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Projexct Essay

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Below is an essay on "Projexct" from Anti Essays, your source for research papers, essays, and term paper examples.

CHAPTER ONE

INTRODUCTION
Transfer of information (speech, music, image, computer data etc.) by radio can be presented in its simplest form with block - diagram as in Figure 1.1. That is a transmission realized by amplitude - modulated signal. Since, in our example, the information being transferred is the sound, the first step of such transmission is converting the sound into electrical signal, this being accomplished by a microphone. The low - frequency (LF) voltage at microphone output (Figure 1.1a), that represents the electrical "image" of the sound being transferred, is being taken into the transmitter. There, under the effect of LF signal, the procedure called amplitude modulation is being carried out, and on its output high - frequency (HF) voltage is generated, its amplitude changing according to the current LF signal value. HF voltage creates HF current in the antenna, thus generating electromagnetic field around it. This field spreads through the ambient space, being symbolically shown on Figure 1.1 with dashed circles. Traveling at the speed of light (c=300 000 km/s), the electromagnetic field gets to the reception place, inducing the voltage in the reception antenna, as shown on Figure 1.1-c. This voltage has the same profile as the one on Figure 1.1-b, except it has much smaller amplitude. In the receiver, the amplification and detection are carried out first, resulting with the LF voltage on its output, that has the same profile as the one on Figure 1.1-a. This voltage is then transformed into sound by loudspeaker, that sound being exactly the same as the sound that acted upon the microphone. This, naturally, is the way it would be in ideal case. Back to reality, due to device imperfection as well as the influence of various disturbances, the sound being generated by the loudspeaker differs from the one that acts upon the microphone membrane. The block - diagram on Figure 1.1 (excluding the HF signal shape) is also applicable in case of radio...

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  • Submitted by: jamescharles
  • on March 8, 2014
  • Category: Science And Technology
  • Length: 724 words
  • Views: 126
  • Popularity Rank: 524004
  • 1 rating(s)

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