The easiest way to contact a person is to pick up the phone, dial a number and you can have the conversation with that person even if the person is many miles away or anywhere on the earth. Nearly 100 years back you have to write a message or letter which reaches in days but now the whole scenario has changed. So how this small device works?
It converts the speech or sound energy to electrical energy which can be sent anywhere. All the telephone systems are connected and controlled by central offices or exchanges which give path for all the electric signals to travel.
The working of first telephone was almost similar to the today’s phone. The waves of sound coming out from the mouth are exactly copied by the transmitter. Carbon grains are present behind the transmitter so when the electric waves pass through them it gets vibrated according to the electric energy they are receiving and on the other side there is coiled wire having magnet within it attached to the diaphragm. Now according to the current the wire gets vibrated so as the diaphragm. So these vibrations move air and create sound on the other end.
Working of telephone is almost same as in past but only the microphones were as simple as carbon granules compressed between two thin metal plates other things are as it was in the past. A switch for the connection of network is called the hook and a speaker.
Your telephone is generated with the power of 48V in the exchanges but the old and ordinary offices use 400 ohm line relay coils in series with a line whereas in 48V there is 200 to 400 ohm series.
Alexander Graham Bell
LOC
Fascinating facts about the invention of the Mobile Phoneby Joel Engel and Richard Frenkiel in 1983 MOBILE TELEPHONE
AT A GLANCE:Today's communications industry would not be what it is without the contributions made by Richard H. Frenkiel and Joel S. Engel. The big breakthrough came when AT&T Labs researchers Frenkiel and Engel divided wireless communications into a series of cells, then automatically switched callers as they moved so that each cell could be reused. This led to the development of cellular phones and made today’s mobile communications possible.
Invention: mobile telephone
Function: noun / mo·bile tele·phone Definition: A mobile radiotelephone, often in an automobile, that uses a network of short-range transmitters located in overlapping cells throughout a region, with a central station making connections to regular telephone lines. Also called cellular telephone
Inventor: Joel Engel and Richard Frenkiel
Criteria: First practical cellular telephone system. Birth: Richard Frenkiel, March 4, 1943 in Brooklyn, New York
Joel Engel, February 4, 1936 in New York City Nationality: American
1. Hello?
"Hello" is such a characteristic American greeting that, back when I was a child in Korea, it was our name for Americans. It was, after all, the first sound out of the GIs’ mouths when they saw anyone. Now that I am a professor with twenty years of academic inquiry behind me, I turn again to the question of why Americans say "Hello" and not "Good day" or its many counterparts -- "Bon jour," "Guten Tag," "Buon giorno," "G’day" -- to greet each other; and I do this because my inquiry into the origins of symbols and folk meanings seems constantly to skirt around the profound meanings of the utterly mundane.
Hello, Good-bye
So what does it actually mean when one says "Hello?" to answer the telephone? The word itself is incredibly complex, as you have seen, but its function is very pragmatic. We use "Hello" as a sort of sonarping! to establish the terms of our relationship to that faceless (i.e., "hidden") voice on the other end of the line. The meaning of the word is full of potentials that become activated during the conversation so that it could range across the full spectrum. A good example of this variation is what happens when you get no answer on the other end and your first cheerful "Hello" becomes subsequently darker as you repeat it, "Hello? Hello? Hello? Hello!" ending, perhaps as an expression of great anxiety or as the preface to a threat.
Inside a Telephone
A simple telephone
The very simplest working telephone would look like this inside.
As you can see, it only contains three parts and they are all simple:
- A switch to connect and disconnect the phone from the network - This switch is generally called thehook switch. It connects when you lift the handset.
- A speaker - This is generally a little 50-cent, 8-ohm speaker of some sort.
- A microphone - In the past, telephone microphones have been as simple as carbon granules compressed between two thin metal plates. Sound waves from your voice compress and decompress the granules, changing the resistance of the granules and modulating the current flowing through the microphone.
That's it! You can dial this simple phone by rapidly tapping the hook switch -- all telephone switches still recognize "pulse dialing." If you pick the phone up and rapidly tap the switch hook four times, the phone company's switch will understand that you have dialed a "4."
The only problem with the phone shown above is that when you talk, you will hear your voice through the speaker.
