background image

Troubleshooting

Gemini Profiling System

0695-SOM-00001, Issue: 03

60

© Tritech International Ltd.

same subnet and the PC routing table needs to be set up so that packets are routed

correctly to the sonar. If the sonar is receiving ping requests then the IP address of

the PC will appear in the 

Connected IP Address

 field in the advanced settings

page of the software.

If the sonar is connected to the PC then the most likely cause is particularly bad packet

loss on the network between sonar and PC.

Note

The sonar will only respond to ping requests from IP addresses on the

same subnet as the sonar. Some firewalls have been known to cause this

issue. To view the computers routing table type 

route print

 from the

command line.

Update rate is slow and there are sometimes large gaps

between pings

VDSL System

 - The VDSL link is susceptible to electrical noise induced by turning

other devices on and off such as thrusters on an ROV. If the link keeps going down

try using the “Medium Noise” or “High Noise” VDSL setting in the advanced option.

Higher Noise settings trade off speed for reliability of the network link. This may

reduce the ping rate slightly but the link will be more reliable in the presence of noise.

Check all connectors on the VDSL twisted pair, poor contacts have been known to

cause this issue.

Ethernet System

 – There may be noise induced onto the Ethernet cables, be sure to

route these as far away as practicable from noise sources.

All Systems

 – Some poor quality PC network cards have problems with the large data

rate from the Gemini sonar and drop a significant amount of packets. If you have

large packet loss, try updated network card drivers and a different brand of network

card. Also check that the PC and graphics chipset meet the minimum specification.

Sonar goes offline while operating on deck

The  sonar  head  outputs  heat  to  the  body  casing  (using  it  as  a  heatsink)  which  is

dissipated to the surrounding water during normal operation.

In order to protect the internal electronics from damage due to overheating a thermal

cut-off will shut down the sonar if it gets too warm. It will be necessary to allow the

unit to cool down before it will operate again.

The unit should not be operated out of water for extended periods.

Summary of Contents for 620pd Profiling

Page 1: ...Gemini Profiling System 0695 SOM 00001 Issue 03 1 Tritech International Ltd Gemini Profiling System Product Manual 0695 SOM 00001 Issue 03 ...

Page 2: ...s supplied by Tritech International Ltd on the understanding that it may not be copied used or disclosed to others except as authorised in writing by Tritech International Ltd Tritech International Ltd reserves the right to change modify and update designs and specifications as part of their ongoing product development programme All product names are trademarks of their respective companies ...

Page 3: ...2 Burton 5506 1506 Auxiliary Port 16 4 7 Cable Specification 17 4 7 1 Ethernet Cable 17 4 7 2 VDSL Cable 17 4 7 3 RS232 Cable 18 4 8 Offsets 19 5 Gemini Profiler Installation 20 5 1 Installing the Sonar Head 20 5 2 Electrical Communication Notes 21 6 Care Maintenance of the Gemini Profiler 23 6 1 After using the sonar 23 6 2 If storing the sonar for extended periods 23 6 3 Regular maintenance 23 I...

Page 4: ... Log Directory Selector 43 12 3 11 Sound Velocity Indicator 44 12 3 12 Palette Selector 44 12 3 13 Gain Assist 44 12 3 14 Gain Control 45 12 3 15 Range Control 45 12 3 16 Indicators 45 12 3 17 Scan Sector 46 12 3 18 Measurements 47 12 4 Advanced Controls on Advanced Screen 47 12 4 1 Choose and Position the Equipment 47 12 4 2 Units 48 12 4 3 Sound Velocity 48 12 4 4 Compression 49 12 4 5 Inter pin...

Page 5: ...1 Issue 03 5 Tritech International Ltd C Setting the Gemini Device IP Address in Gemini Software 66 D Gemini Software String Decode 67 E Optional Surface Adapters 68 E 1 Dimensions 68 E 2 Ethernet Adapter 68 E 3 VDSL Adapter 69 Glossary 70 ...

Page 6: ...or firmware revision numbers 3 A clear fault description 4 Details of any remedial action implemented Contamination If the product has been used in a contaminated or hazardous environment you must de contaminate the product and report any hazards prior to returning the unit for repair Under no circumstances should a product be returned that is contaminated with radioactive material The name of the...

