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CANTASS Flashcards

(54 cards)

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1
Q

What is the purpose of CANTASS?

A

To provide the ship with a long range passive SONAR used for detection, tracking, and classifying subsurface contacts

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2
Q

What is the length of the array?

A

~875 ft

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3
Q

How many total hydrophones?

A

764

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4
Q

How many modules?

A

20

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5
Q

Describe the modules in general

A

20 modules with coax cables for passing information and two steel cables that handles mechanical strength. They are connected through locking tabs that provide mechanical and electrical connection. Outer shell is made up of flexible rubber that is filled with ISOPAR-M.

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6
Q

What is the purpose of ISOPAR-M?

A

To provide buoyancy and to act as a pressure, thermal and conductive medium between the ocean and the module’s sensors.

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7
Q

What is the drogue?

A

75 feet of nylon rope at the aft end of the array. Allows CANTASS to be deployed easier and reduces whipping effects.

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8
Q

What is the purpose of the HDTM?

A

The HDTM (Heading, Depth, Temperature Module), contains various sensors that collects and transfers the information in its name. It also receives, digitizes, and multiplexes the acoustic data from the VLFM into two feeds before forwarding that data to the TDM (telemetry drive module).

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9
Q

What are the acoustic modules?

A

There are 16 acoustic modules that are broken down into 4 different groups: VLFM, LFM, MFM, and HFM. Each module consists of hydrophones, amplifiers and multiplexers.

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10
Q

What is the VLFM?

A

Very low frequency module. Contains 48 hydrophones per module and picks up frequencies between 0-190 Hz.

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11
Q

What is the LFM?

A

Low frequency module. There are 4 of these with 48 hydrophones each and they pick up 190-375 Hz.

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12
Q

What is MFM?

A

Medium frequency modules. There are 2 with 48 hydrophones in each and they pick up 375-750 Hz.

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13
Q

What is HFM?

A

High frequency modules. There are two with 46 hydrophones each. They pick up frequencies between 750-1500 Hz.

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14
Q

What is the purpose of the TDM?

A

The telemetry drive module (TDM) provides the array’s timing and control circuits. It digitizes and multiplexes received analog data, amplifies it and transmits them to the receiver using Manchester encoding. It also handles the command decoding, performance monitoring, fault finding, test signal generation, array status and voltage protection.

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15
Q

What is the VIM?

A

Vibration Isolation Module (VIM). There are two of these and they provide mechanical isolation from vibrations transmitted by the tow cable. This means they act as a safety device by providing slack and dampening during changes in speed. It contains a nylon hose and a low-stretch nylon rope. Nylon hose provides dampening at speeds less than 15 knots, and the nylon rope provides dampening at speeds greater than 15 knots.

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16
Q

What is the stowage and handling system in general?

A

It is the system that is used to deploy, tow and retrieve the array group and to perform maintenance on the array.

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17
Q

What is the fairlead?

A

The fairlead is located on the aft side of the towed array equipment group and it is used to provide a water-lubricated path through the transom. It contains a wiper to remove excess water from the tow cable during retrieval.

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18
Q

What is the level-wind assembly?

A

It guides the array group onto the winch layering system to ensure a tight, consistent wrap during retrieval. It has a DC servo drive motor that is mounted on the port side of the level-wind support frame that drives the level wind carriage. The level wind can be moved either automatically or manually at the control station.

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19
Q

What is the winch?

A

The winch is used to deploy, tow, retrieve, and stow the array group. The drive assembly is made up of a hydraulic motor, hydraulic pump, a servo control valve, filters and a 40 hp AC main drive motor.

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20
Q

What can be used to lock the winch in place?

A

A hydraulically actuated spring-loaded break assembly.

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21
Q

What can be used during towing operations to prevent undesired payout?

A

A pawl.

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22
Q

What is the emergency pump?

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A

A 7.5 hp pump that can be used to turn the bull-gear sprocket to recover the array. In the event of hydraulic failure, the brake and pawl can be disengaged by a hand pump and then the emergency pump can be used.

23
Q

What is the handling drum?

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A

It is a drum that is used to temporarily store the tow cable during maintenance and the de-tensioning processes of the array. The level-wind is not required for transfer between the winch and handling drum.

24
Q

What is the module storage?

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A

Extra modules can be stored in the towed equipment room for redundancy. They are stored on racks that surround the room.

