1 / 51

Lesson 1 Topics PSTN Overview The Role of The PSTN CPE – An Example, How A

The. Public Switch Telephone Network. Lesson 1 Topics PSTN Overview The Role of The PSTN CPE – An Example, How A Telephone Works. Thought For The Week Building on Lessons Learned In TCM 134. STUDY GUIDE. Study This Set Of PowerPoint Slides

aadi
Download Presentation

Lesson 1 Topics PSTN Overview The Role of The PSTN CPE – An Example, How A

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 Public Switch Telephone Network • Lesson 1 Topics • PSTN Overview • The Role of The PSTN • CPE – An Example, How A • Telephone Works Thought For The Week Building on Lessons Learned In TCM 134

  2. STUDY GUIDE • Study This Set Of PowerPoint Slides • Complete Assignment 1 And Post All Answers • In The Lesson 1 Drop Box By The Due Date.

  3. Objectives • In This Lesson, You Will Learn How The Public • Switch Telephone Network (PSTN) Was • Originally Designed To Carry Voice Services. • Next, We Will Learn That The Original Design • Of The PSTN Has Evolved To Carry Most Of • Today’s Advanced Voice, Data And Video • Services. • You Will Study A Brief Overview Of The PSTN – • A Building Block For Our Course. • Finally, You Will Learn How One Piece Of CPE • Works In Conjunction With The PSTN.

  4. Section 1.1 – PSTN Overview

  5. What Is The PSTN? • The Public Switch Telephone Network (PSTN) • Is A Mesh Network Of Lines, Trunks, Switches, • Etc. That Connects Customer Provided • Equipment (CPE) Together To Allow The CPE To • Communicate Together. • The PSTN Was Originally Designed To Optimize • The Transmission Of Voice Services.

  6. Major Elements Of The PSTN CO Class 1 Switch PSTN CO Class 2 Switch Digital Interoffice Trunks CO Class 5 Switch Analog Loop Digital Loop PBX or KTS Residence CPE Office Bldg

  7. The Four Major Elements Of The PSTN • There Are Four Major Elements Of Today’s Public • Switched Telephone Network (PSTN). • Customer Premises Equipment (CPE) • Access System • Transport • Signaling

  8. Customer Premises Equipment • Prior To 1984 And The Breakup Of The AT&T Monopoly, • All Parts Of The Public Switched Telephone Network Was Owned And Operated By The Telephone Company. • After 1984, The Ownership And Maintenance Of All Telecommunications Equipment And Wiring On The Customer’s Site Became The Responsibility Of The Customer.

  9. Customer Premises Equipment Includes: • Telephones • Fax Machines • Wiring & Jacks • Multiplexers • Cross Connect Systems • Computers • PBXs • Key Systems • CSUs • DSUs • Video Codecs • Etc.

  10. Customer Premises Equipment - Continued: • Each Of These Pieces Of CPE Are Different. • They Each Work Differently Electronically, And Many • Have Different Ways In Which They Connect To The • PSTN. • Later In This Lesson We Will Study In More Detail, As • One CPE Example, How Telephones Work Electronically • And How They Connect To The PSTN. • Later In This Course, We Will Study How Several Other • CPEs Work Electronically And How They Connect To • The PSTN.

  11. Demarcation Point • The FCC Defined A Point, The Demarcation Point, In The • Telecommunications Network That Separates CPE From • Telephone Company-Provided Equipment And Wiring. • The Demarcation PointIs Often Referred To As The Demarc.

  12. Access System • The Access Component Of The PSTN Provides Customers • All Of The Wiring And Equipment For The Customer’s • CPE To Be Connected To The Central Core Of The Public • Switched Telephone Network. • The Access System Includes Both Lines And Trunks And The • Termination Equipment In The End Office. • Access Lines And Trunks Along With The Telephone Poles, • Conduits, Connector Boxes, Etc. Are Referred To As The • LocalLoop.

  13. Central Office Termination Equipment • Some Samples Of End Office Termination Equipment.

  14. Access System • Most Access Circuits Run From The Carrier’s Central Office • And A Residence Are Analog Circuits (Ref. Slide 6). • Most Access Circuits Run Between The Carrier’s Central • Central Office And Businesses With Private Branch • Exchanges Are Digital Circuits (Ref. Slide 6). • Since Most Circuits That Connect Central Offices To • Customer Premises Are Connected To Residences, Then, Most • Circuits In The Local Loop Are Analog.

