change masking logic to consider constant PRF cases

Author: ehavazli

prep/NISAR_prep.ipynb

@@ -429,7 +429,12 @@
     "    x = f[f\"/science/LSAR/GUNW/grids/frequencyA/unwrappedInterferogram/{pol}/xCoordinates\"][:]\n",
     "    y = f[f\"/science/LSAR/GUNW/grids/frequencyA/unwrappedInterferogram/{pol}/yCoordinates\"][:]\n",
     "    mask_raw = f[f\"/science/LSAR/GUNW/grids/frequencyA/unwrappedInterferogram/mask\"][()]\n",
-    "    mask = np.where(mask_raw != 11, 0, 1)\n",
+    "\n",
+    "    water_mask = (mask_raw // 100) == 1\n",
+    "    ref_subswath = (mask_raw // 10) % 10\n",
+    "    sec_subswath = mask_raw % 10\n",
+    "    is_valid = (ref_subswath > 0) & (sec_subswath > 0)\n",
+    "    mask = (is_valid) & ~water_mask\n",
     "\n",
     "dx = float(x[1] - x[0])\n",
     "dy = float(y[1] - y[0])\n",