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Waveform Basics Presented by: Greg Glenn Sr. Director of RF Engineering SOLiD 4/8/16Copyright © 2016 | CIBET | All rights reserved1
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This is a basic overview of different modulation wave forms you are bound to see in use with todays current over the air protocols. 4/8/16Copyright © 2016 | CIBET | All rights reserved2
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An Unmodulated RF signal is known as a Continuous Wave (CW) signal or CW carrier 4/8/16Copyright © 2016 | CIBET | All rights reserved3
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How do signals carry data and information? 4/8/16Copyright © 2016 | CIBET | All rights reserved4
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Modulation is the addition of information to an electronic or optical carrier signal. A carrier signal is one with a steady waveform, constant height (amplitude) and frequency. Information can be added to the carrier by varying its state, amplitude, frequency, phase.amplitudefrequency phase 4/8/16Copyright © 2016 | CIBET | All rights reserved5
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The Mix of Waveforms/Modulation formats 4/8/16Copyright © 2016 | CIBET | All rights reserved6
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State Change or CW 4/8/16Copyright © 2016 | CIBET | All rights reserved7
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Analog forms of modulation 4/8/16Copyright © 2016 | CIBET | All rights reserved9
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Amplitude Modulation (AM) varies the amplitude of the RF carrier based on intensity of the information signal. Frequency Modulation varies the frequency of the RF carrier based on the intensity information signal. 4/8/16Copyright © 2016 | CIBET | All rights reserved11
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Phase Modulation (PM) varies the phase of the RF carrier based on intensity of the information signal. 4/8/16Copyright © 2016 | CIBET | All rights reserved12
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Digital forms of modulation 4/8/16Copyright © 2016 | CIBET | All rights reserved13
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FSK - Frequency Shift Keying PSK - Phase Shift Keying BPSK - Binary Phase Shift Keying QPSK - Quadrature Phase Shift Keying 4/8/16Copyright © 2016 | CIBET | All rights reserved14
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QAM - Quadrature Amplitude Modulation 16 QAM - 16 Point Quadrature Amplitude Modulation 64 QAM - 64 Point Quadrature Amplitude Modulation 4/8/16Copyright © 2016 | CIBET | All rights reserved15
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Multiple Access Techniques Courtesy of Qualcomm, Inc. 4/8/16Copyright © 2016 | CIBET | All rights reserved16
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Access Modes FDD - Frequency Division Duplexing TDD – Time Division Duplexing 4/8/16Copyright © 2016 | CIBET | All rights reserved17
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FDD Uplink and downlink separated by frequency 4/8/16Copyright © 2016 | CIBET | All rights reserved18 UL/DL Offset Channel Frequency Channel BW Reverse Channel Forward Channel Channel BW
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TDD Both downlink and uplink share the same frequency 4/8/16Copyright © 2016 | CIBET | All rights reserved19
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Notes about high speed waveforms (LTE) 4/8/16Copyright © 2016 | CIBET | All rights reserved20
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While LTE uses adaptive coding it is important to understand that high SNR and low EVM is of utmost importance to maintain 64 QAM at the best coding rate. 4/8/16Copyright © 2016 | CIBET | All rights reserved25
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Take Away Current modulation formats require 26 dB or higher SNR to maintain highest performance. High linearity low EVM amps are a must to pass these waveforms. It is the DAS integrator, not the customer, that should be the expert on the DAS systems that you are involved in designing and installing. 4/8/16Copyright © 2016 | CIBET | All rights reserved26
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