# Shared Flashcard Set

## Details

Highlighted Dex info
Highlighted Dex
111
Aviation
Not Applicable
03/30/2012

Term
 How do we measure wavelength
Definition
 Measure from one crest to another
Term
 Unit of measure for wavelength
Definition
 meter
Term
 Definition of frequencyMeasured in:Unit of measure
Definition
 how many cycles per secondCycles per secondHertz
Term
 Speed of light
Definition
 300 million meters per second
Term
 1000 hertz:1,000,000 hertz:1,000,000,000 hertz:
Definition
 kilohertzmega hertzgiga hertz
Term
 Relationship of frequency and wavelength
Definition
 inversely relatedW*F=C
Term
 Definition of Phase
Definition
 the process of the wave building to a crest, then collapsing to a trough
Term
 Definition of Constructive interference
Definition
 waves in phase amplify
Term
 Definition of destructive interference
Definition
 waves 180 degrees out of phase eliminate each other
Term
 What determines polarity
Definition
 electric field
Term
 Define Horizontal polarityWhat is it used for?
Definition
 e field parallel to the horizonLow-level aircraft detection
Term
 Define Vertical polarityWhat is it used for?
Definition
 e field perpendicular to horizonUsed to decluttering
Term
 Define Circular polarityWhat is it used for?
Definition
 e field constantly shifts from vertical to horizontalWeather penetration
Term
 What is the HF frequency band?
Definition
 2-30 MHz
Term
 What is HF frequency generally used for?
Definition
 Long Haul Comm
Term
 How many types of frequency classification systems are there?
Definition
 4
Term
 The L-Band cover's what frequencies?
Definition
 1-2 GHz
Term
 The following defines? Pitch (freq) of an audio tone is higher when the source is moving toward the listener?
Definition
 Doppler Shift (Radar reflected from an object approaching the tx'er will be at a slightly higher freq, from a receding object a lower freq.)
Term
 Solar and cosmic noise rapidly drop off at what freq?
Definition
 100 MHz
Term
 True or False? Waves attenuate (lose strength) as they travel any distance?
Definition
 TRUE
Term
 Atmospheric Attenuation is negligible at low freq, but begins to assert itself as what freq is approached?
Definition
 10 Ghz
Term
 At 22.24 GHz, we can reach a resonant freq called the?
Definition
 Water line, at this freq water vapor attenuation becomes severe.
Term
 ____________ is the bending of electromagnetic energy?
Definition
 Refraction
Term
 Freq & Refraction are related how?
Definition
 Inversely proportional (When Frequency increases, Refraction decreases and visa versa.)
Term
 Where is refraction often times the worst?
Definition
 Coastal sites
Term
 HF spans what portion of the spectrum? Characteristics of HF?
Definition
 2-30 MHz / Long Haul Comm / Noisy
Term
 VHF FM spans what portion of the spectrum? Characteristics of VHF FM?
Definition
 30-80 MHz / Used by ground troops
Term
 VHF AM spans what portion of the spectrum? Channels are spaced every ______ MHz?
Definition
 116-152 MHz / 0.025 MHz
Term
 UHF spans what portion of the spectrum? Characteristics and channel spacing?
Definition
 225-400 MHz / Military Aircraft Use / 0.025
Term
 Two different types of Communication Electronic attack?
Definition
 Noise Jamming & Spoofing
Term
 ________________ denies the use of freq by saturating it with a powerful radio signal?
Definition
 Noise Jamming
Term
Definition
 Spoofing
Term
 1st 2 lines of defense against jamming are?
Definition
 Brevity and Chattermark
Term
 This is a anti-jamming frequency hopping system used for communications usually in the UHF spectrum?
Definition
 HAVE QUICK
Term
 The Army's version of HAVE QUICK is called?
Definition
 SINCGARS
Term
 ABC / KMT / JRF / RIT / WIF Answer using challenge and reply ?
Definition
 K / I / A / P / R
Term
 2301 / 1938 / 0234 Answer using Transmission Authentication?
Definition
 TB / ST / NB
Term
 EW stands for what? What type of radar system was an EW? What does EW provide?
Definition
 Early Warning / CHAIN HOME / low freq's which provide enemy's position, speed and heading, lacks precision.
Term
 AI stands for what? What does AI sacrifices _________ for light weight and close-in precision?
Definition
 Airborne Incecept / Long Range
Term
 GCI stands for what? What does GCI combine?
