Two faults reported from in front of the window, both of them the map saying
something confidently and wrongly.
Tiles that did not arrive. Resizing the window does not refetch the map: the
window deliberately fetches more world than it shows, so a resize still fits
inside what is in hand and gets stretched to the new size. It refetches when
the view leaves that box, which is what a new station does -- and that fetch
asks a volunteer-funded server for a hundred tiles that have never been on
this disk, all at once, at the sharper zoom the bigger window chose. Some of
them are refused.
What the window did with a refusal was draw it. A tile that never arrived
leaves its square of the canvas black, and black is not a neutral colour
here: the brightness is inverted on the way in, because a printed map is ink
on paper and this picture is the other way round. So the darkest possible
square came out as the brightest thing on the picture, a glowing rectangle
where the map should be. Measured on a reproduction, one missing tile in
eighteen put thirteen thousand pixels at full brightness -- and dragged the
floor of the map's own contrast down to black with it, so thirteen thousand
four hundred and ninety pixels changed in all: the whole map was redrawn
dimmer to make room for a square that was not there. Then it was kept, cached
under the view it was fetched for, until the view moved again.
So the missing squares are asked for again at once, and only those, the rest
being on the disk by then; what is still missing is drawn as bare ground and
left out of the reckoning when the darkest and brightest of the map are worked
out, which puts the same reproduction at two pixels changed rather than
thirteen thousand four hundred and ninety, a hairline where a cell is averaged
over part of a tile and part of nothing; and the map is kept as provisional
rather than as the last word, asked for again half a minute later, four
attempts in all, each retrying its own misses once.
Found while measuring that: the politeness pause between requests was being
paid on every tile, including the ones read straight back off the disk. Two
hundred and twenty tiles at an eighth of a second is twenty-six seconds of
sleeping to redraw a view that was entirely cached, and it would have made
asking again for three missing squares cost the wait for the two hundred that
were not. The constant's own comment already said it should only be paid on a
tile that was not already there. Now it is.
The APRS map's units. Setting imperial changed nothing at all about the
window: the unit it measures in was hardcoded to kilometres, and that one
value drives the ring labels and the scale along the bottom; and --radius was
always read as kilometres, so the rings were not merely mislabelled, they were
at the wrong distance from the flag. A ring is what a distance gets judged
against by eye, and one labelled in a unit it was not drawn in is a wrong
answer given confidently. The aircraft side has done this properly all along
-- a radius read in whatever unit the speeds are in, and no unit suffix on the
setting because the suffix belongs to the other setting -- so this now mirrors
it exactly. At --radius 100 in imperial the outermost ring stands seventy-
five statute miles from the flag and says so, where it used to stand seventy-
five kilometres and say kilometres whatever you had asked for.
Twenty-one new tests against sixteen deliberately broken builds. One
survived, and removing what it broke was the right answer rather than
strengthening a test: a check that the remembered request still matched the
map in hand could not be made to fail, a request for a different view being
taken up only after the slot it guards is already full. The tests do not
trust the drawing to mark its own homework -- the one that matters walks north
from the flag by each ring's radius and measures the great-circle distance
with a haversine written in the test, then checks that against the printed
label. Full suite 2685 passed. Built as 2026-09-21_03.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016PsWPTweCT6pwxKngvVxcg
Three things asked for, and a fourth found while doing them.
The map looked like a photograph of a map, and did so twice over. The
window fetched at its own pixel size but for a box a third larger in each
direction -- the margin added to stop the ground blinking -- and then cut
the middle out, so every pixel was enlarged by two thirds. It now asks
for enough pixels to cover the bigger box at the window's own detail.
Underneath that, both the window and the animation took the nearest source
pixel: the tile mosaic is commonly half again the size of the picture, so
most of every tile was thrown away and what survived was the aliasing.
Both now average the source pixels that fall in each output cell, done as
the difference of a running total rather than a loop.
An aircraft that goes quiet now fades instead of vanishing. Taking it off
between one frame and the next says it stopped existing; fading says it
stopped talking, which is what happened. It fades where it was last
actually seen and never along a reckoned track, because the reason for
giving up on it is that where it would be by now is a guess. --fade sets
how long, and it is in the menu. The window has alpha and fades smoothly;
an indexed picture cannot blend, so the animation gained a fourth ramp at
a seventh of full and fades in four steps, which at a second apart reads
as a fade. A trail fades with the aircraft it belongs to, and the box
goes before the symbol does.
The aircraft's country of registration carries a flag now as well as the
two ends of its route, from the register where one answered and from the
address block otherwise.
And the fourth: the window's header counted an aircraft that had gone
quiet as overhead, which was saying more than had been heard.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016PsWPTweCT6pwxKngvVxcg
Four things the ADS-B mode was missing, and one it was actively getting
wrong.
The band plan lists 1090 MHz because that is where ADS-B is, so choosing
it from the band plan is the obvious thing to do -- and it records the
bursts as clicks in a WAV file and decodes nothing, silently. Both the
scanner and the menus now say so, before the sweep starts, and name the
mode that does decode it. It is not refused: looking at the raw spectrum
is a fair thing to want.
Menu 5, Aircraft (ADS-B), is the whole mode without a command line. Every
option on one screen with a line saying what it does, ?N for the long
version and the flag it corresponds to, l to listen, m to draw a map from
any log, s to keep the options. The listening and the drawing moved into
bandsaunter/aircraft.py so the menus and the command line run the same
code.
While it listens the screen is a live board: one line per aircraft in the
order first heard, the counter climbing as frames arrive, height coloured
low warm to high cold with an arrow for climb or descent, the age of the
last report going green to red, and the line removed once nothing has been
heard for --hold seconds, everything below moving up. The registers are
asked while it runs, so registration, type, operator and route fill
themselves in as the answers arrive.
--speed-unit knots|mph|kph changes the heading of that board, the speed
beside every aircraft on the map and the speeds in the report, and moves
the distances with it so that one picture never carries two different
miles. The log stays in knots, which is what the aircraft broadcast.
And there is a real map under the flight paths: {z}/{x}/{y} tiles fetched
once, cached in ~/.cache/bandsaunter/tiles, reprojected from Web Mercator
pixel by pixel, inverted and dimmed so the aircraft stay the brightest
thing on the picture. The PNGs are decoded here -- zlib and the five row
filters from the specification, checked byte for byte against Pillow on
real tiles -- so nothing new is depended on. Tiles are cached and never
re-fetched, every request says who is asking, and the attribution is drawn
onto the picture, because a GIF travels without its readme.
conftest now fails any test that reaches for a tile server or a register.
It caught four of these on the way in.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016PsWPTweCT6pwxKngvVxcg
The Dust Council