Telecommunications Fundamentals ELEX 3530

BASIC COMMUNICATION SYSTEMS

• General description of signals and analyze their characteristics in time and frequency domain.
• Describe the essential elements of a communication system.
• Describe time-division and frequency-division multiplexing.
• Explain the relationship between channel bandwidth, baseband bandwidth, and transmission line.
• List the requirements for distortionless transmission, and describe some of the possible deviations from this ideal.
• Use frequency-domain representations of signals, and convert simple signals between time and frequency domains.
• Use a table of Fourier series to find the frequency-domain representations of common waveforms.

RADIO FREQUENCY CIRCUITS

• Analyze various amplifiers, phase lock loop and frequency synthesis.
• Explain the differences in operation and construction between circuits that operate at low frequencies and those that operate at radio frequencies.
• Describe the characteristics of Class A, B, and C amplifiers, and decide which type is the most suitable for a given application.
• Analyze radio-frequency amplifier circuits, both narrowband and broadband, and choose the correct configuration for a given application.
• Describe, draw circuits for, and analyze the most common types of radio-frequency oscillator circuits, and discuss their relative stability.
• Explain the operation of varactor-tuned voltage-controlled oscillators, and calculate the variation of frequency with tuning voltage.
• Describe the operation of crystal-controlled oscillators, and explain their advantages and disadvantages compared with LC oscillators. Perform frequency-stability calculations for crystal oscillators.
• Describe the function of a mixer and analyze several circuits, explaining how and where they are used, and calculating output frequencies.
• Explain the operation of a phase-locked loop.
• Define the lock and capture range for a phase-locked loop.
• Draw a block diagram of a frequency synthesizer, explain its operation, and calculate output frequencies.

AMPLITUDE MODULATION

• Analyze mixing of signals with a focus on amplitude modulation process.
• Explain the need for modulation in communication systems.
• Distinguish between baseband, carrier, and modulated signals, and give examples of each.
• Write the equation for a modulated signal and use it to list and explain the various types of continuous-wave modulation.
• Write the time-domain equation for an AM signal, and describe how the equation relates to the signal itself.
• Sketch an AM signal in both the time and frequency domains.
• Define the modulation index, calculate it, and measure it using either an oscilloscope or a spectrum analyzer.
• Describe the effects of overmodulation, and explain why it must be avoided.
• Sketch, and explain the operation of, simple AM modulators and demodulators.
• Calculate the bandwidth of an AM signal, and explain why bandwidth is an important factor in a communications system.
• Calculate power and voltage for an AM signal, and for each of its components.
• Discuss the requirements and specifications of AM transmitters, and determine whether a given transmitter is suitable for a particular application.

AM TRANSMITTERS

• Analyze transmission circuits and understand the importance of SNR, harmonics and other interfering parameters.
• Draw block diagrams for several types of transmitters, and explain their operation.
• Analyze the operation of transmitter circuits.
• Perform measurements on AM transmitters. Explain the advantages of suppressed-carrier, and of single-sideband, transmission over standard AM.
• Calculate the improvements in signal-to-noise ratio that result from the use of suppressed-carrier and single-sideband techniques.
• Describe the operation of a balanced modulator and sketch the output in both time and frequency domains, for typical input signals.
• Trace the signal path for transmit and receive operation, in a block diagram of a single-sideband transceiver, and determine which components are used for both.
• Perform tests on single-sideband transmitters to measure peak envelope power and suppression of harmonics and other spurious signals.
• Describe several practical communication systems that used suppressed-carrier and/or single-sideband techniques.

AM RECEIVERS

• Analyze receiver circuits and understand the importance of specifications for various suitability needs.
• Describe the basic superheterodyne system, and explain why it is the preferred design for most receivers.
• Choose suitable intermediate frequencies, and calculate image rejection for a receiver.
• Explain the requirements for each stage in a receiver, and suggest suitable types of circuits to fulfill the requirements.
• Analyze a circuit diagram for a receiver or transceiver to find the function of each stage.
• Describe the filter method of single-sideband generation, and calculate suitable filter and oscillator parameters to produce a given sideband at a given carrier frequency.
• Describe the operation of communications receivers that are capable of single-sideband reception, and show how they differ from receivers designed only for full-carrier AM.

ANGLE MODULATION

• Analyze angle modulation (FM and PM).
• Describe and explain the differences between amplitude and angle modulation schemes, and the advantages and disadvantages of each.
• Describe and explain the differences between frequency and phase modulation, and show the relationship between the two.
• Calculate bandwidth, sideband frequencies, carrier and sideband voltage and power levels, and modulation index for frequency- and phase-modulated signals.
• Explain the capture effect and noise threshold for FM signals.
• Perform measurements on FM signals using a spectrum analyzer.
• Describe the ways in which FM transmitters and receivers differ from those for AM, and explain why they differ.
• Analyze the operation of direct modulators.
• Calculate the carrier frequency and deviation for FM transmitters.
• Analyze the operation of the following type of FM detector: discriminator.
• Explain the reasons for the use of limiters in FM receivers, and describe the operation of a limiter.

Effective as of Fall 2015