Network Cables Online Blog    

Q. How can a beam of light possibly carry information?
A. The one’s and zero’s of the binary data are converted to light pulses and sent down the fibre at very high frequencies.

Q. For every pulse of light that is sent down a fibre optic cable there is some light which is lost because it is beyond critical angle and cannot be reflected. If part of this mode is lost then doesn’t that mean the data is sent as incomplete? How can the computer make sense of an incomplete signal? Could you explain this situation.
A. The data is sent as a stream of bits and so the amount of light that is lost merely reduces the strength of the signal. The pulses of light that reach the other end will have lost some of their strength but they will still be large enough to reassemble into bytes of information. Multi-mode transmission simply means that the light travelling down the fibre will take multiple paths, it does not mean that each mode is transmitting different data. Each pulse of light comprises all modes.

Q. Finally, I know that the time between transmitting each pulse must be enough so that the first pulse completely arrives at the receiver before the second pulse does. What happens if two pulses do crossover one another? Do they mix to create a different pulse, does the PC say transfer error, or the screen freezes etc.?
A. The pulses all travel at the same speed so it is not possible for one to overtake another. The main reasons for errors in a fibre system are too much attenuation (reduction in signal strength), and reflections or backscatter at poor connections which if large enough will interfere with the signal.