Photophone 450
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
The Twisted-Pair Telephone Transmission Line
High Frequency Design From November 2002 High Frequency Electronics Copyright © 2002, Summit Technical Media, LLC TRANSMISSION LINES The Twisted-Pair Telephone Transmission Line By Richard LAO Sumida America Technologies elephone line is a This article reviews the prin- balanced twisted- ciples of operation and Tpair transmission measurement methods for line, and like any electro- twisted pair (balanced) magnetic transmission transmission lines common- line, its characteristic ly used for xDSL and ether- impedance Z0 can be cal- net computer networking culated from manufactur- ers’ data and measured on an instrument such as the Agilent 4395A (formerly Hewlett-Packard HP4395A) net- Figure 1. Lumped element model of a trans- work analyzer. For lowest bit-error-rate mission line. (BER), central office and customer premise equipment should have analog front-end cir- cuitry that matches the telephone line • Category 3: BWMAX <16 MHz. Intended for impedance. This article contains a brief math- older networks and telephone systems in ematical derivation and and a computer pro- which performance over frequency is not gram to generate a graph of characteristic especially important. Used for voice, digital impedance as a function of frequency. voice, older ethernet 10Base-T and commer- Twisted-pair line for telephone and LAN cial customer premise wiring. The market applications is typically fashioned from #24 currently favors CAT5 installations instead. AWG or #26 AWG stranded copper wire and • Category 4: BWMAX <20 MHz. Not much will be in one of several “categories.” The used. Similar to CAT5 with only one-fifth Electronic Industries Association (EIA) and the bandwidth. the Telecommunications Industry Association • Category 5: BWMAX <100 MHz. -
United Telephone Company of Texas, Inc. GENERAL EXCHANGE TARIFF D/B/A Centurylink Title Page (C) First Revised Sheet No
United Telephone Company of Texas, Inc. GENERAL EXCHANGE TARIFF d/b/a CenturyLink Title Page (C) First Revised Sheet No. 1 Cancels Original Sheet No. 1 GENERAL EXCHANGE TARIFF Schedule of Rates and Charges Together With Rules and Regulations Applicable To Services Provided In The Territory Served By This Company Within The State of Texas ISSUED: October 21, 2009 EFFECTIVE: November 20, 2009 United Telephone Company of Texas, Inc. GENERAL EXCHANGE TARIFF d/b/a CenturyLink Adoption Notice (C) First Revised Sheet No. 1 Cancels Original Sheet No. 1 GENERAL EXCHANGE TARIFF ADOPTION NOTICE Effective July 28, 2009, United Telephone Company of Texas, Inc. registered the fictitious name (N) CenturyLink. Effective November 20, 2009, United Telephone Company of Texas, Inc. d/b/a Embarq, began operating under the name CenturyLink. As such, United Telephone Company of Texas, Inc. d/b/a CenturyLink hereby adopts, ratifies, and makes its own, in every respect as if the same had been originally filed by it, all schedules, rules, notices, concurrences, schedule agreements, divisions, authorities or other instruments whatsoever, filed with the Public Utility Commission, State of Texas, by or adopted by United Telephone Company of Texas, Inc. d/b/a Embarq between June 5, 2006 and November 19, 2009. By this notice, United Telephone Company of Texas, Inc. d/b/a CenturyLink also adopts and ratifies all supplements or amendments to any of the above schedules, etc., which United Telephone Company of Texas, Inc. d/b/a Embarq has heretofore filed with said Commission. (N) Effective June 5, 2006, United Telephone Company of Texas, Inc. -
Digital Subscriber Line (DSL) Technologies
CHAPTER21 Chapter Goals • Identify and discuss different types of digital subscriber line (DSL) technologies. • Discuss the benefits of using xDSL technologies. • Explain how ASDL works. • Explain the basic concepts of signaling and modulation. • Discuss additional DSL technologies (SDSL, HDSL, HDSL-2, G.SHDSL, IDSL, and VDSL). Digital Subscriber Line Introduction Digital Subscriber Line (DSL) technology is a modem technology that uses existing twisted-pair telephone lines to transport high-bandwidth data, such as multimedia and video, to service subscribers. The term xDSL covers a number of similar yet competing forms of DSL technologies, including ADSL, SDSL, HDSL, HDSL-2, G.SHDL, IDSL, and VDSL. xDSL is drawing significant attention from implementers and service providers because it promises to deliver high-bandwidth data rates to dispersed locations with relatively small changes to the existing telco infrastructure. xDSL services are dedicated, point-to-point, public network access over twisted-pair copper wire on the local loop (last mile) between a network service provider’s (NSP) central office and the customer site, or on local loops created either intrabuilding or intracampus. Currently, most DSL deployments are ADSL, mainly delivered to residential customers. This chapter focus mainly on defining ADSL. Asymmetric Digital Subscriber Line Asymmetric Digital Subscriber Line (ADSL) technology is asymmetric. It allows more bandwidth downstream—from an NSP’s central office to the customer site—than upstream from the subscriber to the central office. This asymmetry, combined with always-on access (which eliminates call setup), makes ADSL ideal for Internet/intranet surfing, video-on-demand, and remote LAN access. Users of these applications typically download much more information than they send. -
