(
课件网) Space exploration Cross-curricular connection Pre-reading Do you ever go on road trips with your family How do you find your way Do you use any map apps How does the app help you find your way to the destination The app shows us where we are. It gives us the fastest way to get to the destination, and it also tells us where to drive and when to turn. The app also shows us traffic in real time. How does the app know where you are It uses signals from satellites in space. navigation / n v ɡe n/ 导航 satellite / s t la t/ 卫星 Discuss in pairs. How does BDS Work Let’s explore the science behind it! How BDS works What is BDS BDS, officially known as the BeiDou Navigation Satellite System, is one of the global navigation satellite systems. How does BDS work BDS is a group of satellites in orbit around the Earth. Each satellite sends radio signals to the Earth with information. The signals answer two important questions: “Where in space is the satellite ” and “When did the signal leave the satellite ” The radio signal travels through space at the speed of light—that is 299,792 kilometres a second! Back here on Earth, your phone receives the signal and compares it to the exact time of arrival. The phone then calculates how far it is from the satellite. One satellite is not enough. Your phone needs information from four satellites to calculate your location. It does this all the time. So, when we use a BDS device, we won’t get lost. What’s special about BDS We can also use BDS for two-way communication. In areas without any mobile network, people can send text messages through BeiDou satellites. How do we use BDS If your phone supports BDS, it will automatically pick the navigation system with the best signal at the time. Can we use BDS outside China Yes, we can use BDS outside China, but its accuracy is higher in China and the Asia-Pacific region. BDS = BeiDou Navigation Satellite System It is a Global Navigation Satellite System (GNSS). It helps us find our location anywhere on Earth. Read the definition. What does “BDS” stand for, and what is it What is it used for While-reading–What is BDS Where are the BDS satellites 2. What do the satellites send to the Earth 3. How can we receive the BDS signals 4. How many satellites does your phone need to calculate your location They are in orbit around the Earth. Radio signals with information about their location and time. We can receive the signals with a phone or other device that supports BDS. Four. Look at the text and answer the questions. While-reading–How does BDS work 1. What is special about BDS We can use BDS for two-way communication. In areas without any mobile network, GPS only allows you to receive signals, but people can both receive and send text messages through Beidou satellites. Example: The engine on a ship breaks down when a fisherman is out at sea. There is no mobile network, and the ship’s radio doesn’t work. ... ...
