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);
 }