Wireless Networks
SUBJECT WIRELESS NETWORKS SESSION 2 WIRELESS Cellular Concepts and Designs" SESSION 2 Wireless A handheld marine radio. Part of a series on Antennas Common types[show] Components[show] Systems[hide] Antenna farm Amateur radio Cellular network Hotspot Municipal wireless network Radio Radio masts and towers Wi-Fi 1 Wireless Safety and regulation[show] Radiation sources / regions[show] Characteristics[show] Techniques[show] V T E Wireless communication is the transfer of information between two or more points that are not connected by an electrical conductor. The most common wireless technologies use radio. With radio waves distances can be short, such as a few meters for television or as far as thousands or even millions of kilometers for deep-space radio communications. It encompasses various types of fixed, mobile, and portable applications, including two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of applications of radio wireless technology include GPS units, garage door openers, wireless computer mice,keyboards and headsets, headphones, radio receivers, satellite television, broadcast television and cordless telephones. Somewhat less common methods of achieving wireless communications include the use of other electromagnetic wireless technologies, such as light, magnetic, or electric fields or the use of sound. Contents [hide] 1 Introduction 2 History o 2.1 Photophone o 2.2 Early wireless work o 2.3 Radio 3 Modes o 3.1 Radio o 3.2 Free-space optical o 3.3 -
Letter from Alexander Graham Bell to Alexander Melville Bell, February 26, 1880, with Transcript
Library of Congress Letter from Alexander Graham Bell to Alexander Melville Bell, February 26, 1880, with transcript ALEXANDER GRAHAM BELL TO HIS FATHER A. MELVILLE BELL 904 14th Street, N. W., Washington, D. C. Feb. 26th, 1880. Dear Papa: I have just written to Mamma about Mabel's baby and I now write to you about my own! Only think! — Two babies in one week! The first born at 904 14th Street — on the fifteenth inst., the other at my laboratory on the nineteenth. Both strong vigorous healthy young things and both destined I trust to grow into something great in the future. Mabel's baby was light enough at birth but mine was LIGHT ITSELF! Mabel's baby screamed inarticulately but mine spoke with distinct enunciation from the first. I have heard articulate speech produced by sunlight! I have heard a ray of the sun laugh and cough and sing! The dream of the past year has become a reality — the “ Photophone ” is an accomplished fact. I am not prepared at present to go into particulars and can only say that with Mr. Tainter's assistance I have succeeded in preparing crystalline selenium of so low a resistance and so sensitive to light that we have been enabled to perceive variations of light as sounds in the telephone. In this way I have been able to hear a shadow, and I have even perceived by ear the passage of a cloud across the sun's disk. Can Imagination picture what the future of this invention is to be! I dream of so many important and wonderful applications that I cannot bring myself to make known my discovery — until I have demonstrated the practicability of some of these schemes. -
Alexander Graham Bell
WEEK 2 LEVEL 7 Alexander Graham Bell Alexander Graham Bell is the famous inventor of the telephone. Born in Scotland on March 3, 1847, he was the second son of Alexander and Eliza Bell. His father taught students the art of speaking clearly, or elocution, and his mother played the piano. Bell’s mother was almost deaf. His father’s career and his mother’s hearing impairment influenced the course of his career. He became a teacher of deaf people. As a child, Bell didn’t care for school, and he eventually dropped out. He did like to solve problems though. For example, when he was only 12, he invented a new farm implement. The tool removed the tiny husks from wheat grains. After the deaths of his two brothers from tuberculosis, Bell and his parents moved from Europe to Canada in 1870. They thought the climate there was healthier than in Scotland. A year later, Bell moved to the United States. He got a job teaching at the Boston School for Deaf Mutes. © 2019 Scholar Within, Inc. WEEK 2 LEVEL 7 One of his students was a 15-year-old named Mabel Hubbard. He was 10 years older than she was, but they fell in love and married in 1877. The Bells raised two daughters but lost two sons who both died as babies. Bell’s father-in-law, Gardiner Hubbard, knew Bell was interested in inventing things, so he asked him to improve the telegraph. Telegraph messages were tapped out with a machine using dots and dashes known as Morse code. -
Central Telecom Long Distance, Inc
