110 lines
6.2 KiB
Markdown
110 lines
6.2 KiB
Markdown
---
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title: "Project Drogheda — GNSS Findings Summary (Beamer source)"
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created: 2026-06-20
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owner: Leo Rodriguez (Helgen)
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type: findings-summary
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purpose: source material for a later LaTeX Beamer deck
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scope: 20 Jun 2026 bench captures + RTK14_440 healthy baseline + config files
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tags: [drogheda, hbox, gnss, rtk, ntrip, findings, presentation]
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---
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# GNSS Findings Summary — Project Drogheda (20 Jun 2026)
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> Presentation-ready. Each `##` is a candidate slide; bullets are speaker points.
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> Full detail: `2026-06-20_Drogheda_Bench-Log-Analysis_v1.0.md`. Tooling: `log-analysis/`.
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## 1 · What we did
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- Analyzed three independent log views per unit from the 20 Jun bench: u-blox receiver
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(`.ubx`), 4G-NTRIP-Master console (`.log`), and a server-side retranslator capture
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(tcpdump). Decoded the NTRIP-caster and ZED-F9P config files.
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- Built local tooling (in-browser **Log Explorer**, batch analyzer, dark dashboard) and
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established a **healthy GNSS baseline**.
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## 2 · Headline: the GNSS receivers are fine — RTK is not being achieved
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- **Every board produces valid NMEA** — good satellite counts (6–12) and HDOP (≈0.75–1.5).
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The **ZED-F9P is not the failure.**
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- **No unit reached RTK fix.** Every epoch is **SPS (quality 1)**; zero quality 4/5.
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Centimetre positioning was never delivered.
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- **Why:** corrections are not being applied — a combination of (a) corrections sourced
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from a **free public caster (rtk2go.com, no SLA)**, (b) the NTRIP correction client
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rarely reaching "connected," and (c) bench/indoor sky. The F9P config is actually
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**correct** (GGA on UART2 @1 Hz) — but the dump is **RAM-only; flash persistence is
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unverified** (a config lost on power-cycle would silently break the feed).
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## 3 · The healthy baseline (RTK14_440) — what "good" looks like today
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- Proven **end-to-end**: **984 packets, steady 1 Hz, zero dropouts**, valid Querétaro
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position delivered to the server — live in Wialon and the monitor.
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- **12 sats, HDOP 0.75** — excellent geometry. **But SPS, not RTK.**
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- So **"healthy delivery" ≠ "RTK."** The baseline is *healthy SPS + reliable delivery*;
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raise the bar to a fix-≥4 capture once corrections work.
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## Update — 22 Jun 2026: live field capture + two ceilings on RTK
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> A fresh live `udp/5010` server capture (not the 20-Jun bench) caught two units at once.
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- **Telemetry forwarding CONFIRMED.** Enabling `$PUBX` (u-blox *proprietary* `$P…`, the
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same class as our planned `$PHLG`) on the F9P **UART2** → it reaches the server **intact**,
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next to GGA/RMC. The 4G NTRIP Master is a **transparent forwarder**, so **in-band unit
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health (`$PHLG`) to the server is viable** — proven with zero extra hardware.
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- **A natural A/B on RTK** (same capture):
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- **H0014 (Querétaro bench)** — RSSI **−93**, **SPS (quality 1)**. It sits in a **basement**.
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- **H0017 (Veracruz / ICAVE field)** — RSSI **−51**, **DGPS (quality 2, RMC mode `D`,
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base id 0133)** — i.e. it **is** applying corrections.
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- **Two independent ceilings on RTK** (refines §2's "RTK not achieved"):
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1. **Sky / antenna placement** — RTK fix is carrier-phase; a **basement caps it** no matter
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how good the corrections are. (Per Leo: bench antenna placement — not fixable there.)
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2. **Corrections pipeline** — H0017 has good sky + signal yet only reaches **DGPS, not RTK
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(4/5)**, pointing back at the **free rtk2go caster + RAM-only F9P config** as a *separate*
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limit present everywhere.
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- **Cleanest next test:** one **open-sky capture** (roof/outdoors) with a **proper caster +
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FLASH-saved config** — that isolates the two ceilings and shows whether a fix ≥4 is reachable.
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- **Watchdog implication:** a healthy unit can legitimately sit at SPS/DGPS (basement, or field
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on a weak caster) → **never power-cycle on no-RTK alone** (already enforced by the v2.1
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SPS-thrash guard; the v2.2 `$PHLG` will make this visible per-unit).
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## 4 · The diagnostic trap (and a retraction)
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- The **4G-NTRIP-Master console is an unreliable health signal.** The provably-healthy
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baseline logs the **same sparse console** (only cellular `NET` lines, no forwarding
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lines) as units that *looked* failed.
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- **Retraction:** the earlier "master-14 ingest fault" is **withdrawn** — master 14 is the
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baseline and demonstrably forwards. **Only master 21 is a confirmed fault** (modem never
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registers: `0xFFFFF` + 511 AT-parser errors).
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- **Lesson:** per-unit health must come from a component that *parses the fix itself* — the
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Blackpill — logged in a trustworthy form.
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## 5 · Heat is not implicated by these logs
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- Room-temperature bench captures, no thermal channel (v1). The faults reproduce **cold**,
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so heat is **not** the cause of what we see here. The **field** thermal hypothesis stays
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open — needs a thermocouple cabinet soak and/or v2 MCU-temp logging.
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## 6 · Changes made this activity
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- **Blackpill v2.1 logging spec** — replace the self-overwriting ANSI dashboard with a
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**structured, timestamped, parseable** stream (state, fix, packets, battery, MCU temp,
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recovery, **reset cause**). Makes per-unit health unambiguous from the unit's own log.
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- **Log tooling** — `hbox-log-tools` repo on `git.helgen.dev`: in-browser Log Explorer
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(parse + auto-plot + compare to baseline + PNG/SVG export), batch analyzer, dark dashboard.
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- **Corrected analysis + findings doc** (the master-14 retraction above).
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## 7 · Next steps
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1. **Persist the F9P config to FLASH and verify** (RAM-only is a power-cycle risk); check
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the simpleRTK2B Pro `XBEE↔UART2` switch.
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2. **Move corrections off rtk2go** to a dedicated caster (HelgenSRV) with uptime.
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3. **Open-sky RTK retest** with a verified caster → confirm fix ≥4/5.
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4. **Connect the Blackpill** with v2.1 logging → capture a true per-unit health log
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(drops into the Log Explorer as a fifth view).
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5. **Modem triage master 21** (known-good SIM/antenna; swap to confirm).
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6. **Thermal soak test** to settle the field heat hypothesis.
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## One-line takeaway
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> The radios work; we are delivering a **standalone-GPS** position reliably, **not RTK**.
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> The blockers are the **correction source/persistence** and **observability** — both now
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> addressed by config/caster changes and the new Blackpill logging + tooling.
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