public boolean isValidFile(RandomAccessFile raf) {
    int data_msecs = 0;
    short data_julian_date = 0;

    try {
      raf.order(RandomAccessFile.LITTLE_ENDIAN);
      raf.seek(0);
      raf.skipBytes(14);
      short message_type = raf.readShort();
      if (message_type != 1) return false;

      raf.skipBytes(12);
      // data header
      byte[] b4 = raf.readBytes(4);
      data_msecs = bytesToInt(b4, true);
      byte[] b2 = raf.readBytes(2);
      data_julian_date = (short) bytesToShort(b2, true);
      java.util.Date dd = Cinrad2Record.getDate(data_julian_date, data_msecs);

      Calendar cal = new GregorianCalendar(new SimpleTimeZone(0, "GMT"));
      cal.clear();
      cal.setTime(dd);
      int year = cal.get(Calendar.YEAR);
      cal.setTime(new Date());
      int cyear = cal.get(Calendar.YEAR);
      if (year < 1990 || year > cyear) return false;
      return true;
    } catch (IOException ioe) {
      return false;
    }
  }
  private void makeVariableNoCoords(
      NetcdfFile ncfile, int datatype, String shortName, String longName, Variable from) {

    Variable v = new Variable(ncfile, null, null, shortName);
    v.setDataType(DataType.BYTE);
    v.setDimensions(from.getDimensions());
    ncfile.addVariable(null, v);

    v.addAttribute(new Attribute(CDM.UNITS, Cinrad2Record.getDatatypeUnits(datatype)));
    v.addAttribute(new Attribute(CDM.LONG_NAME, longName));

    byte[] b = new byte[2];
    b[0] = Cinrad2Record.MISSING_DATA;
    b[1] = Cinrad2Record.BELOW_THRESHOLD;
    Array missingArray = Array.factory(DataType.BYTE.getPrimitiveClassType(), new int[] {2}, b);

    v.addAttribute(new Attribute(CDM.MISSING_VALUE, missingArray));
    v.addAttribute(
        new Attribute("signal_below_threshold", new Byte(Cinrad2Record.BELOW_THRESHOLD)));
    v.addAttribute(
        new Attribute(CDM.SCALE_FACTOR, new Float(Cinrad2Record.getDatatypeScaleFactor(datatype))));
    v.addAttribute(
        new Attribute(CDM.ADD_OFFSET, new Float(Cinrad2Record.getDatatypeAddOffset(datatype))));
    v.addAttribute(new Attribute(CDM.UNSIGNED, "true"));

    Attribute fromAtt = from.findAttribute(_Coordinate.Axes);
    v.addAttribute(new Attribute(_Coordinate.Axes, fromAtt));

    Vgroup vgFrom = (Vgroup) from.getSPobject();
    Vgroup vg = new Vgroup(datatype, vgFrom.map);
    v.setSPobject(vg);
  }
 private void readOneRadial(Cinrad2Record r, int datatype, Range gateRange, IndexIterator ii)
     throws IOException {
   if (r == null) {
     for (int i = gateRange.first(); i <= gateRange.last(); i += gateRange.stride())
       ii.setByteNext(Cinrad2Record.MISSING_DATA);
     return;
   }
   r.readData(volScan.raf, datatype, gateRange, ii);
 }
  private void makeCoordinateDataWithMissing(
      int datatype,
      Variable time,
      Variable elev,
      Variable azi,
      Variable nradialsVar,
      Variable ngatesVar,
      List groups) {

    Array timeData = Array.factory(time.getDataType().getPrimitiveClassType(), time.getShape());
    Index timeIndex = timeData.getIndex();

    Array elevData = Array.factory(elev.getDataType().getPrimitiveClassType(), elev.getShape());
    Index elevIndex = elevData.getIndex();

    Array aziData = Array.factory(azi.getDataType().getPrimitiveClassType(), azi.getShape());
    Index aziIndex = aziData.getIndex();

    Array nradialsData =
        Array.factory(nradialsVar.getDataType().getPrimitiveClassType(), nradialsVar.getShape());
    IndexIterator nradialsIter = nradialsData.getIndexIterator();

    Array ngatesData =
        Array.factory(ngatesVar.getDataType().getPrimitiveClassType(), ngatesVar.getShape());
    IndexIterator ngatesIter = ngatesData.getIndexIterator();

    // first fill with missing data
    IndexIterator ii = timeData.getIndexIterator();
    while (ii.hasNext()) ii.setIntNext(MISSING_INT);

    ii = elevData.getIndexIterator();
    while (ii.hasNext()) ii.setFloatNext(MISSING_FLOAT);

    ii = aziData.getIndexIterator();
    while (ii.hasNext()) ii.setFloatNext(MISSING_FLOAT);