Page 7: ...current topic Important When this is shown there is potential to cause harm to the device due to static discharge The components should not be handled without appropriate protection to prevent such a discharge occurring Caution This highlights areas where extra care is needed to ensure that certain delicate components are not damaged Warning DANGER OF INJURY TO SELF OR OTHERS Where this symbol is ...

Page 8: ...Gemini Profiling System 0695 SOM 00001 Issue 03 8 Tritech International Ltd Part I Introduction to the System ...

Page 9: ...automatically detect which connection is available and switch to that connection a different cable is required see Section 4 7 Cable Specification The VDSL option allows a single twisted pair to be used for communication to from the sonar at high speeds dependent on the length and quality of the cable The Tritech International Ltd supplied VDSL Hub takes the two wire VDSL input and bridges it to E...

Page 10: ...i range require a higher specification of hardware than other Tritech products so will only work with the later versions of the SCU from SCUv5 onwards either Windows XP or Windows 7 versions The profiling heads should be connected to the SCU through a Gemini Hub or Ethernet VDSL adapter If integrating the SCU into a network as illustrated in Chapter 2 Example Survey Setup then depending on the con...

Page 11: ...d 2 Example Survey Setup Note Tritech International Ltd are able to supply the Gemini Profilers Gemini Hub and a Surface Control Unit SCU but all other hardware shown will be supplied by other manufacturers and is therefore not supported in any depth within this documentation ...

Page 12: ...able from Tritech International Ltd detailing the steps necessary to properly integrate the Gemini Profiler system with external survey packages For advice please contact Tritech International Ltd providing the details for the survey package which is being used or alternatively visit www tritech co uk and download the relevant manuals ...

Page 13: ...Gemini Profiling System 0695 SOM 00001 Issue 03 13 Tritech International Ltd Part II Gemini Profiler Head ...

Page 14: ...4 Tritech International Ltd 4 Gemini Profiler Specification 4 1 Dimensions Forward Facing Unit Not to scale dimensions in mm 120 318 336 Ø140 225 Ø145 50 80 4 2 Dimensions Downward Facing Unit Not to scale dimensions in mm 456 474 Ø140 Ø145 50 98 170 ...

Page 15: ...cations Electrical and Communications Power Consumption 37W max range dependent head unit only Supply Voltage 20 75V DC Data Communications Ethernet up to 80m or VDSL up to 1000m VDSL Cable Length Maximum length for VDSL and power is 300m if power is provided locally e g by the ROV then maximum cable length for VDSL communication only is 1000m 4 5 Physical Properties Physical Properties Property T...

Page 16: ...rams show pin orientation of the connector face on the sonar head 4 6 1 Burton 5506 1508 Main Port Pin Function Diagram 1 Ethernet RX 2 Ethernet RX 3 Ethernet TX 4 DC 5 VDSL 6 Ethernet TX 7 DC Ground 0V 8 VDSL 5506 1508 4 6 2 Burton 5506 1506 Auxiliary Port Pin Function Diagram 1 RS232 RX 2 RS232 TX 3 DC 4 DC Ground 0V 5 RS232 TTL Ground 6 TTL IN 5506 1506 ...

Page 17: ...termittent operation This should be connected to the Burton 5506 1508 Main port on the sonar head Ethernet Cable Specification Burton 55A1 1508 Cable Colour Specification Function 1 Red UTP 2 24AWG Ethernet RX 2 White UTP 2 24AWG Ethernet RX 3 Blue UTP 1 24AWG Ethernet TX 4 Red 20AWG DC 6 White UTP 1 24AWG Ethernet TX 7 Black 20AWG DC Ground 0V Minimum dynamic bend radius 130mm static 36mm 4 7 2 V...

Page 18: ...m static 35mm 4 7 3 RS232 Cable The Burton 5506 1506 Auxiliary port is designed for use as an interface for auxiliary sensors and is able to provide power and communicate using the RS232 protocol The cable should be shielded RS232 Cable Specification Burton 55A1 1506 Cable Colour Specification Function 1 Red UTP 2 24AWG RS232 RX 2 White UTP 2 24AWG RS232 TX 3 Red 20AWG DC 4 Black 20AWG DC Ground 0...

Page 19: ...he middle of the receive transducer face as shown Port Receive RX Transmit TX 0 Starboard The view shows the sonar head as it would look from underneath the survey vessel with the front of the vessel at the top of the page i e the sonar transmitter to the fore with the port side correctly aligned on the left Note This offset datum applies to both forward and downward facing variants ...

