Angular JS http POST无法使用PHP

I am developing a mobile app using Angular JS , I am trying to do a POST request to PHP server using the following $http request

$http({
            type: "POST",
            dataType: 'json',
            url: "http://myling.wilson34.com/saveInterpreter.php",
            data: data,
            headers: {
               'Content-Type': 'application/json' 
            }
        })

but its return an empty $_POST I have tried

'Content-Type': 'application/x-www-form-urlencoded

but with no luck , any help with that please ?