    // now set the  coordinate variables from the Cinrad2Record radial
    int last_msecs = Integer.MIN_VALUE;
    int nscans = groups.size();
    try {
      for (int scan = 0; scan < nscans; scan++) {
        List scanGroup = (List) groups.get(scan);
        int nradials = scanGroup.size();

        Cinrad2Record first = null;
        for (int j = 0; j < nradials; j++) {
          Cinrad2Record r = (Cinrad2Record) scanGroup.get(j);
          if (first == null) first = r;

          int radial = r.radial_num - 1;
          timeData.setInt(timeIndex.set(scan, radial), r.data_msecs);
          elevData.setFloat(elevIndex.set(scan, radial), r.getElevation());
          aziData.setFloat(aziIndex.set(scan, radial), r.getAzimuth());

          if (r.data_msecs < last_msecs)
            logger.warn("makeCoordinateData time out of order " + r.data_msecs);
          last_msecs = r.data_msecs;
        }

        nradialsIter.setIntNext(nradials);
        ngatesIter.setIntNext(first.getGateCount(datatype));
      }
    } catch (java.lang.ArrayIndexOutOfBoundsException ae) {
      logger.debug("Cinrad2IOSP.uncompress ", ae);
    }
    time.setCachedData(timeData, false);
    elev.setCachedData(elevData, false);
    azi.setCachedData(aziData, false);
    nradialsVar.setCachedData(nradialsData, false);
    ngatesVar.setCachedData(ngatesData, false);
  }
  private void makeCoordinateData(
      int datatype,
      Variable time,
      Variable elev,
      Variable azi,
      Variable nradialsVar,
      Variable ngatesVar,
      List groups) {

    Array timeData = Array.factory(time.getDataType().getPrimitiveClassType(), time.getShape());
    IndexIterator timeDataIter = timeData.getIndexIterator();

    Array elevData = Array.factory(elev.getDataType().getPrimitiveClassType(), elev.getShape());
    IndexIterator elevDataIter = elevData.getIndexIterator();

    Array aziData = Array.factory(azi.getDataType().getPrimitiveClassType(), azi.getShape());
    IndexIterator aziDataIter = aziData.getIndexIterator();

    Array nradialsData =
        Array.factory(nradialsVar.getDataType().getPrimitiveClassType(), nradialsVar.getShape());
    IndexIterator nradialsIter = nradialsData.getIndexIterator();

    Array ngatesData =
        Array.factory(ngatesVar.getDataType().getPrimitiveClassType(), ngatesVar.getShape());
    IndexIterator ngatesIter = ngatesData.getIndexIterator();

    int last_msecs = Integer.MIN_VALUE;
    int nscans = groups.size();
    int maxRadials = volScan.getMaxRadials();
    for (int i = 0; i < nscans; i++) {
      List scanGroup = (List) groups.get(i);
      int nradials = scanGroup.size();

      Cinrad2Record first = null;
      for (int j = 0; j < nradials; j++) {
        Cinrad2Record r = (Cinrad2Record) scanGroup.get(j);
        if (first == null) first = r;

        timeDataIter.setIntNext(r.data_msecs);
        elevDataIter.setFloatNext(r.getElevation());
        aziDataIter.setFloatNext(r.getAzimuth());

        if (r.data_msecs < last_msecs)
          logger.warn("makeCoordinateData time out of order " + r.data_msecs);
        last_msecs = r.data_msecs;
      }

      for (int j = nradials; j < maxRadials; j++) {
        timeDataIter.setIntNext(MISSING_INT);
        elevDataIter.setFloatNext(MISSING_FLOAT);
        aziDataIter.setFloatNext(MISSING_FLOAT);
      }

      nradialsIter.setIntNext(nradials);
      ngatesIter.setIntNext(first.getGateCount(datatype));
    }

    time.setCachedData(timeData, false);
    elev.setCachedData(elevData, false);
    azi.setCachedData(aziData, false);
    nradialsVar.setCachedData(nradialsData, false);
    ngatesVar.setCachedData(ngatesData, false);
  }
  public Variable makeVariable(
      NetcdfFile ncfile,
      int datatype,
      String shortName,
      String longName,
      String abbrev,
      List groups)
      throws IOException {
    int nscans = groups.size();

    if (nscans == 0) {
      throw new IllegalStateException("No data for " + shortName);
    }

    // get representative record
    List firstGroup = (List) groups.get(0);
    Cinrad2Record firstRecord = (Cinrad2Record) firstGroup.get(0);
    int ngates = firstRecord.getGateCount(datatype);

