Source: China Radio Management
Author: Liu Mingxing, Zhao Zhe, Zhang Ning
Building on our analysis of China's first amateur satellite, this article examines the current in-orbit amateur satellites, retired amateur satellites, and future planned amateur satellites operated by China. It summarizes the key characteristics of China's development of amateur satellite activities.
- Our domestically launched amateur satellites
According to the amateur satellite communication records provided on the AMSAT website, there are currently 10 amateur satellites in orbit from China, namely the XW-2 series, the CAS-4 series, LilacSat-2, and FMN-1. Please see Table 1 for details.
The operators of these satellites include amateur satellite organizations, commercial companies, and universities. The wide range of participating entities provides numerous opportunities and platforms for engaging in related activities.
1.1 The XW-2 （CAS-3） series of satellites
At 7:01 AM on September 20, 2015, the Hope-2 series satellites launched from the Taiyuan Satellite Launch Center. The series consists of a total of six satellites, including two 20 kg CubeSats （1）, three 10 kg CubeSats （CAS-3A）, and two 1 kg CubeSats （2）.
（CAS-3B/3C/3D） XW-2A satellite
The XW-2A （3） satellite carries a U/V mode, 20 kHz bandwidth linear forwarder, and operates on a sun-synchronous orbit at an altitude of 400 km.
Figure 1: Schematic diagram of the XW-2A satellite
（CAS-3E/3F） XW-2 B/2C/2D satellite
The XW-2B/2C/2D （CAS-3H） are a set of identical satellite constellations, each equipped with a U/V mode 20kHz linear transmitter and operating on a sun-synchronous orbit at an altitude of 500km.
Figure 2: Schematic diagram of the XW-2B/2C/2D satellite
（CAS-3H） XW-2E/2F satellite
The XW-2E/2F （FENGMANIU-1） are two small satellites, each equipped with a U/V mode 20 kHz linear transmitter, operating on a sun-synchronous orbit at an altitude of 500 km.
Figure 3: Schematic diagram of the XW-2E/2F satellite
The figure below shows the forwarder frequency configuration for the Hope-2 series satellites.
Figure 4: Schematic diagram of frequency configuration for the XW-2E series satellites
The repeaters for the XW-2 series satellites operate in the VHF/UHF frequency band (145/430 MHz), which is widely used by amateur radio enthusiasts. All satellites in this series are equipped with identical linear repeaters and a single, quarter-wave whip antenna. Each satellite has one UHF antenna and one VHF antenna, as shown below, along with the detailed frequency scheme.
Table 2: Desired uplink frequencies for the "Hope-II" series satellites
Table 3: Desired downlink frequency configuration for Satellite No. 2
The Hope-2 series satellites are designed with an integrated approach, standardizing on-board electronic equipment, making onboard devices universally compatible, and eliminating cables within the satellite. Relevant Chinese institutions have explored and implemented the initial application of Picosatellites through the development of the Hope-2 series, achieving in-orbit autonomous management and multi-mode heterogeneous backup technologies for Picosatellites. This has led to the establishment of a standardized and universal Picosatellite product system and standard protocols, laying the foundation for the subsequent development and use of application-oriented Picosatellites.
1.2 LilacSat-2 (BP-1B) satellite
The LilacSat-2 （CAMSAT） satellite, also known as LilacSat-2, was developed by Harbin Institute of Technology. It carries an FM forwarder operating in the V/U frequency band and is currently in operation on a sun-synchronous orbit at an altitude of 500 km. LilacSat-2 and the XW-2 series satellites were successfully launched using a single Long March 6 rocket, achieving a "two-star" launch configuration. The image below shows a schematic diagram of the star-on structure and functional modules of LilacSat-1.
Figure 5: Starboard view of the Purple Jasmine-1 satellite
The A-type test and control transceiver is a V/U software radio transceiver that uses an IQ zero-frequency/low-frequency architecture, enabling multi-channel transmission and reception, as well as flexible configuration and switching of various RF parameters. It also includes a multi-mode amateur radio forwarder based on this platform. The downlink modes include: 1.2/9.6 kbps BPSK, 1.2 kbps MSK, 1.2 kbps AFSK, and FM, with a maximum output power of 27 dBm; the uplink mode includes AFSK and FM. The B-type test and control transceiver is an FSK transceiver in the L/U frequency band, which can operate in full duplex mode. Its downlink data rate is 1.2/4.8 kbps, with a maximum output power of 27 dBm.
