MODULATION

                                     MODULATION 

MODULATION

MODULATION IS REQUIRED BECAUSE OF THE FOLLOWING REASONS WHILE TRANSMITTING BASEBAND [A.F MODULATING SIGNAL]

A. SIZE OF ANTENNA

B. EFFECTIVE POWER RADIATED BY AN ANTENNA

C. AS THE FREQUENCY OF BASEBAND IS LESS IT CON.T TRANSMITTED OVER A LARGE DISTANCE. [ 20HZ-20KHZ]

MODULATION

                      AUDIO FREQUENCY

                                      AF MODULATING SIGNAL

                                               m=AmSinWmt

                       HIGH FREQUENCY

                                          HF CARRIER WAVE    

                                              c=Ac Sin(wct+Q)

MODULATION

MODULATION IS THE PROCESS IN WHICH AUDIO ANY MODULATED SIGNAL IS SUPERIMPOSE ON A HIGH-FREQUENCY CARRIER WAVE THEN ONE OF THE CHARACTERISTICS OF HIGH-FREQUENCY CARRIER WAVE VARIES WITH RESPECT TO AUDIO FREQUENCY MODULATING SIGNAL AND A NEW WAVE IS FORMED KNOWNS AS MODULATED WAVE.

TYPES OF MODULATION:-

1. A.M [ AMPLITUDE MODULATION]

IN THIS, MODULATION, THE AMPLITUDE OF THE HIGH-FREQUENCY CARRIER VARIES WITH RESPECT TO THE AUDIO FREQUENCY MODULATED SIGNAL.

2. F.M [ FREQUENCY MODULATION]

IN THIS MODULATION, THE FREQUENCY OF HIGH-FREQUENCY CARRIER WAVES VARIES WITH RESPECT TO AUDIO FREQUENCY MODULATED SIGNALS.

3. P.M [ PHASE MODULATION]

IN THIS MODULATION, THE PHASE OF HIGH-FREQUENCY CARRIER WAVES VARIES WITH RESPECT TO AUDIO FREQUENCY MODULATED.

4. P'M [ PULSE MODULATION]

IT IS A SPECIAL MODULATION.

PULSE MODULATION 

IT IS A SPECIAL MODULATION IN WHICH A.F MODULATED SIGNAL IS SUPERIMPOSED ON A HIGH-FREQUENCY DIGITAL CARRIER WAVE HAVING 2 LEVELS. DUE TO THIS MODULATION AMPLITUDE, POSITION, OR DURATION OF HIGH-FREQUENCY DIGITAL CARRIER WAVE VARIES WITH RESPECT TO AUDIO FREQUENCY MODULATED SIGNALS