AM TRANSMITTER

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AM TRANSMITTER In an  AM  ( amplitude modulation )  transmitter  the amplitude (strength) of the carrier wave is varied in proportion to the modulation signal. In an FM (frequency modulation)  transmitter  the frequency of the carrier is varied by the modulation signal. There are two basic configuration for transmitters. High level modulation low level modulation  High level modulation In high power modulation signal,the carrier voltage is modulated at highest power level.the require power level is obtained by class c power amplifier.The block diagram of high level modulation as shown in fig(a). low level modulation In the low level modulation system, the carrier is modulated at low power level and the carrier power is subsequently raised to the desire level in the class B amplifier . transmitters using high power level are widely use at present .The block diagram of high level modulation as shown in fig(b). advantage AM sign
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FREQUENCY SHIFT KEYING

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Frequency-shift keying  is the frequency modulation system in which digital information is transmitted through the discrete frequency change of a carrier wave. The technology is use in communication system. such as amateur radio, caller ID, and urgent situation broadcasts. The simplest FSK is binary FSK (BFSK). BFSK uses a pair of discrete frequencies to transmit binary (0s and 1s) information. With this scheme, the “1” is called the mark frequency and the “0” is called the space frequency.


FSK modulated wave shown in fig.1

ADVANTAGE

  1. It has low probability of error.
  2. It provide high signal to noise ratio (SNR).
DISADVANTAGE 
  1. High power consume.
  2. High bandwidth.
APPLICATION
  1. Radio transmission.
  2. Satellite link.
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