Central Telecom Long Distance, Inc. 102 South Tejon Street, 11th Floor Colorado Springs, CO 80903. Telecommunications Service Guide For Interstate and International Services May 2016 This Service Guide contains the descriptions, regulations, and rates applicable to furnishing of domestic Interstate and International Long Distance Telecommunications Services provided by Central Telecom Long Distance, Inc. (“Central Telecom Long Distance” or “Company”). This Service Guide and is available to Customers and the public in accordance with the Federal Communications Commission’s (FCC) Public Availability of Information Concerning Interexchange Services rules, 47 CFR Section 42.10. Additional information is available by contacting Central Telecom Long Distance, Inc.’s Customer Service Department toll free at 888.988.9818, or in writing directed to Customer Service, 102 South Tejon Street, 11th Floor, Colorado Springs, CO 80903. 1 INTRODUCTION This Service Guide contains the rates, terms, and conditions applicable to the provision of domestic Interstate and International Long Distance Services. This Service Guide is prepared in accordance with the Federal Communications Commission’s Public Availability of Information Concerning Interexchange Services rules, 47 C.F.R. Section 42.10 and Service Agreement and may be changed and/or discontinued by the Company. This Service Guide governs the relationship between Central Telecom Long Distance, Inc. and its Interstate and International Long Distance Service Customers, pursuant to applicable federal regulation, federal and state law, and any client-specific arrangements. In the event one or more of the provisions contained in this Service Guide shall, for any reason be held to be invalid, illegal, or unenforceable in any respect, such invalidity, illegality or unenforceability shall not affect any other provision hereof, and this Service Guide shall be construed as if such invalid, illegal or unenforceable provision had never been contained herein. -
Introduction to Digital Subscriber's Line (DSL) Chapter 2 Telephone
Introduction to Digital Subscriber’s Line (DSL) Professor Fu Li, Ph.D., P.E. © Chapter 2 Telephone Infrastructure · Telephone line dates back to Bell in 1875 · Digital Transmission technology using complex algorithm based on DSP and VLSI to compensate impairments common to phone lines. · Phone line carries the single voice signal with 3.4 KHz bandwidth, DSL conveys 100 Compressed voice signals or a video signals. 1 · 15% phones require upgrade activities. · Phone company spent approximately 1 trillion US dollars to construct lines; · 700 millions are in service in 1997, 900 millions by 2001. · Most lines will support 1 Mb/s for DSL and many will support well above 1Mb/s data rate. Typical Voice Network 2 THE ACCESS NETWORK • DSL is really an access technology, and the associated DSL equipment is deployed in the local access network. • The access network consists of the local loops and associated equipment that connects the service user location to the central office. • This network typically consists of cable bundles carrying thousands of twisted-wire pairs to feeder distribution interfaces (FDIs). Two primary ways traditionally to deal with long loops: • 1.Use loading coils to modify the electrical characteristics of the local loop, allowing better quality voice-frequency transmission over extended distances (typically greater than 18,000 feet). • Loading coils are not compatible with the higher frequency attributes of DSL transmissions and they must be removed before DSL-based services can be provisioned. 3 Two primary ways traditionally to deal with long loops • 2. Set up remote terminals where the signals could be terminated at an intermediate point, aggregated and backhauled to the central office. -
Alexander Graham Bell 1847-1922
NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA BIOGRAPHICAL MEMOIRS VOLUME XXIII FIRST MEMOIR BIOGRAPHICAL MEMOIR OF ALEXANDER GRAHAM BELL 1847-1922 BY HAROLD S. OSBORNE PRESENTED TO THE ACADEMY AT THE ANNUAL MEETING, 1943 It was the intention that this Biographical Memoir would be written jointly by the present author and the late Dr. Bancroft Gherardi. The scope of the memoir and plan of work were laid out in cooperation with him, but Dr. Gherardi's untimely death prevented the proposed collaboration in writing the text. The author expresses his appreciation also of the help of members of the Bell family, particularly Dr. Gilbert Grosvenor, and of Mr. R. T. Barrett and Mr. A. M. Dowling of the American Telephone & Telegraph Company staff. The courtesy of these gentlemen has included, in addition to other help, making available to the author historic documents relating to the life of Alexander Graham Bell in the files of the National Geographic Society and in the Historical Museum of the American Telephone and Telegraph Company. ALEXANDER GRAHAM BELL 1847-1922 BY HAROLD S. OSBORNE Alexander Graham Bell—teacher, scientist, inventor, gentle- man—was one whose life was devoted to the benefit of mankind with unusual success. Known throughout the world as the inventor of the telephone, he made also other inventions and scientific discoveries of first importance, greatly advanced the methods and practices for teaching the deaf and came to be admired and loved throughout the world for his accuracy of thought and expression, his rigid code of honor, punctilious courtesy, and unfailing generosity in helping others. -
Carrier Locator: Interstate Service Providers
Carrier Locator: Interstate Service Providers November 1997 Jim Lande Katie Rangos Industry Analysis Division Common Carrier Bureau Federal Communications Commission Washington, DC 20554 This report is available for reference in the Common Carrier Bureau's Public Reference Room, 2000 M Street, N.W. Washington DC, Room 575. Copies may be purchased by calling International Transcription Service, Inc. at (202) 857-3800. The report can also be downloaded [file name LOCAT-97.ZIP] from the FCC-State Link internet site at http://www.fcc.gov/ccb/stats on the World Wide Web. The report can also be downloaded from the FCC-State Link computer bulletin board system at (202) 418-0241. Carrier Locator: Interstate Service Providers Contents Introduction 1 Table 1: Number of Carriers Filing 1997 TRS Fund Worksheets 7 by Type of Carrier and Type of Revenue Table 2: Telecommunications Common Carriers: 9 Carriers that filed a 1997 TRS Fund Worksheet or a September 1997 Universal Service Worksheet, with address and customer contact number Table 3: Telecommunications Common Carriers: 65 Listing of carriers sorted by carrier type, showing types of revenue reported for 1996 Competitive Access Providers (CAPs) and 65 Competitive Local Exchange Carriers (CLECs) Cellular and Personal Communications Services (PCS) 68 Carriers Interexchange Carriers (IXCs) 83 Local Exchange Carriers (LECs) 86 Paging and Other Mobile Service Carriers 111 Operator Service Providers (OSPs) 118 Other Toll Service Providers 119 Pay Telephone Providers 120 Pre-paid Calling Card Providers 129 Toll Resellers 130 Table 4: Carriers that are not expected to file in the 137 future using the same TRS ID because of merger, reorganization, name change, or leaving the business Table 5: Carriers that filed a 1995 or 1996 TRS Fund worksheet 141 and that are unaccounted for in 1997 i Introduction This report lists 3,832 companies that provided interstate telecommunications service as of June 30, 1997. -
Telecommunications Provider Locator
Telecommunications Provider Locator Industry Analysis & Technology Division Wireline Competition Bureau February 2003 This report is available for reference in the FCC’s Information Center at 445 12th Street, S.W., Courtyard Level. Copies may be purchased by calling Qualex International, Portals II, 445 12th Street SW, Room CY- B402, Washington, D.C. 20554, telephone 202-863-2893, facsimile 202-863-2898, or via e-mail [email protected]. This report can be downloaded and interactively searched on the FCC-State Link Internet site at www.fcc.gov/wcb/iatd/locator.html. Telecommunications Provider Locator This report lists the contact information and the types of services sold by 5,364 telecommunications providers. The last report was released November 27, 2001.1 All information in this report is drawn from providers’ April 1, 2002, filing of the Telecommunications Reporting Worksheet (FCC Form 499-A).2 This report can be used by customers to identify and locate telecommunications providers, by telecommunications providers to identify and locate others in the industry, and by equipment vendors to identify potential customers. Virtually all providers of telecommunications must file FCC Form 499-A each year.3 These forms are not filed with the FCC but rather with the Universal Service Administrative Company (USAC), which serves as the data collection agent. Information from filings received after November 22, 2002, and from filings that were incomplete has been excluded from the tables. Although many telecommunications providers offer an extensive menu of services, each filer is asked on Line 105 of FCC Form 499-A to select the single category that best describes its telecommunications business. -
CALRAD 70 Series - Telephone Accessories
CALRAD 70 series - telephone accessories CALRAD’S NEW TELEPHONE HEADSETS HANDS FREE TELEPHONE HEADSETS Calrad’s telephone headsets help reduce phone fatigue and provides hands-free convenience for working on computer data entry, taking notes, and in fact do the work you need to do and talk on the phone at the same time. Adjustable volume control, telephone/headset selection switch, voice mute button. All units come with base unit, headset, and cables. 70-600 TELEPHONE LINE POWERED This unit works directly when connected to your telephone. Requires two AA batteries, not included. 70-601 BATTERY POWERED This unit works with most home type instruments. A selectable configuration switch is provided on the side of the unit for easy interfacing to your telephone equipment. This unit connects to your handset jack on the telephone. Two AA batteries not included. 70-602 BATTERY / DC POWERED This unit works with most business type instruments. A selectable configuration switch is provided on the side of the unit for easy interfacing to your telephone equipment. This unit easily connects to your handset jack on the telephone. A small opening on the front of the unit is provided so that a small phillips screwdriver can be used to adjust the microphone gain. Two AA batteries/AC adapter not included. AC adapter is 45-756-S. FLUSH MOUNT, SINGLE-JACK FLUSH MOUNT, MODULAR WALL PLATES DECORA STYLE For new construction or conversion to modular instruments. Screw terminals. MODULAR WALL PLATES 70-403 ..................................................4-Wire, Ivory Wall plates designed to accept 70-403-W ..........................................4-Wire, White modular plugs.