Signal

Computer stored data is called digital data (combination of 0 and 1). But when we send voice (we talk) or data from Surveillance camera then it supplies analog signal. But the cable can’t carry this digital data and analog signal directly. Cause we have to create voltage for that.

Cable passes the voltage is digitally converted analog signal. So first analog signals have to convert into binary form (digital data) then into digitally converted analog signal.

Now we will learn how original analog signal is converted into digital data. So first we have to learn a little about Signal..

Signal:

A Signal is sequence of discrete, discontinuous voltage pulses. This voltage oscillates and create a form is called Waveform. There are different types of wave- Sine Wave, Square Wave etc. 

The distance between maximum and minimum wave is called Amplitude. Biggest amplitude means more powerful signal. This power is measured by Ampere. And how many waves oscillate per second is called Frequency. The unit of measure frequency is Hertz. In computer processor 400 mega Hertz means 400 million-hertz or cycle can complete per second.

There are two types of signal- Analog signal & Digital signal.

Analog signal: When we talk it makes an analog signal. Analog signal creates sine wave. When signal frequency is 20 hertz to 2 kilohertz, then we can hear. Radio signal is also an analog signal. But AM (Amplitude Modulation) radio signal frequency is 530-1700 kilohertz. And FM (Frequency Modulation) radio frequency is 88-108 Mega hertz. So we can’t hear that.

Digital signal: Digital signal creates square wave. Computer uses digital signal for there internal relation between devices. There are two types of digital signals

1.      Current State Encoding

2.      State Transition Encoding.

In Current State Encoding 0, 1 decided by Voltage. Positive volt represents in binary 1 and negative volt represents in binary 0. In State Transition Encoding the period of high voltage to low voltage is represent 1 and period of low voltage to high voltage represents as 0.

Computer data is already digital data. But first we will learn how original analog signal (voice or camera data) converts into digital data.

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