Design and Development of Ground Station Network for Nano-Satellites, Thailand Ground Station Network

Transcription

1 Design and Development of Ground Station Network for Nano-Satellites, Thailand Ground Station Network Apiwat Jirawattanaphol 1,2,a, Suramate Chalermwisutkul 1, and Phongsatorn Saisujarit 1 1 King Mongkut's University of Technology North Bangkok, Bangkok, Thailand 2 Laboratory of Spacecraft Environment Interaction Engineering Kyushu Institute of Technology, Kitakyushu, Japan a apiwatjira26@gmail.com (Corresponding author) Abstract Thailand ground station network is designed to support the communication systems of CubeSats by connecting the four ground stations of each member via internet to increase the communication time between the ground stations and the satellites. Thus, the network operation can increase the downlink data throughput. During the operation time, each ground station shall access the operation schedule pre-programed in the network server, and uplink a set of command to the CubeSats, as well as receive mission data from them by using the satellites tracking system. Later, the received mission data will be stored in the network server database for further post processing and analysis. Keywords: CubeSat, Satellite Communication, Satellite Ground Station, Ground Station Network 1. Introduction KNACKSAT [1] is a CubeSat project under development by the students and faculty members of King Mongkut s University of Technology North Bangkok (KMUTNB). The project was initiated in 2012 with a financial support from the Office of National Broadcasting and Telecommunications Commission of Thailand (NBTC) to design and fabricate a 1U nanosatellite named KNACKSAT carrying a digital camera as the main payload which is planned to be launched from the Dnepr rocket in the fiscal year At the same time, Thailand has other two nanosatellite projects with JAISAT-1, a project of the Radio Amateur Society of Thailand (RAST) and STEP-1 project of SpaceBox laboratory [2]. To enhance the communication from the satellites to multiple ground stations in Thailand using UHF/VHF amateur radio bands, Thailand ground station network is planned. 2. Thailand Ground Station Network Thailand ground station network aims to connect four ground stations in Thailand together via internet. The ground station network can increase the reliability of the downlink as well as the data throughput from the satellites. Moreover, Thailand ground station network will lead to more contributions and interest in satellite projects as well as in the Thai space program. The current Thailand ground station network members are King Mongkut's University of Technology North Bangkok (KMUTNB) with the ground station in Bangkok, The Radio Amateur Society of Thailand (RAST) with the ground station in Bangkok, PSU Witthayanusorn school (PSUWit) with the ground station in Hatyai and Thailand DX Association (HSDXA) with the ground station in Phitsanulok. Currently, the ground stations of RAST and PSUWit have been installed, whereas the other ground stations are under development. Figure 1 shows the locations of the ground stations in the Thailand ground station network.

2 Fig. 1. Locations the ground stations in the Thailand ground station network 3. System Architecture and Design Thailand ground station network architecture includes three main parts: Ground Station PC at each ground station, the Network Server and the Mission Control Center. Figure 2 shows the architecture of Thailand ground station network Ground Station PC (GS PC) at each ground station shall be connected with a Software Define Radio (SDR) module to receive a mission data from the satellites and transfer the received mission data to the Network Server. Moreover, the ground station PC shall access to the operation schedule in the Network Server for the ground station operation. Network Server (NS) is working as a database which collects the downlink mission data received from each ground station PC and to store the ground station operation schedule to control each ground station to send telecommand to the satellites. Mission Control Center (MCC) can access to the mission data and program the ground station operation schedule into the Network Server. Fig. 2. Architecture of Thailand ground station network

3 Conference Proceedings The 8th Thailand-Japan International Academic Conference Ground Station Hardware Configuration Figure 3 shows the proposed ground station hardware configuration for Thailand ground station network. The proposed ground station configuration can support the operation of KNACKSAT and other nanosatellites that use UHF/VHF amateur radio bands in the Low Earth Orbit (LEO) with a capability to decode and encode mission data from satellites using AFSK, FSK and GMSK modulation. The ground station PC is connected as a network with a central server via the Internet. Fig. 3. SDR-based ground station design for the members of Thailand ground station network The RTL-SDR [3] is a Software Define Radio (SDR) module that uses a DVB-T TV dongle based on the RTL2832U chipset. The RTL-SDR has an operating frequency range from 24 MHz to 1766 MHz with all mode reception features CW/FM/SSB and a 2.4 MS/s sampling rate. The RTL-SDR works as a radio receiver to receive the radio frequency signal, then converts it to the I/Q data before passing this to the ground station PC. Fig. 4. The RTL-SDR Software Define Radio module The Low Noise Amplifier (LNA) is design using a MGA GaAs MMIC amplifier which supports the frequency range from 435 MHz to 438 MHz with a built-in band pass filter for the 70 cm amateur radio band. Fig MHz band Low Noise Amplifier Circuit