A "real" telephone
Most people find that annoying, so any "real" phone contains a device called a duplex coil or something functionally equivalent to block the sound of your own voice from reaching your ear. A modern telephone also includes a bell so it can ring and a touch-tone keypadand frequency generator. A "real" phone looks like this.
Still, it's pretty simple. In a modern phone there is an electronic microphone,amplifier and circuit to replace the carbon granules and loading coil. The mechanical bell is often replaced by a speaker and a circuit to generate a pleasant ringing tone. But a regular $6.95 telephone remains one of the simplest devices ever.
| Fascinating facts about the invention of the Mobile Phoneby Joel Engel and Richard Frenkiel in 1983 | MOBILE TELEPHONE | ||||||||||||||||||||||||
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1. Hello?
"Hello" is such a characteristic American greeting that, back when I was a child in Korea, it was our name for Americans. It was, after all, the first sound out of the GIs’ mouths when they saw anyone. Now that I am a professor with twenty years of academic inquiry behind me, I turn again to the question of why Americans say "Hello" and not "Good day" or its many counterparts -- "Bon jour," "Guten Tag," "Buon giorno," "G’day" -- to greet each other; and I do this because my inquiry into the origins of symbols and folk meanings seems constantly to skirt around the profound meanings of the utterly mundane.
"Hello" is such a characteristic American greeting that, back when I was a child in Korea, it was our name for Americans. It was, after all, the first sound out of the GIs’ mouths when they saw anyone. Now that I am a professor with twenty years of academic inquiry behind me, I turn again to the question of why Americans say "Hello" and not "Good day" or its many counterparts -- "Bon jour," "Guten Tag," "Buon giorno," "G’day" -- to greet each other; and I do this because my inquiry into the origins of symbols and folk meanings seems constantly to skirt around the profound meanings of the utterly mundane.
Hello, Good-bye
So what does it actually mean when one says "Hello?" to answer the telephone? The word itself is incredibly complex, as you have seen, but its function is very pragmatic. We use "Hello" as a sort of sonarping! to establish the terms of our relationship to that faceless (i.e., "hidden") voice on the other end of the line. The meaning of the word is full of potentials that become activated during the conversation so that it could range across the full spectrum. A good example of this variation is what happens when you get no answer on the other end and your first cheerful "Hello" becomes subsequently darker as you repeat it, "Hello? Hello? Hello? Hello!" ending, perhaps as an expression of great anxiety or as the preface to a threat.
So what does it actually mean when one says "Hello?" to answer the telephone? The word itself is incredibly complex, as you have seen, but its function is very pragmatic. We use "Hello" as a sort of sonarping! to establish the terms of our relationship to that faceless (i.e., "hidden") voice on the other end of the line. The meaning of the word is full of potentials that become activated during the conversation so that it could range across the full spectrum. A good example of this variation is what happens when you get no answer on the other end and your first cheerful "Hello" becomes subsequently darker as you repeat it, "Hello? Hello? Hello? Hello!" ending, perhaps as an expression of great anxiety or as the preface to a threat.
Inside a Telephone
A simple telephone
The very simplest working telephone would look like this inside.
As you can see, it only contains three parts and they are all simple:
- A switch to connect and disconnect the phone from the network - This switch is generally called thehook switch. It connects when you lift the handset.
- A speaker - This is generally a little 50-cent, 8-ohm speaker of some sort.
- A microphone - In the past, telephone microphones have been as simple as carbon granules compressed between two thin metal plates. Sound waves from your voice compress and decompress the granules, changing the resistance of the granules and modulating the current flowing through the microphone.
That's it! You can dial this simple phone by rapidly tapping the hook switch -- all telephone switches still recognize "pulse dialing." If you pick the phone up and rapidly tap the switch hook four times, the phone company's switch will understand that you have dialed a "4."
The only problem with the phone shown above is that when you talk, you will hear your voice through the speaker.
A "real" telephone
Most people find that annoying, so any "real" phone contains a device called a duplex coil or something functionally equivalent to block the sound of your own voice from reaching your ear. A modern telephone also includes a bell so it can ring and a touch-tone keypadand frequency generator. A "real" phone looks like this.
Still, it's pretty simple. In a modern phone there is an electronic microphone,amplifier and circuit to replace the carbon granules and loading coil. The mechanical bell is often replaced by a speaker and a circuit to generate a pleasant ringing tone. But a regular $6.95 telephone remains one of the simplest devices ever.
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