public static int extractRD(byte[] rec, int offset){
      System.out.println("RDLengthSize : " + (rec[offset+1] & 0xFF));

      System.out.print("Après RDLength : ");

        for(int c=0; c < (rec[offset+1] & 0xFF ); c++){
            System.out.print( hexToASCII(Integer.toHexString(rec[offset +c] & 0xff)));
        }