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As consolidated from stromgade @stromgade thread [the personality at SatelliteObservation.net] on this matter:

Extremely interesting interview of academician Li Deren on the future of Chinese Earth observation:

original link: https://mp.weixin.qq.com/s/-x7Du8uW-KOJwjA-0-kGxw


On the dual nature of the Gaofen satellites "a total of 14 satellites after years of research, which are what we now call high-resolution earth observation satellites, of which 1-7 are civilian satellites, and 8-14 are military satellites. These 14 satellites can be said to be a full military-civilian integration."

He confirms a resolution of 0.1m for GF-11, as expected:


GF-11: How do you say KENNEN in Chinese?
Posted on 2 August 2018 by gosnold

He also says the radar satellites reach 0.5m (presumably for the newest, GF-12), and that GF-13 has 15m resolution.

There is a lot of discussion on stereo mapping, and on reducing data latency. On the latter three examples are given:

1) tracking ships in the China Sea from LEO, and using a GEO relay sending it to users in less than one minute.

That makes the ocean surveillance constellation a very lethal system:


The Chinese maritime surveillance system
Posted on 20 September 2016 by gosnold

2) Detecting fires using a thermal IR payload and distributing the detections directly to firemen's phones using the BeiDou SMS service.

3) Adding navigation payloads to EO satellites to improve user's geolocation accuracy.


He states China is moving to an integrated PNTRC concept (Position, Navigation, TIming, Remote sensing, Communications), in three steps: first, a local coverage of the Chinese coasts with 20 LEO sats and three GEO relays, to get a revisit every 15 minutes.

Then, a regional coverage of China and the Belt & Road countries with 50 optical, 50 radar and 150 communication satellites.

Finally, a global coverage every 5 minutes, with 200 EO and 300 comms satellites.

This is very similar to the American approach led by the Space Development Agency:


The American proliferated LEO architecture
Posted on 6 June 2020 by gosnold

Thanks @luritie and @HenriKenhmann for pointing out the interview!

OP (2020.11.07):

From Henri Kenhmann at East Pendulum on 2020.11.07:

According to Li Deren, a PhD at the University of Stuttgart (Universität Stuttgart) and an academician at the Chinese Academy of Engineering and the Chinese Academy of Sciences, China has already completed tests to identify moving naval targets with its satellites, at an accuracy of 10 meters, in less than one minute.


Interviewing Li Deren (excerpt about identifying moving naval targets with Chinese satellites)...png



Information is transferred to the ground by these satellites via GEO communication satellites, then routed to “users” using 5G or fiber optic networks.

The trials are part of a program called "Earth Observation Brain" (对地观测脑).
 
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CZ-8 spotted at Wenchang for ground tests today ahead if its NET Late December test flight.


Maybe it would be better for you to post it in the following threads:-):
 
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China Telecom launches service packages for satellite communications to the public - cnTechPost
Jan 11, 2020

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China Telecom hosted the Tiantong Satellite Business Conference on Friday to formally launch satellite communications services to the public.

Tiantong satellite mobile communication system is China's first self-constructed satellite mobile communication system with wide-area coverage and all-weather communication.

It has realized the R&D and production of satellites, chips, terminals, and gateways in China, guaranteeing users' communication security, and getting rid of long-term dependence on foreign satellite mobile communication services.

The Tiantong satellite mobile communication system achieves full coverage of China's territory and territorial waters, providing users with all-weather, all-day, stable and reliable mobile communication services.

Users can use Tiantong satellite mobile phones or terminals in the satellite service area to perform voice, SMS, data communication and location services.

Tiantong's satellite business uses mobile phone numbers beginning with 1740, which has achieved interconnection with the communication networks of domestic and foreign communication operators and achieved "communication with anyone at any place in the country at any time".

At present, the Tiantong satellite service has released a consumer-facing package. At present, the monthly voice package of 100 yuan includes 60 minutes of satellite calls, and the monthly package of 300 yuan includes 20M data.

