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ELECTRONIC COMMUNICATIONS FUNDAMENTALS

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The  purpose of any communication system is to transfer information from one point to another through a communication link. The very first system that electrically transferred information was the human voice in the form of a code called the Morse code.which was converted back to words at the receiving end through human translation.​

Such a system was slow and wasn't enough as people had a natural desire and need to communicate rapidly between distant points on the earth. As that goal became a reality coupled with the evolution of new technology following the invention a vacuum  tubes and transistors, new and more advanced applications were realized such as the radio, television, radar and telemetry. Still the field of communication is a rapid field where extremely advanced system were developed such as WI-FI and cellular phone technology.

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Subjects covered in this training session are:

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INTRODUCTORY TOPICS:

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  • The topics in this chapter present a basic review of some electronics topics such as the decibel measurement, importance of noise and its spectrum and measurement, frequency filters and carrier signals generations. The topics explained in this chapter are:​

    • The db In Communications.

    • Noise, Spectrum and Calculations.

    • Bandwidth and Information.

    • LC Circuits and Filters.

    • Oscillators.

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AMPLITUDE MODULATION TRANSMISSION:

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  • Direct Transmission of intelligible signals would result is severe interference. Imagine that multiple people are attempting to relay information to a single destination at the same time. This happens because voice signal frequencies are the same and signals that have the same frequency tend to mix with each other. In addition, a voice signal can only travel so far. Imagine having to relay a voice signal from one city to another, An impossible task in addition to the fact that huge antennas are required. Some mean of relaying such voice or music signals is devised by having a carrier signal carry the voice and music information a far distance. By modulating the characteristics of the signal that can be achieved. Topics covered in this chapter are:

    • Amplitude Modulation (AM) Fundamentals.

    • Percent Modulation.

    • Amplitude Modulation Analysis

    • AM Generation.

    • AM Transmitter Systems.

    • Transmitter Measurements.

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AMPLITUDE MODULATION RECEPTION:

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  • When AM transmitted signals are received by an antenna, they are usually very small. Therefore amplification of the signal is necessary with low noise characteristics and should be able to tune to the frequency of the received signal and its side-bands. while at the same time avoid interference from a neighboring station. After tuning to the carrier signal desired, the task of extracting the information from the carrier is performed by using a detector circuit followed by using an Audio amplifier. Automatic Gain Control is also achieved using such circuits. Topics covered in this chapter are: 

    • Receiver Characteristics.

    • AM Detection.

    • Super Heterodyne Receivers.

    • Automatic Gain Control.

    • AM Receiver Systems.

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SINGLE SIDE-BAND COMMUNICATIONS

  • The communication frequency spectrum is a very crowded one. Corporations Frequency bandwidths are allocated by the government FCC. With single side band communication, bandwidth necessary to relay the same information is tremendously reduced along with the power needed to transmit the same information. Under SSB, the information contained in one side band is sufficient to recover the intelligence transmitted. Topics covered in this chapter are:

    • Single Side-band Characteristics.

    • Side-Band Generation.

    • SSB Filters.

    • SSB Transmitters.

    • SSB Demodulation.

    • SSB Receivers.


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FREQUENCY MODULATION TRANSMISSION:

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  • In Amplitude modulation (AM), the information /intelligence was embedded on the amplitude of the carrier. In frequency modulation (FM), the information is embedded  in the phase or the frequency of the carrier signal. Th difference between the two is that PM is the amount of phase change proportional to the intelligence amplitude, while FM is the amount of frequency deviation from the carrier signal frequency. FM has the advantage of not being susceptible to noise signals as AM is. Topics covered in this chapter are:

    • Angle Modulation.

    • FM Analysis.

    • Noise Suppression.

    • Direct FM Generation.

    • Indirect FM Generation.

    • FM transmitter Circuits.

    • Stereo FM.

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FREQUENCY MODULATION RECEPTION:

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  • The basic FM receiver uses the super heterodyne principal. It has many similarities to the AM receiver with the difference that instead of using a detector as in the AM receiver, a discriminator is used. The Discriminator extracts the intelligence from the high frequency carrier and can also be called the detector, as in AM receiver. The discriminator however is a device in which amplitude variations are derived in response to frequency or phase variation and it is the preferred term for describing an M demodulator Topics covered in this chapter are: 

    • RF Amplifiers.

    • Limiters.

    • Discriminators.

    • Phase Locked Loop.

    • Stereo Demodulation

    • FM Receivers.


                                                                                                                                                                                                    

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