22 lines
1.5 KiB
Plaintext
22 lines
1.5 KiB
Plaintext
C-mirroring WLS + PPS timing simulation
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========================================
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epochs: 900
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raw WLS bias/c range: -5.888015 .. 0.673753 ms
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derived GPS reference RMS error: 60.522 ns
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capture-to-commit delay mean/p99: 21.600 / 31.529 ms
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first HOW used as receive-now, median phase error: -249.876 ms
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first HOW + 180 ms + 68.802 ms, median phase error: -1.074 ms
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4 satellites: position RMS=103.877 m, timing RMS=144.920 ns
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5 satellites: position RMS=20.194 m, timing RMS=45.603 ns
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7 satellites / drop-reacquisition: position RMS=14.626 m, timing RMS=36.888 ns
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timestamped PI: tail phase RMS=274.256 ns, |phase| p95=410.422 ns, PPS RMS=815.642 ns, rejected stale commits=0
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timestamped, PI disabled: tail phase RMS=233589.285 ns, |phase| p95=302907.720 ns, PPS RMS=181358.257 ns, rejected stale commits=0
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untagged APB-now PI: tail phase RMS=18651473.186 ns, |phase| p95=19146158.593 ns, PPS RMS=18060541.154 ns, rejected stale commits=0
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Interpretation:
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- bias/c is millisecond-scale because it contains the 68.802 ms synthetic datum and the minimum satellite path.
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- epoch-aligned TOW (first delivery: HOW + 180 ms) + STARTOFFSET - bias/c reconstructs GPS time at the paired timestamp.
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- treating that old reference as valid at APB arrival converts software latency into PPS phase error.
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- timestamping removes that phase misassociation; control application delay remains only as loop delay.
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- baremetal applies the fixed 180 ms readout correction once; the PPS peripheral must not add it again.
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