public function convertToNato($string)
    {
        $natoReturn = array();

        for($i=0; $i < strlen($string); $i++) {
            $currentLetter=substr($string,$i,1);

            if (! empty($this->nato[$currentLetter])) {
                $natoLetter = strtolower($this->nato[$currentLetter]);
            } else if (! empty($this->nato[strtolower($currentLetter)])) {
                $natoLetter = strtoupper($this->nato[strtolower($currentLetter)]);
            } else {
                $natoLetter = $currentLetter;
            }
            $natoReturn[] = $natoLetter;
        }

        return implode(" ",$natoReturn);
    }