init

2026-10-21 19:32:02 -04:00
commit b74d278c8e
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+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports["default"] = dopplerFactor;
+var earthRotation = 7.292115E-5;
+var c = 299792.458; // Speed of light in km/s
+/**
+ * Negative range rate means the satellite is moving towards the observer and
+ * its frequency is shifted higher because 1 minus a negative range rate is
+ * positive. If the range rate is positive, the satellite is moving away from
+ * the observer and its frequency is shifted lower.
+ */
+function dopplerFactor(observerCoordsEcf, positionEcf, velocityEcf) {
+  var rangeX = positionEcf.x - observerCoordsEcf.x;
+  var rangeY = positionEcf.y - observerCoordsEcf.y;
+  var rangeZ = positionEcf.z - observerCoordsEcf.z;
+  var length = Math.sqrt(Math.pow(rangeX, 2) + Math.pow(rangeY, 2) + Math.pow(rangeZ, 2));
+  var rangeVel = {
+    x: velocityEcf.x + earthRotation * observerCoordsEcf.y,
+    y: velocityEcf.y - earthRotation * observerCoordsEcf.x,
+    z: velocityEcf.z
+  };
+  var rangeRate = (rangeX * rangeVel.x + rangeY * rangeVel.y + rangeZ * rangeVel.z) / length;
+  return 1 - rangeRate / c;
+}