Tiantong satellite mobile phones are required to use this service. However, according to China Telecom, such phones are generally much more expensive than regular phones.

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China launches new mobile telecommunication satellite
Source: Xinhua| 2020-11-13 01:35:47|Editor: huaxia

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A Long March-3B carrier rocket blasts off from the Xichang Satellite Launch Center in southwest China's Sichuan Province on Nov. 12, 2020. China successfully launched Tiantong 1-02, a new mobile telecommunication satellite, from the Xichang Satellite Launch Center on Thursday. The satellite was launched at 23:59 (Beijing Time) by a Long March-3B carrier rocket. (Photo by Guo Wenbin/Xinhua)

XICHANG, Nov. 12 (Xinhua) -- China successfully launched a new mobile telecommunication satellite from the Xichang Satellite Launch Center in southwest China's Sichuan Province on Thursday.

The Tiantong 1-02 satellite was launched at 23:59 (Beijing Time) by a Long March-3B carrier rocket.

Tiantong-1 is a satellite mobile communication system independently developed and built by China. It consists of a space segment, ground segment, and user terminal.

Developed by the China Academy of Space Technology, the Tiantong 1-02 satellite will establish a mobile network with ground facilities to provide all-weather, all-time, stable and reliable mobile communication services such as voice, short message and data for users in China and its surrounding areas, the Middle East, Africa and other related regions, as well as most sea areas in the Pacific Ocean and Indian Ocean.

Thursday's launch was the 352nd by the Long March rocket series.

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Breaking !!

林晓弈
14分钟前 来自 微博视频
今天10时59分左右,快舟一号甲运载火箭携带着银河航天的5G试验卫星成功起飞。
Today at around 10:59, KZ-1A rocket successfully lift off with Galaxy Space's 5G experimental satellite.

Update:

China Aerospace

9 minutes ago
[The “Kuaizhou FuQiangfu” rocket successfully launched GalaxySpace first satellite] At 11:02 on January 16, 2020, the commercially labelled as "FuQiangfu" KZ-1A-Y9 carrier rocket was launched at The Jiuquan Satellite Launch Center using single rocket single satellite method to send the first satellite of GalaxySpace into a predetermined orbit, and the launch mission was a complete success. This is the first launch of Kuaizhou rocket in 2020. The first satellite of GalaxySpace launched by FuQiangfu is a low-orbit broadband communications satellite that is independently developed by GalaxySpace(Beijing) Technology Co., Ltd. and benchmarks at international advanced level. The satellite uses communication frequency bands such as Q/V and Ka, and has a transparent transmission capability of 10Gbps. It can provide users with broadband communication services through satellite terminals. After the satellite enters orbit, relevant technical and business operation verification will be carried out in orbit.

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BeiDou system passes verification standard of ICAO
Source: Global Times Published: 2020/11/17 19:31:37

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File photo of a model of the Beidou Satellite Navigation System.Photo:Xinhua

China's domestically developed BeiDou satellite navigation system, or BDS, has passed an assessment of critical standardization work at the International Civil Aviation Organization (ICAO), state broadcaster China Central Television (CCTV) reported Tuesday, citing the Chinese civil aviation authority and China Satellite Navigation Office.

Chinese analysts hailed the move as significant in the promotion of the global navigation system.

All performance indicators of the system completed expert technical verification on the Sixth Navigation Systems Panel (NSP/6) of the ICAO held from November 2 to 13, which represents the completion of the core and most important work of officially incorporating the BDS-3 into the ICAO's standards.

The technical verification of BDS-3 is the first time that a BDS civil signal has been qualified by the international organization. The ICAO has the highest requirements for global navigation satellite systems, and the verification by the ICAO proves BDS-3 has the ability to provide navigation services for global civil aviation.

Wang Yanan, chief editor of Aerospace Knowledge magazine, told the Global Times that the verification is an important step in the development of the navigation system, as global airlines can now choose, as allowed by the ICAO, to incorporate the system as a source of navigation service.

