 I have with me Dr. Chung Hao Han from the Beijing Satellite Navigation Center in China. Dr. Han, you are dealing with the Beidou navigation system. What exactly is it? It's my pleasure to answer your question. Beidou system is developed by the Chinese government. You know, following radio communication, internet, the global navigation satellite system has changed our life. So, the Chinese government pay attention to great importance to Beidou system because it's a big national infrastructure. So, the Beidou system is like the global positioning system, GPS, GLONASS, and Galileo is the same kind of system? Almost the same. You know, navigation satellite system usually provides position, velocity, and timing service. Beside of this, Beidou satellite system also provides short message and position report and wide area difference services. So, how many satellites do you have in space to have your coverage? According to the project schedule, the Beidou system will be built in three steps. We have just finished the second step. And the constellation of Beidou system at present consists of 14 space vehicles. So, what time scale do you use in your navigation system? You know, a global navigation satellite system indeed is a price, time measurement, and time securization system. We must keep uniform and continuous time scale to use for the satellite securization and for the satellite orbit determination. So, are you based on the universal time coordinates, UTC? We use the time scale, we call the Beidou system time, and maybe a simple pride to call this BDT. BDT is uniform and continuous time scale, just like GPS T without a second. And the origin is from the origin or the start point. It's January 1, 2006, it's a Sunday. And so, Beidou time is different to UTC. It's a two second or higher UTC. So, in ITU today we are discussing the international time scale and the future of that time scale. And there's been a proposal to eliminate the leap second. What is your opinion on that? To my opinion, the irregular insertion of the leap second is not convenient for most users. If we stop to insert the leap second, maybe it's beneficial not only to GNSS operator but also to the users. You know, the transformation between UTC and the system time may be simple. Dr. Han, thank you very much for being with us at ITUTB. Thank you, it's my pleasure.