Page 20: ...at side and end on views of the sonar cone are as follows For Vessel Installations The profiling heads can be installed over the side of the survey vessel or within a moon pool if one is available Installation within a moon pool will provide a more stable operating environment but it must be ensured that the sonar path to the seabed is clear and not obstructed by the vessel hull For over the side ...

Page 21: ... at least two or three coatings For ROV Installations The sonar heads should be mounted in the correct orientation along the trim of the vehicle and it should have an unrestricted view of the seabed The head should be clamped securely around the main part of the body tube Any metallic clamps should be electrically insulated from the sonar body by either rubber or plastic strips or mounting bracket...

Page 22: ...pped in the connection could result in an electrical short Caution If the Gemini has two ports then the unused port must have a blanking cap fitted prior to immersing in water Failure to do this will cause permanent damage Caution If using alcohol or IPA to clean out the connector take care that it does not come into contact with any other part of the sonar If an O ring is present it should be fir...

Page 23: ...necessary leave to air dry before stowing Pack into storage container along with several pouches of silica gel 6 3 Regular maintenance There are no user serviceable parts inside the sonar and it is not necessary to take it apart for any maintenance tasks In light usage as long as the unit is washed thoroughly with clean fresh water after every use and dried before storage no further maintenance is...

Page 24: ...Gemini Profiling System 0695 SOM 00001 Issue 03 24 Tritech International Ltd Part III Gemini Hub ...

Page 25: ...luminium and stainless steel Operating Temperature 5 to 40 C Storage Temperature 20 to 50 C Operating Environment Indoor use only 7 3 Electrical and Communication Power Consumption 120W maximum BNC PPS Voltage 5V TTL Supply Voltage 90 264V AC at 47 63 Hz Main Fuses 4A 250V 5x20mm glass antisurge Communication Ports 1 x Gigabit Ethernet RJ45 2 x Ethernet or VDSL Souriau 8 x Serial RS232 DE 9 1 x BN...

Page 26: ...et port Port J which is for connection to an IT infrastructure It will also have two Ethernet ports as detailed below which provide power and communications to the Gemini heads Pin Function Diagram Photograph A Ethernet RX B Ethernet RX C Ethernet TX D DC E DC F Ethernet TX G DC Ground H DC Ground J not connected K not connected L not connected M cable screen Souriau UTS71412S Using cabling provid...

Page 27: ...k is recommended to ensure sufficient bandwidth 7 3 3 VDSL Configuration In VDSL configuration the Gemini Hub will have a single Ethernet port Port J which is for connection to an IT infrastructure It will also have two VDSL ports Port K and Port L as detailed below which provide power and communications to the Gemini heads VDSL Cable Length Maximum length for VDSL and power is 300m if power is pr...

Page 28: ...ustrial computer equipment and fixed in place using the four mounting holes on the front panel The handles are to aid insertion into a rack system and are not designed to be used as a means for carrying the Hub Caution The power lead should be plugged into a suitable location to allow for access and disconnection at all times to provide a method of cutting power to the unit and should be labelled ...

Page 29: ...n existing IT infrastructure i e the sonar head is located on the other side of a network switch then it will be necessary to construct a cable that does not connect to the power output Tritech International Ltd can provide such a cable Port J is for connection to an Ethernet infrastructure and it carries data from all of the connected sensors on the Hub including data from the DE 9 ports and time...

Page 30: ...BNC connector and accepts standard 5V TTL PPS Transistor Transistor Logic Pulse Per Second data from a GPS device the GPS will also have to be connected to a free RS232 port on the Gemini Hub Earth Point rear panel The hub unit is fitted with an earth point on the rear panel Caution This earth point is a functional earth and not a protective earth For protective purposes the earth should be connec...

Page 31: ...oisture Warning Do not remove the cover of the hub unit doing so may expose the user to risk of electrical shock If it becomes necessary to change the main fuse of the unit the following procedure should be used 1 Turn off power and remove the power lead from the unit 2 Locate the fuse holder in between the switch and the power in socket 3 Pull out the fuse holder and replace fuses with two of the...

Page 32: ...Gemini Profiling System 0695 SOM 00001 Issue 03 32 Tritech International Ltd Part IV Gemini Software ...

Page 33: ...n use The latest version can be downloaded from www tritech co uk The Gemini software is also supplied with the sonar on a USB memory stick as a Windows Installer Package known as an msi file Doubling clicking the installation file will start the Windows Installer and install the software onto the computer During installation follow the installer instructions if required making any appropriate sel...

