1 / 28

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.

gala
Download Presentation

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

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related