What type of equipment often generates many spurious emissions?
Rapid tuning methods.
What intermodulation frequency components can cause EMI in the receiver/transmitter?
Sum and difference
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
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
What AM receivers are particularly susceptible to power line noise?
Relays may cause interference inside receivers because of broadband radiated noise originating from what?
The opening and closing of the contacts
How would you normally eliminate EMI caused by sodium and mercury vapor lights?
Installing new bulbs
What is the purpose of the AFSIR program?
To document and resolve spectrum interference problems.
Under the AFSIR program, what organizational level must begin an investigation to identify the source of EMI?
The lowest unit level affected.
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.
How do you confirm an EMI problem?
Check with other users of the same frequency and determine whether they receive the EMI.
If your EMI sounds like noise, what are the possible sources of these interferences?
- Power lines
- Welding equipment
Who is responsible for recording specific information concerning EMI?
You, the operator
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
How should an AFSIR report be submitted?
Through chain of command, then to their MAJCOM, and then to the AFSMO.
What document contains guidelines for classifying EMI reports?
CJCSI 3320.02B, Joint Spectrum Interference Resolution (JSIR)
What service provided by the 85 EIS analyzes and recommends corrective actions for reported EMI problems?
Quick fix interference reduction capability (QFIRC)
What is the objective of the JSIR program?
Report and assist with the resolution of EW and recurring EMI.
Who maintains a central database of EMI cases, resolutions, and lessons-learned for all DOD EMI?
Joint Spectrum Center
What would you like to do?
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