Graphical demonstration of the coherent demodulation of GMSK

Ho Huat Peh, Tjeng Thiang Tjhung, Fumiyuki Adachi, Tony Quee Seng Quek

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    In this paper, we demonstrate through graphical means the coherent demodulation of Gaussian Minimum-Shift-Keying (GMSK) that is made possible because the pulses after the Gaussian lowpass filter retain the unit area such that the phase deviation has the π/2 value. Although it is straightforward to show analytically that the MSK waveform can be split into two antipodal pulse streams modulating an in-phase and quadrature carriers, so that coherent demodulation can be applicable, it is not the case with GMSK, because the modulating signal consists of overlapping pulses with analytically intractable Q function describing the pulse shape. By computing the access phase function θ(t) and plotting cos θ(t) and sin θ(t), we can see that the plots of cos θ(t) and sin θ(t) for GMSK retain the synchronized and staggered nature of those of MSK, suggesting the possibility of coherent demodulation as in MSK. We then show a simple way to compute the bit error probability of GMSK for a few values of the Gaussian lowpass filter bandwidth.

    Original languageEnglish
    Title of host publicationICCE 2010 - 3rd International Conference on Communications and Electronics
    Pages1-5
    Number of pages5
    DOIs
    Publication statusPublished - 2010 Dec 1
    Event3rd International Conference on Communications and Electronics, ICCE 2010 - Nha Trang, Viet Nam
    Duration: 2010 Aug 112010 Aug 13

    Publication series

    NameICCE 2010 - 3rd International Conference on Communications and Electronics

    Other

    Other3rd International Conference on Communications and Electronics, ICCE 2010
    Country/TerritoryViet Nam
    CityNha Trang
    Period10/8/1110/8/13

    Keywords

    • Bit error probability
    • Coherent demodulation
    • GMSK

    ASJC Scopus subject areas

    • Computer Networks and Communications
    • Electrical and Electronic Engineering

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