Read the Morse a station sends over its own carrier

A base station identifying itself in CW does not key its carrier. The
carrier stays up and the ident is an audio tone keyed inside it, which
a detector looking for a keyed carrier sees as a carrier that never
stops. On the land-mobile bands that is nearly all the Morse there is,
and none of it was being read: an ident of KSQ330 sat in the middle of
a 27-second capture on 154.369 MHz, cleanly keyed at 22 WPM, and the
capture was filed as voice with no Morse in it at all.

Three things were in the way, and each was found by measuring rather
than by reading.

The whole-recording decode ran only for captures recorded in cw mode.
An ident over FM is recorded in nfm, so it was never looked for. It
now runs for every capture.

The tone was sought in the first four seconds of the audio and nowhere
else, so a tone that had not started yet could not be found -- on the
capture above it locked onto the harmonic of something else. It is now
averaged over the whole clip.

And the steady tone either side of the ident was read as a character
the window had sliced, which dropped the first and last letter and,
through complete_text, the whole callsign: one word with no gap in it
to survive the drop. A mark far longer than any dash is not a
truncated element, it is the transmission the ident was sent over.

Even fixed, the decoder measures its tone and its key-down threshold
over the whole of whatever it is handed, so a half-minute recording
with five seconds of keying in the middle measures both from the other
twenty-five. So the audio is searched a few seconds at a time, plus
the whole capture -- that one matters for a beacon keying throughout,
where the longest window is the best one and leaving it out lost an
ident the decoder had always read.

Nothing was loosened. Every window is judged by is_morse exactly as a
whole capture is. Across 677 real captures the search claimed Morse in
four: KSQ330 and WNRS309, both FCC land-mobile callsigns and neither
seen before; a 20 WPM burst on 70 cm reading as E7HNN, plausible and
unverified; and noise on 445.5 MHz reading as "T T T E E E E E E E E".
That last one is the new rule -- E and T are the one-element
characters, so a decode of nothing but those can hardly be wrong,
because there is nothing in it to get wrong. With it the count is
three.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016PsWPTweCT6pwxKngvVxcg

README.md

@@ -1460,6 +1460,35 @@ and on the same map: **spoken and transcribed, sent in Morse, or carried in
 the header of an APRS packet.** Neither of the last two involves a speech
 recogniser, so a machine with none installed still builds a map.
 
+**Morse over a carrier.** A base station identifying itself in CW does not
+key its carrier: the carrier stays up and the ident is an audio tone keyed
+inside it. A CW detector looking for a keyed carrier sees a carrier that
+never stops, so none of it was being read — and on the land-mobile bands
+that is nearly all of it. An ident of `KSQ330` sat in the middle of a
+27-second capture on 154.369 MHz, cleanly keyed at 22 WPM, and the capture
+was filed as voice with no Morse in it at all.
+
+Two things were in the way. The decoder picks its tone and its key-down
+threshold from the whole clip it is handed, so a half-minute recording with
+five seconds of keying in the middle measures both from the other
+twenty-five; and it treated the steady tone either side of the ident as a
+character sliced by the window, dropping the first and last letter — and
+with them, since a callsign is one word with no gap in it, the whole thing.
+
+So the recorded audio of **every** capture is now searched, a few seconds at
+a time, and a mark far longer than any dash is read as what it is rather
+than as a truncated element. Nothing was loosened to make that work: each
+window is judged by the same test a whole capture is.
+
+Across 677 real captures it claimed Morse in four. Two were idents —
+`KSQ330` and `WNRS309`, each an FCC land-mobile callsign, neither of which
+the scanner had ever seen. One was a 20 WPM burst on 70 cm that reads as
+`E7HNN`, which is plausible and unverified. The fourth was noise on
+445.5 MHz reading as `T T T E E E E E E E E`, and that one taught the last
+rule: E and T are the one-element characters, so a decode made only of them
+can hardly be wrong — there is nothing in it to get wrong — and no station
+has ever identified itself that way. With that rule the count is three.
+
 Where the gaps came from decides whether they can be closed. A transcript's
 spacing is the recogniser's guess, so `KU 0W` may be joined; a word gap in
 Morse is seven dot units the sender chose, so `KU0W K` is a station signing