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You are reading a page from a free video eBook called Heaven or Hell It's Your Choice, for more information click on the website button above.

A laymen's guide to bandwidth and fiber optic networks.

The first real cable and wireless (radio) networks used simple Morse code to send signals. The most famous Morse message was SOS, which translated to, 3 dot's, 3 dashes, followed by another 3 dots. (Remember the telegraph office in old movies, with some poor guy tapping away on a switch - beeb_ beeb_ beeb_______beeeeeb________beeeb and so on).

In other words the person sending the message would literally have to tap a switch, e.g. tapping quickly 3 times on the switch equaled 3 dots, representing an S in Morse code, followed by 3 slower taps equaling 3 dashes representing an O, followed by another 3 quicker taps once again representing an S. So at the other end of the line, the receiver would hear 3 short tones followed by 3 longer tones and then 3 shorter tones once again. The Morse alphabet broke all letters down into a combination of dots (short tones) and dashes (longer tones).  SOS being the international signal for help, I'm sure it meant, Save Our Soles.

So whatever message you wished to send, could easily be sent over the airwaves or through wires by simply pulsing signals in a prearranged code.

This simple example, is still very similar in principle to how computers send and receive information over all current digital networks. Instead of dashes and dots, signals are broken down into packets of data, represented by extremely accurate timed signals, being pulsed over wireless, phone, fiber optic, and satellite networks etc. These signals represent 1's and 0's, so 00001 may = the letter A and 00011 may = the letter B and so on. So in a timed sequence, zero may = no pulse and one may = a pulse, so the quicker the pulses can be sent, the quicker the data can be pushed around a network. This in essence, is the definition of bandwidth, in other words instead of somebody tapping a switch to represent on or off, we now have a transistor or chip doing it for us, so the quicker these switches, switch on and off, the higher the bandwidth. So if you press the switch once a second, then this translates to 1 Hz (hertz), in technical speak. So as long as all the computers connected to the network know the code, then messages can be sent backward and forward through the network. One MHz (Megahertz) equals one million cycles per second or equivalent to the morse code man tapping his morse code key, a million times within a second.

And now for the film version:-

Photonic or fiber optic networks are capable of using light to send signals, so allowing the switch or in this case the light to be switched on and off very quickly. So at one end of a fiber optic cable you would have a laser switching on and off extremely quickly and at the other end you would have a light sensor. Every time the sensor saw a flash of light, it could send that signal to a computer, the computer could then say to itself, ok this means 1 and when the light sensor did not see a flash, then the computer could see this as a zero. Of course this is all timed and done extremely quickly, with millions of flashes of light being sent down the cable, representing millions of ones and zeros (binary code). These millions of 1's and 0's are stored in the computers memory, ready to then to be reassembled or translated back into the original message, just like Morse code.

The latest developments in optical networking, is towards using shorter pulses of light and multiple wavelengths. What this means in simple terms is that the pulses sent, are much quicker, whilst multiple wavelengths means different colours. Because different frequencies of light do not interfere with each other, a green light can be sent down a fiber optic cable at the same time as you can send a red light. This in effect means that you can send twice as much data down the same cable, without having to lay a new cable. Obviously there are many colours available, so this allows masses of data to be sent down a single cable. Multi spectrum technology is still in it's infancy and it is pain to install by all accounts, but this is the future for high speed optical networks.

I hope you now understand bandwidth and optical networks.


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Author Alan Keeling