SSC16-VII-5 High bit-rate communication in X band for small earth observation satellites - Result of 505 Mbps demonstration and plan for 2 Gbps link - Hirobumi Saito Inst. Space and Astronautical Science, JAXA, Japan Hirobumi Saito (1), Tomoya Fukami (2), Hiromi Watanabe (2), Atsushi Tomiki (1), Takahide Mizuno (1), Naohiko Iwakiri (3), Shin-ichi Nakasuka (2), Takahiro Shinke (4), Kaname Kojima (4), Koichi Kawamoto (5), Osamu Shigeta (6), Hitoshi Nunomura (6), Yasuaki Kanda (7), Hideki Kayaba (8) 1
OUTLINE 1. Demonstration of High Speed Down Link 505Mbps from Small Earth Observation Satellite Hodoyoshi-4 (60kg). 2. Plan of 2-4Gbps from 100kg class Satellite for Synthetic Aperture Radar (SAR) 2 505 Mbps Frequency :X-Band (8GHz) Small Atmospheric Attenuation, compared with Ka and Optical Band Band Width: Only 375 MHz High Spectral-Efficiency Modulation 64 Amplitude Phase Shift Keying 6bit in 1 symbol. 6 bit/hz Complex Constellation
Background 3 High Performance Earth Observation Satellites need High Bit Rate Down Link WorldView-3 (2,800 kg) 1.2 Gbps 8PSK in X-band SkySat-2 (100 kg) 300Mbps 8PSK in X-band 30 cm/pixel 85 cm/pixel High Speed Down Link is required for huge amount of observed Data Terra Bella
High Speed X-band Transmitter for Small Satellite Small Size 1.3kg & Small Power 22W 64APSK, 505Mbps 125MHz RF bandwidth in X-band Frequency RF Output Symbol Rate Modulation 8160± 60 MHz 2 W 100 Msps QPSK, 16QAM (option) 8PSK, 16APSK, 32APSK, 64APSK, 64QAM 72 to 540 Mbps Turbo (SCCC) LVDS 28 V, 22 W 12 10 7.3 cm 1,330 g Data Rate ECC Data IF DCPower Size Mass Op Temp -20 to +50 C Total Doze 20 krad 4 Outlook of Developed X-Band Transmitter
Technology 1. Error Correction Code 5 High Performance Turbo Code(SCCC) CCSDS 131.2-B-1 4dB higher Coding Gain than Reed-Solomon Zodiac Cortex HDR Demodulator is partially compatible to this ECC Turbo (CCSDS 131.2-B-1 ACM17, 348Mbps Reed-Solomon(255,223) 350Mbps 4dB better @ BER=10 6 16QAM 350 Mbps (BER) Simulation
Technology 2. High frequency-efficiency Modulation 6 High Bit Rate CCSDS 131.2-B-1 Combination of Modulation Scheme and ECC (Turbo) 100 M Symbol/sec In Signal I-Q plane QPSK 2bit/Hz 200 Mbps 300 Mbps 8-PSK 3bit/Hz 600 Mbps 64 Amplitude Phase Shift Keying 64APSK 6bit by one symbol 6bit/Hz 16APSK 4bit/Hz 400 Mbps 500 Mbps 32APSK 5bit/Hz Adaptive Modulation
Technology 3. RF Power Amplifier 7 1/3 Power of total TX consumes at RF power amplifier Amplifier must be used at high efficiency region due to power saving Input constellation is distorted by nonlinearity (AM-AM,AM-PM) Then Output constellation is degraded. Input IQ Constellation Nonlinear Amplifier Output I-Q Constellation Q 2 18 10 I Output Power Output Phase Input Power 16 QAM 4bit by 1 symbol AM & PM Distortion Nonlinearity and Inter Symbol Interference
Technology 3. Nonlinearity of Power Amplifier 16 QAM Ideal Costellation AM/AM AM/PM IQ Constellation Q 2 18 10 I 8 GaAs (AB-Class) 28% efficiency Output [dbm] Input [dbm] Phase Shift [degree] Input [dbm] Output [dbm] GaN (AB-Class) 47% efficiency Input [dbm] Phase Shift [degree] Input [dbm] Output [dbm] GaN (F-Class) 57% efficiency Input [dbm] Phase Shift [degree] Input [dbm]
Technology 4. On-Board Antenna 9 Small on-board MGA Active element Passive element Feed point 2 2 array Patch Antenna Size 7 7 cm Mass 69 g Gain 13.5 dbi @8.2GHz Beam Angle 30 Be- coated Kapton (UV shield)
Technology 5. S&X 3.8m Ground Antenna 10 S band (TT&C), X band (Data Down Link) dual frequency Antenna 3.8m ring-focus Gregorian Dia Gain 3.8 m 36 dbi @ S band 47.5 dbi @ X band 3.8m Antenna on ISAS building
Technology 6. Ground Receiver/Demodulator 11 Zodiac Cortex HDR Demodulator can process 64APSK in real time. However Expensive. Newly developed Non-Realtime Software Demodulator Ant chamber Operation Room IF signal is stored at Data recorder After Pass, Software Demodulation & Decoded with PC. Double Precision, Floating Process Small Demodulation Loss
Bit Error Rate vs Received Es/No (CCSDS131.2-B-1) 12 100M symbol/sec max 348 Mbps 16QAM Linear Channel Distortion Channel (EM+Demodulator) 505 Mbps at Es/No=20dB 64APSK 236 M 263 M 290 M 319 M 349 M 411 M 443 M 476 M 505 M 538 M 10-1 10-2 Bit error rate 10-3 10-4 10-5 Nonlinearity degrades 2dB for 64APSK 10-6 6 8 10 12 14 16 18 20 22 Es/No [db]
On-Board 64APSK, 505 Mbps Experiment at Hodoyoshi-4 60kg Flight Model of Hodoyoshi-4 (Right) 13
Demonstration: Link Calculation 14 Es/No [db] 24 22 20 18 16 14 12 10 Elevation [degree] 64 APSK 505M bps Error Free Es/No>19.5dB Elevation > 40deg 8 0 15 30 45 60 75 90 Received Es/No vs Satellite Elevation General Parameter Value Unit Orbit altitude 628 km Elevation angle 45.0 deg. Satellite Transmitter Frequency 8160 MHz Symbol rate 100 Msps Amplifier output power 2 W Circuit loss 1 db Antenna peak gain 13.5 dbi Antenna pointing loss 0.5 db Channel Losses EIRP 15 dbw Free space loss 169.6 db Atmospheric loss 0.5 db Ground Station Receiver Antenna peak gain 47.5 dbi System noise temperature 120 K Station G/T 26.71 db/k Received C/No 100.2 db Received Es/No 20.2 db
On-Board 64APSK, 505 Mbps Experiment 15 505 Mbps 64APSK Demonstration with Hodoyoshi-4 Elevation 83.3deg,Slant Range 658 km Received C/No = 100 dbhz Received Es/No = 20 db Received I-Q Constration Demodulation(600 Mbps) : BER 2.7 10 2 Decoding (505 Mbps) : BER < 7.6 10 7 Power [db] 80 70 60 50 Turbo Decoding : 7 Iteration 40 0 50 100 150 200 Frequency [MHz] Received Spectrum of IF signal 64APSK Ant Pointing errors degrade 2.5dB (satelllite attitude control + ground antenna pointing error)
Possible Max Down Link Data (Calculation) 16 550 90.0 500 450 400 Bit Rate 64APSK EL>24deg 81.8 73.6 65.5 350 57.3 Bit rate [Mbps] 300 250 200 150 QPSK 16QAM EL<24deg Elevation 49.1 40.9 32.7 24.5 Elevation [degree] 100 50 36.7 Gbytes / pass 16.4 8.2 0 0.0-400 -350-300 -250-200 -150-100 -50 0 50 100 150 200 250 300 350 400 Time [second] Calculation Condition Max EL=86deg, BER < 10-6, Margin1 db QPSK + 16QAM + 64APSK 36.7 Gbytes / pass
Next Stage of 2-3Gbps Down Link in X band X-band for Earth Observation Satellite is 8025-8400MHz with 375MHz width Present System : 64APSK, 505Mbps with 125MHz bandwidth (8100-8225MHz) Next Stage : Two Channels of RHCP, LHCP, 64APSK with full band 375MHz bandwidth in X-band 17 80 Power [db] 70 60 50 40 0 50 100 150 200 Frequency [MHz] 64APSK 125MHz 505Mbps 8100 8225MHz Present 505 Mbps Next 1-2Gbps RHCP LHCP x 2 polarization Channel 64APSK 1-2Gbps 375MHz 8025 64APSK 8400MHz 1-2Gbps 375MHz 8025 8400MHz
New Technologies for 2-4Gbps 18 Symbol Rate 100Msps 350Msps Wide Band RF Amplifier with Small Distortion. High Speed FPGA and DA Converter On-board RHCP/LHCP Antenna with XPD > 30dB Corrugated Horn Antenna + Septum Polarizer Larger Ground Antenna with XPD > 30dB ECC : CCDSD131.2-B-1(Turbo) DVB-S2X (LDPC) Plan to demonstrate in 2018
Dual Polarization MGA with high XPD 19 RHCP & LHCP for Independent 2 channel High Cross Polarization Discrimination (XPD>30dB) Corrugated Horn MGA 17dBi +Septum Polarizer + Coaxial Adaptor Total length 20cm Coaxial Adapter Septum Polarizer Corrugated Horn Ka band Dual Polarization Ant
Conclusion 20 Developed 64APSK Transmitter for 50kg-class Satellite Demonstrated 505Mbps Down Link with Hodoyoshi-4 Sat Non real-time Software Processing will Speed up with High Performance Graphic Processing Unit (GPU). Next Stage 2-4Gbps in X-band (DVB-S2X ) We are developing the next generation system Polarization Multiplication + 350M symbol /sec Plan to demonstrate in 2018