Definition
 Ground Controlled Incercept / Long Range and Precision
Term
 AEW stands for what? What problem did AEW overcome and how?
Definition
 Airborne Early Warning / Detecting low flying targets by elevating the radar.
Term
 4 different types of radio freq generators used what are they?
Definition
 Klystron, Twystron, Magnetron, Microwave Transistors
Term
 3 drawbacks of Klystrons?
Definition
 5-50 minute warm up period, heavy, and produced X-rays.
Term
 Positive of Klystrons?
Definition
 Very powerful and extremely stable
Term
 Difference between Twystron and Klystron?
Definition
 Twystron has advantage of "freq agility"
Term
 What are some benefits of Magnetron?
Definition
 Small, light, inexpensive
Term
 What's the major drawback of a Magnetron?
Definition
 Not precise
Term
 What is the greatest strength of Microwave Transistors?
Definition
 Don't need warm up time
Term
 Super Heterodyne Rx'er does what?
Definition
 Mixed the faint signals w/ a strong, stable, known freq. This produced two harmonic freq's that cloned the original signal of interest, and did so w/o adding noise or distortion.
Term
 What determines range resolution?
Definition
 Pulse Width
Term
 What could possible occur if we increase PRF?
Definition
 Potential exists for 2x bang targets
Term
 As far as PRF is concerned what is required for two planes to be seen as two planes?
Definition
 Planes must be at least 1/2 a pulse width behind the lead target
Term
 Ghost image's on a radar scope are AKA?
Definition
 Second-bang Targets
Term
 Doppler blind speeds exist, if a certain part of the signal hits the target the radar won't recognize it.
Definition
Term
 If PRF increases what is more likely to occur?
Definition
 Second-bang Targets
Term
 What shape is a Parabolic Reflector? What type of beam does it produce?
Definition
 Round / Pencil Beam
Term
 What is one way pencil beams search for targets?
Definition
 Raster Scan (adjusts azimuth and elevation coverage to cover more or less territory depending on the situation)
Term
 What are Fan Beams useful for? What is the signal's trajectory from a fan beam?
Definition
 EW & AEW / Vertical
Term
 What can Fan Beams not do accurately?
Definition
 Measure Altitude
Term
 A radar with a vertical aparatus will have a beam with what trajectory?
Definition
 Horizontal
Term
 What can a horizontal beam measure accurately?
Definition
 Altitude
Term
 With GCI and AEW radars, fan shaped beams have to estimate target height, what is the common error rate in feet?
Definition
 5,000 ft +/-
Term
 What is widely used by GCI radars to find altitude?
Definition
 Beam Stacking
Term
 What is the preferred height finding method of AEW platforms when working over water?
Definition
 Multi-Path
Term
 What did the planar array signifcantly reduce?
Definition
 Side and Back lobes
Term
 What was the biggest drawback to the planar array?
Definition
 Mass, typically 5 to 10x that of a relector w/ the same aperture (rx sz)
Term
 What type of radar is rigidly mounted; with no gimbal and no physical movement of the antenna?
Definition
 AESA - Active electronically scanned arrays
Term
 What are three things that the AESA is proficient at?
Definition
 Can change beam shape, can rx and process multiple signals, can be used as an aux intel asset
Term
 The Tall King and FPS-24 were what?
Definition
 Big heavy GCI radars, that used low freq's to extend range. They were inflexable and hard to mx. The weight of the antenna was the biggest problem.
Term
 Pulse compression increases our likelyhood of detecting an object at a given range by how much?
Definition
 4x; Pulse compression factor of four.
Term
 Increasing our average power by turning on the tx more often which in turn increases the PRF increases the possiblity of what occuring?
Definition
 Second-bang Targets
Term
 By increasing to medium PRF what is the primary benefits?
Definition
 Significant increase in range as well as a true look-down doppler capablity. (bottom line, increases our ability to detect targets)
Term
 What is the fix for second bang targets?
Definition
 Staggered PRF - rx'er only reports targets that both PRF's agree on, we will have defeated the 2nd bang problem
Term
 By increasing to High PRF what is the primary benefits?
Definition
 Greatly increases our range and gives us unambiguous Doppler processing.
Term
 In High PRF when the target drops from our display what has the target gone into?
Definition
 Doppler Notch
Term
 What PRF is being utilized when invisibility to targets crossing our path or running away from us is granted?
Definition
 High PRF
Term
 What is the most widely used jamming device?
