joshruby/nightjar-flight-20260804-2

nightjar flight — 2026-08-04, second sortie

The same rig and site as nightjar-flight-20260804, flown ~80 minutes later, but a deliberately different profile and the first flight of a control-loop change. GPS truth is again excellent: 7,817 valid UTC stamps out of 7,818.

Envelope — read this before comparing to the first sortie

	this flight	first sortie
airborne	784 s (13.1 min)	1252 s (20.9 min)
max height	16 m	276 m
max slant range	374 m	473 m
path flown	2304 m	3021 m
window (UTC)	18:10:15 – 18:23:20	16:46:25 – 17:07:17

⚠ This is a LOW flight. 16 m of altitude at 374 m of range is an elevation angle of about 2.4° — the drone is essentially on the treeline, not against clean sky. That matters in three independent ways, and it makes a naive flight-to-flight comparison invalid:

• the background is foliage and horizon clutter, not uniform sky, so the detection problem is categorically harder than the first sortie's high-altitude passes;
• a horizontal microphone array's elevation sensitivity goes as sin(el), so at ~2° the array is at the null of its elevation response — near-zero information on that axis;
• conversely azimuth sensitivity goes as cos(el) and is near its maximum here.

Any per-flight difference in track time or detection rate between the two sorties is therefore confounded by profile, not attributable to the code change below.

What changed in the loop between the two sorties

This flight carries a fix to the cued zoom climb. The cue's containment focal was being computed on every acoustic cue (~7.1 mm, from FOV ≥ 2·k·σ at the tilt-ladder spacing), stored, and never commanded — the cued-search path had a goto that deliberately ignores zoom plus a branch that only ever widens, so the climb half did not exist. The first sortie sat at a median 4.31 mm — full wide — across the 69% of its time spent searching.

Measured effect here:

	first sortie	this flight
SEARCH median zoom	1.00×	2.53×
time above 2×	4.4%	61.6%

And this flight exposed the follow-on bug, which is why the data is worth keeping: the climb drove at full lens speed into a 1 mm deadband and overshot badly — SEARCH focal ran median 10.88 / p75 11.8 / max 20.03 mm against a 7.07 mm ceiling. Above the containment ceiling the field of view no longer holds k·σ, and ~12 mm re-opens a ~10° vertical blind stripe between 24° ladder rungs. The fix (proportional to the remaining gap) post-dates this recording, so this session shows the overshoot in the wild.

Also live for the first time: a state-dependent acoustic presence gate (strict while tracking, relaxed while searching). Within minutes it posted cues at 13 dB that the previous fixed 14.6 dB threshold would have discarded. audio/cue_log.jsonl stamps thr_db and nj_state on every candidate so each cue can be attributed to the threshold in force.

Contents

audio/uma16_<epoch>.wav    UMA-16, 16 ch, 48 kHz, S16_LE, 5-min splits
audio/sb_<epoch>.wav       SB-POLARIS, 8 ch, 48 kHz, S32_LE, 5-min splits
audio/cue_log.jsonl        cue gate log, now carrying thr_db + nj_state per candidate
video_segments.tar         1080p native + 768x432 substream, H.264 -c copy, 60 s MPEG-TS
blackbox/state.jsonl       tracker FSM ~2.9 Hz: state, pose, focal, error, detection, track
blackbox/frames.tar        2,324 substream stills, named f<epoch_ms>.jpg
dji/*.csv, *.txt           decoded + original DJI FlightRecord (CUSTOM.dateTime = true UTC)

Channel identity is not guessable. UMA-16 0-based channel 9 is a dead electronic-floor channel — exclude it and run on 15. SB-POLARIS has 3 live capsules of 8; this session they are [0, 3, 5] (live ~−70 dBFS, dead ~−190). Detect them by RMS rather than hardcoding.

⚠ The two arrays use different sample widths — UMA S16_LE, SB S32_LE. Reading both as int16 splits every SB sample in half, scrambles channel identity and destroys the spectrum.

Calibration as flown

az_offset_deg 300.87, invert_az true, re-solved the morning of this flight from the JBL beacon (spread 0.10°, 41 dB). SB-POLARIS → camera was also solved for the first time that morning — az_offset_deg 102.6, invert_az false, rotation only — but nothing consumed SB bearings during this flight; the cue chain is UMA-only. Cue producer was the cheap daemon (SUBHUNT=0). Site notch 100–200 Hz. Start pose pan 45 / tilt 45.

Caveat on GPS-referenced pixel work

Attempts to place the drone in the image from GPS reach a floor of about 5° of bearing error on this data. The cause is the DJI GPS itself: ±2–5 m of position at the 20–45 m ranges where the optical correspondences live is 4–9° of bearing. Fitting a pose-vs-GPS time offset does not help (best dt ≈ +0.05 s). A static-mount fit is impossible — of 2,281 blackbox frames, 123 carry a YOLO box and 686 have a still mount, and zero have both, because the mount servos whenever it is tracking. Treat any in-frame or pixel-level claim derived from GPS here as approximate.