    String scanDimName = "scan" + abbrev;
    String gateDimName = "gate" + abbrev;
    Dimension scanDim = new Dimension(scanDimName, nscans);
    Dimension gateDim = new Dimension(gateDimName, ngates);
    ncfile.addDimension(null, scanDim);
    ncfile.addDimension(null, gateDim);

    ArrayList dims = new ArrayList();
    dims.add(scanDim);
    dims.add(radialDim);
    dims.add(gateDim);

    Variable v = new Variable(ncfile, null, null, shortName);
    v.setDataType(DataType.BYTE);
    v.setDimensions(dims);
    ncfile.addVariable(null, v);

    v.addAttribute(new Attribute(CDM.UNITS, Cinrad2Record.getDatatypeUnits(datatype)));
    v.addAttribute(new Attribute(CDM.LONG_NAME, longName));

    byte[] b = new byte[2];
    b[0] = Cinrad2Record.MISSING_DATA;
    b[1] = Cinrad2Record.BELOW_THRESHOLD;
    Array missingArray = Array.factory(DataType.BYTE.getPrimitiveClassType(), new int[] {2}, b);

    v.addAttribute(new Attribute(CDM.MISSING_VALUE, missingArray));
    v.addAttribute(
        new Attribute("signal_below_threshold", new Byte(Cinrad2Record.BELOW_THRESHOLD)));
    v.addAttribute(
        new Attribute(CDM.SCALE_FACTOR, new Float(Cinrad2Record.getDatatypeScaleFactor(datatype))));
    v.addAttribute(
        new Attribute(CDM.ADD_OFFSET, new Float(Cinrad2Record.getDatatypeAddOffset(datatype))));
    v.addAttribute(new Attribute(CDM.UNSIGNED, "true"));

    ArrayList dim2 = new ArrayList();
    dim2.add(scanDim);
    dim2.add(radialDim);

    // add time coordinate variable
    String timeCoordName = "time" + abbrev;
    Variable timeVar = new Variable(ncfile, null, null, timeCoordName);
    timeVar.setDataType(DataType.INT);
    timeVar.setDimensions(dim2);
    ncfile.addVariable(null, timeVar);

    // int julianDays = volScan.getTitleJulianDays();
    // Date d = Cinrad2Record.getDate( julianDays, 0);
    // Date d = Cinrad2Record.getDate(volScan.getTitleJulianDays(), volScan.getTitleMsecs());
    Date d = volScan.getStartDate();
    String units = "msecs since " + formatter.toDateTimeStringISO(d);

    timeVar.addAttribute(new Attribute(CDM.LONG_NAME, "time since base date"));
    timeVar.addAttribute(new Attribute(CDM.UNITS, units));
    timeVar.addAttribute(new Attribute(CDM.MISSING_VALUE, new Integer(MISSING_INT)));
    timeVar.addAttribute(new Attribute(_Coordinate.AxisType, AxisType.Time.toString()));

    // add elevation coordinate variable
    String elevCoordName = "elevation" + abbrev;
    Variable elevVar = new Variable(ncfile, null, null, elevCoordName);
    elevVar.setDataType(DataType.FLOAT);
    elevVar.setDimensions(dim2);
    ncfile.addVariable(null, elevVar);

    elevVar.addAttribute(new Attribute(CDM.UNITS, "degrees"));
    elevVar.addAttribute(
        new Attribute(
            CDM.LONG_NAME,
            "elevation angle in degres: 0 = parallel to pedestal base, 90 = perpendicular"));
    elevVar.addAttribute(new Attribute(CDM.MISSING_VALUE, new Float(MISSING_FLOAT)));
    elevVar.addAttribute(new Attribute(_Coordinate.AxisType, AxisType.RadialElevation.toString()));

    // add azimuth coordinate variable
    String aziCoordName = "azimuth" + abbrev;
    Variable aziVar = new Variable(ncfile, null, null, aziCoordName);
    aziVar.setDataType(DataType.FLOAT);
    aziVar.setDimensions(dim2);
    ncfile.addVariable(null, aziVar);

    aziVar.addAttribute(new Attribute(CDM.UNITS, "degrees"));
    aziVar.addAttribute(
        new Attribute(CDM.LONG_NAME, "azimuth angle in degrees: 0 = true north, 90 = east"));
    aziVar.addAttribute(new Attribute(CDM.MISSING_VALUE, new Float(MISSING_FLOAT)));
    aziVar.addAttribute(new Attribute(_Coordinate.AxisType, AxisType.RadialAzimuth.toString()));

