Tiantong Satellite

News Excerpt: 

Chinese scientists have developed the world's first satellite capable of enabling smartphone calls directly without the need for ground-based infrastructure such as mobile towers.

About the news:

  • The deployment of the Tiantong-1 series involves launching three satellites orbiting synchronously at an altitude of 36,000 kilometers. This has the potential to revolutionize communication across the Asia-Pacific region, from the Middle East to the Pacific Ocean.
  • However, the realization of direct satellite connectivity for mobile phones posed formidable technical challenges, particularly concerning passive intermodulation (PIM) interference. 
  • PIM has plagued commercial communication satellite networks, hindering further technological advancements. In response, Chinese scientists spearheaded groundbreaking research to mitigate PIM effects.

What is PIM?

  • PIM is interference resulting from the nonlinear mixing of two or more frequencies in a passive circuit. If the interference coincides with a network’s base receive frequencies, it can cripple network performance.
  • PIM lowers the reliability, capacity and data rate of cellular systems.
  • PIM is a growing issue for cellular network operators. PIM issues may occur as existing equipment ages, when co-locating new carriers, or when installing new equipment. PIM is a particular issue when overlaying (diplexing) new carriers into old antenna runs.
  • PIM can create interference that will reduce a cell’s receive sensitivity or even block calls. This interference can affect both the cell that creates it, as well as other nearby receivers.


  • Named after the Chinese term for “connecting with heaven,” reminiscent of the biblical Tower of Babel, the project symbolized a commitment to enhancing communication resilience in the face of adversity.
  • The idea is, that in the case of an emergency where mobile connectivity may be severely impacted because of a natural calamity or any other disaster, people can call for help directly, by connecting to an overhead communication orbiter.
  • The idea for such a satellite came about after 2008, when Sichuan, a province in southwestern China, was struck by a devastating magnitude-8 earthquake, resulting in the tragic loss of over 80,000 lives.
  • What made the situation far worse back then was the communication breakdowns in affected areas, which in turn severely hindered rescue operations, thus compounding the crisis.
  • In response to this disaster, the Chinese government started the Tiantong Project, a satellite communication system. 
  • The purpose of the satellite is to provide universal access to communication services irrespective of socio-economic status.

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