system design of a digital high-speed modular satellite

System Design of a Digital High-Speed Modular Satellite Downlink

Sören F. PeikInst. of Aerospace Technology Bremen

Outline

The DATARAINSystem

Conclusions

Design for Space

Motivation

Motivation

Satellite for Scientific Missions

GroundStation 1

GroundStation 2

Telemetry

Instruments~1 GBits/s

MassStorage~1 TBit

Downlink~100Mbit/s

User

DownLink

IntersatelliteLink

TelemetryLink

101101011

Ground Station

1000 MBit/s

Design forSpace

Challenge 1:Space Environment

VacuumTemperatureVibration Radiation

Challenge 2:Bandwidth Efficiency

f [MHz]8025 8400

CCSDS DSN

Challenge 3:Reliability

Challenge 4:Doppler Shift

v

5 1 0 1 5 2 08 . 1 9 9 8

8 . 1 9 9 8

8 . 1 9 9 9

8 . 1 9 9 9

8 . 2

8 . 2 0 0 1

8 . 2 0 0 1

8 . 2 0 0 2

8 . 2 0 0 2C 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

t [ m i n u t e s ]

f [G

Hz]

● CCSDS Compliant● Space Qualifiable Transmitter● Low Mass, Low Power System● X-Band System 8025-8040 MHz,

Options for other Bands

● Achievable Rates using =0.35 Roll-off:

Modulation Bit/Hz max. Data RateQPSK 2 Bit/Hz 555,56 MBit/s8 PSK 3 Bit/Hz 833,34 MBit/s

16 QAM 4 Bit/Hz 1111,12 MBit/s

Requirements:

The System

Transmitter Channel

DA

TA I

N

Receiver

DA

TA O

UT

Transmitter:

IF-Board

RF-Frontend

Antenna

8 G

Hz

1.4

GH

z

BasebandProcessor

Blockdiagram

LO

IF-Filter

Anti Aliasing Filter

IQ-Mod.

DAC

LODAC

FPGA

RF-FilterP.-Amp.Mixer

Imagerejection

Filter

LO

Interface

PC

Power Supply

3.3V 5V

Base Band Board IF-Board RF-Front-End X-Band

RF-Front-End C-Band

12V

I

Q

Interface


Imagerejection

Filter

LO

Baseband Processor

DAC

LODAC

FPGA

Interface

PC

Base Band Board

I

Q

Interface

Baseband Processor

ClockFPGAPower Supply

I+

I-

Q-

Data InputConfiguration Interface

Q+

D/A Converter

Simulation versus Measurement

16 APSK

IF Board

LO

IF-Filter

Anti Aliasing Filter

IQ-Mod.

IF-Board

I

Q

RF Front End


Imagerejection

Filter

LO

RF-Front-End X-Band

RF Spectrum

Receiver

ADCand

FPGAIQ-Demodulator

LP-Filter

LP-Filter

Freq. Generator

BP-Filter Mixer AGC

Freq. Generator

LN-Amp.

DA

TAMixer BP-Filter

Freq. Generator

BP-Filter

Receiver

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

Thank You

system design of a digital high-speed modular satellite

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