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38 Cards in this Set
- Front
- Back
Amplitude
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Relative indication of the amount of energy the wave transmits
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Wavelength
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Distance in space occupied by one cycle of a radio wave at any given instant
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Cycle
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Combination of one complete positive and one complete neagtive alternation
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Frequency
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Number of vibrations, or cycles, of a wave train in a unit of time
measured in Hertz |
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Ground Wave
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Radio waves that travel near the surface of the Earth
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Sky Wave
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Radio waves that are reflected back to Earth from the ionosphere
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Space Wave
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Hase two paths
Transmit ant to recieve ant directly through air (Primary) Other is reflected from the ground |
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Natural Horizon
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Line of sight horizon
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Radio horizon
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1/3 farther than natural horizon
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Refraction
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Bending of the waves as they move from one medium to another in which the velocity of propagation is different
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Diffraction
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Radio wave that meets an obstacle has a natural tendency to bend around the obstacle
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Reflection
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Bouncing off objects
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Aborption
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Loss of engergy on radio wave
Pronounced effect on Recieve Strength and Distance of comms |
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Attenuation
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Decrease in intensity of signal, beam, or wave as result of absorption of energy and of scattering out of the path of a detector.
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3 basic characteristics of sound
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source or transmitter
Medium for carrying sound (air, water, metal, etc) Detector or receiver |
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Reciprocity
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Interchangeability of the same antenna for transmitting and receiving
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Gain
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Focused the radiated RF into narrower patterns. The higher the gain of an antenna the smaller the effective angle of use.
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Polarization
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Orientation of the electric field vector of the elecromagnetic wave produced by the antenna.
Vertical, Horizontal, Elliptical |
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Discuss the basic concept of how RADAR works
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Radar dish, or antenna, transmits pulses of radio waves or microwaves which bounce off any object in their path. The object returns an tny part of the wave's energy to a dish or antenna which is usually at the same site as the transmitter.
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Doppler Effect
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The apperant change in freq or pitch when a sound source moves either toward or away from the listener, or the listener moves toward or away.
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ECHO
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Repetition of a signal by reflection from a surface
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Sea Return
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Radar echoes caused by waves of the sea
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Clutter
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Unwanted radio frequency signals in a search radar
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Ground Clutter
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Unwanted radar echoes caused by terrain and man-made features
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Sea Clutter
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Unwanted radio Frequency signals caused by changing conditions at sea (waves, fog, etc)
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Range
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Max distance at which a radar set is irdinarily effective in detecting objects.
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Virus
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Malicious program that modifies other hose files or boot areas to replicate. Rely on users to transfer file in order to spread to other computers.
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Trojan Horse
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Non-replicating program masquerading as a legitimate program
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Worm
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Replicating code that uses its own program coding to spread with minimal user involvement. Can spread across networks.
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Mixture
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Bundles some of the worst aspects of viruses, worms, trojan horses and malicious code into one single threat.
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Who came up with a standard naming scheme for malicious code?
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Computer Antivirus Researchers Organization
(CARO) Called the CARO naming convention |
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What are the parts of a virus name?
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-Family Name
-Group Name -Major Variant -Minor Variant -Modifier |
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What are some of the rules for naming a virus?
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-Don't name it after a location
-Don't use company or brand names -Don't invent a new name if there is an existing name |
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Describe the functions of Active-X.
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Interactive technology used to run programs over the Internet
Example: ActiveX component can scan fro viruses using a browser |
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Describe the dangers associated with Active-X.
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ActiveX control can do almost anything it wants.
Has full access to your system including Hard Drive and system functions |
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Describe the function of Macros
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Language built into a word processing document (Word)
Some applications run automatically when document is opened |
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Describe the dangers associated with Marco Viruses
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Macro virus can copy its self to default word document and then infect any word document opened.
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Hoax Viruses
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Chain mail claiming gloom and doom
No true danger. Only trust virus alerts from a valid source. |