The Purple Mountain No. 1 satellite's primary purpose is to build an in-orbit test platform for flight software, used to analyze the effects of single space particles on FPGA software functionality and performance. The satellite also uses onboard electronic devices to perform tasks such as global aircraft ADS-B status information monitoring and tracking of large wild animal movements. Additionally, the satellite carries an industrial infrared camera to explore the feasibility and effectiveness of using nanosatellites for ground environment monitoring.
Figure 6: Structure diagram of Purple Jasmine-1 satellite
The radio system of the Purple Jasmine 2 satellite includes transceivers A and B, a GPS/BD2 receiver, a wideband receiving module, and associated antennas, as shown in the diagram.
Figure 7: Block diagram of the Purple Jasmine-1 satellite's radio system.
The UHF band antenna for the Purple Jasmine No. 1 satellite consists of a dual-polarization, omnidirectional array made up of four tilted 1/4 wavelength dipole antennas; the VHF and AIS antennas use 1/4 wavelength patch antennas made from titanium nickel alloy material; the L-band and BG2/GPS antennas use microstrip antennas.
The special feature of Purple Jasmine No. 1 lies in the fact that it was designed and built by 15 university students from Harbin Institute of Technology, which is a beneficial experiment involving primary and secondary school students in space exploration.
1.3 CAS-4 series satellites
The CAS-4 (ZhuHai-1/2) series consists of amateur payloads carried on remote sensing satellites. Currently, there are two CAS-4A/4B satellites in orbit. The CAS-4A and CAS-4B are two remote sensing satellites on the ZhuHai-1 constellation, OVS 1A and OVS 1B, which were launched on June 15, 2017, and operate on an inclined orbit at an altitude of 500km. These small satellites are equipped with linear transponders in the U/V band (downlink: 145MHz frequency band / uplink: 435MHz frequency band), and they also perform optical remote sensing tasks.
The downlink frequency of the CAS-4A linear forwarder is 145.87 MHz, the uplink frequency is 435.22 MHz, and the telemetry frequency is 145.835 MHz; the downlink frequency of the CAS-4B linear forwarder is 145.925 MHz, the uplink frequency is 435.280 MHz, and the telemetry frequency is 145.890 MHz.
Figure 8: Simulated image of the "Zhuhai No. 1" satellite.
The two CAS-4 series satellites were launched by private space agencies, and their distinguishing feature is that they are carried on a remote sensing satellite. This represents another beneficial experiment.
1.4 FMN-1 （BIT） satellite
On February 2, 2018, at 15:51, the first privately-owned satellite developed in China was successfully launched from the Jiuquan Satellite Launch Center. Feng Lun, chairman of Wind Horse Capital and initiator of the project, stated that he hopes to achieve integration between satellites and mobile phones through "Wind Horse No. 1," exploring new ways for media interaction. The dimensions of "Wind Horse No. 1" are 300mm in size.100mm100mm, similar in size to a shoe box, weighing 4 kg, and consuming 8W of power. It is equipped with a 4K high-definition panoramic camera that can display 360-degree space HD photos. The "Fengma Niu No. 1" satellite is an attempt to explore new applications in the space business. This satellite carries amateur radio payloads, providing a communication platform for enthusiasts worldwide, with uplink and downlink frequencies of 145.945MHz and 435.35MHz respectively.
Figure 9: Simulated image of the "Feng Ma Niu No. 1" satellite.
"风马牛一号" is the first satellite to use satellites as a medium, with content delivery as its core function. The satellite will also carry a children's choir version of "Thousand Character Classic" into space. Once in orbit, in conjunction with ground-based receiving equipment, it can receive real-time imagery. In addition to applications and exploration for media, it will also promote public welfare and aerospace education.
Figure 10: Simulated image of the "Fengma Niu No. 1" satellite.
