Workdocumentation 2018-08-18

Wolfgang Fahl

go:java:

go[edit]

// rvp6LittleEndian converts the raw two byte tuple of little endian encoded composite products
// to radar video processor values (rvp-6). NaN may be returned when the no-data flag is set.
func (c *Composite) rvp6LittleEndian(tuple [2]byte) float32 {
	var value int = 0x0F & int(tuple[1])
	value = (value << 8) + int(tuple[0])

	if tuple[1]&(1<<5) != 0 { // error code: no-data
		return NaN
	}

	if tuple[1]&(1<<6) != 0 { // flag: negative value
		value *= -1
	}

	conv := c.rvp6Raw(value) // set decimal point

	// little endian encoded formats are also used for mm/h
	if c.DataUnit != Unit_dBZ {
		return conv
	}

	// Even though this format supports negative values and custom
	// precision they do not make use of this and we still have to subtract
	// the bias and scale it (RADVOR FX, dBZ)
	return toDBZ(conv)
}

// rvp6Raw converts the raw value to radar video processor values (rvp-6) by applying the
// products precision field.
func (c *Composite) rvp6Raw(value int) float32 {
	return float32(value) * float32(math.Pow10(c.precision))
}

Java[edit]

 // rvp6LittleEndian converts the raw two byte tuple of little endian encoded
  // composite products
  // to radar video processor values (rvp-6). NaN may be returned when the
  // no-data flag is set.
  public static float rvp6LittleEndian(Composite c, byte... tuple) {
    int value = 0x0F & tuple[1];
    value = (value << 8) | (tuple[0]&0x0f);

    if ((tuple[1] & (1 << 5)) != 0) { // error code: no-data
      return Float.NaN;
    }

    if ((tuple[1] & (1 << 6)) != 0) { // flag: negative value
      value *= -1;
    }

    float conv = (float) c.rvp6Raw(value); // set decimal point

    // little endian encoded formats are also used for mm/h
    if (c.getDataUnit() != Unit.Unit_dBZ) {
      return conv;
    }

    // Even though this format supports negative values and custom
    // precision they do not make use of this and we still have to subtract
    // the bias and scale it (RADVOR FX, dBZ)
    return Conversion.toDBZ(conv);
  }

  // rvp6Raw converts the raw value to radar video processor values (rvp-6) by applying the
  // products precision field.
  public static double rvp6Raw(Composite c, int value)  {
    double rvalue=value * c.getPrecisionFactor();
    return rvalue;
  }

Difference Examples[edit]

first column: Java - second column: go third colum difference * 10

...
518, 32:   0,9 !=  18,5 d*10=176,0
519, 32:   0,8 !=  16,8 d*10=160,0
520, 32:   0,7 !=  15,1 d*10=144,0
517, 33:   0,9 !=  15,3 d*10=144,0
518, 33:   1,3 !=  22,1 d*10=208,0
519, 33:   1,1 !=  20,3 d*10=192,0

Cause: 0x0F mask needs to be 0xFF for tuple[0]!