diff --git a/changelog.json b/changelog.json
index fa43548..82a5cf4 100644
--- a/changelog.json
+++ b/changelog.json
@@ -10,7 +10,8 @@
       "Fixed OpsLog re-tuning its own rig from its own radio broadcasts, which dropped the CAT link on every JTDX or WSJT-X “Fake It” transmission.",
       "New device: a bench power supply on Modbus RTU (BSIDE, Wanptek and kin) — its output switched from Station Control, with volts, amps and watts.",
       "SPID rotator: a Rot1Prog controller turned nearly a full circle the wrong way for every heading — its commands take three digits, not four.",
-      "The compass now follows a turning antenna smoothly, and a rotator test that only reads the heading says so instead of naming PstRotator."
+      "The compass sweeps with a turning antenna instead of jumping, and the controller is polled once for the whole app rather than by each panel.",
+      "A rotator test that only reads the heading now says so, instead of naming PstRotator for a move it never commanded."
     ],
     "fr": [
       "Clic droit : mettre à jour le comté US des contacts sélectionnés depuis la base ULS, pour remplacer un comté renommé ou supprimé.",
@@ -20,7 +21,8 @@
       "Corrigé : OpsLog réaccordait sa propre radio depuis ses propres diffusions, ce qui coupait le lien CAT à chaque émission JTDX ou WSJT-X en « Fake It ».",
       "Nouvel appareil : alimentation de laboratoire en Modbus RTU (BSIDE, Wanptek et similaires) — sortie commutée depuis Contrôle station, avec V, A et W.",
       "Rotator SPID : un contrôleur Rot1Prog tournait presque un tour complet à l’envers pour chaque azimut — ses commandes tiennent trois chiffres, pas quatre.",
-      "Le compas suit désormais une antenne en rotation sans à-coups, et un test de rotator qui ne fait que lire l’azimut le dit au lieu de citer PstRotator."
+      "Le compas suit l’antenne en rotation au lieu de sauter, et le contrôleur est interrogé une fois pour toute l’application, plus par chaque panneau.",
+      "Un test de rotator qui ne fait que lire l’azimut le dit, au lieu de citer PstRotator pour un mouvement jamais commandé."
     ]
   },
   {
diff --git a/frontend/src/App.tsx b/frontend/src/App.tsx
index 8179595..18144be 100644
--- a/frontend/src/App.tsx
+++ b/frontend/src/App.tsx
@@ -21,7 +21,7 @@ import {
   GetCATState, SetCATFrequency, SetCATMode, SwitchCATRig, EntryBandChanged, FlexApplyBandAntenna, FlexApplyBandPower,
   GetSecretStatus, UnlockSecrets,
   RefreshCtyDat, DownloadAllReferenceLists,
-  RotatorGoTo, RotatorStop, GetRotatorHeading, SetActiveRotor,
+  RotatorGoTo, RotatorStop, SetActiveRotor,
   GetDBConnectionInfo, GetLogbookRevision,
   GetUltrabeamStatus, SetUltrabeamDirection, UILog,
   GetAntGeniusStatus, GetAntGeniusSettings, AntGeniusActivate,
@@ -107,6 +107,7 @@ import { DetailsPanel, type DetailsState } from '@/components/DetailsPanel';
 import { SendSpotModal, type RecentSpotQSO } from '@/components/SendSpotModal';
 import { WinkeyerPanel, type WKStatus, type WKMacro } from '@/components/WinkeyerPanel';
 import { RotorCompass } from '@/components/RotorCompass';
+import { subscribeRotorHeading, pokeRotorHeading } from '@/lib/rotorHeading';
 import { writeUiPref } from '@/lib/uiPref';
 import { formatDateTimeUTC } from '@/lib/dateFormat';
 import { titleCase, sentenceCase } from '@/lib/textCase';
@@ -2390,22 +2391,12 @@ export default function App() {
     };
   }, []);
 
-  // Poll the rotator for the live antenna heading (status bar and compass).
-  // Cheap when it is disabled — the backend just reads settings and returns.
-  //
-  // 700 ms, not three seconds: a turning antenna moved the needle in steps of
-  // about thirteen degrees, which reads as a compass that jumps rather than one
-  // that sweeps. A heading query is a few bytes on a serial controller or one
-  // short exchange over TCP.
-  useEffect(() => {
-    let alive = true;
-    const tick = async () => {
-      try { const h: any = await GetRotatorHeading(); if (alive) setRotatorHeading(h); } catch {}
-    };
-    tick();
-    const id = window.setInterval(tick, 700);
-    return () => { alive = false; window.clearInterval(id); };
-  }, []);
+  // The live antenna heading, from the shared poller in lib/rotorHeading — fast
+  // while the antenna turns, slow while it is parked, and ONE loop however many
+  // panels are watching. This used to be its own interval alongside Station
+  // Control's, so the controller was polled twice over whenever that tab was
+  // open, and every poll opens and closes the port.
