ObservedMeasurement.java

  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.estimation.measurements;

  19. import java.util.List;

  21. import org.orekit.propagation.SpacecraftState;
  22. import org.orekit.utils.ParameterDriversProvider;


  25. /** Interface for measurements used for orbit determination.
  26.  * <p>
  27.  * The most important methods of this interface allow to:
  28.  * <ul>
  29.  *   <li>get the observed value,</li>
  30.  *   <li>estimate the theoretical value of a measurement,</li>
  31.  *   <li>compute the corresponding partial derivatives (with respect to state and parameters)</li>
  32.  * </ul>
  33.  *
  34.  * <p>
  35.  * The estimated theoretical values can be modified by registering one or several {@link
  36.  * EstimationModifier EstimationModifier} objects. These objects will manage notions
  37.  * like tropospheric delays, biases, ...
  38.  * </p>
  39.  * @param <T> the type of the measurement
  40.  * @author Luc Maisonobe
  41.  * @since 8.0
  42.  */
  43. public interface ObservedMeasurement<T extends ObservedMeasurement<T>> extends ComparableMeasurement, ParameterDriversProvider {

  45.     /** Enable or disable a measurement.
  46.      * <p>
  47.      * Disabling a measurement allow to not consider it at
  48.      * one stage of the orbit determination (for example when
  49.      * it appears to be an outlier as per current estimated
  50.      * covariance).
  51.      * </p>
  52.      * @param enabled if true the measurement will be enabled,
  53.      * otherwise it will be disabled
  54.      */
  55.     void setEnabled(boolean enabled);

  57.     /** Check if a measurement is enabled.
  58.      * @return true if the measurement is enabled
  59.      */
  60.     boolean isEnabled();

  62.     /** Get the dimension of the measurement.
  63.      * <p>
  64.      * Dimension is the size of the array containing the
  65.      * value. It will be one for a scalar measurement like
  66.      * a range or range-rate, but 6 for a position-velocity
  67.      * measurement.
  68.      * </p>
  69.      * @return dimension of the measurement
  70.      */
  71.     int getDimension();

  73.     /** Get the theoretical standard deviation.
  74.      * <p>
  75.      * The theoretical standard deviation is a theoretical value
  76.      * used for normalizing the residuals. It acts as a weighting
  77.      * factor to mix appropriately measurements with different units
  78.      * and different accuracy. The value has the same dimension as
  79.      * the measurement itself (i.e. when a residual is divided by
  80.      * this value, it becomes dimensionless).
  81.      * </p>
  82.      * @return expected standard deviation
  83.      * @see #getBaseWeight()
  84.      */
  85.     double[] getTheoreticalStandardDeviation();

  87.     /** Get the base weight associated with the measurement
  88.      * <p>
  89.      * The base weight is used on residuals already normalized thanks to
  90.      * {@link #getTheoreticalStandardDeviation()} to increase or
  91.      * decrease relative effect of some measurements with respect to
  92.      * other measurements. It is a dimensionless value, typically between
  93.      * 0 and 1 (but it can really have any non-negative value).
  94.      * </p>
  95.      * @return base weight
  96.      * @see #getTheoreticalStandardDeviation()
  97.      */
  98.     double[] getBaseWeight();

  100.     /** Add a modifier.
  101.      * <p>
  102.      * The modifiers are applied in the order in which they are added in order to
  103.      * {@link #estimate(int, int, SpacecraftState[]) estimate} the measurement.
  104.      * </p>
  105.      * @param modifier modifier to add
  106.      * @see #getModifiers()
  107.      */
  108.     void addModifier(EstimationModifier<T> modifier);

  110.     /** Get the modifiers that apply to a measurement.
  111.      * @return modifiers that apply to a measurement
  112.      * @see #addModifier(EstimationModifier)
  113.      */
  114.     List<EstimationModifier<T>> getModifiers();

  116.     /** Get the satellites related to this measurement.
  117.      * @return satellites related to this measurement
  118.      * @since 9.3
  119.      */
  120.     List<ObservableSatellite> getSatellites();

  122.     /** Estimate the theoretical value of the measurement, without derivatives.
  123.      * <p>
  124.      * The estimated value is the <em>combination</em> of the raw estimated
  125.      * value and all the modifiers that apply to the measurement.
  126.      * </p>
  127.      * @param states orbital states corresponding to {@link #getSatellites()} at measurement date
  128.      * @return estimated measurement
  129.      * @since 12.1
  130.      */
  131.     default EstimatedMeasurementBase<T> estimateWithoutDerivatives(SpacecraftState[] states) {
  132.         return estimateWithoutDerivatives(0, 0, states);
  133.     }

  135.     /** Estimate the theoretical value of the measurement, without derivatives. For use in orbit determination.
  136.      * <p>
  137.      * The estimated value is the <em>combination</em> of the raw estimated
  138.      * value and all the modifiers that apply to the measurement.
  139.      * </p>
  140.      * @param iteration iteration number
  141.      * @param evaluation evaluations number
  142.      * @param states orbital states corresponding to {@link #getSatellites()} at measurement date
  143.      * @return estimated measurement
  144.      * @since 12.0
  145.      */
  146.     EstimatedMeasurementBase<T> estimateWithoutDerivatives(int iteration, int evaluation, SpacecraftState[] states);

  148.     /** Estimate the theoretical value of the measurement, with derivatives.
  149.      * <p>
  150.      * The estimated value is the <em>combination</em> of the raw estimated
  151.      * value and all the modifiers that apply to the measurement.
  152.      * </p>
  153.      * @param iteration iteration number
  154.      * @param evaluation evaluations number
  155.      * @param states orbital states corresponding to {@link #getSatellites()} at measurement date
  156.      * @return estimated measurement
  157.      */
  158.     EstimatedMeasurement<T> estimate(int iteration, int evaluation, SpacecraftState[] states);

  160.     /**
  161.      * Get the type of measurement.
  162.      * <p>
  163.      * Default behavior is to return the class simple name as a String.
  164.      * @return type of measurement
  165.      */
  166.     default String getMeasurementType() {
  167.         return this.getClass().getSimpleName();
  168.     }
  169. }
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