FM Transmitter of 1 KW rating

Provision of guard bands diminished adjacent-channel interference between FM stations. Boosting of the highest modulating frequencies before transmission and their attenuation after reception reduced noise. Thus it became possible to transmit stereophonic sound.

Stereophonic sound
   Two ears enable us to perceive direction and depth of sound. Normal radio cannot create this perception. We can sense direction and depth of sound if we use two separate channels for recording, broadcasting and reproduction. We call it stereophonic effect. We multiplex and transmit the left and the right channels of a stereo recording.

stadium. Multiplexing is similar to that. Time-division multiplexing divides a wave (car) into time-slots (seats). Each slot carries a different voice or data signal (one player from each team). We can combine several independent signals (playersof different teams) and transmit them at a time. At the receiving end, another multiplexer breaks the frame apart and presents each signal (player) to its respective receiver (team). How stereo is broadcast and received
The station transmits ‘L+R’ element (right channel added to the left), an ‘L-R’ element (right channel subtracted from the left), and a pilot signal.
    The listener’s receiver detects and isolates either. We add both elements to

When we vary the amplitude of a radio wave according to changes in a sound wave, we do amplitude modulation (AM). When we vary the frequency instead, we do frequency modulation (FM).

Why FM?
   Two drawbacks of AM are noise and the lack of fidelity.

Noise:
   Storms and electric machines create waves similar to radio signals. A radio receiver cannot

KHz only. They kept each channel 20 KHz wide to house maximum stations in this narrow band. Most AM stations actually use 15 KHz to avoid interference with adjacent channels. In practice the highest audio frequency that an AM station can carry is half of its carrier frequency. Hencein this case it is only 7.5 KHz or 7,500 Hz. Butradio receiver must reproduce the entire span upto 20,000 Hz in order togive high-fidelity sound. Since that is not possible in

  Special radio receiver separates and restores the channels to their original pattern.

What is multiplexing?
  Suppose you want to convey four cricket teams from a hotel to the stadiumYou send captains in one car, vice-captains in another, wicket-keepers in the third, et al. As the a cars reach the stadium, each   player joins his captain. Each team that split at the hotel gets together at the

  get the left channel and subtract them to get the right. We amplify each channel separately to produce stereophonic effect.
   We cannot transmit the left and the right components directly. As broadcaster, you would like to reach also those listeners who possess common non-stereo receivers. ‘L+R’ element recreates the attributes of non-stereo transmission that even ordinary

discern useful signals from disturbances. That is why AM reception is often noisy.

Lack of fidelity:
   Humans can hear frequencies from 15 to 15,000 Hz, and sense them upto 20,000 Hz. When pioneers set up the first broadcast stations, electronic components could handle 500 to 1,600

   AM, it cannot reproduce realistic music.
   By World War II, it was feasible to transmit radio waves from 30,000 to 300,000 KHz (30 to 300 MHz). That made it possible to assign Very High Frequency (VHF) band from 88 to 108 MHz to FM broadcasting. Each stationreceived channel width of 200 KHz.