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The product lifecycle - upgrading: Ring, Ring, East Coast Calling

The product lifecycle - upgrading: Ring, Ring, East Coast Calling. Lecture 14: Unit 7a Disasters, Failures and other Dangerous Things. Characteristic data of a wave. 6 periods in 1 second = Frequency 6 cycles/sec or hertz. Amplitude (similar to volume). T. time. Period = 1/6 seconds.

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The product lifecycle - upgrading: Ring, Ring, East Coast Calling

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  1. The product lifecycle - upgrading:Ring, Ring, East Coast Calling Lecture 14: Unit 7a Disasters, Failures and other Dangerous Things

  2. Characteristic data of a wave 6 periods in 1 second = Frequency 6 cycles/sec or hertz Amplitude (similar to volume) T time Period= 1/6 seconds

  3. Acoustic X Ray Light Microwaves = smaller period = ultra high frequency = gigahertz Short waves = short period = high frequency = megahertz Medium waves = medium period = Low frequency = kilohertz Long waves = long period = Low frequency = hertz Types of waves

  4. Energy transfer and Speed in waves The speed of sound in the air is roughly 340 meter/sec = 765 miles/hour = Mach 1 Speed = Distance / time = Wavelength / Period = Wavelength * Frequency Source: http://www.glenbrook.k12.il.us/GBSSCI/PHYS/mmedia/waves/ltm.html

  5. A Dynamic Speaker

  6. Phone Components • Start with the basic audio components • Mic, amplifier, speaker • Add • A way to dial • A ringer • A way to tell if the phone is ‘off hook’

  7. Overview OfTelephone Equipment • History • A brief overviewfrom 1876 to 1965 • The evolution of the telephone network • Two important revolutions in service (1960s-1990s) • From analog to digital • Out-of-band switching

  8. History:The Beginning • In 1876 the telephone was invented by both • Elisha Gray • Alexander Graham Bell • Bell beats Gray to the US Patent Office by six hours • After a long legal battle, Bell’s patent was upheld

  9. History:The First Telephone Networks • On July 9, 1877, three telephone researchers, Sanders, Hubbard and Bell, form the first Bell telephone company. • On January 28, 1878, the first commercial telephone network is built in New Haven, CT • had a manual switchboard • served 21 telephones on 8 lines • This network is quickly followed by other larger networks in different parts of the US (Source: http://www.privateline.com/ TelephoneHistory2A/Telehistory2A.htm)

  10. Old Telephones

  11. History: An Important Decision • The Bell Telephone company decides • to lease their telephones ! • license franchises instead of selling them • Direct Result • Creates a constant cash flow • Since phones are leased, they must be higher quality • Innovation takes a backseat to the quality assurance • Result • Change will become evolutionary instead of revolutionary • This will not change until mid 1960’s

  12. History:Things Become More Connected • On February 28, 1885, AT&T becomes the first long distance telephone company • only Bell Telephone license franchises can use its lines • In 1889, Hartford, CT sees the first public coin telephone • to use, you gave money to an attendant • By 1892, the Bell Company controlled 240,000 telephones • in addition, many independent companies exist

  13. History:Things Become More Automatic • In 1878, Thomas Watson invents the ringer • In 1891, Almon Strowger invents the Step by Step or SXS system • replaces the switchboard operator when placing a local call • requires a new phone first with buttons, and later, dialers • In 1892, the first automatic commercial exchange began operating in La Porte, IN • In 1896, the first dial telephone system begins operating in Milwaukee's City Hall • The Bell company will not start using switched networks until 1919

  14. Evolution:From mechanical to electronic switching (Source: http://www.privateline.com/ TelephoneHistory2/History2.html)

  15. Evolution:From mechanical to electronic switching • In 1921, the Bell System introduces thefirst commercial panel switch • A very noisy and not too reliable electro-mechanical switch • In 1938, they introduce the crossbar switch • Still electro-mechanical, but much more reliable • In 1962, they introduce the first electronic switch using vacuum tubes • It basically does not work • In 1965, they develop the computerized switch • Uses transistors, and this time, works so well that they start replacing all electro-mechanical switches • This will lead to two revolutions in the way the telephone network works (Source: http://www.privateline.com/ TelephoneHistory2/History2.html)

  16. Evolution:A simple circuit switch network • Telephones are connected to switches at the local office (or exchange) switch, also known as the “local loop” • These switches are connected to other switches which can route your phone call to other exchanges