"Fengma Niu No. 1" was the world's first panoramic satellite, and as the first satellite-based media platform, it brought "both distance and proximity" to the public. Through scientific technology, it overcame the barriers of time and space, allowing the public to receive images and sounds from distant outer space. However, it did not create a sense of distance or reduce public participation; instead, as a new media platform, it stimulated public interest through novel content. Before the launch of the satellite, the Fengma team launched a campaign to collect "dream voices," and the collected blessings would be sent up with the satellite, travel around the Earth, and then return to the ground. This event alone involved over 1,000 people.
The success of the "Wind Horse No. 1" satellite is largely due to China's rapid development in civilian space technology. The project also focuses on public benefit and aerospace education, creating a virtuous cycle. The Wind Horse team has developed proprietary hardware for receiving satellite signals, and collaborates with leading domestic youth aerospace education institutions to create a series of courses and activities based on satellite signal reception. This aims to activate the interest of the general public, especially children, in the field of aerospace, maximizing the social significance and value generated by the satellite.
- Our retired amateur satellites
The development of amateur satellite activities in China has been rapid, and several satellites have already retired, including the CAS-2, CAS-6, and CAS-7 series. Details are provided below.
2.1 CAS-2 series satellites
The planned launches of the CSA-2A1 and CSA-2A2 satellites, originally scheduled for 2015, have been replaced by satellites from the CAS-3 series. Specifically, the CAS-2T satellite (also known as the Futong Shanyao No. 1 satellite) is a satellite equipped with experimental amateur radio payload technology.
Figure 11: Schematic diagram of the Fengtai No. 1 satellite
2.2 CAS-6 Satellites
CAS-6 (Tianqi-1/TQ-OSCAR-108/TO-108) is a gravitational wave detection experimental satellite carrying amateur radio payloads. It was launched on December 20, 2019. The satellite was built by the Dongfang Satellite Company for Zhongshan University and Huazhong University of Science and Technology. Its dimensions are 490mm x 499mm x 430mm, its weight is approximately 35kg, and it carries a VHF-band CW remote telemetry beacon and a linear forwarder with a bandwidth of 20kHz and an atmospheric wind detector (Atmospheric Wind).
Figure 12: CAS-6 satellite test diagram
The Long March 11 carrier rocket, which was launched on CAS-6 satellite, marked China's first attempt at launching a satellite from the sea and was a significant milestone.
2.3 CAS-7 Satellites
CAS-7B （APSCO） is an amateur radio satellite that combines education with space exploration. The China Amateur Satellite Group （CAMSAT） is collaborating with the Beijing Institute of Technology (BIT) to provide support for launching the satellite, and many faculty and students at BIT are involved in the development and testing of the satellite. CAS-7B was launched into its designated orbit in late July 2019.
With the support of CAMSAT, Beijing Institute of Technology established a hobby radio club (call sign: BI1LG). Through studying related knowledge of amateur radio satellite communication, university students not only experienced endless fun but also developed a passion for space exploration. This provided them with practical experience that would be beneficial for their future studies.
Figure 13: CAS-7 satellite experiment diagram
CAS-7B is a 1.5U CubeSat satellite. One side of the satellite is covered with a soft, thin film sphere with a diameter of 500 mm and a mass of approximately 3 kg. The satellite maintains its stability by passively controlling its orbit using an aerodynamic drag sail. The satellite operates on a 300 km circular orbit with an inclination of 42.7 degrees. The satellite is equipped with VHF antennas: a monopole antenna with a quarter-wavelength, maximum gain of 0 dBi, located on the +Y side; two monopole antennas in the UHF band with a quarter-wavelength, maximum gain of 0 dBi, located on the -Z and +Z sides. CW telemetry beacon frequency: 435.715 MHz/20 dBm, V/U frequency hopping transceiver downlink: 435.690 MHz/20 dBm, bandwidth 16 kHz, V/U frequency hopping transceiver uplink: 145.900 MHz, bandwidth 16 kHz.