Page 34: ...ess in Windows XP or Appendix B Setting the computer IP address in Windows 7 10 3 1 Check the operation of the Gemini sonar If the correct changes have been made to the Gemini Sonar it should now show as connected in the Gemini Software If nothing is displayed check that all values entered were correct and it may be necessary to rerun the Gemini Software to establish a link The Gemini Software ret...

Page 35: ...use they will both be using the default IP address To set the IP address of the Gemini System devices 1 Set the IP address of the computer 192 168 2 100 with a subnet mask of 255 255 255 0 2 Change the IP address of the Gemini Profiler from the default value 192 168 2 201 to the desired value The status information will remain in the Gemini Software but it will no longer be possible to communicate...

Page 36: ...ng on the tabs at the top left hand of the screen The two screens are the User screen and the Advanced screen The User screen allows the maximum amount of screen to be used for data display and the Advanced screen enables adjustment of the sonar settings Note The User screen is not considered separately within this document the User screen has a subset of the controls for the Advanced screen with ...

Page 37: ...d corner are the controls for arranging the display and selecting the directory data is to be logged to The indicator for the sound velocity is also situated in this area of the screen In the middle of the left hand side of the screen is the palette selector On the lower left hand side of the screen are the range and gain controls for the sonar On the lower right hand side of the sonar display are...

Page 38: ... the Sonar ID entered in the Sonar box of the configuration settings is not one of the sonars visible to the Gemini software when the Sonar button is pressed the software will present one of two messages If only one sonar is visible the software will offer the chance to start imaging from that sonar Clicking Yes will cause the software to select the sonar which is visible to it Clicking No will ac...

Page 39: ... software will stop logging to the current file and open a new file to resume logging The name of the new file will be based on the time the file was opened If data is logged for a significant period of time a number of files will be created each with a different filename indicating when the data was first logged to that file For example if the Log Directory selector is showing that the directory ...

Page 40: ...e between the repeat being active and inactive Load Button When the Load button is pressed the software will open a file selector to allow the user to select a previously recorded data file to be replayed To replay the data recorded at 4 30 02pm on 18th October 2014 file selector would look like this and the file 163002_IMG ecd should be selected When replaying a log file the filename together wit...

Page 41: ... data directory with a filename of Gemini_nnnn jpg where nnnn is an incrementing index number for the image For example using a logging directory of C GeminiData the first image captured would be stored in the file C GeminiData Images Gemini_0001 jpg When the image has been captured the Gemini software will display a message as below giving the name of the file This message will be displayed for f...

Page 42: ...the software 12 3 7 Flip Image Left Right If the sonar is mounted upside down the software has the ability to flip the image from left to right as viewed on the computer screen so that the image still appears correctly oriented to the user The illustration above shows the button in the non flipped state 12 3 8 Draw Grid The Draw Grid button when clicked draws the range and bearing grid on the imag...

Page 43: ...d area will follow the mouse pointer 12 3 10 Log Directory Selector The Log Directory selector shows the currently selected directory which will be used to save data recorded by the software For a description of how the directories and files used by the software when recording data refer to Section 12 3 4 Capture Screen and Section 12 3 5 Record as WMV When the text below the Log Directory box is ...

Page 44: ...rs The palette bar on the left hand side of the screen shows the mapping currently being used Clicking on the palette bar opens a palette selector which allows the selection of the palette to use As the mouse is hovered over the different palettes the sonar image will preview that palette Note A contrasting colour scheme should be chosen for the image palette and targets see Section 12 4 9 Digitis...

Page 45: ...ered using keyboard shortcuts z to decrease gain a to increase gain Note The gain control is only for the display image and has no effect on the digisation of targets 12 3 15 Range Control The Range slider at the bottom left hand side of the display is used to change to the range of the image being acquired by the Gemini Sonar The range can be changed by either clicking on the dark blue indicator ...

Page 46: ...t allow the scan sector also known as the aperture to be adjusted Adjusting the scan sector can be useful if the area of interest is narrow such as a pipe trench the beam setup will also require adjustment see Section 12 4 8 Beam Setup Click and hold the mouse over one of the handles The clicked handle and any other handles that will move when the mouse is dragged will be highlighted Square shaped...

