function xbxhr() {
  var xhr;
  try {
    xhr = new ActiveXObject("Msxml2.XMLHTTP");
  }
  catch (e) {
    try {
      xhr = new ActiveXObject("Microsoft.XMLHTTP");
    }
    catch (E) {
      xhr = false;
    }
  }
  if (!xhr && typeof XMLHttpRequest!='undefined') {
    try {
      xhr = new XMLHttpRequest();
    } 
    catch (e) {
      xhr=false;
    }
  }
  return xhr;
}
var offImg;
var onImg;
function initRead() {
  document.write('<img id="r_Rocket" src="images/toweroff.gif" alt="">');
  offImg=new Image();
  offImg.src=rtDir+"/images/toweroff.gif";
  onImg=new Image();
  onImg.src=rtDir+"/images/toweron.gif";
  window.setInterval(getState, 30000);
  getState();
}
function getState() {
  var radioState = new xbxhr();
  var rrr=new Date();
  radioState.open('GET', rtDir+'/rocketState.dat?random='+rrr.valueOf(), true);
  radioState.onreadystatechange=function() {
    if(radioState.readyState==4) {
      var txt = radioState.responseText;
      if(txt) {
        var e=document.getElementById('r_Rocket');
				if(e) {
          if(txt.indexOf('onair') == 0) e.src = onImg.src;
          if(txt.indexOf('offair') == 0) e.src = offImg.src;
				}
      }
    }
  }
  radioState.send(null);
}
initRead();