feat(sat): Doppler tracking on the radio

The hard part of satellite tuning is not the arithmetic, it is deciding
who owns the dial. A tracker that forces both frequencies fights the
operator every time they turn the knob to follow a station across a
linear transponder; one that never touches the receiver leaves them
chasing a signal that slides nine kilohertz across a 70 cm pass.

So the operator owns the receiver and the tracker follows them. Every
second it asks the radio where the receiver actually is. Where it put it,
nothing has changed. Further than a dial-turn's tolerance, and the
operator has chosen a station: what they landed on is converted back into
a nominal frequency, and the transmitter is derived from that. Which is
the division of labour on a linear bird — the operator listens, the radio
does the sums.

Three ways to reach the radio, because a satellite pair is a shape of
operating rather than a manufacturer's feature. An IC-9700 or IC-9100 is
asked for its OWN satellite mode: it pairs main and sub, gives full
duplex, and keeps the dials linked the way its designers meant, which is
always better than an imitation built out of split. A Flex gets two
slices, A the downlink and B the uplink, created when missing, because
"slice B does not exist" is not something to make an operator fix at the
start of a ten-minute pass. Everything else gets the downlink, and is
told so — half the job announced beats half the job hidden.

What goes in the log is the NOMINAL pair. Two stations working each other
through a transponder read different numbers off their dials at the same
instant; the only figure they can both agree on is the transponder's own.
FREQ is the uplink and FREQ_RX the downlink — the one place a satellite
QSO differs from every other kind, and the reason FREQ alone cannot
describe one.

changelog.json

@@ -3,10 +3,12 @@
     "version": "0.27.17",
     "date": "",
     "en": [
-      "[NEW] Satellites. A new tab (Tools → Satellites) tracks the amateur birds: a map with each satellite's footprint and the selected one's path over the ground, the next passes with their maximum elevation, and — for the satellite you are on — the azimuth, the elevation and the Doppler-corrected downlink and uplink. Orbital elements come from Celestrak (with a mirror behind it) and are kept on disk, so the tab is full the moment it opens even with no internet; elements for a bird no feed carries yet can be pasted in and survive every refresh. The shipped frequency list covers the FM and linear satellites and QO-100, and lives in a file you can correct yourself when a transponder is switched."
+      "[NEW] Satellites. A new tab (Tools → Satellites) tracks the amateur birds: a map with each satellite's footprint and the selected one's path over the ground, the next passes with their maximum elevation, and — for the satellite you are on — the azimuth, the elevation and the Doppler-corrected downlink and uplink. Orbital elements come from Celestrak (with a mirror behind it) and are kept on disk, so the tab is full the moment it opens even with no internet; elements for a bird no feed carries yet can be pasted in and survive every refresh. The shipped frequency list covers the FM and linear satellites and QO-100, and lives in a file you can correct yourself when a transponder is switched.",
+      "Doppler tracking drives the radio. Track puts the rig on the satellite and keeps it there, once a second: an IC-9700 or IC-9100 in its own satellite mode, a FlexRadio on two slices (A the downlink, B the uplink, created if they are missing, full duplex on) — and any other radio on the downlink, which it says plainly rather than half-doing the job. Tune the receiver where you like: the tracker reads the dial, takes it as the station you have chosen, and moves the transmitter to match. QSOs made while tracking are logged with the NOMINAL frequencies, SAT_NAME, SAT_MODE and PROP_MODE=SAT — the transponder's own numbers, which both stations can agree on, rather than where one radio happened to be."
     ],
     "fr": [
-      "[NOUVEAU] Satellites. Un nouvel onglet (Outils → Satellites) suit les satellites amateurs : une carte avec l'empreinte de chacun et la trace au sol de celui qui est sélectionné, les prochains passages avec leur élévation maximale, et — pour le satellite en cours — l'azimut, l'élévation et les fréquences de descente et de montée corrigées de l'effet Doppler. Les éléments orbitaux viennent de Celestrak (avec un miroir derrière) et sont conservés sur disque : l'onglet est rempli dès son ouverture, même sans internet. Les éléments d'un satellite qu'aucun flux ne diffuse encore peuvent être collés à la main et survivent à chaque mise à jour. La liste de fréquences fournie couvre les satellites FM et linéaires ainsi que QO-100, dans un fichier que vous pouvez corriger vous-même quand un transpondeur change de mode."
+      "[NOUVEAU] Satellites. Un nouvel onglet (Outils → Satellites) suit les satellites amateurs : une carte avec l'empreinte de chacun et la trace au sol de celui qui est sélectionné, les prochains passages avec leur élévation maximale, et — pour le satellite en cours — l'azimut, l'élévation et les fréquences de descente et de montée corrigées de l'effet Doppler. Les éléments orbitaux viennent de Celestrak (avec un miroir derrière) et sont conservés sur disque : l'onglet est rempli dès son ouverture, même sans internet. Les éléments d'un satellite qu'aucun flux ne diffuse encore peuvent être collés à la main et survivent à chaque mise à jour. La liste de fréquences fournie couvre les satellites FM et linéaires ainsi que QO-100, dans un fichier que vous pouvez corriger vous-même quand un transpondeur change de mode.",
+      "Le suivi Doppler pilote la radio. « Suivre » met le poste sur le satellite et l'y maintient, chaque seconde : un IC-9700 ou IC-9100 dans son propre mode satellite, un FlexRadio sur deux slices (A la descente, B la montée, créées si elles manquent, full duplex activé) — et n'importe quelle autre radio sur la descente seule, ce qu'elle annonce clairement plutôt que de faire le travail à moitié. Accordez le récepteur où vous voulez : le suivi lit le VFO, y voit la station que vous avez choisie, et déplace l'émetteur en conséquence. Les QSO faits pendant le suivi sont enregistrés avec les fréquences NOMINALES, SAT_NAME, SAT_MODE et PROP_MODE=SAT — les chiffres du transpondeur, sur lesquels les deux stations peuvent s'accorder, plutôt que l'endroit où une radio se trouvait."
     ]
   },
   {