  15. Access System – Residential Access • Each Customer Circuit Is A Two-Wire Cable From The • Customer Demarc Out To The First Cross Connection Box Class 5 Switch • A & B – Cross • Connection Pedestal • Or Cross Connection • Box

  16. Access System – Residential Access • Even Though Customer Circuits Are Two-Wire Cable, • Carriers Will Install Either 2-Pair, Or 4-Pair Cable. • Customer Circuits Are Combined With Other Circuits At The • Cross Connection Box Class 5 Switch 100-Pair Cable 2-Pair Cable

  17. Access System – Residential Access Class 5 Switch • Each Customer Circuit Is A Two-Wire Cable From The • Customer Demarc Out To The First Cross Connection Box. • From The CrossConnection Box To The Central Office The • Customer Two-Wire Circuit Is Carried Inside Of A Much • Thicker Cable That Carries 100 Pairs Of Cable Or More. • Each Customer’s Two-Wire Circuits Remain Separate From • Other Customer’s Circuits Which Are Carried On Separate • Sets Of Wires.

  18. Sample 4-Pair Cable • The Photo Below Shows A 4-Pair Copper Wire Cable • Similar To The Type Of Cable That Might Be Run To A • Residence. • Each Pair Of Cable Supports A Separate Circuit. • Because Of The Cost Of Installing Outside Cable, Carriers • Usually Install More Than 1 Pair Of Wires. Metal Conductor Plastic Insulator

  19. Access System – Business Access Trunks Business W/ PBX Class 5 Switch • Access For Small Business Customer Circuits Are Similar To • Residential Access Circuits. • Business Trunks From PBXs Are Digital, Usually T1s Or T3s. • If The Trunks Are T1s, 24 Separate End-User Applications • Are Carried On One Set Of Wires At A Time. • We’ll Study More About Data Rates Of Trunks In The • Lessons In Module 3 Of Our Text.

  20. Transport Component Of The PSTN • Transport Means Transmission – Taking Voice, Data, And • Video Signals From One Subscriber’s Access Line And • Delivering Them To Another Customer’s Access Line. • The End-Office, Or Class 5 Central Office Is The Point Where • All Customer Access Lines Connect. • The Trunks Within The Transport Core Include A Wide • Variety Of Transmission Speeds (e.g. T1, T3, OC-1, OC-12) • And Transmission Media (e.g. Copper And Optical Fiber). • We’ll Study More About The Transport System Later In This • Course.

  21. Signaling Component Of The PSTN • Signaling Means The Controlling Of Calling Including: • Setting Up A Path For A Conversation Through The • Transport Core. • Maintaining And Terminating The Conversation Path. • Collecting Billing Information. • Handling Other Supervisory Functions. • We’ll Study More About The Signaling System Later In • This Course.

  22. Section 1.2 – The Role Of The PSTN

  23. The Role Of The PSTN • Many People View Voice Services, And The PSTN • Used To Deliver Those Services, As “Old, Ho- Hum” • Topics. • Those People Reason That The Most Lucrative, • Future Growth Areas In Telecommunications Will • Be In Data Services As Opposed To Voice Services. • Many Of Those People Believe That • Telecommunications Students Should Not Study • Topics Related To Voice Communications Services • And The PSTN.

  24. The Role Of The PSTN - Continued • Those Same People Believe That Data • Communications Will Underpin The New • Emerging Technologies And Will Be The “Wave • Of The Future”. Why Then Study Plain Old Telephony?

  25. Throughout This Course We Will Learn How POTS And The PSTN Play Vital Roles In Providing Many Services Such As: • Voice-over-IP (VoIP) • Third Generation • Cellular • Internet Applications • E-Mail • E-Commerce • WANs & MANs • Etc., Etc., Etc. Today’s Emerging Technologies Do These Services Seem Like POTS!

  26. Several Examples Of The Role Of The PSTN Cellular – Many Major Cellular Features Depend On The PSTN – Two Examples Follow

  27. A Cell Call Placed To A Land-Based Phone Travels Through The PSTN CO Class 1 Switch Cellular User CO Class 2 Switch Digital Interoffice Trunks CO Class 5 Switch Radio Controller Analog Loop Residence CPE MTSO

  28. Cellular Roaming Depends On The PSTN SS7 Network Roaming Cellular User STP STP SSP SS7/ PSTN SSP VLR HLR RoamingMTSO Home MTSO Cellular Roaming Would Not Be Possible Without SS7 Network In PSTN

  29. Another Example Of The Role Of The • PSTN Private Line Data Networks Rely On Several Elements Of The PSTN

  30. PSTN Backbone Circuits Are Provisioned To Create Corporate Private-Line Data Networks Site D Site A OC3 Private Line Router T3 Private Line Router 56 Kbps Private Line T1 Private Line Site E 56 Kbps Private Line Router Router 56 Kbps Private Line Site C Router Site B

  31. Internet Access Relies On The PSTN – Another Example

  32. ISP Access Use PSTN Circuits Corporate End-User CO Class 1 Switch PSTN CO Class 2 Switch Digital Interoffice Trunks MCDL CO Class 5 Switch Analog Loop Multiplexed/Channelized Digital Loop ISP Residential End-User Router

