1. satellite internet of things, in layman's terms, is to do internet of things projects through satellite communication. Generally, Internet of Things projects are completed through the 2G/3G/4G network, but for some special projects, because the signal of the 2G/3G/4G network is not good or can not be used, the data collected by the Internet of Things terminals must be sent back to the background by satellite communication, such as desert areas, oceans or some remote no-man's land.

2.？ Commercialization problem

It has been used commercially in China. I can share a project we have done.

Project background

Monitoring the transport fleet in Gobi desert area mainly collects the positioning information of vehicles, and can realize one-button alarm in case of emergency. Based on the location information, some functions such as equipment management and geofencing are developed on the platform side. Generally speaking, the customer requirements are not complicated. The main difficulty is that the ground network signal is not very good, and there is no signal at all in a large area. It is necessary to consider satellite communication to ensure the transmission of information.

Satellite communication tariff

We have inspected several satellite systems: Beidou (short message), Iridium satellite module and Inmarsat, and they are not very satisfied. Satellite communication is the cheapest way to transmit location information through Beidou SMS. At present, the Internet access fee is 600 yuan, and the traffic fee is 850 yuan for one year (not limited to sending messages casually within one year), but it is said that the hardware stability is not very good, and foreign signals are still unstable; Iridium satellite communication costs are a bit high, 10 yuan/1000 bytes; Finally, under the recommendation of a friend, I found the agent of ORBCOMM in China, because it is said that ORBCOMM mainly makes low-orbit satellites, and the communication fee is relatively cheap. In fact, it is not much cheaper. The satellite communication fee they gave was 9 yuan/1000 bytes. But they put forward another idea: dual-link communication between 2G network and satellite network. When there is a ground signal, you can send data through the 2G network to realize the Internet of Things card. When there is no terrestrial network, data can be transmitted by satellite, so the overall tariff is cheaper. According to our calculation, sending a positioning message through ORBCOMM satellite is about 10 bytes, which means that 1 message is converted into 1 cent, which is basically acceptable.

Power supply problem

Because our equipment is used in the car, we get power directly from the cigarette lighter on the car, but considering that the car will turn off in an emergency and the rescue equipment needs to work continuously, we have a built-in battery. Don't disclose the battery capacity yet. Under normal circumstances, a single battery can supply power for 5-8 days, and there is no problem for 3-4 days in an emergency (in an emergency, the frequency of equipment sending information has increased).

Answer the above question: If you want to send data by satellite at high frequency, you must have a stable power supply. However, in specific projects, the situation is different. For example, our equipment sends information by satellite every 20 minutes by default, and each transmission is about 50mAh. As far as I know, some satellite positioning devices installed on containers (containers running at sea) send a message every day, so that a small solar panel can ensure power supply.

Signal problem

At present, a basic condition of all satellite communication is that the terminal antenna needs to establish a direct line with the satellite, that is, there can be no shielding in the middle, and once there is shielding, it can not be connected. In this case, the city is definitely useless, and it is not very useful in the city. There is no problem in using satellites in remote Gobi desert and at sea.

Hardware equipment size

You may be curious? How big a device does it take to receive such a weak signal? Let me put some pictures.

Look at our terminal equipment first:

Shenzhen new space-time intelligent system co., ltd.

The antenna is the key:

Roof-mounted satellite antenna

The satellite host integrates GPS and satellite communication module. In order to transmit information through the ground network, a 2G vehicle-mounted locator (this is cheaper) is also set up. As the master device, the 2G positioning device is connected with the satellite module through the 232 protocol. When the ground network cannot be searched, data will be sent through the satellite terminal. On the project of space-based Internet of Things, welcome to discuss!