4 Conference Proceedings The 8th Thailand-Japan International Academic Conference 2016 ADF7021 [4] is a narrow band transceiver which can operate in the frequency range from 80 MHz 650 MHz. This module has a capability to transmit the Frequency Shift Keying (FSK) modulated data with Gaussian and raised cosine filtering at a maximum RF output power of 13 dbm. This transceiver module has been used in on-board the communication systems of OUTFI-1, AAUSAT3 and ESTCube1 CubeSat projects which have already been launched and are operating in space. KNACKSAT project will also use this transceiver module on-board of the 1U nanosatellite. So, the ground station design using this module shall be able to communicate with the aforementioned CubeSats operating already in space. Fig. 6. Narrow-Band Transceiver ADF Ground Station Software Configuration Fig. 7. Orbitron tracking software The proposed ground station software architecture consists of a tracking software, a Software Define Radio (SDR) control software and a radio modem software. The Orbitron satellite tracking software [5] is used to control the ground station hardware such as the antenna rotor and the Software Define Radio (SDR) module. The Orbitron software can access to the satellites Two-Line Element (TLE) orbital data from NORAD. By that means, Orbitron predicts the real-time satellites trajectory using NORAD SGP4/SDP4 prediction model. During the pass, Orbitron sends the signal automatically to control the antenna rotor via serial port communication (RS-232). At the same time, Orbitron makes a Doppler shift frequency correction by tuning the frequency of the Software Define Radio module.

5 Fig. 8. SDR# Software The SDR# software is a free receiver control software for Software Define Radio module. The standard SDR# software feature includes a standard FFT display and waterfall, recording plugin, a frequency manager and a digital noise reduction plugin. SDR# can also perform automatic Doppler shift frequency correction by exchange its data with the Orbitron tracking software. Fig. 9. UZ7HO SoundModem and High-Speed SoundModem software The UZ7HO SoundModem and High-Speed SoundModem software [6] is a software packet radio Terminal Node Control (TNC) that uses a computer soundcard as a radio modem and supports AX.25 protocol. The SoundModem can work with AFSK, QPSK and BPSK modulation at a maximum data rate of 4,800 bps and the High-Speed SoundModem software can work with the G3RUH and GMSK modulation at a maximum data rate of 19,200 bps. 4. Experiment Result The experiment was done using the ground station system similar to that in Fig.3. The first test has been done by tracking and receiving signals from HORYU-IV and XI-IV satellites during the pass and complete receiving the signal with a good result. The second test has been done by receiving the signal from a table satellite transmitter which transmits AFSK signal at 1,200 bps data rate and FSK as well as GMSK signals at 9,600 bps data rate.

6 5. Conclusions Thailand ground station network is proposed and designed to support the CubeSats communication systems using UHF/VHF frequency band by connecting the four ground stations of each members via internet in order to increase the communication time between the ground stations and the satellites. With Thailand ground station network, the downlink reliability and the data throughput can be significantly improved. References [1] P. Saisujarit, S. Srikitsuwan, S. Chotichanthawewong, D. Saentawee, T. Inmori, S. Kuntanapreeda, CubeSat Project for Space Technology Demonstration in Thailand, in Nano-satellite symposium., Tokyo, Japan, 2013 [2] SpaceBox STEP-1 project proposal., [Online], Available: [3] RTL-SDR specification, [Online], Available: [4] High Performance Narrow-Band Transceiver IC- datasheet, Analog Device.,2014 [5] S. Stoff. (2007). Orbitron Tracking software Available HTTP: [6] UZ7HO SoundModem, [Online], Available: