Digital modulation techniques

dmt

1. UNIT 2 DIGITAL MODULATION TECHNIQUES

2. INTRODUCTION WHAT IS MODULATION : In electronics and telecommunications , modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a modulating signal that typically contains information to be transmitted. . Digital modulation uses discrete signals for modulating a carrier wave i.e if a binary signal modulates a high frequency carrier signal then it is called as “Digital modulation”

3. Types of digital modulation There are several kinds of  digital modulation techniques  are available based on the requirement which includes the following . ASK or Amplitude shift Key FSK or Frequency shift key PSK or Phase shift key

4. Synchronous and Asynchronous detection Generally there are two types of Demodulation techniques . They are 1.Asynchronous Demodulation/detection 2.Synchronous Demodulation/detection The clock frequency at the transmitter when matches with the clock frequency at the receiver, it is known as a  Synchronous method , as the frequency gets synchronized. Otherwise, it is known as  Asynchronous .

5. Amplitude-shift keying (ASK) Amplitude-shift keying  ( ASK ) is a form of  amplitude modulation  that represents  digital   data  as variations in the  amplitude  of a  carrier wave . In an ASK system, the binary symbol 1 is represented by transmitting a fixed-amplitude carrier wave and fixed frequency for a bit duration of T seconds. If the signal value is 1 then the carrier signal will be transmitted; otherwise, a signal value of 0 will be transmitted.