Little bits that make up the digital world of the Net

SURAT, July 3: When television came on the `scene' I used to wonder how images could be relayed instantaneously, and that too without any ph...

SURAT, July 3: When television came on the `scene’ I used to wonder how images could be relayed instantaneously, and that too without any photographic medium. Similarly, many of us might be puzzled over how images and sound could be sent over telephone wires on the Internet. Lets see how this is done.

All of us know that the digits 0 to 9 form the basis of all the numbers in this world (for this example we ignore the decimal and minus signs). In the digital world of the Internet the digits 0 and 1 are all that are used to represent the whole spectrum of numbers, pictures, sound and data. This numbering system is called binary system as there are only two digits. Hence each of these 0s and 1s are `bits’, short for binary digits.

A bit of the digital world, has no colour, or weight, and can travel at very fast speeds. Think of it as the DNA of information. It’s only important characteristic is a state of being, on or off, true or false, up or down, black or white. It is a separate matter that for practical purposes we consider a bit to be a 1 or a 0.

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In the early days of computing, a string of bits most commonly represented commands, alphabets and information. Bits were the underlying particle of digital computing, but over the past many years the binary vocabulary has been expanded to include much more than just numbers.

We have been able to digitize more types of information, like audio and video, rendering them into a similar reduction of 1s and 0s. When we talk of digitising sound or picture what we are doing is taking samples of the sound or picture signal and storing it as a bit. If these bits are very closely spaced, they can be used to play back the same sound or picture. The successive and discrete measures are so closely spaced in time that we experience them as a continuous tone.

Digitising information has many advantages, besides the fact that computer circuits understand only the 1s and 0s.

Bandwidth is a term everyone associated with the cyberworld will come across at some time or the other. It refers to the number of bits that can be transmitted per second through a given channel. The channel may be copper wire, radio spectrum or optical fibre. Bandwidth is a measure of how many bits can get down a given pipe. Therefore when we say that we cannot use Pune’s telephone lines for sending video or audio effectively, we mean that its bandwidth does not allow us to send more that 9,600 or 14,400 bits per second. High fidelity sound needs a bandwidth of 64,000 bits per second. And video needs much greater bandwidth. The speed at which we are making advances in telecommunication technology is phenomenal. As recently as the early 90s, many people were skeptical of the viability of digital video.

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Now, it is a reality in the West. This is possible because technology to enable very high levels of data compression is available.

Data compression means the ability to pack more information represented by the 1s and 0s in the same space. When we digitise all the media, the exciting world of multimedia becomes a reality. The mixing of audio, video and date is called multimedia. A new kind of bit has also been born, a bit that tells you about the other bits. Such bits are called headers. They are like a table of contents. They give the computer information about the signal. These two facts have altered the media landscape dramatically and offer exciting possibilities like video on demand.

In the next article let us explore more on this topic and take up modems also. What say?