"This is important basic work. The incorporation into ICAO standards will open up more application scenarios for the BDS," Wang said. "More foreign airlines are expected to use the BDS under a cooperation framework."

It is also the first time that China's civil aviation industry has successfully promoted a domestically created and built complex system to join the ICAO standard with its own team as the core, according to the CCTV report. It builds a solid foundation for China to promote the BDS' application in the aviation sector during the 14th Five-Year Plan (2021-25) period.

According to the work plan of the ICAO navigation system expert group, the BDS-3 team provided demonstration materials, completed the verification of all technical indicators, and obtained the unanimous approval of the other three mainstream navigation systems (GPS in the US, GLONASS in Russia and Galileo in Europe) and passed the final verification process.

The ICAO navigation system expert group will report the meeting result to the Air Navigation Commission for further discussion. The BDS-3 will be officially written into ICAO standards and announced worldwide after the discussion is finished.

In June, China completed the BDS - China's largest space-based system - and commissioned the system to offer full global services in August.

As of the end of 2019, more than 6.5 million road vehicles, 40,000 postal and express delivery vehicles, 80,000 buses in 36 major cities, 3,200 inland navigation facilities, and 2,900 marine navigation facilities had adopted services from the BDS in the Chinese mainland, forming the world's largest dynamic monitoring system for road vehicles.

In the first quarter of 2020, more than 70 percent of smartphones in China used BeiDou services.
 
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The Yaogan-30 constellation is over

By CLEMENTM | East Pendulum (2020-11-23)

The Yaogan-30 constellation has already been the subject of two previous articles, but this should be the last: Following the launch of the 7th trio of satellites, the constellation now has six orbital planes distributed evenly. It has therefore reached its full capacity and its final form.

2020-11-17-20_35_25-yaogan30-STK-11-3D-Graphics-1-Earth.png

The six orbital planes of the constellation

Having only six orbital planes with seven launches might seem odd. As pointed out in a
previous article, the third and fourth launches injected their satellites into the same orbital plane, and created a “train” of five satellites that follow each other very closely. This makes it possible to have an extremely high revisit rate when this train passes over a region of interest.

A satellite out of service

The other particularity of the constellation is that one of the satellites of the sixth group is out of service, or in any case that its propulsion system is: Yaogan 30T (international designator 2020-021C) is not correctly positioned in its orbital plane. Normally the three satellites of the same plane are phased at 120° from each other, to maximize the coverage of the constellation. On the other hand, Yaogan 30T and 30S are currently very close to each other, which makes one of the two redundant.

The one with the problem is Yaogan 30T, as can be seen in this graph comparing the orbital elements of the sixth group.

The 30T satellite has not made any maneuvers since it first came into orbit, and therefore performs more revolutions per day around the Earth than the other two. This means that its position in the orbital plane is constantly changing, and the fact that it is currently close to 30S is only a coincidence. It will move away in the course of time.

We can compare with what happens in the case of a group whose three satellites are perfectly functional, as is the case for the last launch.

The satellites were launched together and therefore at the beginning the curves are confused. Then they used their thrusters to maneuver and each has a different number of revolutions per day. This allowed them to position themselves on a different sector of the orbit. They let this position drift until the 120° phase between the satellites was reached, then froze their orbital configuration by maneuvering again so that they all had exactly the same number of revolutions per day. This ensures that they stay in sync in their orbit.

It is possible that China will end up replacing the satellite that is out of service, because that would improve the coverage offered by the constellation, making it more regular with fewer interruptions. This would be a good opportunity for one of the new small Chinese launchers like the CZ-11 rocket, since a single Yaogan-30 type satellite represents a small payload.


Coverage

Speaking of coverage, let's take a look at what the constellation can do. Given its inclination, it is optimized to observe the environment close to China, in particular the approaches to its Pacific coast. Taipei, the capital of Taiwan, is therefore a very representative area of interest, especially since the recent rearmament efforts of the Republic of China with the United States have heightened tensions in the region.