+  useEffect(() => subscribeRotorHeading((h) => setRotatorHeading(h as any)), []);
 
   // Poll the Ultrabeam antenna for its connection + pattern direction.
   useEffect(() => {
@@ -5496,7 +5487,7 @@ export default function App() {
                   </button>
                   <button
                     type="button"
-                    onClick={() => RotatorStop().catch((err) => setError(String(err?.message ?? err)))}
+                    onClick={() => { pokeRotorHeading(); RotatorStop().catch((err) => setError(String(err?.message ?? err))); }}
                     title="Stop rotation"
                     className="px-1.5 py-0.5 border-l border-info-border text-danger hover:bg-danger-muted hover:text-danger-muted-foreground cursor-pointer transition-colors"
                   >
@@ -6286,8 +6277,8 @@ export default function App() {
                 rotorEnabled={rotatorHeading.enabled && rotatorHeading.ok}
                 rotors={(rotatorHeading as any).rotors}
                 activeRotor={(rotatorHeading as any).active}
-                onSelectRotor={(i) => { SetActiveRotor(i).then(() => GetRotatorHeading()).then((h: any) => setRotatorHeading(h)).catch((err) => setError(String(err?.message ?? err))); }}
-                onGoto={(az) => RotatorGoTo(Math.round(az), -1).catch((err) => setError(String(err?.message ?? err)))}
+                onSelectRotor={(i) => { SetActiveRotor(i).then(pokeRotorHeading).catch((err) => setError(String(err?.message ?? err))); }}
+                onGoto={(az) => { RotatorGoTo(Math.round(az), -1).then(pokeRotorHeading).catch((err) => setError(String(err?.message ?? err))); }}
                 onClose={() => { setShowRotor(false); writeUiPref('opslog.showRotor', '0'); }}
               />
             </div>
diff --git a/frontend/src/components/StationControlPanel.tsx b/frontend/src/components/StationControlPanel.tsx
index 062c4c8..19c32e9 100644
--- a/frontend/src/components/StationControlPanel.tsx
+++ b/frontend/src/components/StationControlPanel.tsx
@@ -7,13 +7,14 @@ import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from '@
 import { cn } from '@/lib/utils';
 import { useI18n } from '@/lib/i18n';
 import { writeUiPref } from '@/lib/uiPref';
+import { subscribeRotorHeading, pokeRotorHeading } from '@/lib/rotorHeading';
 import { RotorCompass } from '@/components/RotorCompass';
 import { AmpCard } from '@/components/AmpCard';
 import { TunerCard } from '@/components/TunerCard';
 import type { TGStatus } from '@/components/TunerGeniusPanel';
 import {
   GetStationDevices, SaveStationDevices, GetStationStatus, StationSetRelay,
-  GetRotatorHeading, RotatorGoTo, RotatorStop, SetActiveRotor,
+  RotatorGoTo, RotatorStop, SetActiveRotor,
   GetUltrabeamStatus, SetUltrabeamDirection, UltrabeamRetract, MotorSetElement, MotorReadElements,
   MotorTuneKHz, MotorNudgeKHz, SetMotorFollow,
   ListDenkoviDevices, ListSerialPorts, TestStationDevice,
@@ -547,27 +548,21 @@ export function StationControlPanel({ centerLat, centerLon, bearing }: RotatorPr
       setStatus(Object.fromEntries(s.map((d) => [d.id, d])));
     } catch { /* ignore transient */ }
   }, []);
-  const pollRot = useCallback(async () => {
-    try { setRot((await GetRotatorHeading()) as any); } catch { /* ignore */ }
-  }, []);
   const pollAnt = useCallback(async () => {
     try { setAnt((await GetUltrabeamStatus()) as any); } catch { /* ignore */ }
   }, []);
 
   useEffect(() => { loadDevices(); }, [loadDevices]);
+  // The heading comes from the shared poller: one loop for the whole app, fast
+  // while the antenna turns and slow while it is parked. Every poll opens and
+  // closes the controller's port, and this panel used to run its own alongside
+  // the status bar's — the same controller asked twice over.
+  useEffect(() => subscribeRotorHeading((h) => setRot(h as any)), []);
   useEffect(() => {
-    poll(); pollRot(); pollAnt();
+    poll(); pollAnt();
     const id = window.setInterval(() => { poll(); pollAnt(); }, 3000);
-    // The rotor gets its own, faster tick. On three seconds the compass moved in
-    // steps of about thirteen degrees while the antenna was turning, which reads
-    // as a needle that jumps rather than one that sweeps — and an operator
-    // watching a tower wants to see it move. One heading query is a few bytes on
-    // a slow serial line or one short TCP exchange; the relay boards and the
-    // antenna controller are the expensive polls, and they stay at three
-    // seconds.
-    const rotId = window.setInterval(() => { pollRot(); }, 700);
-    return () => { window.clearInterval(id); window.clearInterval(rotId); };
-  }, [poll, pollRot, pollAnt, devices.length]);
+    return () => window.clearInterval(id);
+  }, [poll, pollAnt, devices.length]);
 
   const persistOrder = (next: string[]) => { setOrder(next); writeUiPref('opslog.stationOrder', JSON.stringify(next)); };
   // Reorder so `dragged` lands just before `target`.
