1   /* Copyright 2002-2025 CS GROUP
2    * Licensed to CS GROUP (CS) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * CS licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *   http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.orekit.gnss.antenna;
18  
19  /**
20   * Model for antennas phase center variations.
21   * @author Luc Maisonobe
22   * @since 9.2
23   */
24  public interface PhaseCenterVariationFunction {
25  
26      /**
27       * Evaluate phase center variation in one signal direction.
28       * @param polarAngle angle from antenna axial direction
29       * (zenith angle for receiver antennas, nadir angle for
30       * GNSS satellites antennas)
31       * @param azimuthAngle angle around axial direction, counted from +X to +Y
32       * (note that this convention is consistent with
33       * {@link org.hipparchus.geometry.euclidean.threed.Vector3D#getAlpha()
34       * Vector3D.getAlpha()}, but it is <em>different</em> from
35       * {@link org.orekit.utils.TrackingCoordinates#getAzimuth() TrackingCoordinates.getAzimuth()},
36       * so care must be taken when using this for ground receivers)
37       * @return phase center variation in the signal direction (m)
38       */
39      double value(double polarAngle, double azimuthAngle);
40  
41  }