-The first category is that of light terminals. Generally speaking, these terminals fit in the hand, they often provide a telephony service, and possibly low-speed data exchange as well. Here are two examples. The first one, illustrated here, is a Thuraya telephone. The picture on the left shows the phone, and the one on the right shows the same phone, with its satellite antenna extended. This model is a bit old, approximately 12 years old, so quite old actually. But in spite of its age, it provides many very interesting services, and above all it is a multi-technology terminal. It can be used for satellite telephony, as well as for regular terrestrial cellular telephony. When terrestrial cellular coverage is available, it can use regular networks, and when coverage is not available, extending the antenna enables it to use the satellite service. The terminal also includes a GPS receiver, and therefore can send its own GPS position, via SMS for example. Finally, the terminal can also be used for data exchange. The data exchange is indeed very slow, in this case 9.6 kilobits per second, but it is sufficient to send faxes for example. As I said, this model is a bit old, 12 years old. There are of course much more recent models. The difference with these more recent models, also provided by Thuraya, is that their interface includes a color display, the form factor is even smaller, and above all, the data exchange capabilities have evolved. Indeed, data can be sent at 15 kilobits per second, and received at 60 kilobits per second. One may ask why there is such an asymmetry between the uplink and the downlink throughputs. This is perfectly normal, remember all the link budget calculations. Indeed, the terminal's antenna is smaller and has less gain than the satellite's antenna, and above all, the terminal's transmit power is also lower. This explains the lower uplink throughput. Now you might ask how much all this costs. The terminal is roughly in the same price range as a non-subsidized smartphone. I am talking about France, where mobile telephone operators are allowed to subsidize the purchase of the terminal. We saw that the purchase cost of a terminal was approximately the price of a smartphone, and as for the usage cost, it is between 1.3 dollar and 2.5 dollars per minute to make a call. Calling the speaking clock can indeed be costly, but the advantage is that it works everywhere. This was our first example of a terminal. Our second example is a geolocation terminal, which operates using the Iridium constellation, that I already talked about in week 2. What can this terminal do? It also includes a GPS receiver, and therefore can be used to send regular location reports, containing the position of the person carrying the terminal. This position is sent via the Iridium constellation as a small message with a maximum size of 300 bytes. It travels through the Iridium constellation until it reaches one of the operator's gateways, at which point it is delivered via e-mail to the various persons having subscribed to this location report service. This is the type of service that was used by the French Civil Security Force when it was deployed as part of the Fukushima operation. To give you an idea of its form factor, the terminal weighs 184 grams, and is approximately 10 centimeters long. It is also interesting to note that if only three location reports are sent every day, the terminal's battery life lasts over two months. One last element, about costs this time, if I am in Japan, for example, sending short text messages with this terminal will cost less than if I had a French mobile phone subscription and that I wanted to send text messages via SMS. So here are two examples of terminals, one for sending location reports, so rather for data exchange, and the other for mobile telephony.