NVSC 401 Exam #1

Rocket

Self propelled projectile

Missle

Self propelled and guided projectile

Bombs

Dropped and unguided ordnance

Torpedo

Self propelled underwater explosive

3 Phases of Fire Control Problem

Detect
Track
Engage

What are the two wave types?

Mechanical
Elctromagnetic

Mechanical Wave

Requires medium
ie. sound, water, seismic

Electromagnetic Wave

Requires no medium

Radio, X-rays, light

Wave Properties & Definition

Frequency - rate at which the propagating wave expands and collapses (Hertz 1/s)
Period - time to complete one cycle (time)
Velocity - speed that wave travels
Wavelength - dis. b/w two identical points on wave
Amplitude - height of the wave

What are the Signal Loses?

Spreading - energy distributed over larger area
Scattering - energy bouncing off particels within a medium
Absorption - energy dissipated into medium

What is Attenuation?

Combination of all the signal loses
Helps determine what signal to use!

What is Interference?

Constructive - energy add & doubles
Destructive - energy cancels & is nothing (how noise canceling headphones work)

What does PRT & PRF stand for

Pulsed Repetition Time
Pulsed Repetiton Frequncey

What do you add to get PRT?

Pulse Width (PW)
Rest Time (RT)

How do you get PRF?

Inverse of PRT

Why do we use RADAR?

Not limited by visual reference!
Use data in fire control systems!

How do you solve for Duty Cycle?

Pulse Width/Pulse Repetition Time

What is Pulse Width?

Active transmit time or duration of EM pulse

Pros of Short PW?

Reduced max radar range
Better range resolution
Shorter min detectable range

Pros of Long PW?

Increased max radar range
Degraded range resolution
Longer min detectable range

What is Unambiguous Range?

Max range that a target can be that provides an accurate calculation of range

What is Range Resolution?

Minimum seperation in distance between two objects before they merge to one

How do wide & narrow beamwidth differ?

Wide used for search radar w/ poor accuracy
Narrow used for targeting radar w/ higher accuracy

What does beamwidth essentially determine?

Determines the angular accuracy of the RADAR

Why is beam forming important?

Increases range, accurancy and efficiency

How is beam forming achieved?

By manipulating the shape of the lobe that is transmitted
- Antenna Arrays
- Quasi Optical reflectors

Why is polarization important?

Determines what can be transmitted & recieved
- Linear
- Circular/Helical

What is Transmit Power?

Power out of the transmitter
- More power = longer max detection & larger size of radar

What is Effective Antenna Aperture?

Measure of actual antenna performance (transmitting & receiving)

What is Radar Cross Section?

Effective target area that reflects radar energy back to the receiver

How do you minimize radar cross section?

Material
Size
Shape
Aspect Angle (way at which you look at in)

What is Receiver Sensitivity?

The minimum signal strength a receiver can detect while still producing a usable, reliable output.

What is Threshold Level?

Minimum signal strength that must be present for a receiver or detector to reliably recognize that a signal exists

What is Scan Rate?

How fast an antenna is rotated either physically or elctronically

What is a Servo Tracking System?

A feedback-controlled mechanism that automatically adjusts its position or orientation to continuously follow and stay locked onto a moving target or reference signal.

Pros & Cons of Servo Tracking System?

Limitations
- Platfrom instability
- Inability of mech systems to anticipate movement
- Lag time

What is Track While Scan (TWS)?

Radar mode that continuously scans the area while simultaneously updating and maintaining tracks on multiple targets.

Difference between Servo Tracking & Track While Scan?

Servo can only handle single target & has lag since waiting for feedback
TWS can handle multiple targets & predicts where target will be

What does Electronic Warfare consist of?

Electronic Support
Electronic Attack
Electronic Protection

Define Electronic Warfare

Military action involving the use of electromagnetic energy to control the EM spectrum

How do we use EA?

WJamming
Medium modifiers
Improving own platform stealth
Destruction of enemy sensor systems

What is SIGNIT?

Signals Intelligence
- Electronic Intelligence is derived from emissions like radar
- Comms Intelligence is derived from communications

What is the order of the EM Spectrum?

Radio
Micro
Infrared
Visible
Ultraviolet
x-rays
Gamma Rays

What do NVG’s need to operate?

Some light electrons that are accelrated by electrodes & enhanced by phosphor screen

What do IR systems need to operate?

No visible light
Just a contrast in heat from source & environment

What is Exitance Contrast?

Ability to discern what target is based on difference in energy detected from target vs background

What determines IR imager performance?

Spatial Resolution
Thermal Resolution

What is Spatial Resolution?

Imagine system’s ability to distinguish seperate objects

What is Thermal Resolution?

Ability to detect small variations in temperature differences