A bench scope separates Vtop/Vbase from Vmax/Vmin because a band-limited
edge overshoots and rings: the mock's `square` at 30 harmonics reaches
±1.179 where its plateau is ±1. On the rippled square the old readings were
a property of the edges rather than of the waveform -- `top` 0.986496,
`amplitude` 1.179350 -- and `amplitude` reported the overshoot.
`top`, `bottom` and `amplitude` are now the flat levels and their delta.
A flat level is a density question -- the plateau holds most of the
samples and the ringing a few percent -- so `measure_scan_buckets()` folds
a 64-bin histogram of the whole buckets' midpoints while it has the list in
hand (one observation per bucket, each bin carrying its buckets' exact sum
and finite count), and `measure_flat_levels()` takes, either side of the
split, the densest bin holding at least half the densest one's buckets --
the outermost of those, which is what makes a waveform with no plateau read
its peak -- and the exact mean of the samples of the buckets within 5 % of
the window's peak-to-peak of it. 5 % is deliberately under the ~9 %-of-swing
Gibbs overshoot. `amplitude` is `top - bottom` (a scope's Vamplitude), not
the half-swing it was.
Measured, fast mock, 2 s window, harmonics 0 -> 30: top 1.000000 ->
0.999983, bottom -1.000000 -> -0.999983, amplitude 2.000000 -> 1.999966,
while `peak to peak` keeps the extremes (2.000000 -> 2.358701). On the 1 Hz
sine top is 0.957988 (it was 0.636620, the half-wave mean; a sine has no
plateau, so the densest band is at its peak) with sd 0.0014 over a scrolling
window, and `peak to peak` is still exactly 2.
No raw pass and no new fetch: the histogram is the same fetched bucket list
read a second time, gated on a pane that holds one of the three types.
`raw` is unchanged (0.1% clean, 2.1% with the --noise 0.1 interferer,
against 0.1%/2.1% before) for 0.44 -> 0.50 ms and 0.52 -> 0.65 ms a pass.
A window the pyramid cannot summarize -- an hf-filtered walk, or one shorter
than a bucket -- keeps the old readings: the mean of each side of the split,
and the window's peak to peak for amplitude.
Docs: the flat-level invariant (and the two 2/pi assertions it replaces),
the probe readings, the manual's measurements page and the README.
`MeasureOptions` gains `noise_pct` (the hysteresis band, % of the window's peak-to-peak,
defaulting to the 10 % the file-scope constant held) and `hf_fc` (a one-pole HF reject over
the measured window). The band's measured rationale moves with the number rather than
becoming an orphan comment, and `measure_set_level()` takes the fraction as an argument
because the band is a per-measurement setting while the call is once per level.
`MeasureFilter` is that reject as a walk carries it: one pole, one state word, `a == 1` a
pass-through so an unfiltered walk pays a multiply and no branch, and a non-finite sample
passing through without touching the state. Both raw walks step it -- and stepping it is why
`measure_accumulate()` now loops samples-outer/levels-inner: a levels-outer loop would step
one filter state once per level per sample, and every level after the first would read a
signal filtered k times over. The inner `continue` is a `continue` of the *level* loop, which
is what it has to be: a sample inside one level's band may be outside another's.
`measure_uses_noise()` names the three types the band reaches (the crossing types -- a band
moves the edge decision and nothing else), and both bucket functions say in their comments
that a bucket aggregates unfiltered samples, so a walk with a reject must not use them.
This leaves `ui_measure.cpp`'s five call sites failing to compile, deliberately: they are the
next task, and pretending otherwise would mean a shim that the task then deletes.
period, frequency and pulse duration counted every sign change about a single
level, which is unusable on any real signal: the mid level is exactly where a
waveform moves fastest, so an interferer faster than the fundamental recrosses
it several times per true crossing. A 5 Hz sine with a 500 Hz tone at a tenth of
the amplitude read 79 crossings for 9, period=0.025622 against 0.2.
MeasureLevel gains a hysteresis band sized once in measure_set_level(): a tenth
of the window's peak-to-peak, clamped to half the room to the nearer extreme so
a threshold set near one stays usable. The band moves the edge decision only --
the sum/count split stays at the bare level, since that split is top/bottom and
has a documented exact reading. The bucket fast path tests the band and the
level separately rather than folding them, or it would refuse exactly the
buckets a crossing passes through: clean cost is unchanged at raw=0.1% and
1.41 ms a recompute.
tools/mock_udpstreamer.py gains --noise, defaulting to 0 so the exact probe
assertions still hold.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The flicker ("no data" at no constant frequency, worse with the measurements
and cursors panes up) was a torn read of the window's first stamp: acquire()
pins the window to the ring's oldest slot, and reading it at paint time races
the producer lapping it, returning a stamp one ring span too new. x0() is the
origin every trace point is reconstructed from, so one torn read produced a
refused neighbours(), a filter that dropped three quarters of the points, and
a polyline shifted off its axis. It is cached by acquire() under the lock now.
EventSeries::neighbours() answered from the (x - x0)/dx grid, whose drift from
the real arrival stamps arrives as a constant offset in seconds -- a doubling
share of the screen per zoom step, which is the "zooming into a held event
clips it more from the left" report. Both series binary-search the stamps now.
The measurements pane went through the LOD pyramid rather than reading its
window raw (19.7 ms per recompute to 1.2 ms, 0.1% of a 2 M-sample window) and
recomputes on a cadence; the math engine lost a per-slot heap allocation, a
per-sample source lookup by name and a fetch_add that cost more than the
arithmetic it counted.
The cursors pane's mix mode drew a line per *named* slot, so a slot holding a
signal that can never produce a channel -- the stream's timestamp -- got a row
that could only read "--", and such names were re-saved every session. It
counts bound traces now and apply_layout() refuses them.
Four toolbar icons are drawn for this app and compiled in as a GResource: the
stock ones were a record dot for the trigger and three magnifiers for cursors,
measurements and math.
New probes and dump lines for all of it (trace ink, measure cost, math cost,
event zoom, toolbar icons); README and CLAUDE.md record what they cure.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Martino Ferrari