SubFrameAlmanac.java
/* Copyright 2002-2024 Thales Alenia Space
* 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.gnss.rflink.gps;
import org.hipparchus.util.FastMath;
import org.orekit.gnss.metric.parser.Units;
/**
* Container for sub-frames 5, page 1-24.
* <p>
* Table 20-1, sheet 4 and table 40-1, sheet 4 in
* <a href="https://navcen.uscg.gov/sites/default/files/pdf/gps/IS-GPS-200N.pdf">NAVSTAR
* GPS Space Segment/Navigation User Segment Interface</a>, IS-GPS-200N, 22 Aug 2022
* </p>
* @author Luc Maisonobe
* @since 12.0
*/
public class SubFrameAlmanac extends SubFrame45 {
/** Index of e field. */
private static final int E = 9;
/** Index of TOA field. */
private static final int TOA = 10;
/** Index of δi field. */
private static final int DELTA_I = 11;
/** Index of dot(Ω) field. */
private static final int OMEGA_DOT = 12;
/** Index of SV health field. */
private static final int SV_HEALTH = 13;
/** Index of √a field. */
private static final int SQRT_A = 14;
/** Index of Ω₀ field. */
private static final int UPPERCASE_OMEGA_0 = 15;
/** Index of ω field. */
private static final int LOWERCASE_OMEGA = 16;
/** Index of M₀ field. */
private static final int M0 = 17;
/** Index of AF0 field. */
private static final int AF0 = 18;
/** Index of AF1 field. */
private static final int AF1 = 19;
/** Simple constructor.
* @param words raw words
*/
SubFrameAlmanac(final int[] words) {
// create raw container
super(words, AF1 + 1);
// populate container
setField(E, 3, 6, 16, words);
setField(TOA, 4, 22, 8, words);
setField(DELTA_I, 4, 6, 16, words);
setField(OMEGA_DOT, 5, 14, 16, words);
setField(SV_HEALTH, 5, 6, 8, words);
setField(SQRT_A, 6, 6, 24, words);
setField(UPPERCASE_OMEGA_0, 7, 6, 24, words);
setField(LOWERCASE_OMEGA, 8, 6, 24, words);
setField(M0, 9, 6, 24, words);
setField(AF0, 10, 22, 8, 10, 8, 3, words);
setField(AF1, 10, 11, 11, words);
}
/** Get the PRN code phase of the SV.
* @return PRN code phase
*/
public int getPRN() {
// sub-frames that contain almanacs use the SV-ID for the PRN
return getSvId();
}
/** Get eccentricity.
* @return eccentricity
*/
public double getE() {
return FastMath.scalb((double) getField(E), -21);
}
/** Get Time Of Almanac.
* @return Time Of Almanac (seconds)
*/
public int getToaA() {
return getField(TOA) << 12;
}
/** Get Δi.
* @return Δi (rad)
*/
public double getDeltai() {
return Units.SEMI_CIRCLE.toSI(FastMath.scalb((double) getField(DELTA_I), -19));
}
/** Get dot(Ω).
* @return dot(Ω) (rad/s)
*/
public double getOmegaDot() {
return Units.SEMI_CIRCLE.toSI(FastMath.scalb((double) getField(OMEGA_DOT), -38));
}
/** Get SV health.
* @return SV health
*/
public int getSvHealth() {
return getField(SV_HEALTH);
}
/** Get √a.
* @return d√a (√m)
*/
public double getSqrtA() {
return FastMath.scalb((double) getField(SQRT_A), -11);
}
/** Get Ω₀.
* @return Ω₀ (rad)
*/
public double getUppercaseOmega0() {
return Units.SEMI_CIRCLE.toSI(FastMath.scalb((double) getField(UPPERCASE_OMEGA_0), -23));
}
/** Get ω.
* @return ω(rad)
*/
public double getLowercaseOmega() {
return Units.SEMI_CIRCLE.toSI(FastMath.scalb((double) getField(LOWERCASE_OMEGA), -23));
}
/** Get M₀.
* @return M₀ (rad)
*/
public double getM0() {
return Units.SEMI_CIRCLE.toSI(FastMath.scalb((double) getField(M0), -23));
}
/** Get af₀.
* @return af₀ (second)
*/
public double getAF0() {
return FastMath.scalb((double) getField(AF0), -20);
}
/** Get af₁.
* @return af₁ (second/second)
*/
public double getAF1() {
return FastMath.scalb((double) getField(AF1), -38);
}
}