Radio height.

    Args:
        msg (String): 28 bytes hexadecimal message string

    Returns:
        int: radio height in ft

def rh45(msg):
    """Radio height.

    Args:
        msg (String): 28 bytes hexadecimal message string

    Returns:
        int: radio height in ft

    """
    d = hex2bin(data(msg))
    if d[38] == '0':
        return None
    rh = bin2int(d[39:51]) * 16
    return rh