2.2 KiB
SignalSim Galileo E1 bit-generation trace
Inspected project: globsky/SignalSim, commit
80b262113e77c4482ca9f5cbfef9bcada402ed28.
| Layer | E1B status | E1C status | Evidence/qualification |
|---|---|---|---|
| Navigation fields | Generated from RINEX ephemeris, almanac, UTC/iono | N/A pilot | INavBit::GetWordData, setters called by IFdataGen |
| Navigation page | 500-symbol, 2-second I/NAV page | N/A | INavBit::GetFrameData |
| CRC | CRC-24Q over 196 bits | N/A | Crc24qEncode |
| Channel encoding | Galileo convolutional encoder with tail bits | N/A | GalConvolutionEncode |
| Interleaving | 8 by 30 traversal for both page halves | N/A | final loops in GetFrameData |
| Sync | 10 symbols 0101100000 before each 240-symbol half |
N/A | SyncPattern |
| Symbols | One encoded E1B symbol per 4 ms | 25-symbol overlay sequence | SignalAttributes[9]; SecondaryCodeE1 |
| Spreading | 4092-chip E1B memory code | 4092-chip E1C memory code | E1MemoryCode, GetMemorySequence |
| Modulation | BOC(1,1), amplitude -DataBit/sqrt(2) |
BOC(1,1), amplitude PilotBit/sqrt(2) |
SatelliteSignal.cpp, SatIfSignal.cpp |
| IF samples | Combined complex IQ at RF-center offset | Combined complex IQ | IFdataGen quantizer/output path |
The I/NAV stream is not random dummy data. It includes CRC, convolutional encoding, interleaving, sync, page timing, TOW/WN fields where applicable, and ephemeris/almanac content. Limitations are also explicit: unsupported word types above 20 become dummy word 63, and reserved/SAR/spare content includes fixed zero placeholders.
Receiver-side evidence recovered 469 raw E1B symbols after the tracking
transient and found two exact 0101100000 sync words 250 symbols apart with
zero errors over the 20 known sync symbols. Receiver-side deinterleaving, FEC
decoding, page parsing, and CRC validation are not implemented, so this result
must not be described as decoded navigation bits or decoded I/NAV pages.
E1C evidence found secondary phase 10, normalized correlation 0.9830, and zero sign errors over 100 primary-code periods. The implemented 25-symbol constant was verified against generated samples but was not independently certified against an external ICD table in this work.