Java tutorial
/* * Copyright (C) 2016 The Android Open Source Project * * Licensed 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 android.location; import android.annotation.IntDef; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; /** * This class represents the current state of the GNSS engine. * This class is used in conjunction with the {@link GnssStatus.Callback}. */ public final class GnssStatus { // these must match the definitions in gps.h /** Unknown constellation type. */ public static final int CONSTELLATION_UNKNOWN = 0; /** Constellation type constant for GPS. */ public static final int CONSTELLATION_GPS = 1; /** Constellation type constant for SBAS. */ public static final int CONSTELLATION_SBAS = 2; /** Constellation type constant for Glonass. */ public static final int CONSTELLATION_GLONASS = 3; /** Constellation type constant for QZSS. */ public static final int CONSTELLATION_QZSS = 4; /** Constellation type constant for Beidou. */ public static final int CONSTELLATION_BEIDOU = 5; /** Constellation type constant for Galileo. */ public static final int CONSTELLATION_GALILEO = 6; /** @hide */ public static final int GNSS_SV_FLAGS_NONE = 0; /** @hide */ public static final int GNSS_SV_FLAGS_HAS_EPHEMERIS_DATA = (1 << 0); /** @hide */ public static final int GNSS_SV_FLAGS_HAS_ALMANAC_DATA = (1 << 1); /** @hide */ public static final int GNSS_SV_FLAGS_USED_IN_FIX = (1 << 2); /** @hide */ public static final int GNSS_SV_FLAGS_HAS_CARRIER_FREQUENCY = (1 << 3); /** @hide */ public static final int SVID_SHIFT_WIDTH = 8; /** @hide */ public static final int CONSTELLATION_TYPE_SHIFT_WIDTH = 4; /** @hide */ public static final int CONSTELLATION_TYPE_MASK = 0xf; /** * Used for receiving notifications when GNSS events happen. */ public static abstract class Callback { /** * Called when GNSS system has started. */ public void onStarted() { } /** * Called when GNSS system has stopped. */ public void onStopped() { } /** * Called when the GNSS system has received its first fix since starting. * @param ttffMillis the time from start to first fix in milliseconds. */ public void onFirstFix(int ttffMillis) { } /** * Called periodically to report GNSS satellite status. * @param status the current status of all satellites. */ public void onSatelliteStatusChanged(GnssStatus status) { } } /** * Constellation type. * @hide */ @Retention(RetentionPolicy.SOURCE) @IntDef({ CONSTELLATION_UNKNOWN, CONSTELLATION_GPS, CONSTELLATION_SBAS, CONSTELLATION_GLONASS, CONSTELLATION_QZSS, CONSTELLATION_BEIDOU, CONSTELLATION_GALILEO }) public @interface ConstellationType { } final int[] mSvidWithFlags; final float[] mCn0DbHz; final float[] mElevations; final float[] mAzimuths; final int mSvCount; final float[] mCarrierFrequencies; GnssStatus(int svCount, int[] svidWithFlags, float[] cn0s, float[] elevations, float[] azimuths, float[] carrierFrequencies) { mSvCount = svCount; mSvidWithFlags = svidWithFlags; mCn0DbHz = cn0s; mElevations = elevations; mAzimuths = azimuths; mCarrierFrequencies = carrierFrequencies; } /** * Gets the total number of satellites in satellite list. */ public int getSatelliteCount() { return mSvCount; } /** * Retrieves the constellation type of the satellite at the specified index. * * @param satIndex the index of the satellite in the list. */ @ConstellationType public int getConstellationType(int satIndex) { return ((mSvidWithFlags[satIndex] >> CONSTELLATION_TYPE_SHIFT_WIDTH) & CONSTELLATION_TYPE_MASK); } /** * Gets the identification number for the satellite at the specific index. * * <p>This svid is pseudo-random number for most constellations. It is FCN & OSN number for * Glonass. * * <p>The distinction is made by looking at constellation field * {@link #getConstellationType(int)} Expected values are in the range of: * * <ul> * <li>GPS: 1-32</li> * <li>SBAS: 120-151, 183-192</li> * <li>GLONASS: One of: OSN, or FCN+100 * <ul> * <li>1-24 as the orbital slot number (OSN) (preferred, if known)</li> * <li>93-106 as the frequency channel number (FCN) (-7 to +6) plus 100. * i.e. encode FCN of -7 as 93, 0 as 100, and +6 as 106</li> * </ul></li> * <li>QZSS: 193-200</li> * <li>Galileo: 1-36</li> * <li>Beidou: 1-37</li> * </ul> * * @param satIndex the index of the satellite in the list. */ public int getSvid(int satIndex) { return mSvidWithFlags[satIndex] >> SVID_SHIFT_WIDTH; } /** * Retrieves the carrier-to-noise density at the antenna of the satellite at the specified index * in dB-Hz. * * @param satIndex the index of the satellite in the list. */ public float getCn0DbHz(int satIndex) { return mCn0DbHz[satIndex]; } /** * Retrieves the elevation of the satellite at the specified index. * * @param satIndex the index of the satellite in the list. */ public float getElevationDegrees(int satIndex) { return mElevations[satIndex]; } /** * Retrieves the azimuth the satellite at the specified index. * * @param satIndex the index of the satellite in the list. */ public float getAzimuthDegrees(int satIndex) { return mAzimuths[satIndex]; } /** * Reports whether the satellite at the specified index has ephemeris data. * * @param satIndex the index of the satellite in the list. */ public boolean hasEphemerisData(int satIndex) { return (mSvidWithFlags[satIndex] & GNSS_SV_FLAGS_HAS_EPHEMERIS_DATA) != 0; } /** * Reports whether the satellite at the specified index has almanac data. * * @param satIndex the index of the satellite in the list. */ public boolean hasAlmanacData(int satIndex) { return (mSvidWithFlags[satIndex] & GNSS_SV_FLAGS_HAS_ALMANAC_DATA) != 0; } /** * Reports whether the satellite at the specified index was used in the calculation of the most * recent position fix. * * @param satIndex the index of the satellite in the list. */ public boolean usedInFix(int satIndex) { return (mSvidWithFlags[satIndex] & GNSS_SV_FLAGS_USED_IN_FIX) != 0; } /** * Reports whether a valid {@link #getCarrierFrequencyHz(int satIndex)} is available. * * @param satIndex the index of the satellite in the list. */ public boolean hasCarrierFrequencyHz(int satIndex) { return (mSvidWithFlags[satIndex] & GNSS_SV_FLAGS_HAS_CARRIER_FREQUENCY) != 0; } /** * Gets the carrier frequency of the signal tracked. * * <p>For example it can be the GPS central frequency for L1 = 1575.45 MHz, or L2 = 1227.60 MHz, * L5 = 1176.45 MHz, varying GLO channels, etc. If the field is not set, it is the primary * common use central frequency, e.g. L1 = 1575.45 MHz for GPS. * * For an L1, L5 receiver tracking a satellite on L1 and L5 at the same time, two measurements * will be reported for this same satellite, in one all the values related to L1 will be filled, * and in the other all of the values related to L5 will be filled. * * <p>The value is only available if {@link #hasCarrierFrequencyHz(int satIndex)} is {@code true}. * * @param satIndex the index of the satellite in the list. * * @return the carrier frequency of the signal tracked in Hz. */ public float getCarrierFrequencyHz(int satIndex) { return mCarrierFrequencies[satIndex]; } }