btec_mobile_1 - Mobile Communications Systems Janaka...

Info iconThis preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
Mobile Communications Systems Janaka Harambearachchi
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
1 Analogue modulation : time domain (waveforms), frequency domain (spectra), amplitude modulation (am), frequency modulation (fm), phase modulation (pm) 2 Digital modulation : waveforms and spectra, Frequency Shift Keying (FSK), Binary Phase Shift Keying (BPSK) [including Gaussian Minimum Shift Keying (GMSK)], Quadrature Phase Shift Keying (QPSK) [including π/4QPSK] 3 Error coding : General principles of block, convolutional, parity, interleaving 4 Compression : Regular Pulse Excitation – Linear Predictive Coding – Long Term Prediction (RPE-LPC-LTP) Modulation, coding, compression and encryption techniques
Background image of page 2
Communication is the transfer of information from one place to another. This should be done - as efficiently as possible - with as much fidelity/reliability as possible - as securely as possible Communication System: Components/subsystems act together to accomplish information transfer/exchange. Overview
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Output message Input message Input Transducer Transmitter Channel Receiver Output Transducer Elements of a Communication System
Background image of page 4
Input Transducer: The message produced by a source must be converted by a transducer to a form suitable for the particular type of communication system. Example: In electrical communications, speech waves are converted by a microphone to voltage variation. Transmitter: The transmitter processes the input signal to produce a signal suits to the characteristics of the transmission channel. Signal processing for transmission almost always involves modulation and may also include coding . In addition to modulation, other functions performed by the transmitter are amplification , filtering and coupling the modulated signal to the channel.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Channel: The channel can have different forms: The atmosphere (or free space), coaxial cable, fiber optic, waveguide, etc. The signal undergoes some amount of degradation from noise, interference and distortion Receiver : The receiver’s function is to extract the desired signal from the received signal at the channel output and to convert it to a form suitable for the output transducer. Other functions performed by the receiver: amplification (the received signal may be extremely weak), demodulation and filtering. Output Transducer: Converts the electric signal at its input into the form desired by the system user. Example: Loudspeaker, personal computer (PC), tape recorders.
Background image of page 6
To be transmitted, Information (Data) must be transformed to electromagnetic signals.
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Electromagnetic Waves Electromagnetic Waves . .
Background image of page 8
Electromagnetic Waves Electromagnetic Waves . .
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Electromagnetic Spectrum http://www.edumedia-sciences.com/a185_l2-transverse- electromagnetic-wave.html
Background image of page 10
Electromagnetic Spectrum
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Wave length Frequency Designations Transmission Media Propagation Modes Representative Applications Frequency 1 cm Extra High Frequency (EHF) 100 GHz 10 cm Super High Frequency (SHF) Satellite, Microwave relay, Earth-satellite radar. 10 GHz
Background image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 68

btec_mobile_1 - Mobile Communications Systems Janaka...

This preview shows document pages 1 - 13. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online