ION Technical Content
BOC Modulation Waveforms
| Abstract: | This paper is concerned with the evolution of modulation waveforms finding application in recent navigation satellite transmissions. Specifically, we focus on the waveforms used for sub carrier modulation with binary signals, and the spectra of the resulting waveforms. These are generalized to multi-level waveforms that can be simply implemented by multi-phase constant envelope signals, well adapted to high power amplifiers used in satellite payloads. A family of equations is derived for the spectra of such signals. These include the spectra of both 3-level and 5-level BOC sub carriers. The theory is general and is extendible to sub carrier modulation with higher numbers of levels and the use of non-binary spreading code waveforms. One important suggestion, (J-L Issler, CNES), is the use of cosine sub carrier phasing, rather than sine phasing. The results of analysis are also applied to this case for the first time. Spectral Separation Coefficients (SSC) are one of the metrics used to compare the interactions between signals in the same spectrum space. A section is included, therefore, on developments in SSC Theory. There are two useful enhancements. One introduces the effects of protection filters that further isolate different signal types whilst the second derives SSC's computable in the time domain - this is useful for complex signal shapes. The combination of the two is a more complete theory providing an armory of techniques useful in designing navigation signals able to compete within the current crowded spectra. This is useful in the design of candidate signals for Galileo, able to occupy the E1-L1-E2 frequency band alongside CA code transmissions from GPS and the BOC(10,5) spectrum proposed for M-code. |
| Published in: |
Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR |
| Pages: | 1044 - 1057 |
| Cite this article: | Pratt, A.R., Owen, J.I.R., "BOC Modulation Waveforms," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 1044-1057. |
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