Figure 14: Flight performance of CAS-7 satellite
As a scientific and technological verification microsatellite, the "Beihang 1" satellite successfully completed two innovative research validation tasks: the "Sailball" technology and the new space radio technology. Notably, this is the first time that China has used and validated space "Sailball" technology in an orbital mission.
"Sailball" technology and the related flexible, lightweight spacecraft technology involve storing flexible materials within a satellite's compartment in a folded state. Once the satellite is successfully launched into orbit, the flexible material is released and expands to form a spherical shape. The volume of the spherical structure is several times larger than that of the satellite, effectively acting as a sail for the satellite. In the future, "sailball" technology will directly serve deep-space exploration missions such as small celestial body detection. The backup satellite for BP-1B, BP-1A, is expected to be launched in 2021.
- Subsequent amateur satellites in China
3.1 CAS-5 Satellite System
The CAS-5 series consists of two satellites, CAS-5A and CAS-5B, originally planned for launch in 2018. CAS-5A is a 6U CubeSat, and the following amateur radio payloads are planned to be carried:
Among the transponders mentioned above, except for the H/U mode transponder with a bandwidth of 15 kHz, all other transponders have a bandwidth of 30 kHz. The plan is to deploy them in a sun-synchronous orbit with an altitude of 530 km and an inclination of 97.5 degrees.
Figure 15: CAS-5A satellite simulation
The CAS-5B satellite is a femto-satellite, weighing only 0.5 kg, and is part of the Femto-Satellite project. It carries a CW beacon in the UHF frequency band and is deployed alongside the CAS-5A satellite.
3.2 CAS-8 Satellites
The planned CAS-8 satellite system is a student microsatellite project initiated by the Asia-Pacific Space Cooperation Organization (APSCO). APSCO was established in 2008 and is a government-to-government organization headquartered in Beijing, with member countries including Bangladesh, China, Mongolia, Pakistan, Peru, Thailand, Turkey, and Indonesia. The CAS-8 satellite project consists of four satellites, including two 30 kg microsatellites, one experimental microsatellite CAS-8A for technology verification, and one primary microsatellite CAS-8B, as well as two 3U CubeSats, CAS-8C and CAS-8D.
The CAS-8 satellite project, led by the Beijing University of Aeronautics and Astronautics, is collaborating with China Amateur Satellite Organization (CAMSAT). This collaboration will integrate amateur radio into the project, and together, they will lead the remaining 7 member countries of the Asia-Pacific Space Cooperation Organisation to complete the project.
CAS-8A includes a V/U linear repeater, a CW beacon in the UHF band, an AX.25 4k8/9k6 GMSK remote beacon, and a downlink link for S-band 192kbps GMSK image and 4k8/9k6 GMSK remote data.
The expected frequencies for the four satellites are:
CAS-8 will be the first amateur satellite in China to establish an interplanetary link. It represents a new experiment, accumulating experience for future amateur constellations. The CAS-8 project aims to provide students and teachers from member countries of the Asia-Pacific Space Cooperation Organization with a platform for learning space technology and practicing satellite engineering. Through the design, development, in-orbit testing, and application of small satellites, the project will enhance the aerospace education level of member countries and contribute to building a "Belt and Road" space information corridor with member countries of the Asia-Pacific Space Cooperation Organization.
Furthermore, CAS-8 will enable the synergistic effect of the eight APSCO member states through the amateur radio alliance established via space cooperation. This will provide new educational tools for young students in APSCO member countries to conduct self-training, mutual exchange, and technical investigations. It will also offer a new satellite platform for amateur radio enthusiasts worldwide.
- Summary
Based on the development history of amateur satellites in China, Chinese amateur satellites are still in the stage of technological exploration and accumulation. They primarily involve integrating amateur satellite transponders onto commercial satellites, providing a platform for enthusiasts to communicate.
From the perspective of participating units in amateur satellite projects, there are both amateur satellite organizations and research institutions such as universities. This indicates that the advanced nature and exploratory aspects of the technology have significant importance.
Currently, the development of amateur satellites in China is relatively good. Many commercial satellites carry payloads developed by amateur satellite enthusiasts, but the strong commercial atmosphere may hinder enthusiasts' exploration of space communication technologies.
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