CP‐SAR Onboard Aircraft

Fig. . Ground station for our microsatellite CP‐SAR

3. Microsatellite CP‐SAR

Fig. shows model of CP‐SAR onboard microsatellite Microsatellite CP‐SAR, kg class that developed in Josaphat Microwave Remote Sensing Laboratory JMRSL , Center for Environmental Remote Sensing, Chiba University. We proposed meshed parabolic antenna to reduce weight of SAR system to realize class SAR onboard microsatellite. Fig. shows deployment experiment of meshed parabolic antenna of Microsatellite CP‐SAR. Fig. 8 shows microsatellite is composed by Command and Data andling Sub‐system CDS , Communication Subsystem CMS , Electrical Power Subsystem EPS , Altitude Control Subsystem ACS and payload. CDS uses Leon card, low power supply card LVPS , O card, payload O card, and non‐volatile memory card. CMS is composed by LVPS, low power supply card, S band transmitter receiver STX and SRX and antenna for telemetry, X band transmitter and antenna for data downlink. EPS is composed solar panel, solar power regulator, power supply card, power distribution card, Li‐on battery pack and battery control card. ACS employs LVPS, actuators reaction wheels assembly–RWA and electromagnetic torque bar‐EMTB and sensors coarse sun sensor‐CSS and three‐axis magnetometer‐TAM , and GPS Receiver‐ GPSR. Payload is composed by main sensor CP‐SAR for Earth surface monitoring and minor sensors: electron density – temperature probe EDTP for ionospheric monitoring. Power network of our microsatellite is shown on Fig. . We also develop SAR ground test measurement system as shown on Fig. , with moving precision of robot is . mm. We also develop sub mission sensors, i.e. GPS‐RO and electron density ‐ temperature probe EDTP to monitor ionospheric phenomena. We will employs these ionospheric observation sensors simultaneously with our CP‐SAR to monitor ionosphere and global land deformation. Therefore we could mapping pre‐cursors of earthquake by using our microsatellites in the future.

4. Ground Station

Fig. shows our satellite ground station with S band for command‐telemetry and X band for mission data downlink. The . m diameter of antenna and main control room of satellite ground station locates at Center for Environmental Remote Sensing, Chiba University. Command Unit S band has output power Watts, frequency , to , Mz, LCP and PCM, BPSK, PM and FSK modulations, and bitrate , BPSK, . kbps FSK. Telemetry Unit S Band works with frequency , to , Mz, LCP and PCM, BPSK, PM and FSK modulations, bitrate . Mbps BPSK, 8. kbps FSK. Data Receiver Unit X band works with frequency 8, to 8, Mz, LCP, QPSK modulation, bitrate Mbps QPSK.

5. Summary

n this paper, we introduce the progress of development on CP‐SAR onboard UAV, Boeing ‐ aircraft, and microsatellite in our laboratory. The CP‐SAR sensor is designed as small, lightweight and low power consumption system. The CP‐SAR sensor is developed to radiate and receive elliptically polarized wave, including circularly and linearly polarized waves. n the near future, this sensor will be installed on Boeing ‐ aircraft and microsatellite that will be applicable for land cover mapping, disaster monitoring, snow cover and oceanography monitoring etc. We also develop ionospheric observation sensors that is introduced in this paper too. n the future, these sensors could be employed for observation of ionosphere and global land deformation simultaneously for disaster monitoring and prediction. Acknowledgement Josaphat Microwave Remote Sensing Laboratory JMRSL thanks to Chiba University Global Prominent Research Program; the Japan Society for the Promotion of Science JSPS ; the Japanese Ministry of Education and Technology Monbukagakusho No. K and No. ; JCA‐JST SATREPS Program, Bhimasena, ndonesian Aerospace Agency LAPAN etc for supporting this research. References Sri Sumantyo, J.T. , Microwave Remote Sensing Research and Education at Center for Environmental Remote Sensing, Chiba University, EEE Geoscience and Remote Sensing Society GRSS Newsletter, ssue , pp. ‐ 8. Sri Sumantyo, J.T. , Chapter . Circularly Polarized Synthetic Aperture Radar onboard Unmanned Aerial Vehicle CP‐SAR UAV , Autonomous Control Systems and Vehicles, Kenzo Nonami edn., Springer. Yohandri, V. Wissan, . Firmansyah, P. Rizki Akbar, J.T. Sri Sumantyo, and . Kuze, Development of Circularly Polarized Array Antenna for Synthetic Aperture Radar Sensor nstalled on UAV, Progress in Electromagnetics Research C, Vol. , pp. ‐ . Joint Scientific Symposium IJJSS 2016 Chiba, 20‐24 November 2016 8 Topic : Remote Sensing Phase Coded Stepped Frequency Linear Frequency Modulated Waveform Synthesis Technique for Ultra‐Wideband Synthetic Aperture Radar CUA Ming Yam a, , KOO Voon Chet a , LM eng Siong a , Chan Yee Kit a , Josaphat Tetuko Sri Sumantyo b a Faculty of Engineering and Technology, Multimedia University, Jalan Ayer Keroh Lama, 75450 Bukit Beruang, Melaka, Malaysia b Josaphat Microwave Remote Sensing Laboratory JMRSL, Center for Environmental Remote Sensing, Chiba University, 1‐33 Yayoi, Inage, Chiba 263‐8522 Japan Abstract This paper presents the design work of Phase Coded PC Stepped Frequency Linear Frequency Modulated SF c ‐LFM technique targeted for use in Ultra‐Wide Band UWB Synthetic Aperture Radar SAR . The technique is a hybrid approach that employs digital waveform synthesis technique for baseband LFM pulse generation and analogue microwave up‐conversion technique. n this work, a train of phase coded baseband LFM pulses is generated using a custom designed Field Programmable Gate Array FPGA waveform synthesis board and each baseband pulses are then up‐converted to different adjacent band in the carrier band. The collected train of pulses is then re‐combined and processed, to synthesis an ultra‐wideband pulses. The experimental results show that the technique is able to synthesize a UWB SAR LFM pulse signal. The main advantage of the technique is its capability to improve existing SAR system resolution without having to increase the baseband bandwidth of the system. Keywords Keywords: UWB; SAR; Linear FM; Stepped‐Frequency; Signal Synthesis.

1. Introduction

SAR is a modern radar system that utilizes pulse compression technique to improve its system resolution whilst maintaining the pulse width of the signal Skolnik, ; Ulaby et. al, 8 . t uses match‐filtering technique to compress a wide pulse into a very narrow impulse response Barton, 88; Mahafza, 8 . SAR system has stringent requirement in its signal Time Bandwidth Product TBP . The TBP determines the pulse compression ratio, which is the quantitative measure on the system’s range resolution. Conventionally, a large bandwidth signal can be synthesised using a Voltage Controlled Oscillator VCO . owever, this method is not suitable for SAR signal synthesis as the VCO has a very slow sweep time Chan and Lim, 8 . On the other hand, due to the limitation in DACs sampling speed, the digital approach is more suitable for low bandwidth Mz signal synthesis applications. Furthermore, increasing the DACs sampling speed introduces new issues in hardware system design, and also increases the Corresponding author. Tel.: +8 ‐ ‐ 8‐ 8 E ‐mail address: mychuachiba‐u.jp 9 requirement of Analogue‐to‐Digital Converter ADC sampling speed and system bus data transfer rate. n order to solve the problem, a new technique on Phase Coded Stepped Frequency Linear FM SF c ‐LFM method is proposed for Ultra‐Wide Band UWB SAR signal generation.

2. Phase Coded SF

c ‐LFM Waveform Synthesis Technique n traditional, SAR transmits a single burst baseband LFM pulse at every Pulse Repetition nterval PR . The transmitted pulse is in its carrier frequency, , given as, Π ∙ ∙ n the proposed Phase Coded SF c ‐LFM technique, multiple burst of phase coded LFM pulse or known as intra‐pulses was transmitted, for every SAR PR interval. They were separated by an intra‐PR interval, _ so that the current listening echo does not overlap with the transmission of the succeeding pulse. Figure a illustrates an example of the time‐frequency plot for burst SF c ‐LFM waveform and Figure b shows an example of the time domain plot of these pulses. Equation below formulates SF c ‐LFM signals where each intra‐pulses were phase coded. ∙ ∑ ∙ ∏ ∙ where, = number of transmitted pulse within an PR interval n = integer number of , , … N = _ _ = intra pulse PR = the implemented phase coding scheme a b Figure : a Time‐Frequency Plot for SF c ‐LFM n= , b Time‐Domain Plot for SF c ‐LFM Baseband Pulses n= n the proposed technique, each phase coded intra‐pulses were mixed with different adjacent carrier frequencies. For design simplicity, an assumption is made that only even number of intra‐pulses are transmitted N is an even number and N . Thus, the up‐converted signals then can be further expressed as, _ ∙ ∑ ∙ ∏ ∙ ∙ where f n is the desired adjacent carrier frequency denoted as,