System Design of a Digital High-Speed Modular Satellite Downlink - PowerPoint PPT Presentation

System Design of a Digital High-Speed Modular Satellite Downlink Sören F. Peik Inst. of Aerospace Technology Bremen

Outline Motivation Design for Space The DATARAIN System Conclusions

Motivation

Satellite for Scientific Missions Mass Instruments Intersatellite Storage Downlink ~1 GBits/s ~1 TBit ~100Mbit/s Link Telemetry Telemetry Link Down Link Ground Ground Station 1 Station 2 User

1000 MBit/s Ground Station 101101011

Design for Space

Challenge 1: Space Environment Vibration Temperature Vacuum Radiation

Challenge 2: Bandwidth Efficiency CCSDS DSN 8025 8400 f [MHz]

Challenge 3: Reliability

Challenge 4: Doppler Shift C e n t e r f r e q u e n c y o v e r t h e t r a n s m i s s i o n t i m e 8 . 2 0 0 2 8 . 2 0 0 2 8 . 2 0 0 1 v 8 . 2 0 0 1 f [ G H z ] 8 . 2 8 . 1 9 9 9 8 . 1 9 9 9 8 . 1 9 9 8 8 . 1 9 9 8 5 1 0 1 5 2 0 t [ m i n u t e s ]

Requirements: ● CCSDS Compliant ● Space Qualifiable Transmitter ● Low Mass, Low Power System ● X-Band System 8025-8040 MHz, Options for other Bands ● Achievable Rates using α =0.35 Roll-off: Modulation Bit/Hz max. Data Rate QPSK 2 Bit/Hz 555,56 MBit/s 8 PSK 3 Bit/Hz 833,34 MBit/s 16 QAM 4 Bit/Hz 1111,12 MBit/s

The System

DATA OUT DATA IN Transmitter Receiver Channel

Transmitter: 1.4 GHz 8 GHz RF- Baseband IF- Frontend Processor Board Antenna

Blockdiagram Base Band Board IF-Board RF-Front-End X-Band Anti Aliasing Filter I n I I t Image DAC n rejection e t IF-Filter Filter IQ-Mod. Mixer P.-Amp. RF-Filter r e f r FPGA a f c a e c DAC Q e P LO LO LO C RF-Front-End C-Band Image rejection Mixer Filter P.-Amp. RF-Filter 3.3V 5V 12V Power Supply LO

Baseband Processor Base Band Board I n I I t DAC n e t r e f r FPGA a f c a e c Q DAC e P LO C

Baseband Processor Configuration Interface D/A Converter Data Input I+ I- Q+ Q- FPGA Clock Power Supply

Simulation versus Measurement

16 APSK

IF-Board Anti Aliasing Filter IF Board I IF-Filter IQ-Mod. Q LO

RF Front End RF-Front-End X-Band Image rejection Mixer Filter P.-Amp. RF-Filter LO

RF Spectrum

Receiver Receiver LP-Filter ADC DATA LN-Amp. BP-Filter Mixer BP-Filter AGC Mixer BP-Filter IQ-Demodulator and FPGA LP-Filter Freq. Generator Freq. Generator Freq. Generator

Conclusions ● Space Calls for a Deliberate Design ● High Speed Links are a Challenge for Digital and Analog System Sections ● We still Need Analog Design (Electromagnetic Waves are Analog) ● Interaction of Digital and Analog Sections is a Must

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