Release Notes — v0.6.9¶

IGS-product integer PPP-AR via Bias-SINEX OSB phase biases¶

Release date: 2026-05-24 Type: Feature — integer ambiguity resolution for correction = "igs" (post-processing) Branch: release/v0.6.9

Overview¶

v0.6.9 extends the correction = "igs" axis from float-only PPP (v0.6.7) to integer PPP-AR, using satellite phase biases from a Bias-SINEX Observable-Specific Bias (OSB) product — e.g. the CODE MGEX IAR OSB.BIA. Integer resolution gives faster convergence and cm-level fixed solutions.

This is the "Phase 2" item of the correction axis (docs/design/configuration.md), following the v0.6.7 IGS-files float PPP (#130/#135/#137) and v0.6.8 IGS-RTS float PPP (#138).

Major changes¶

Integer PPP-AR for correction = "igs" (#142)¶

Integer resolution from IGS precise products needs the uncombined measurement model plus a satellite phase-bias product:

• corr_meas() (src/pos/mrtk_ppp.c), when uncombined (ionosphere = "est-stec"), applies the per-signal satellite code bias to the pseudorange and phase bias to the carrier from nav->osb (the Bias-SINEX OSB). Removing the satellite phase bias makes the float ambiguity integer-recoverable, so ppp_amb_ILS can fix the wide-/narrow-lane. It is gated on uncombined mode, so the float iono-free path (ionosphere = "dual-freq") stays bit-identical — float results are unchanged with AR off (before/after guard).
• udsatpb() (src/pos/mrtk_rtkpos.c) gains a Bias-SINEX phase-bias source (pppsatpb enum 2:bia). Previously only SSR/FCB fed nav->osb.spb, so file-based OSB phase biases were loaded then dropped. The new source is reached only when no SSR/FCB phase bias exists, so MADOCA / CLAS / VRS are unaffected.
• resolve_correction() requires ionosphere = "est-stec" when correction = "igs" is combined with ambiguity resolution — the iono-free combination has a single ambiguity per satellite, so AR would otherwise be a silent no-op.

PPP-AR zero-ambiguity guard (dual-frequency)¶

The extra-wide-lane step called the Kalman update with na = 0 on a dual-frequency setup, invoking LAPACK DGETRF with n = 0 (XERBLA "parameter 4 illegal") and aborting the whole AR before the wide-/narrow-lane steps. update_states() (src/pos/mrtk_ppp_ar.c) now treats na <= 0 as a no-op. This is a latent bug that affected any dual-frequency PPP-AR; multi-frequency AR (MADOCA / CLAS, nf ≥ 3) is unaffected (bit-identical).

Validation¶

• GEONET FUJISAWA (GSI 93034, Trimble geodetic), 2026-01-21, GPS+Galileo, uncombined PPP-AR with COD MGEX OSB.BIA, against the GSI F5 coordinate: ~31 % integer-fix over a 2 h window (100 % once converged), 3D ≈ 6.7 cm (dominated by the data's ~7 cm Up bias, which the float carries too).
• The IGS float PPP is cross-checked against upstream RTKLIB 2.4.3 rnx2rtkp on identical inputs: both ≈ 8.4 cm 3D vs the GSI coordinate — i.e. no meaningful degradation. (RTKLIB has no integer PPP-AR — its ppp_ar() is a stub — so the fixed solution has no upstream counterpart.)
• New igs_pppar_ge (GPS+GAL, asserts the integer-fix rate via compare_pos_abs.py --min-fix-rate) and igs_pppar_gps (GPS-only) regression groups.

Constellations¶

The AR engine is multi-GNSS (GPS / Galileo / QZSS / BeiDou via [ambiguity_resolution].systems; GLONASS is float-only). With the COD MGEX OSB, GPS + Galileo is the dependable combination: that product's QZSS phase biases are L1/L5 only (no L2, so the l1+2 pair can't fix QZSS) and it carries no BeiDou phase biases. See docs/guide/configuration.md.

IGS-RTS quick-start guide (#148)¶

Adds docs/guide/quickstart-igs-rts.md and a real-time NTRIP sample conf/igs/rtkrcv_igsrts.toml for the v0.6.8 IGS-RTS float PPP feature.

Files Changed¶

Upgrade notes¶

• Existing configs need no change. Float correction = "igs" (ionosphere = "dual-freq") is unchanged and bit-identical.
• To run integer PPP-AR, use the uncombined model and supply an OSB phase-bias product:
  TOML

  [positioning]
  correction = "igs"
  [positioning.atmosphere]
  ionosphere = "est-stec"      # uncombined — required for AR
  [ambiguity_resolution]
  mode = "continuous"
  [files]
  bias_sinex = "COD0MGXFIN_<yyyyddd>0000_01D_01D_OSB.BIA"   # NOT dcb=
  

  See conf/igs/rnx2rtkp_igspppar.toml. GPS-only often has too few satellites for reliable narrow-lane fixing on short sessions (the wide-lane still fixes); GPS + Galileo is recommended.
• Real-time / live-stream integer PPP-AR (correction = "igs-rts" with CNES SSR phase biases, MT1265-1267) is a tracked follow-up (#151).

Test Results¶

The igs_pppar_gps / igs_pppar_ge groups pass, along with the existing IGS float and MADOCA / CLAS regression tests (bit-identical where guarded). The only failures are the two known pre-existing ones on the maintainer host — rtkrcv_rt (real-time timing) and madocalib_pppar_ion_check (LAPACK vs embedded-LU numerical difference, CLAUDE.md §7.2) — both unrelated to this release.

PRs¶

• #150 — feat(ppp): IGS-product integer PPP-AR via OSB phase biases (#142)
• #148 — IGS-RTS PPP quick-start guide

Closes¶

• #142 — feat(ppp): IGS-product PPP-AR (integer ambiguity resolution with OSB phase biases)