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APPENDIX H 215 Appendix H Signal Structure Options Ten signal structure enhancement options were considered by the committee, as shown in Table H-1. Each involves possible changes to L1 or L2, as well as a possible signal transmission on a new frequency. The options are listed in priority order.
Table H-1 Signal Structure Options Option L1 L2 L4 Advantages Relative to the Disadvantages Relative to the Earliest Possible Implementation Current Configuration Current Configuration APPENDIX H 1 Y C/A Y Pa-like code wide-band signal Ionospheric correction; improved Must jam two bands; satellite and IIR accuracy; anti-jam; 10-dB receiver costs increase; satellite improvement over narrow- band in power requirements increase; interference rejection; faster cycle frequency allocation considerations ambiguity; fast acquisition; easier direct Y- code acquisition; can track to lower elevation angles than codeless receivers 2a Y C/A Y C/A-like code narrow -band Ionospheric correction; improved Must jam two bands; satellite and IIR signal accuracy, anti-jam; 10-dB receiver costs increase; satellite improvement over narrow- band in power requirements increase; interference rejection; faster cycle frequency allocation considerations ambiguity; fast acquisition; easier direct Y- code acquisition; can track to lower elevation angles than codeless receivers 2b Y C/A Y with C/A-like code added to null of L2 Ionospheric correction; improved Must jam two bands; satellite and IIR narrow-band signal accuracy; anti-jam; 10-dB receiver costs increase; satellite improvement over narrow- band in power requirements increase; interference rejection; faster cycle frequency allocation considerations ambiguity; fast acquisition; easier direct Y- code acquisition; can track to lower elevation angles than codeless receivers 3 Y C/A Y C/A C/A- or P-like code narrow Improved accuracy, improved anti- More difficult to deny signal by IIF or wide band signal jam for civilians; ionospheric jamming; more satellite power correction; cycle ambiguity required 4 Y C/A Y C/A Y-like code(military only) Improved anti-jam for the military Military receiver costs may IIF wide-band signal ionospheric correction for increase; must jam two bands; civilians; improved cycle may require more satellite power; ambiguity; improved direct frequency allocation considerations acquisition of Y-code 216
5 Y C/A Y â Baseline Baseline Baseline 6 Pa C/A Y â Improved accuracy, improved anti-jam; current military dual-frequency receivers IIF some codeless receivers will have won't work; some current civilian codeless APPENDIX H improved performance receivers won't work; must make changes to satellite 7 Y C/A Pa â Improved accuracy, anti-jam; civil More difficult to deny signal by jamming, IIF ionospheric; correction cycle ambiguity current military dualfrequency receivers won't work; must make changes to satellite 8 Y C/A C/A â Civil ionospheric correction; improved Military receiver costs increase; must jam (Current) II/IIA cycle ambiguity, some jam resistance two bands; satellite power may increase; no dual-frequency military ionospheric correction 9 Pa C/A Pa Y-like code(military only) wide-band Precision; improved anti-jam; provides Military receiver costs increase; must jam IIF signal ionospheric correction for civilian users; two bands; satellite power may increase; improved cycle ambiguity possible frequency allocation difficulties; no dual-frequency military-only ionospheric correction a. "P" refers to the unencrypted code 217