    // add gate coordinate variable
    String gateCoordName = "distance" + abbrev;
    Variable gateVar = new Variable(ncfile, null, null, gateCoordName);
    gateVar.setDataType(DataType.FLOAT);
    gateVar.setDimensions(gateDimName);
    Array data =
        Array.makeArray(
            DataType.FLOAT,
            ngates,
            (double) firstRecord.getGateStart(datatype),
            (double) firstRecord.getGateSize(datatype));
    gateVar.setCachedData(data, false);
    ncfile.addVariable(null, gateVar);
    radarRadius = firstRecord.getGateStart(datatype) + ngates * firstRecord.getGateSize(datatype);

    gateVar.addAttribute(new Attribute(CDM.UNITS, "m"));
    gateVar.addAttribute(new Attribute(CDM.LONG_NAME, "radial distance to start of gate"));
    gateVar.addAttribute(new Attribute(_Coordinate.AxisType, AxisType.RadialDistance.toString()));

    // add number of radials variable
    String nradialsName = "numRadials" + abbrev;
    Variable nradialsVar = new Variable(ncfile, null, null, nradialsName);
    nradialsVar.setDataType(DataType.INT);
    nradialsVar.setDimensions(scanDim.getName());
    nradialsVar.addAttribute(new Attribute(CDM.LONG_NAME, "number of valid radials in this scan"));
    ncfile.addVariable(null, nradialsVar);

    // add number of gates variable
    String ngateName = "numGates" + abbrev;
    Variable ngateVar = new Variable(ncfile, null, null, ngateName);
    ngateVar.setDataType(DataType.INT);
    ngateVar.setDimensions(scanDim.getName());
    ngateVar.addAttribute(new Attribute(CDM.LONG_NAME, "number of valid gates in this scan"));
    ncfile.addVariable(null, ngateVar);

    makeCoordinateDataWithMissing(
        datatype, timeVar, elevVar, aziVar, nradialsVar, ngateVar, groups);

    // back to the data variable
    String coordinates =
        timeCoordName + " " + elevCoordName + " " + aziCoordName + " " + gateCoordName;
    v.addAttribute(new Attribute(_Coordinate.Axes, coordinates));

    // make the record map
    int nradials = radialDim.getLength();
    Cinrad2Record[][] map = new Cinrad2Record[nscans][nradials];
    for (int i = 0; i < groups.size(); i++) {
      Cinrad2Record[] mapScan = map[i];
      List group = (List) groups.get(i);
      for (int j = 0; j < group.size(); j++) {
        Cinrad2Record r = (Cinrad2Record) group.get(j);
        int radial = r.radial_num - 1;
        mapScan[radial] = r;
      }
    }

    Vgroup vg = new Vgroup(datatype, map);
    v.setSPobject(vg);

    return v;
  }
  public void open(RandomAccessFile raf, NetcdfFile ncfile, CancelTask cancelTask)
      throws IOException {
    NexradStationDB.init();

    volScan = new Cinrad2VolumeScan(raf, cancelTask);
    if (volScan.hasDifferentDopplarResolutions())
      throw new IllegalStateException("volScan.hasDifferentDopplarResolutions");

    radialDim = new Dimension("radial", volScan.getMaxRadials());
    ncfile.addDimension(null, radialDim);

    makeVariable(
        ncfile,
        Cinrad2Record.REFLECTIVITY,
        "Reflectivity",
        "Reflectivity",
        "R",
        volScan.getReflectivityGroups());
    int velocity_type =
        (volScan.getDopplarResolution() == Cinrad2Record.DOPPLER_RESOLUTION_HIGH_CODE)
            ? Cinrad2Record.VELOCITY_HI
            : Cinrad2Record.VELOCITY_LOW;
    Variable v =
        makeVariable(
            ncfile,
            velocity_type,
            "RadialVelocity",
            "Radial Velocity",
            "V",
            volScan.getVelocityGroups());
    makeVariableNoCoords(
        ncfile, Cinrad2Record.SPECTRUM_WIDTH, "SpectrumWidth", "Spectrum Width", v);

    if (volScan.getStationId() != null) {
      ncfile.addAttribute(null, new Attribute("Station", volScan.getStationId()));
      ncfile.addAttribute(null, new Attribute("StationName", volScan.getStationName()));
      ncfile.addAttribute(
          null, new Attribute("StationLatitude", new Double(volScan.getStationLatitude())));
      ncfile.addAttribute(
          null, new Attribute("StationLongitude", new Double(volScan.getStationLongitude())));
      ncfile.addAttribute(
          null,
          new Attribute("StationElevationInMeters", new Double(volScan.getStationElevation())));