Page 47: ... single click on the cone will show the position of the click Clicking at one point on the cone and holding the left mouse button down whilst moving the mouse will give a measurement between the two points When any measurement has been taken clicking outside the cone will turn the measurement off 12 4 Advanced Controls on Advanced Screen The Configuration Options pane is on the far right of the di...

Page 48: ...head If using a motion reference unit the position of this can be set by inserting values into the MRU row of the table 12 4 2 Units The Units control selects between Metric or Imperial units These are then applied to range lines and any measurements which are taken Note The units selection only affects the screen display Output to the hydrographic survey package is always in SI units 12 4 3 Sound...

Page 49: ...s set to zero and then the compression is applied Increasing the RLE level will increase the efficiency of the compression and hence reduce the bandwidth required to transmit the image data but will remove more and more of the lower levels from the data initially reducing the noise but quickly removing smaller objects weaker targets from the image Enable Compression toggles the compression when cl...

Page 50: ... and red text means it has not and is pinging as fast as it is able to Typically in a survey a regular ping interval is desired for the targets The target rate is not limited by network bandwidth since the target detection digitisation is performed in the sonar head Network bandwidth only limits the image transfer rate The image transfer rate will be reduced if there is insufficient bandwidth avai...

Page 51: ...acoustic frequency of 620kHz 12 4 8 Beam Setup The Beam Setup options allow control of the sector which is scanned by the Gemini sonar this can be useful if the area of interest is quite narrow such a a pipe trench To vary the start and end of the scan sector simply drag the sliders sideways or use the and buttons to increment the values one step at a time The maximum range is from 65 to 65 The Sp...

Page 52: ...points enclosed by the gates are used Note The gates are always in use for target detection i e targets will not be displayed outside these gates For targets and gates the Display button only affect the displaying of the data however to reduce network bandwidth the button for Sonar Image enables or inhibits the data transmission If the sonar image data is inhibited during logging it will not be av...

Page 53: ... to work with the desired network Once the sonar has been successfully configured it should not be necessary to change the settings again unless moving to a different infrastructure 12 4 12 Settings Display Tabs The settings and display tabs are at the bottom of the display window and are for displaying information about the connected sonar s and also for configuration of external devices such as ...

Page 54: ...sonars to be scrolled 12 5 Serial Data Input 12 5 1 Sensors The Sensors tab is for displaying extra information from connected RS232 sensors Note The Settings field of the Sensors tab is only active if logging is taking place Within the Settings field the actions of the operator are recorded so that during play back of the log file it is possible to see which settings have been changed 12 5 2 Gemi...

Page 55: ... The port letter corresponding to the label on the back of the Gemini Hub Mode Can change between an ASCII decode binary decode or can echo the data on one of the other ports ASCII is normal binary only used by Simrad EM3000 Echoing the data provides an alternative option to using a serial splitter cable where a single data feed is required to be input both to the Gemini system and to other system...

Page 56: ...twork data output This is only enabled when the Digitisation network data output format is first set to Tritech see Section 12 4 9 Digitisation The setting controls how RS232 serial data received by the Gemini Hub is retransmitted over Ethernet to the survey software This data can also be disabled if it is not required by the survey software Note The data age status indicator will show the status ...

Page 57: ... if no data is received Age The age of the data shows when the last good data was received see note below Hz The incoming data rate String The incoming data string check this against the chosen Decode if the data indicator is red Gemini RS232 Ports The ports on the rear of any connected Gemini heads This data can be decoded as per the computer COM ports or the data can be routed as an output from ...

Page 58: ...Gemini Profiling System 0695 SOM 00001 Issue 03 58 Tritech International Ltd Part V Troubleshooting and Appendices ...

Page 59: ... problem will be with the network settings on the PC Note Ethernet connection requires Cat5e cable for the entire cable run max 80m lengths of untwisted cable must be kept to an absolute minimum All Systems Some firewalls have been known to cause this issue Contact the network administrator for advice if the sonar is connected to a network where disabling the firewall would present a security risk...

Page 60: ...dvanced option Higher Noise settings trade off speed for reliability of the network link This may reduce the ping rate slightly but the link will be more reliable in the presence of noise Check all connectors on the VDSL twisted pair poor contacts have been known to cause this issue Ethernet System There may be noise induced onto the Ethernet cables be sure to route these as far away as practicabl...