@@ -673,7 +668,7 @@ export function StationControlPanel({ centerLat, centerLon, bearing }: RotatorPr
   // full-width, and they need that room here too.
   const widgets: { id: string; node: React.ReactNode; wide?: boolean }[] = [];
   if (rot.enabled) {
-    widgets.push({ id: 'rotator', node: <RotatorWidget hd={rot} refetch={pollRot} centerLat={centerLat} centerLon={centerLon} bearing={bearing} t={t} /> });
+    widgets.push({ id: 'rotator', node: <RotatorWidget hd={rot} refetch={pokeRotorHeading} centerLat={centerLat} centerLon={centerLon} bearing={bearing} t={t} /> });
   }
   if (ant.enabled) {
     widgets.push({ id: 'antenna', node: <MotorAntennaWidget ant={ant} refetch={pollAnt} t={t} /> });
diff --git a/frontend/src/lib/rotorHeading.ts b/frontend/src/lib/rotorHeading.ts
new file mode 100644
index 0000000..2f2aac1
--- /dev/null
+++ b/frontend/src/lib/rotorHeading.ts
@@ -0,0 +1,87 @@
+import { GetRotatorHeading } from '../../wailsjs/go/main/App';
+
+// One poll loop for the antenna heading, shared by everything that shows it.
+//
+// TWO PROBLEMS THIS FIXES, both of them invisible until you count.
+//
+// The status bar polled, and the Station Control compass polled, and they polled
+// the SAME binding — so with that tab open the rotator was asked twice as often
+// as either component believed. Every backend builds a fresh client per call
+// (spid.New, gs232.NewSerial, dcu1.NewSerial, rotgenius.New…), so one poll is
+// one OPEN and CLOSE of a serial port or a TCP connection, not a read on a link
+// already up.
+//
+// And a fixed interval has no good value. Three seconds moved the needle in
+// steps of about thirteen degrees on a turning antenna — a compass that jumps
+// rather than sweeps. Seven hundred milliseconds sweeps beautifully and opens
+// the controller's port about ten thousand times an hour to watch an antenna
+// that has not moved since breakfast.
+//
+// So: fast while it is turning, slow while it is not. "Turning" is not something
+// these controllers report — a SPID answers a position and nothing else — so it
+// is inferred from the position changing, and held for a few seconds after the
+// last change so the tail of a movement stays smooth.
+
+export type RotorHeading = {
+  enabled: boolean; ok: boolean; azimuth: number;
+  rotors?: string[]; active?: number; motorized?: boolean; raw?: string;
+};
+
+const MOVING_MS = 500;   // while the antenna is turning
+const IDLE_MS = 3000;    // while it is parked — the rate everything used before
+const SETTLE_MS = 6000;  // stay fast this long after the last movement
+
+const subs = new Set<(h: RotorHeading) => void>();
+let timer: number | undefined;
+let inFlight = false;
+let lastAz: number | null = null;
+let lastMoveAt = 0;
+
+function schedule(delay: number) {
+  if (timer !== undefined) window.clearTimeout(timer);
+  timer = window.setTimeout(tick, delay);
+}
+
+async function tick() {
+  // A slow controller must not stack requests behind itself: at 600 baud a SPID
+  // reply takes a fifth of a second on the wire alone, and a port that is still
+  // open from the last poll cannot be opened again.
+  if (inFlight) { schedule(MOVING_MS); return; }
+  inFlight = true;
+  try {
+    const h = (await GetRotatorHeading()) as unknown as RotorHeading;
+    if (h?.ok && typeof h.azimuth === 'number') {
+      if (lastAz !== null && h.azimuth !== lastAz) lastMoveAt = Date.now();
+      lastAz = h.azimuth;
+    }
+    subs.forEach((fn) => { try { fn(h); } catch { /* a subscriber must not stop the loop */ } });
+  } catch {
+    // Leave the last heading alone: a single failed poll on a shared serial port
+    // is not news, and blanking the compass on one would make it flicker.
+  } finally {
+    inFlight = false;
+  }
+  if (subs.size > 0) schedule(Date.now() - lastMoveAt < SETTLE_MS ? MOVING_MS : IDLE_MS);
+  else timer = undefined;
+}
+
+// subscribeRotorHeading starts the loop if it is not running and returns the
+// unsubscribe. The loop stops when the last subscriber leaves.
+export function subscribeRotorHeading(fn: (h: RotorHeading) => void): () => void {
+  subs.add(fn);
+  if (timer === undefined && !inFlight) void tick();
+  return () => {
+    subs.delete(fn);
+    if (subs.size === 0 && timer !== undefined) { window.clearTimeout(timer); timer = undefined; }
+  };
+}
+
+// pokeRotorHeading polls at once and switches to the fast rate — call it after
+// commanding a move, so the needle starts sweeping on the click rather than on
+// whatever was left of a three-second tick.
+export function pokeRotorHeading(): void {
+  lastMoveAt = Date.now();
+  if (timer !== undefined) window.clearTimeout(timer);
+  timer = undefined;
+  void tick();
+}