  17. Revolution 1:From analog to digital information • In 1963, the first telephone switch to use Time Division Multiplexing (TDM) • goes into service in Cocoa Beach, FL • In 1976, the first digital toll network switch • is cut over in Chicago, IL • can handle 550,000 long-distance calls per hour. • In 1982, Illinois Bell begins using the first all-solid-state local digital switching system • By the 1990’s, the complete telephone network becomesdigital

  18. Revolution 1:Analog and Digital Signals • Analog signals • Sounds and electrical signals in the real world are analog • The amplitude of these signalscan have continuous (or non-discrete) values • Digital signals • Any analog signal can berepresented using a digital signal where normally twodiscrete values (one and zero) are allowed

  19. Revolution 1:Digital Signals • Disadvantages • Since a digital signal has less possible amplitude values, it can carry less information • You need to convert to/from analog to use • Advantages • Computers (and electronics in general) can process digital information faster • Digital signals can be sent further and faster because they contain only two different amplitude states

  20. Revolution 1:Analog to Digital Conversion • There are many ways to do anA to D and D to A conversion • Some important factors are • Sample rate • normally, the faster the better • but, the faster you sample • the more digital data to get • Compression (or encoding) method • encoding the absolute value of the analog signal in each sample • requires bigger binary numbers (I.e., more ones and zeros), but does not rely on previous sample values • encoding the relative change from the last sample in each new sample • requires smaller numbers, but can get lost easier

  21. From Analog to Digital Coding • Say the values of the signal you have are • { 1,3,7,8,12,15 } • Using digital numbers you are using the digits from 0 to 9 to represent the values; however, for the case of number 12 and 16 you need to use the position at the left to represent ten so you have the number 12 that actually means • 1*10 + 2 = 12 • I.e. the position on the left-most digit is multiplied by 10. For the case of 15 it would be • 1*10 + 5 = 15 • If the quantity you want to represent is 32 then you really represent • 3*10 + 2 = 32 • How about 328 ? • 3*100 + 2*10 + 8 = 328

  22. Revolution 1:Time Division Multiplexing • One way using digital signals helps • We can send the ones and zeros that represent a sample faster than the rate at which they have to be collected • This means that we can mix (or multiplex) the ones and zeros of several signals on the same single line • The easiest way to do this multiplexing is by using a standard time division (or time slice) • This method is called Time Division Multiplexing (or TDM)

  23. Revolution 1:The hierarchical network • Using TDM (or other methods of multiplexing) • The switch connected to your phone can switch individual phone calls, while • A switch between Fort Worth and some other city can switch as a group a number of calls that are all going to the same city • This group of calls is sent over something called a trunk line

  24. Revolution 2:From in-band to out-of-band switching [1] • Before 1965 • Telephone services (like call waiting) have to be hardwired in the switch • Call setup is done on the same phone lines as the call • this is called in-band switching • 1965 • By adding a special-purpose computer to each switch, services can now be programmed in the switch • since new services can be added by only changing the software, they can be added quicker • but computer power still limits what can be done • Late 1960’s • The switch computers are connected together over separate lines • allowing them to pass call setup and control information without using call lines • this is called out-of-band switching • This allows the addition of extra data and commands, such as who is calling you, wait, transfer, take messages etc.

  25. Revolution 2:From in-band to out-of-band switching [2] • 1970’s • US companies develop a CCS6 standard for out-of-band switching • now switches from different companies can share information • New components called Signal Transfer Points (or STPs) are added to the telephone network • STPs are used to better route out-of-band information • 1980’s • The international SS7 network standard is introduced • It defines three types of components • SSP – Service Switching Point (the original telephone switch) • STP – Signal Transfer Point • SCP – Service Control Point (a database for service information)

  26. Revolution 2:The SS7 Network Overview • Voice (and other service data) flow over the red lines • The actual route of a call is determined by the STP based on the total network loading at the time of the call • Call and service setup flow over the blue lines

  27. Revolution 2:The SS7 Network Details • For reliability, every componentin a SS7 network (except for thelast mile elements) are paired into primary and secondarycomponents • The secondary component isdesigned to listen for indicationsthat the primary component has stopped working and to take over if necessary • The intelligence for the network is primarily in the SCP • These are normally large general-purpose computers running special high-availability databases • SCPs handle network-wide services like • Routing an 800 number to different call centers based on time-of-day • Keeping base station mobile roaming databases up-to-date

  28. Revolution 2:Intelligent Networks • Advantages • Can save the provider money by maximizing utilization of the revenue lines • Can route around problems • Can adapt quickly to new service and signal requirements • Disadvantages • Are expensive to upgrade or replace • This tends to ‘lock in’ older technologies longer • When they do break, they really break! • These are very complex systems with many possible failure points

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