1. 1.1.2 Product Evolution
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2. TELEPHONE
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3. Telegraph Inventor: Samuel B. Morse (1837)
Transmits messages over long distance
Messages received are audible signals
Earlier telegraphs experiments in Germany used bubbles in a glass of water
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4. Morse Code
Language made up of dots and dashes in a pattern to represents letters and numbers
Receiver hears short audible signals for dots and long audible signals for dashes
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5. Telephone Inventor: Alexander Graham Bell (1870s)
Microphone converts sound waves into electrical signals
Earphone converts electrical waves into sound waves
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6. Landlines
Plain Old Telephone Service (Post Office Telephone System) - POTS
2-twisted wire path of bi-directional, full duplex, voiceband
avoids electromagnetic interference & cross talk
Frequency: 300 to 3400 Hz
Subscriber Loop
40 volts DC and 300 ohms
From central office to subscribers home
Analog lines carries control and audio signals
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7. Landline Telephones Hand Cranked Magneto Generator Candlestick
Direct connection to an operator that will connect the call
Candlestick
Direct connection to an operator that will connect the call
Constantly powered
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8. Rotary Dial Telephone
Rotary movement’s sends electrical pulses – length represents a number
Pulse dialing – sounds like a series of clicks
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9. DTMF Telephone Dual-Tone Multi-Frequency
Touch Tone dialing over analog lines
An established tone’s frequency with distinct sine waves represents a number or symbol (* or #)
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10. Analog Signals & Digital Signals
Large signal fluctuations
any continuous signal for which the time varying feature (variable) of the signal is a representation of some other time varying quantity
Digital Signals
Small signal fluctuations
each point in time, the value of the signal must be above or below some discrete threshold
Not subject to electronic noise
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11. Cordless Telephone Uses and RF (radio frequency signal)
Handset communicates with base station
Handset contains rechargeable batteries
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12. Cellular RF digital signals
Sites are spaced apart in hexagonal pattern with 120 degree directional antennas
CDMA (Code Division Multiple Access): encoding signals
Alcalet-Lucent’s Lightradio, size of Rubix Cube, has same technology and power as a large cell tower
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13. Cellular Telephone Transmits and receives signals over a radio link
Connects to cellular network and public telephone network
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14. Satellite Telephone Geosynchronous Satellites (4 at 22,000 miles)
Fixed orbital position
Transmits and receives RF digital signals
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15. Mobile Computing (Smartphone)
A.K.A Personal Digital Assistant (PDA)
Contains a Mobile Operating System
iOS
Android (Linux)
Windows
Blackberry
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16. TELEPHONE FUTURE Video: Apple's iPhone Concept
Video: Sixth Sense Technology
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17. References
"Telephone - Wikipedia, the free encyclopedia." Wikipedia, the free encyclopedia. N.p., n.d. Web. 24 May <