25
What is the control console?
The control station receives ship’s power and directs it to the stowage and handling system. It controls the operation of the handling group. The winch is controlled by a lever and a button on the lever must be held down while the lever is moved fwd/aft to pay out/haul in the cable.
26
What is the array receiver?
Located in the aft sis, the array receiver is internally divided into two components: the power supply and the array receiver controller (ARC). The power supply generates 150 VDC power for the array and 28 VDC power for reference signals. The ARC receives the acoustic and non-acoustic data from the array and de-multiplexes and demodulates it. It then forwards this information to the HSSP in a continuous block through serial connections for the non-acoustic data and a SCSI bus for acoustic data. The ARC also houses circuit cards.
27
What are the circuit cards provided in the ARC?
Analog receiver, Manchester decoding, acoustic and non-acoustic separation, frame synching and parity checking.
28
What is the HSSP?
The High Speed Signal Processor (HSSP) is used to process the raw acoustic data from the array receiver. It performs high-speed arithmetic operations on the digital signal data for functions such as spectral analysis, beam forming and filtering. It uses the time-series data to beam-form, integrate and scale to provide narrowband, broadband, DEMON and audio processing. It performs a FFT on the data in order to conduct spectrum analysis. These multiple sets of data are provided to the DMD for distribution.
29
What is MAPS?
The HSSP only processes part of the frequency range of the data collected by the array (VLF-MF). MAPS can process the entire range. It interfaces directly with the array receiver, meaning if there is a fault down the processing line, it should not affect MAPS.
30
What is the data service rack?
The data service rack provides housing for the power junction box, an audio control panel, a remote control panel, a high density digital recorder (HDDR) and a UPS. The data service rack serves to route power and control signals to and from the sub-assemblies.
31
What is the HDDR?
The high density digital recorder (HDDR) stores the unprocessed data obtained from the array receiver, including acoustic and non-acoustic data for on-board replay and post-mission analysis. It is a magnetic tape recorder and is able to store HF data not able to be processed by the HSSP.
32
What is the DMD?
The Data management and distribution unit (DMD) controls the flow of data from the HSSP, processes display information for the digital processing group, and tracks underwater acoustic contacts. It houses several CCAs, the system controller, tracking processor, display processor, and mass memory. It also connects to CMS through I/O processor #1.
33
What is the maintenance console?
The maintenance console is used to provide an interface for technicians to run diagnostic tests and to display and print errors. The maintenance console can also be used to alter the system’s default parameters.
34
What is the display console assembly?
Each display assembly has a control unit display, two monochrome TV monitors, a power junction box, and a control panel audio.
35
What is the CANTASS control rack?
Located in the ops room on the stud side, the control rack is similar to the data service rack. It houses a power junction box, an audio control panel, a remote control panel, and a video switch assembly and a video graphics recorder. The remote control panel can be assigned as either the master or slave unit. The master unit is typically located in the aft sis.
36
What is the video switch assembly in the CANTASS control rack?
It is used to request the processing of video data from a particular TV monitor by the video graphics recorder which copies the contents of a specified displace console assembly screen onto paper
37
What are the modes of operation for CANTASS?
Array modes: Normal Three Invasive Test Modes Winch modes: Normal Emergency Operational Modes: Run Mode Array Mode Playback Mode Diagnostic Mode
38
What is Normal Array mode?
In normal mode, the information from the hydrophones is transmitted as expected from the array to the processing systems
39
What is three invasive test modes for the array?
In the invasive modes, the array will transmit three different DC levels in place of the acoustic data and zeros in place of non-acoustic data. This mode is used to test the operation of the multiplexers and amplifiers within the array. Each test mode corresponds to a VDC level.
40
What is the normal winch mode?
When in normal mode, all systems within the towed array equipment room can be controlled via the control station.
41
What is the emergency winch mode?
This mode is making use of the emergency motor to move the winch if the main motor malfunctions. The level wind can also be hand-cranked in the event of power loss. Finally, if all else fails and we need to regain maneuverability quickly, the tail can be cut with the cutting tool.
42
What is the run state?
Run state is characterized by two operating modes: array and playback.
43
What is the array operational mode?
In this mode, the array digitizes the analog acoustic signals and sends them to the array receiver where gain normalization occurs. All the data is then transferred to the HSSP for spectral analysis. This new information is passed to the DMD for track processing, display, audio, fine bearing estimation and noise elimination calculations. All of this data is transferred to the HDDR for storage and the display control group for the operators to interpret.
44
What is the playback operational mode?
In playback mode, unprocessed data stored in the HDDR is put through the HSSP as normal where it is processed, sent to the DMD and played back on the display console group.
45
What is the diagnostic operational state?
The diagnostic state is used to provide tests for detection and isolation of hardware faults. These tests are performed by a technician at the maintenance console.
46
What does CANTASS interface with?
EPG&D for power HVAC for cooling of the spaces CMS via I/O Processor 1 at the DMD The bridge status panel IOT indicate deployed status
47
What are some survivability & redundancy factors?
UPS preserves DMD memory for 30 mins Emergency motor for recovery in the case of hydraulic failure Level wind can be moved manually via a hand crank Data can still be collected and stored if HSSP is unavailable The system can work independently of CMS There are two display consoles MAPs can be used independent of the other processing systems
48
What are some trials?
BITs Fault isolation tests (FITs) Seawater short tests - determines if there is a short in the array due to sea water ingress. Test is performed by pressing a switch on the array receiver. Invasive tests - The array produces DC voltages instead of acoustic data and zeroes instead of non-acoustic data IOT test the amplifiers and multiplexers within the array. Managed through the TDM.
49
What are some safety factors?
High voltage electrical precautions High pressure hydraulic precautions Tow cable is under a large amount of tension while in use ISOPAR-M is present- spill kit is located in 2M Ship is considered RAM when CANTASS is deployed
50
What is time division multiplexing?
Time division multiplexing is a way to place multiple signals on a single wire by assigning short time segments. Bandwidth is divided into time slots. Each signal is assigned a specific time slot during which is can use the entire bandwidth of the channel. This process repeats cyclically.
51
What is a FFT?
A fast Fourier transform is used to convert data from the time domain to the frequency domain. It is considered fast because it is being performed on a lower and upper boundary of frequencies. Data converted to the frequency domain can be analyzed easier IOT determine more common or higher power frequencies being picked up.
52
What is the passive sonar equation?
SL - TL = (NL-DI) + DT SL = Source Level TL = Transmission Loss NL = Noise Level DI = Directivity Index DT = Detection Threshold If Left = Right, the probability of detection is equal to whatever number used for detection threshold (typically 50%)
53
What are the 4 layers of the ocean?
Surface Layer (0-60 m) Seasonal Thermocline (60-300 m) Permanent Thermocline (300-900 m) Deep isothermal (>900 m)
54
What are types of sound propagation in water?
Surface duct Sound channel Convergence zones Bottom bounce Direct path

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