function Decoder(bytes, port) {
  
function step_size (lo, hi, nbits, nresv)
{ return 1.0/((((1 << nbits) -1) -nresv)/(hi -lo)); }

function mt_value_decode(value, lo, hi, nbits, nresv)
{ return ((value -nresv /2) * step_size(lo, hi, nbits , nresv) + lo);}


var obj = new Object();
var num;

 obj.bytes = bytes;
 obj.length = bytes.length;
 switch(bytes[0]){
 case 0x05: //Heartbeat
 obj.type = "HEARTBEAT";
 obj.mode = ((1 << 3) - 1) & (bytes[1]>>5);
 obj.battery = Math.round(100* mt_value_decode(bytes[2], 2.8, 4.2, 8, 2)) / 100;
 obj.temperature = Math.round(100* mt_value_decode(bytes[3], -44, 85, 8, 2)) / 100;
 obj.ack = (bytes[4] >> 4) & ((1 << 4)-1);
 break;
 
 case 0x04: //Energy status
 obj.type = "ENERGY STATUS";
 obj.mode = ((1 << 3) - 1) & (bytes[1]>>5);
 obj.battery = Math.round(100* mt_value_decode(bytes[2], 2.8, 4.2, 8, 2)) / 100;
 obj.temperature = Math.round(100* mt_value_decode(bytes[3], -44, 85, 8, 2)) / 100;
 obj.ack = (bytes[4] >> 4) & ((1 << 4)-1);
 break;
 
 case 0x03: //Position
 obj.type = "POSITION";
 obj.mode = ((1 << 3) - 1) & (bytes[1] >> 5);
 obj.battery = Math.round(100* mt_value_decode(bytes[2], 2.8, 4.2, 8, 2)) / 100;
 obj.temperature = Math.round(100* mt_value_decode(bytes[3], -44, 85, 8, 0)) / 100;
 obj.ack = (bytes[4] >> 4) & ((1 << 4)-1);
 obj.position_type = bytes[4] & ((1 << 4) - 1)
 obj.age = mt_value_decode(bytes[5], 0, 2040, 8, 0);
 num = ((bytes[6] << 8|bytes[7]) << 8| bytes[8]) << 8;

 if (num > 2147483647)
 {
   num = num - 268435456;
 }
 obj.lattitude = num/10000000;
 
 num = ((bytes[9] << 8|bytes[10]) << 8| bytes[11]) << 8;

 if (num > 2147483647)
 {
   num = num - 268435456;
 }
 obj.longitude = num/10000000;

}
  return obj;
}