ObservableSatellite.java
/* Copyright 2002-2022 CS GROUP
* Licensed to CS GROUP (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.orekit.estimation.measurements;
import org.hipparchus.util.FastMath;
import org.orekit.utils.ParameterDriver;
/** Class modeling a satellite that can be observed.
*
* @author Luc Maisonobe
* @since 9.3
*/
public class ObservableSatellite {
/** Prefix for clock offset parameter driver, the propagator index will be appended to it. */
public static final String CLOCK_OFFSET_PREFIX = "clock-offset-satellite-";
/** Prefix for clock drift parameter driver, the propagator index will be appended to it. */
public static final String CLOCK_DRIFT_PREFIX = "clock-drift-satellite-";
/** Clock offset scaling factor.
* <p>
* We use a power of 2 to avoid numeric noise introduction
* in the multiplications/divisions sequences.
* </p>
*/
private static final double CLOCK_OFFSET_SCALE = FastMath.scalb(1.0, -10);
/** Index of the propagator related to this satellite. */
private final int propagatorIndex;
/** Parameter driver for satellite clock offset. */
private final ParameterDriver clockOffsetDriver;
/** Parameter driver for satellite clock drift. */
private final ParameterDriver clockDriftDriver;
/** Simple constructor.
* @param propagatorIndex index of the propagator related to this satellite
*/
public ObservableSatellite(final int propagatorIndex) {
this.propagatorIndex = propagatorIndex;
this.clockOffsetDriver = new ParameterDriver(CLOCK_OFFSET_PREFIX + propagatorIndex,
0.0, CLOCK_OFFSET_SCALE,
Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY);
this.clockDriftDriver = new ParameterDriver(CLOCK_DRIFT_PREFIX + propagatorIndex,
0.0, CLOCK_OFFSET_SCALE,
Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY);
}
/** Get the index of the propagator related to this satellite.
* @return index of the propagator related to this satellite
*/
public int getPropagatorIndex() {
return propagatorIndex;
}
/** Get the clock offset parameter driver.
* <p>
* The offset value is defined as the value in seconds that must be <em>subtracted</em> from
* the satellite clock reading of time to compute the real physical date. The offset
* is therefore negative if the satellite clock is slow and positive if it is fast.
* </p>
* @return clock offset parameter driver
*/
public ParameterDriver getClockOffsetDriver() {
return clockOffsetDriver;
}
/** Get the clock drift parameter driver.
* <p>
* The drift is negative if the satellite clock is slowing down and positive if it is speeding up.
* </p>
* @return clock offset parameter driver
* @since 10.3
*/
public ParameterDriver getClockDriftDriver() {
return clockDriftDriver;
}
}