      double latRadiusDegrees = Math.toDegrees(radarRadius / ucar.unidata.geoloc.Earth.getRadius());
      ncfile.addAttribute(
          null,
          new Attribute(
              "geospatial_lat_min", new Double(volScan.getStationLatitude() - latRadiusDegrees)));
      ncfile.addAttribute(
          null,
          new Attribute(
              "geospatial_lat_max", new Double(volScan.getStationLatitude() + latRadiusDegrees)));
      double cosLat = Math.cos(Math.toRadians(volScan.getStationLatitude()));
      double lonRadiusDegrees =
          Math.toDegrees(radarRadius / cosLat / ucar.unidata.geoloc.Earth.getRadius());
      ncfile.addAttribute(
          null,
          new Attribute(
              "geospatial_lon_min", new Double(volScan.getStationLongitude() - lonRadiusDegrees)));
      ncfile.addAttribute(
          null,
          new Attribute(
              "geospatial_lon_max", new Double(volScan.getStationLongitude() + lonRadiusDegrees)));

      // add a radial coordinate transform (experimental)
      Variable ct = new Variable(ncfile, null, null, "radialCoordinateTransform");
      ct.setDataType(DataType.CHAR);
      ct.setDimensions(""); // scalar
      ct.addAttribute(new Attribute("transform_name", "Radial"));
      ct.addAttribute(new Attribute("center_latitude", new Double(volScan.getStationLatitude())));
      ct.addAttribute(new Attribute("center_longitude", new Double(volScan.getStationLongitude())));
      ct.addAttribute(new Attribute("center_elevation", new Double(volScan.getStationElevation())));
      ct.addAttribute(new Attribute(_Coordinate.TransformType, "Radial"));
      ct.addAttribute(
          new Attribute(_Coordinate.AxisTypes, "RadialElevation RadialAzimuth RadialDistance"));

      Array data =
          Array.factory(DataType.CHAR.getPrimitiveClassType(), new int[0], new char[] {' '});
      ct.setCachedData(data, true);
      ncfile.addVariable(null, ct);
    }

    DateFormatter formatter = new DateFormatter();

    ncfile.addAttribute(null, new Attribute(CDM.CONVENTIONS, _Coordinate.Convention));
    ncfile.addAttribute(null, new Attribute("format", volScan.getDataFormat()));
    ncfile.addAttribute(null, new Attribute(CF.FEATURE_TYPE, FeatureType.RADIAL.toString()));
    // Date d = Cinrad2Record.getDate(volScan.getTitleJulianDays(), volScan.getTitleMsecs());
    // ncfile.addAttribute(null, new Attribute("base_date", formatter.toDateOnlyString(d)));

    ncfile.addAttribute(
        null,
        new Attribute(
            "time_coverage_start", formatter.toDateTimeStringISO(volScan.getStartDate())));
    ; // .toDateTimeStringISO(d)));
    ncfile.addAttribute(
        null,
        new Attribute("time_coverage_end", formatter.toDateTimeStringISO(volScan.getEndDate())));

    ncfile.addAttribute(
        null,
        new Attribute(CDM.HISTORY, "Direct read of Nexrad Level 2 file into NetCDF-Java 2.2 API"));
    ncfile.addAttribute(null, new Attribute("DataType", "Radial"));

    ncfile.addAttribute(
        null,
        new Attribute(
            "Title",
            "Nexrad Level 2 Station "
                + volScan.getStationId()
                + " from "
                + formatter.toDateTimeStringISO(volScan.getStartDate())
                + " to "
                + formatter.toDateTimeStringISO(volScan.getEndDate())));

    ncfile.addAttribute(
        null,
        new Attribute(
            "Summary",
            "Weather Surveillance Radar-1988 Doppler (WSR-88D) "
                + "Level II data are the three meteorological base data quantities: reflectivity, mean radial velocity, and "
                + "spectrum width."));

    ncfile.addAttribute(
        null,
        new Attribute(
            "keywords",
            "WSR-88D; NEXRAD; Radar Level II; reflectivity; mean radial velocity; spectrum width"));

    ncfile.addAttribute(
        null,
        new Attribute(
            "VolumeCoveragePatternName",
            Cinrad2Record.getVolumeCoveragePatternName(volScan.getVCP())));
    ncfile.addAttribute(
        null, new Attribute("VolumeCoveragePattern", new Integer(volScan.getVCP())));
    ncfile.addAttribute(
        null,
        new Attribute(
            "HorizonatalBeamWidthInDegrees", new Double(Cinrad2Record.HORIZONTAL_BEAM_WIDTH)));

    ncfile.finish();
  }