The Telephone Analog vs Digital View the video

The Telephone

Analog vs Digital • View the video first: http: //www. diffen. com/difference/Analog_vs _Digital

Analog vs Digital • Analog Wave - analog wave representing the vibrations created by your voice.

Analog vs Digital • However, most things we use in this day and age are passed along via digital information. • Examples : CD’s, MP 3 players, Cell Phones, TV’s, and pretty much all electronic devices from our current era. • Electronics have devices called analog-todigital converter (ADC) and digital-to-analog converter (DAC).

Analog vs Digital • Example: – a phone takes our voice, which is in analog form, and convert it to digital information to pass it along the wires/stellates/towers to the receiver of your phone call which then converts the digital information into an analog form so they can make sense of your words. • All our electronic devices mentioned in the previous slide do this.

Analog vs Digital • An ADC converts the analog wave into a stream of numbers and records the numbers instead of the wave. • The following graphs show analog is transferred to digital information.

Analog vs Digital • Analog Wave needs to be turned into a digital wave.

Analog vs Digital • The green line represents a sample of digital information that is created from the analog wave. This is example creates 1, 000 samples per second • Problem here is the green lines do not accurately collect the precise sound wave.

Analog vs Digital • This converter is at a rate of 4, 000 samples per second. • Notice that this one is a little more precise.

Analog vs Digital • This converter is information at 44, 100 samples per second. • This one produces digital information that is almost precise to the analog wave.

Analog vs Digital • Information at a radio station, or a cellphone tower, or a radio tower, or telephone fiber optics release an analog or digital information. • Our devices have a receiver that reads these waves and converts it into an analog or digital information as needed via an ADC or DAC. • So how is it these waves do not get mixed up in the air?

Analog vs Digital Band/ Use Wavelength Frequency LW (Long wave) 5 km– 1 km 60 k. Hz– 300 k. Hz AM/MW (Amplitude modulation / medium wave) 600 m– 176 m 500 k. Hz– 1. 7 MHz SW (Short wave) 188 m– 10 m 1. 6 MHz– 30 MHz VHF/FM (Very high frequency / frequency modulation) 10 m– 6 m 100 MHz– 500 MHz FM (frequency modulation) 3. 4 m– 2. 8 m 88 MHz– 125 Mhz Aircraft 2. 7 m– 2. 2 m 108– 135 MHz Cellphones 80 cm– 15 cm 380– 2000 MHz Radar 100 cm– 3 mm 0. 3– 100 GHz

The Telephone

Components of the Telephone • A switch - to connect and disconnect the phone from the network. This switch is generally called the hook switch. It connects when you lift the handset. • A speaker - This is generally a little 50 -cent, 8 ohm speaker • A microphone - electronic microphone, amplifier and circuit. • A duplex coil - blocks the sound of your own voice from reaching your ear when you speak into the microphone.

A Visual of a real Telephone

How a phone signal is transferred • http: //electronics. howstuffworks. com/teleph one 3. htm

Telephone Tones • A modern phone system has an electronic switch. When you pick up the phone, the switch senses the completion of your loop and it plays a dial tone sound so you know that the switch and your phone are working. • A dial tone sound is simply a combination of 350 -hertz tone and a 440 -hertz tone.

Dial Tones • The different dialing sounds are made of pairs of tones 1 = 697 Hz + 1, 209 Hz 2 = 697 Hz + 1, 336 Hz 3 = 697 Hz + 1, 477 Hz 4 = 770 Hz + 1, 209 Hz 5 = 770 Hz + 1, 336 Hz 6 = 770 Hz + 1, 477 Hz 7 = 852 Hz + 1, 209 Hz 8 = 852 Hz + 1, 336 Hz 9 = 852 Hz + 1, 477 Hz * = 941 Hz + 1, 209 Hz 0 = 941 Hz + 1, 336 Hz # = 941 Hz + 1, 477 Hz • Sound of a typical tone

Busy Tone • A busy signal that is made up of a 480 -hertz and a 620 -hertz tone, with a cycle of one-half second on and one-half second off, like this:

Bibliography • http: //electronics. howstuffworks. com/teleph one 7. htm • http: //electronics. howstuffworks. com/analogdigital 3. htm • http: //www. explainthatstuff. com/radio. html