Get to Know China’s Tiantong Satellite: You Can Make Calls Without a Cell Signal

Morrissey Technology – An earthquake with a magnitude of 8 that occurred in Sichuan, China, inspired the Chinese government to create the Tiantong Project. This project is a communications satellite system that can overcome telecommunications problems in areas experiencing disasters. The reason is, when the earthquake occurred in Sichuan, communication networks in many cities in China were also affected.

For this reason, the Chinese government has started implementing the Tiantong project, which aims to provide communication access without the need to rely on cellular signals. Tiantong means “connected with heaven”, which refers to the story of the Tower of Babel in the Bible.

The project, which was initiated in 2008, has actually been launching its satellites since August 2016, where they launched the Tiantong-1 satellite, and this was followed by the launch of the 2nd and 3rd satellites in 2020 and 2021.

The three satellites form a network in geosynchronous orbit at an altitude of 36 thousand km, covering the entire Asia Pacific, from the Middle East to the Pacific Ocean. However, only at the end of last September was a cellphone that supported connectivity with this satellite, which was released by Huawei. Then Huawei’s steps were followed by other Chinese cellphone FOR4D brands such as Xiaomi, Honor and Oppo, which offered direct connections to the Tiantong satellite.

These products are in demand by consumers in China, Huawei cellphone sales are estimated to have reached 10 thousand units. Much higher than Starlink internet service subscribers, which only reached 2 million subscribers.

Using this satellite is not free, but the subscription fee is relatively cheap. That is 10 yuan or around IDR 22 thousand per month. Users can make calls to any number even if their cellphone is not connected to a cellular signal.

“Direct connectivity to satellites for mobile phones is becoming a new development trend, and satellite communications will gradually become popular with the general public,” wrote a team of satellite researchers from the China Academy of Space Technology, in a paper published in Aerospace Science and Technology.

However, please note that cellphone communication with this satellite was previously considered impossible, especially with the large number of active cellphones on Earth. The reason is that to be caught on a small cellphone antenna, the satellite needs to “shoot” a very strong signal.

When there are many signals with strong waves on the earth at the same time, each signal will interfere with each other and disrupt the communication path, which is known as passive intermodulation (PIM).

This problem was then able to be solved by the research team from the Tiantong project using various technologies. One of them is the most sensitive PIM FOR4D detection technology, which can determine the location where PIM occurs.

This allows the satellite to obtain very high signal capture sensitivity, and can capture signals from cellphones without an external antenna.