CESSB (controlled-envelope single-sideband) is a narrowbandmodulation method using a single sideband, whose peak envelope level is controlled so that the peak-to-average power ratio of CESSB is much reduced compared to standard SSB modulation and offers improved effective range over standard SSB modulation while simultaneously retaining backwards compatibility with standard SSB radios.
A drawback of standard SSB modulation is the generation of large envelope overshoots well above the average envelope level for a sinusoidal tone (even when the audio signal is peak-limited). In combination with RF amplifiers with non-linear properties this causes severe distortions of the transmitted audio signal. Therefore, the average RF power level must be reduced in order to accommodate the overshoots.
The standard SSB envelope peaks are due to truncation of the spectrum and nonlinear phase distortion from the approximation errors of the practical implementation of the required Hilbert transform. It was recently shown that suitable overshoot compensation (so-called controlled-envelope SSB, or CESSB) achieves about 3.8 dB of peak reduction for speech transmission. This results in an effective average power increase of about 140%.[1] Although the generation of the CESSB signal can be integrated into the SSB modulator, it is feasible to separate the generation of the CESSB signal (e.g. in form of an external speech preprocessor) from a conventional SSB radio. This requires that the SSB radio's modulator be linear-phase and have a sufficient bandwidth to pass the CESSB signal. If an otherwise conventional SSB modulator meets these requirements, then the envelope control by the CESSB process is preserved.[2]
CESSB is being used experimentally by amateur radio operators and is implemented by some radios in the amateur marketplace. SmartSDR software by Flex Radio Systems implements CESSB, as do certain software-defined radios, such as the Apache labs ANAN series and the Elecraft K4.[3]
Modulation for other examples of modulation techniques
Sideband for more general information about a sideband
Referencesedit
^"Controlled Envelope Single Sideband" (PDF). www.arrl.org. 2014-11-01. Retrieved 2017-01-15. by David L. Hershberger, W9GR, QEX, issue Nov./Dec. 2014, pp. 3–13.
^"External Processing for Controlled Envelope Single Sideband" (PDF). www.arrl.org. 2016-01-01. Retrieved 2017-01-15. by David L. Hershberger, W9GR, QEX, issue Jan./Feb. 2016, pp. 9–12.
^"CURRENT K4 PRODUCTION SOFTWARE". www.elecraft.com. Retrieved 2022-06-14.
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controlled, envelope, single, sideband, modulation, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers. This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Controlled envelope single sideband modulation news newspapers books scholar JSTOR January 2017 Learn how and when to remove this message CESSB controlled envelope single sideband is a narrowband modulation method using a single sideband whose peak envelope level is controlled so that the peak to average power ratio of CESSB is much reduced compared to standard SSB modulation and offers improved effective range over standard SSB modulation while simultaneously retaining backwards compatibility with standard SSB radios A drawback of standard SSB modulation is the generation of large envelope overshoots well above the average envelope level for a sinusoidal tone even when the audio signal is peak limited In combination with RF amplifiers with non linear properties this causes severe distortions of the transmitted audio signal Therefore the average RF power level must be reduced in order to accommodate the overshoots The standard SSB envelope peaks are due to truncation of the spectrum and nonlinear phase distortion from the approximation errors of the practical implementation of the required Hilbert transform It was recently shown that suitable overshoot compensation so called controlled envelope SSB or CESSB achieves about 3 8 dB of peak reduction for speech transmission This results in an effective average power increase of about 140 1 Although the generation of the CESSB signal can be integrated into the SSB modulator it is feasible to separate the generation of the CESSB signal e g in form of an external speech preprocessor from a conventional SSB radio This requires that the SSB radio s modulator be linear phase and have a sufficient bandwidth to pass the CESSB signal If an otherwise conventional SSB modulator meets these requirements then the envelope control by the CESSB process is preserved 2 CESSB is being used experimentally by amateur radio operators and is implemented by some radios in the amateur marketplace SmartSDR software by Flex Radio Systems implements CESSB as do certain software defined radios such as the Apache labs ANAN series and the Elecraft K4 3 See also editACSSB amplitude companded single sideband Independent sideband Modulation for other examples of modulation techniques Sideband for more general information about a sidebandReferences edit Controlled Envelope Single Sideband PDF www arrl org 2014 11 01 Retrieved 2017 01 15 by David L Hershberger W9GR QEX issue Nov Dec 2014 pp 3 13 External Processing for Controlled Envelope Single Sideband PDF www arrl org 2016 01 01 Retrieved 2017 01 15 by David L Hershberger W9GR QEX issue Jan Feb 2016 pp 9 12 CURRENT K4 PRODUCTION SOFTWARE www elecraft com Retrieved 2022 06 14 nbsp This article related to telecommunications is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Controlled envelope single sideband modulation amp oldid 1201184249, wikipedia, wiki, book, books, library,
