Radar Flashcards
What does radar stand for
Radio Detection and Ranging
How does Radar work
On the “echo principle”
What does radar do once it transmits
Goes into receive mode.
What is a radar nautical mile
80,915 NM out in one second (161,830 miles per sec) remember
What is signal attenuation
absorption or loss of power
X band radar
3cm Radar short range
S Band
10 cm radar long range
What is the PRR
Number of pulses transmits in one second (pulse repetition rate)
Pulse length
main factor in determining minimum measurable range
Travels 328 yards in one microsec
What is resting time
time elapsed between the end of the first transmission and beginning of the second transmission measured in microseconds
What two factors are in PRR
Pulse rate and resting time
How many times it happens in one second is the PRR
Also prt
What is the main factor in maximum effective range
PRR
What is the main factor in determining minimum measurable range
PL pulse length
Where do you want to put the VRM when measuring distance
inside leading edge or spot closest to you
6/1
Range 6 miles, each ring 1 NM
What is the best way to fix posititon by Radar
two or more ranges
How is pulse length measured
miroseconds
What does PL determine
minimum measurable range
What does PRR determine
Maximum measurable range
What is bearing resolution
ability of the radar to distinguish as two separate targets at the same range but at different bearings
What is the primary value of PI lines
early warning for set and drift
Why is it not acceptable to fix position using floating aids?
Because buoys are not in a fixed position and may be off station enough to cause problems
How many logs does each Radar need
x2 maintenance and performance log
What does the performance log list
type, make and model radar
Idiosyncrasy
What does the maintenance log list
Date of last operator maintenance performed
type, make and model radar
scheduled maintenance or required maintenance
If some one is working on RADAR what do you need to do
post men aloft sign lock out tag out turn off radar
What does the modulator do
establishes the time base (its the brain)
Transmitting
ATR switch open TR closed
Receiving
ATR switch closed TR open
What part of the radar is responsible for building the intermidiate frequency
LNA linear noise amplifier cleans it up
What could cause a misdirect pulse or false/indirect echo
blind or shadow spot caused by an obstruction to the radar antenna
What would cause you to have multiple echos
passing very close to another vessel
What type radar is most effected by weather
3CM x band
What causes spoking
synchronizer malfunction
What would cause your radar to displaying Serrated Range Rings?
DC power malfunction
Indirect Echoes are associated with?
Blind spots
Easiest thing to obtain on RM line
CPA
If R/M same spot what do you have
You and target same course and speed
If e and m on same location what do you have?
Target DIW
E to m
Their course and speed
R to m
Relative motion
E to r
Oir course and speed
What is the difference between vrm and ebl
Vrm measures to inside leading edge
Ebl is measured center mass
Two modes
Stablized unstablized
North up/ heads up
