Our BTS-912ERis a reflectorless (free prism) total station designed with a RS232C compatible and asynchronous serial data transfer interface,digital input keyboard and a large LCD screen with text data displayed on it.It adopts the absolute code technology for angle measurement performance.The vertical angle doesn\\'t need to be initialized after the total station is powered on,and the horizontal angle canbe saved without re-orientation even after the electricity is cut off.This total station also adopts CCD as the receiver,high-speed CPU processor,and the circle to achieve the function of angle reading.