Pete Put It Here Flashcards
Propulsion modes used by NATO diesels (3)
AIP, BATT, DE
What are the power supplies used on Navel Vessels? (3)
50/60 DC power
NATO Submarine designators?
SSBN SSGN SSN
What is the formula often used proportional to? 1/x
RES = 1/DCT or DCT = 1/RES
What is the sonar equation?
SE = SL-PL-AN-RD-DI
Signal excess Source level Propagation loss Ambient noise Recognition differential Directivity index
What is Doppler
An apparent change in frequency due to relative motion between the source and the receiver
What is sound?
A periodic variation in pressure, particle displacement or particle velocity in an elastic medium
What are the mimic/wader frequencies
Mimic (low frequency) 50, 60, 120hz
Wader 180, 300, 500hz
What is MDR?
Median Detection Range - the range at which there is 50% probability of detection from a single sonobuoy
What are the sea bottom composites?
Sand
Rock
Mud/silt
Ooze
What is a choke point?
Geographical features above or below the surface of the water which restricts freedom of movement of a submarine e.g
English Channel
Strait of Gibraltar
Strait of Malacca
What is ambient noise
Any noise which is not target related
What is the three layer ocean model (6 marks)
What are the advantages and disadvantages of nuclear vs diesel submarines?
Diesel - Quiet on BATT / Has to Snort to recharge
Nuc - Range, Speed, endurance / Constant Noise Source
What do you need for a successful underwater detection system?
High Resolution, High Data Rate, Sensitivity for passive
Penetration for active
State the reduction ratio when a six bladed 4s/c surface vessel is fitted with 8 cylinders and
employs a direct drive and has a blade rate 2 that reinforces EFR1
1:1
State the reduction ratio from a six cylinder 4 s/c contact, fitted with a 7 bladed propeller when
BR2 is reinforcing CSR 7.
2:1
What is a Shadow Zone?
A region into which very little acoustic energy penetrates (In accordance with HALT rule)
Define Signal Excess
The amount of signal available for detection
Explain the term Aliasing
Processor Samples 2x frequency bandwidth and therefore creates mirror image. This mirror
image is covered up so that only the desired bandwidth is shown to the operator. Aliasing
eliminates the unwanted frequencies.
Frequency Spectrums of 2 s/c and 4 s/c engines
70-150 ,150+
List the propulsion modes?
DE DR DD TR TE AIP BATTS
What is limiting/ grazing ray?
The ray that grazes the boundary between two layers of different acoustic properties
What are the CZ Ranges for the Mediterranean and the North Atlantic?
MED - 14-18 / NA - 28-32
What is the Critical Angle Ray?
Steepest angle at which there is 100% reflection from boundary layer (i.e. surface or sea
bed/bottom)
What is the lifespan and the depth of a BATHY Buoy? Name of BATHY BOUY
12mins / 2625ft (800m) / SSQ 36B
What is the lifespan and the depth of a DICASS Buoy? Name of DICASS Buoy?
50pingS/1hr / D1 - 50, 150, 300ft / D2 - 90, 400, 1500ft / SSQ62, Directional and Command
Activated Sonobuoy System 62
What is the lifespan and the depths of a DIFAR Buoy? What is the name of a DIFAR Buoy?
0.5/1/2/4/8hrs / 90,200,400,1000ft / SSQ53
What are the frequencies used for detection on a DIFAR Buov?
Pilot Freq 7.5KHz / Reference Freq 15KHz
What are the beams used when processing the signal on a DIFAR Buoy?
Cardiod, Limacon
1What is an Ocean Front?
Boundary between two masses of water with different acousticand thermal properties
What determines the size of the wave?
Duration of wind. wind strength, Fetch surface area
What are the different propagation paths?
Direct Path, Surtace Duct, Sound Channel, (4, Bottom Bounce
