1   /* Copyright 2002-2018 CS Systèmes d'Information
2    * Licensed to CS Systèmes d'Information (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.attitude;
18  
19  import org.orekit.attitudes.AttitudeProvider;
20  import org.orekit.time.AbsoluteDate;
21  
22  /**
23   * Attitude providers for navigation satellites.
24   *
25   * <p>
26   * The attitude mode is compliant with IGS conventions for
27   * spacecraft frame, i.e. the +Z axis is towards Earth and
28   * the +X axis is in the Sun direction. This may be different
29   * from some manufacturers conventions, for example for
30   * GPS blocks IIR/IIRM whose X axis convention is opposite.
31   * </p>
32   *
33   * @author Luc Maisonobe
34   * @since 9.2
35   */
36  public interface GNSSAttitudeProvider extends AttitudeProvider {
37  
38      /** Get start of validity for this provider.
39       * @return start of validity for this provider
40       */
41      AbsoluteDate validityStart();
42  
43      /** Get end of validity for this provider.
44       * @return end of validity for this provider
45       */
46      AbsoluteDate validityEnd();
47  
48  }