1   /* Copyright 2002-2021 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.estimation.measurements.generation;
18  
19  import java.util.List;
20  import java.util.SortedSet;
21  import java.util.TreeSet;
22  
23  import org.orekit.estimation.measurements.ObservedMeasurement;
24  import org.orekit.propagation.SpacecraftState;
25  import org.orekit.propagation.sampling.OrekitStepInterpolator;
26  import org.orekit.time.AbsoluteDate;
27  import org.orekit.time.DatesSelector;
28  
29  
30  /** {@link Scheduler} generating measurements sequences continuously.
31   * <p>
32   * Continuous schedulers continuously generate measurements following a repetitive pattern.
33   * The repetitive pattern can be either a continuous stream of measurements separated by
34   * a constant step (for example one measurement every 60s), or several sequences of measurements
35   * at high rate up to a maximum number, with a rest period between sequences (for example
36   * sequences of up to 256 measurements every 100ms with 300s between each sequence).
37   * </p>
38   * @param <T> the type of the measurement
39   * @author Luc Maisonobe
40   * @since 9.3
41   */
42  public class ContinuousScheduler<T extends ObservedMeasurement<T>> extends AbstractScheduler<T> {
43  
44      /** Simple constructor.
45       * <p>
46       * BEWARE! Dates selectors often store internally the last selected dates, so they are not
47       * reusable across several {@link EventBasedScheduler instances}. A separate selector
48       * should be used for each scheduler.
49       * </p>
50       * @param builder builder for individual measurements
51       * @param selector selector for dates (beware that selectors are generally not
52       * reusable across several {@link EventBasedScheduler instances}, each selector should
53       * be dedicated to one scheduler
54       */
55      public ContinuousScheduler(final MeasurementBuilder<T> builder, final DatesSelector selector) {
56          super(builder, selector);
57      }
58  
59      /** {@inheritDoc} */
60      @Override
61      public SortedSet<T> generate(final List<OrekitStepInterpolator> interpolators) {
62  
63          // select dates in the current step, using arbitrarily interpolator 0
64          // as all interpolators cover the same range
65          final List<AbsoluteDate> dates = getSelector().selectDates(interpolators.get(0).getPreviousState().getDate(),
66                                                                     interpolators.get(0).getCurrentState().getDate());
67  
68          // generate measurements when feasible
69          final SortedSet<T> measurements = new TreeSet<>();
70          for (final AbsoluteDate date : dates) {
71  
72              // interpolate states at measurement date
73              final SpacecraftState[] states = new SpacecraftState[interpolators.size()];
74              for (int i = 0; i < states.length; ++i) {
75                  states[i] = interpolators.get(i).getInterpolatedState(date);
76              }
77  
78              // generate measurement
79              measurements.add(getBuilder().build(states));
80  
81          }
82  
83          return measurements;
84  
85      }
86  
87  }