Page 61: ...necessary to choose one that has a dedicated graphics chip the Intel 2000 3000 chips that use part of the main CPU for graphics processing are inadequate For desktop computers installation of a dedicated 3D graphics card is recommended with optimum results being obtained by using a high resolution screen connected with a digital interface such as DVI Additionally make sure that the rest of the com...

Page 62: ...u select Control Panel From the Control Panel Explorer window that opens double click on Network Connections From the list of available network connections that opens double click on the Ethernet connection which will be used to connect to the Gemini Sonar Click the Properties button on the dialog which opens This will open a dialog which looks like this Scrolling the This connection uses the foll...

Page 63: ...International Ltd Make a note of the settings as currently used by the computer these will be needed to restore the computer to any existing network Refer to the appropriate section of this manual for the correct IP address to use The following screenshot shows the dialog after those changes have been made ...

Page 64: ... though the sequence for other operating systems will be similar Disconnect the computer from any existing network First click on the Start Menu and select Control Panel Under Network and Internet click on View network status and tasks This will bring up the Network and Sharing Center which allows configuration of any networks on the computer Click on Change adapter settings on the left hand pane ...

Page 65: ...ould be displayed Find the entry labelled Internet Protocol Version 4 TCP IPv4 select it and then click on the Properties button In the properties dialog which opens there will either be Obtain an IP address automatically or Use the following IP address selected If an IP address is already present make a note of it before changing any values since it will be needed if the computer is ever restored...

Page 66: ...emini has been entered at the top of the screen the details for the new IP address can be entered Three items need to be entered the Device ID to ensure that the correct Gemini is being altered the new IP Address and the new Subnet Mask Once these details have been entered pressing the Modify Device Details button will start the process of changing the IP address A dialog box will open requesting ...

Page 67: ...ctansHPR Heave Pitch Roll PHTRH OctansLinear Heading Heave Surge Sway HEHDT PHLIN OctansPR Pitch Roll PHTRO SonDepth Depth SONDEP TSS Std 1 Heave Pitch Roll 000000 0000H 0000 0000 Octans Std 2 Heading Heave Pitch Roll 00000 0000H 0000 0000F AML Smart SVP Speed of Sound 0 1500 0 Speed of Sound Speed of Sound 1500 0 Navi Pack Position Heading Pitch Roll G CDL Mini Tilt Pitch Roll P 0000 0R 0000 0 CD...

Page 68: ...rnet adapter to be used with a single Gemini head to allow configuration of the unit E 1 Dimensions Not to scale dimensions in mm 130 151 70 160 E 2 Ethernet Adapter Sonar Head Connector Pin Function Diagram Photograph A Ethernet RX B Ethernet RX C Ethernet TX D DC E DC F Ethernet TX G DC Ground H DC Ground J not connected K not connected L not connected M cable screen Souriau UTS71412S ...

Page 69: ...graph 1 DC Ground 2 DC 3 not connected 4 not connected Souriau UTS7124P E 3 VDSL Adapter Sonar Head Connector Pin Function Diagram Photograph 1 DC Ground 2 DC 3 not connected 4 VDSL 5 VDSL 6 not connected 7 cable screen Souriau UTS7147S VDSL DC Connector Pin Function Diagram Photograph 1 DC Ground 2 DC 3 not connected 4 not connected Souriau UTS7124P ...

Page 70: ...s and control theory DC Direct Current DE 9 A 9 pin D shaped connector commonly used for serial communications on computers DVI Digital Visual Interface a standard connector for connecting from a computer to a monitor Ethernet A family of computer networking technologies for local area networks LANs GB Gigabyte 1000MB Gemini Unless specified this can refer to any of the multibeam sonars in the Gem...

Page 71: ...otion Reference Unit Multibeam A sonar which forms multiple beams of sound so it can update in real time and does not have to perform a full scan like a traditional sonar PC Personal Computer PPS Pulse Per Second PSU Power Supply Unit RAM Random Access Memory RLE Run length Encoding a form of data compression in which sequences of data that have the same value are stored as a single datum point an...

Page 72: ...rsal Time time data closely related to Greenwich Mean Time GMT UTP Unshielded Twisted Pair cable is a standard cable wiring scheme used for communications cable with no cable screen and no pair shielding known as Unshielded Unshielded Twisted Pair U UTP under ISO IEC 11801 VDSL Very high bitrate Digital Subscriber Line a method of communicating down un twisted copper cable at uplink speeds of 18Mb...

Reviews: