Telephone Instruments And Signals Pdf
Telephone Instruments and Signals Presented by: Engr. Micaela Renee Bernardo The telephone was invented by at least four different people in three different countries 1.
Alexander Graham Bell – Scottish American, generally credited as the 'winner' in the race to invent the telephone in the period between 1850 and 1876 2. Johann Philipp Reis – German 3. Antonio Meucci – Italian 4.
Elisha Gray - American In 1876, at the age of 29, Alexander Graham Bell invented his telephone Model of Alexander Graham Bell's Telephone Design sketch of the phone Famous first words: 'Mr. Watson - come here - I want to see you.'
Johann Philipp Reis “Ein Pferd frisst keinen Gurkensalat.” - Words supposedly spoken by Philipp Reis in testing his new telephone invention. Das Reis'sche „Telephon” von 1861 'Telephone' (he was one of the first to coin the term) were manufactured by a German firm, and a few more in England.
Antonio Meucci Meucci’s Teletrofono – speaking Telegraph Has been denied fame and fortune only because he lacked $250 and because Bell himself rifled the files of a patent office, destroying the evidence of Meucci's invention Elisha Gray (1835-1901) Elisha Gray, American inventor, who contested the invention of the telephone with Alexander Graham Bell. He invented a number of telegraphic devices and in 1869 was one of two partners who founded what became Western Electric Company On February 14, 1876, Bell's telephone patent application was filed at the United States Patent Office; Elisha Gray's attorney filed a caveat for a telephone just a few hours later. On September 12, 1878, patent litigation involving the Bell Telephone Company against Western Union Telegraph Company and Elisha Gray began.
1877 First Commercial Telephone 1878 'Coffin' Style Telephone 1882 Western Electric 'three box' Telephone 1880s Desk Telephone Early 1890s Desk Telephone Mid-1890s Desk Telephone 1890s Strowger Automatic Telephone 1890s Western Electric Common Battery Telephone 1890s Western Electric two box phone 1905 Automatic Electric Strowger Telephone 1900s Magneto Telephone 1910 Western Electric Desk Telephone 1920s Western Electric Dial Telephone 1920s/30s Western Electric Desk Telephone 1940s Western Electric Desk Telephone 1990s Telephone Main Parts of a Telephone Set: 1. Transmitter / mouthpiece 2.
Receiver / earpiece 3. Switch Hook 4.
Ringer Parts of Telephone Switch Hook / Plunger – also called the cradle; has a lever spring that is used to initiate or terminate call 2 States: 1. On-Hook – the handset setting when the telephone is idle and the switch is open, thus, no dc current flows through the line. Off-Hook – the condition as soon as the telephone handset is lifted, the switch is closed thus alerting the C.O. To supply a dc current and a dial tone Parts of Telephone Dialer 2 Methods: 1.
Dial Pulsing or Pulse Dialing – is defined as a momentary on-hook condition that causes loop making and breaking from the telephone set dialer toward the C.O. Commonly used for rotary telephone set.
Telephone Instruments And Signals Pdf Format
State of Pulse: 1. Make – circuit closed/off-hook 2.
Break – circuit opened/on-hook Parts of Telephone To transmit a digit, it takes 0.1 second per pulse + 0.5 second interdigital delay time Pulsing speed = number of pulses per second (pps) Pulsing period = make + break pps = 1 / pulsing period Example: How long does it take to dial the number 681-1725 using pulse dialing having an interdigit duration of 0.4 sec.? Example: If a switching machine is set to accept pulses at a rate of 10 pulses per second with a 60% break, find the make interval of the switch. Parts of Telephone 2. Multifrequency Dialing or Dual Tone Multifrequency Dialing (DTMF) – a method that is normally done by combining two of the frequencies in the voice frequency band where the combined frequencies represent one digit recognized by the C.O. Commonly used for touch-tone telephone set.
Example: How long does it take to dial the number 680-1134 using tone dialing with 0.05 second duration for each digit and 0.05 second duration for interdigit? Parts of Telephone Comparison between Rotary & Touch-Tone Dialer: VS. Uses make and break techniques Uses combination of two frequencies Slow Dialing Fast Dialing Heavy electromechanical device Light, mostly electronic device Parts of Telephone Ringer or Bell: - device that converts electrical signals from the C.O. To an audible signal alerting the subscriber that a call is in progress Ringer Circuits: 1.
Classical Bell Type Ringer - is a mechanical bell controlled by an electronic coil 2. Electronic Ringer - the coil controlled bell is replaced by modern electronic ringing chip and small speaker Central Office / Local Exchange Carrier The C.O. Operates to: 1.
Provide battery (DC voltage) to a telephone. This DC voltage is used to operate the telephone and to determine when a subscriber has gone off or on-hook. Provide ringing (AC voltage) voltage to a telephone. This AC voltage operates a bell or buzzer in the telephone to alert the subscriber to an incoming call. Provide dial tone when a subscriber goes off-hook 4. Accept the digits dialed by the subscriber when off-hook 5. Provide switching equipment used to connect a subscriber to the telephone number dialed.