Definition
 Chaff
Term
 _____ is designed to match half the wavelength of the victim's radar RF?
Definition
 Chaff
Term
 What is the EP (electronic protection) against chaff?
Definition
 Doppler processing at med or high PRF.
Term
 What are the three mechanical methods for radar jamming?
Definition
 Chaff, Decoy, and Rope
Term
 What are the three electronic jamming methods?
Definition
 Spot, Sweep & Barrage
Term
 What jamming technique attempts to "fool all of the people all of the time"?
Definition
 Barrage
Term
 "fool some of the people all of the time"?
Definition
 Spot
Term
 "fool all of the people some of the time"?
Definition
 Sweep
Term
 What is the EP (electronic protection) against spot jamming?
Definition
 Frequency agility, the ability to switch to another frequency outside the jamming.
Term
 What is the EP (electronic protection) against sweep jamming?
Definition
 Patience and Persistence
Term
 What is the EP (electronic protection) against Barrage jamming?
Definition
 Pulse compression Techniques - increase avg power to blow through jamming levels.
Term
 What is the best EP (electronic protection) to defeat range deception?
Definition
 Staggered PRF - true target will remain in the same range bin for pulse after pulse, but the recoreded and repeated pulses will fill diff range bins depending on the PRF in use at the time.
Term
 How does the repeater jammer decieve in azimuth?
Definition
 By exploiting the victim radar's side and back lobes.
Term
 What is the EP (electronic protection) of choice to defeat the azimuth deception jammer?
Definition
 Ultra-low side lobes or active side lobe blanking
Term
 What does deception jamming cause?
Definition
 Second-bang Targets
Term
 What frequency is used to interogate a ship or aircraft's IFF? What Freq is used to reply with?
Definition
 1030 MHz / 1090 MHz
Term
 Mode 1 is used by whom and for what? How many digits make up Mode 1? Is it manageable?
Definition
 Military / Mission ID / 2 digits, 1st is 0-7, second is 0-3 / Manageable
Term
 Mode 2 is used by whom and for what? How many digits make up Mode 2? Is it manageable?
Definition
 Military / Personal ID / 4 digits, all 0-7 / none Manageable
Term
 Mode 3 is used by whom and for what? How many digits make up Mode 3? Is it manageable?
Definition
 Military & Civilian / Selective ID / 4 digits, all 0-7 / Manageable
Term
 Mode 3C used by whom and for what? How many digits make up Mode 3C?
Definition
 Military & Civilian / 3 Digit altitude readout / Hooked to altimeter
Term
 Mode 4 is used by whom and for what?
Definition
 Military / Positive electronic ID , Encrypted
Term
 Mode S is used by whom and for what? How many digits make up Mode S?
Definition
 Civil / 24 digits 0-7 plus altitude, heading & speed / Not manageable
Term
 Mode 5 is used by whom and for what? Is it manageable? Is it redundant?
Definition
 Military / Encyrypted version of Mode S. / Not manageable / Yes, redundant with link 16 (JTIDS) provides the same caps, adds jam-resistant freq-hopping and is already a fully funded system.
Term
 What is the USAF IFF system?
Definition
 MK-XII
Term
 What type of radar is used by J-stars?
Definition
Term
 How does SAR work?
Definition
 Makes use of shorter pulse widths and extreme pulse compression to achieve the necessary range resolution.
Term
 What is the size of resolution cell that has been achieved by SAR?
Definition
 4 inches
Term
 How will a moving train appear on a SAR display?
Definition
 It will appear parallel to, but some distance from the tracks. Show's the way things were, not the way they are.
Term
 How does structural attenuation work?
Definition
 a. By carefully arranging the AC’s internal structures, the radio frequencies can be attenuated as much as RAMb. Effectiveness decreases as wavelength increases
Term
 What is impedance matching and how does it work?
Definition
 Use of materials in aircraft construction that don't reflect radio waves very well.
Term
 What types of high-tech application of impedance matching is currently in use?
Definition
 Plastics such as fiberglass or carbon-fiber and ceramics.
Term
 How does faceted surfaces work?
Definition
 Deflect radar beams in every direction except back to the Tx'ing radar, this is called diffusion.
Term
 LPI sensors do what?
Definition
 Make electronic signals quieter
Term
 Over the horizon radar might detect objects at what distance?
Definition
 3,000 miles
Term
 Over the horizon radar tells us where something was like SAR, it is not very acurate range resolution becomes a problem, what is the typical resolution of OTH?
Definition
 10x10 mile grid sq's
Supporting users have an ad free experience!