Based on the 3D models of the satellites that Chinese TV broadcast, they don't appear to carry radar or imaging systems, so they are probably used for electronic intelligence, possibly with a communications function as well. These types of sensors generally need to see their target at an angle of incidence of at least 5°. Based on this assumption, we can calculate the coverage of Taipei over a 24 hour period:

radio - In cyan, the periods of coverage on Taipei by Yaogan-30 Constellation.jpg

In cyan, the periods of coverage

We see that the coverage is almost constant, with the longest interruption lasting around 30 minutes, and most of the interruptions lasting 10 minutes every half hour. The following video shows satellite position and coverage opportunities (in the form of a purple link between the satellite and the ground):

Yaogan-30 coverage of Taipei

However, if we assume that the satellites carry an imaging payload, then the constraints on the angle of incidence are greater, which reduces the coverage. By taking 30° as the minimum angle of incidence, it then becomes:

image - In cyan, the periods of coverage on Taipei by Yaogan-30 Constellation.jpg

In cyan, the periods of coverage

The result is much more sparse, which is quite logical because each satellite must be much higher above the horizon to take an image. However, there is still a very high revisit rate with imaging opportunities every 30 minutes. This allows almost permanent cover, and would give China the ability to track the mobile military assets of its adversaries such as missile batteries or ships.

Plans for the future

This revisit rate is already the highest among all known constellations in China or elsewhere, but China does not intend to stop there, as academician Li Deren explains in a
recent interview:

“The FIRST step is to provide local coverage from the South China Sea to the North China region. This requires around 20 remote sensing satellites and 1 to 3 communication satellites in geostationary orbit to achieve a time resolution of 15 minutes. High-resolution target images and sub-meter navigation and positioning accuracy are sent to users' mobile phones and other smart terminals;


The SECOND step is regional coverage of China and neighboring countries along the Belt and Road. This requires a hundred remote sensing satellites. Among them, half of the remote sensing satellites are optical satellites and the other half are radar satellites to ensure the broadcasting of images by day and night, plus 150 communication satellites;

The THIRD stage is global. To achieve a global service, it is estimated that 200 remote sensing satellites and 300 communications satellites will be required. The service index is the 5-minute time resolution, i.e. the required image target is found within 5 minutes, the resolution and navigation accuracy reach 0.5 m, and the processing and communication time in orbit is less than one minute before being delivered to the user's mobile phone.”

Yaogan-30 is the first step, with 21 satellites optimized for the Chinese coastline. However, it does not hit a revisit every 15 minutes, so Mr. Deren may be talking about another constellation that will be launching in the near future. The use of geostationary satellites as relays, in order to minimize the latency of the system, can however already be implemented on Yaogan-30.

Li Deren also explains that future developments will bring together the traditionally separate functions of communication, Earth observation and positioning in a single system, and that the data will be sent directly to end-user phones to minimize latency and maximize their impact:


«Perceived data will be processed intelligently to provide users with the PNTRC function, P representing position, N navigation route, T time, R remote sensing image, and C communication, i.e. this information can be sent to the receiving device in your hand.«

This plan resembles the U.S. ambitions to develop a multi-layered military constellation for communications, ballistic missile warning and Earth observation. Given the extent of Chinese investment in the field, there is no doubt that they will be able to develop an equivalent system, and that therefore we have not finished hearing about large constellations of Chinese satellites.


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About the Author:

CLEMENTM
is an amateur astronomer in his spare time, also passionate about the space sector, especially Earth observation. He has a blog (in English) on the subject: http://satelliteobservation.wordpress.com and also a twitter account: https://twitter.com/stromgade
 
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CZ-8 spotted at Wenchang for ground tests today ahead if its NET Late December test flight.



Reportedly the stage 1 is modified to be reusable featuring powered vertical landing with deployable landing legs. The YF-100 need to be modified to allow for deep throttling. The strap-ons will stay attached for landing.

 
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