  33. Section 1.3 – Customer Premises Equipment

  34. Customer Premises Equipment • CPE Includes All Telecommunications-Related Equipment That Is Located On The Consumer’s Side of the Demarcation Point. Customer Premises Equipment

  35. Let’s Study How Telephones, One Type Of • CPE, Works Example Of Some Modern Telephones

  36. DIRECT CURRENT • Do You Remember From TCM 134 How DC Current Flows? • Direct Current (DC) • - An Electrical Charge Flows Steadily In One Direction Over the Conductor. + Voltage - Time Voltage Over Time In A DC Circuit

  37. Ohm’s Law: V = I x R I Flows When Switch Closed Resistor R Resistor R I DC Voltage DC Voltage DC Series Circuits With & W/O A Switch

  38. Ohm’s Law: V = I x R • Do You Remember From TCM 134 How A Capacitor Affects • Current Flow In A Circuit? Capacitor Resistor R Capacitor Resistor R Does I Flow? Does I Flow? DC Voltage AC Voltage Does Current Flow In Circuits A Or B?

  39. A View Of A Telephone Set

  40. Functional Diagram – Telephone Set • Examine The Diagram Below To See If You Can Apply Any • Of The Lessons Learned From The Previous Two Slides. • Under What Conditions Will Current Flow (1) Through The • Ringer, (2) Through The Keypad, and (3) Into The Hybrid • Coil. Switch Hook T Receiver 1 2 3 Closed Line From CO 4 5 6 Ringer Hybrid Coil Balancing Network 7 8 9 * 0 # Transmitter R

  41. What Does The Central Office Do To Allow You • To Dial Your Telephone? • What Should The CO Switch Do First? • What Should The CO Switch Do Next? Switch Hook T Receiver 1 2 3 Closed Line From CO 4 5 6 Ringer Hybrid Coil Balancing Network 7 8 9 * 0 # Transmitter R

  42. How Does DTMF Dialing Work? • A Touch Tone Phone Operates By Transmitting A Combination Of Two Frequencies Each Time A Button Is Pressed. • Pressing Each Button Sends Out A Different Combination Of Frequencies.

  43. How Does Rotary Dialing Work? • Rotary Dialing - A User Chooses A Number And Turns A Wheel From That Number To The Finger Stop Then Releases The Wheel. Finger Stop

  44. How Does Rotary Dialing Work? - Continued • The Phone’s Internal Electronics Repeatedly • Breaks The Electric Current To Signal The • Number Dialed. • The Interrupts In The Current Causes Pulses Of • Specific Lengths, • These Pulses Of Interrupted Current Flow Are • Used In Pulse Dialing Rather Than Frequencies • To Represent Each Digit.

  45. How Does Rotary Dialing Work? - Continued • To Dial The Number “2” The Phone’s • Electronics Breaks The Current 2 Times. • To Dial The Number “9” The Phone’s • Electronics Breaks The Current 9 Times. • Question: How Is The Number “0” Dialed?

  46. Operation Of The Receiver And Transmitter • How Is Current Transitioned From The Two-Wire CO Circuit To • The Four Wires Required To Operate The Receiver And • Transmitter? • What Is An Impedance Mismatch & How Does It Apply Here? Switch Hook T Receiver 1 2 3 Closed Line From CO 4 5 6 Ringer Hybrid Coil Balancing Network 7 8 9 * 0 # Transmitter R

  47. Carbon Filled Receiver/Transmitter • Carbon Particles Used To Create Current. • Transmitter - The Input Voice Alternately Compresses • The Carbon Particles Which Create A Matching • Oscillating Current. • Receiver – The AC Current • From The Telephone Wires • Moves A Membrane Which In • Turn Alternately Compresses • The Carbon Particles Which • Produces Sound.

  48. Hybrid Coil And The Balancing Network • What Is The Role Of The Hybrid Coil Or Hybrid Network? • What Is The Role Of The Balancing Network? Switch Hook T Receiver 1 2 3 Closed Line From CO 4 5 6 Ringer Hybrid Coil Balancing Network 7 8 9 * 0 # Transmitter R

  49. How Does The Central Office Ring Your • Telephone? • What Should The CO Switch Do First? • What Should The CO Switch Do Next? Switch Hook T Receiver 1 2 3 Open Line From CO 4 5 6 Ringer Hybrid Coil Balancing Network 7 8 9 * 0 # Transmitter R

  50. Functional Diagram – Telephone Set: Switch • Hook Closed Current Switch Hook T Receiver 1 2 3 Closed Line From CO 4 5 6 Ringer Hybrid Coil Balancing Network 7 8 9 * 0 # Transmitter R Current • When The Switch Hook Is Closed, Current Flows.

More Related