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12006 MAPLD International ConferenceSpaceWire 101 Seminar DESIGN CHALLENGES OF AN ADVANCED SPACEWIRE ASSEMBLY FOR HIGH SPEED INTER-UNIT DATA LINK Joachim.

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Presentation on theme: "12006 MAPLD International ConferenceSpaceWire 101 Seminar DESIGN CHALLENGES OF AN ADVANCED SPACEWIRE ASSEMBLY FOR HIGH SPEED INTER-UNIT DATA LINK Joachim."— Presentation transcript:

1 12006 MAPLD International ConferenceSpaceWire 101 Seminar DESIGN CHALLENGES OF AN ADVANCED SPACEWIRE ASSEMBLY FOR HIGH SPEED INTER-UNIT DATA LINK Joachim Mueller, W.L. Gore&Associates Internet:

2 22006 MAPLD International ConferenceSpaceWire 101 Seminar Motivation System design solutions for advanced communications missions are driving up symbol/data rates with: -Increasingly demanding skew and delay requirements -Critical design issue for the cable assemblies and for an electrical matched and balanced connector in particular. The cable assemblies are used to transfer various types of signals between units on board the spacecraft, e.g.: -Reference/synchronisation clock signals -High data rate serial links such as SpaceWire -Digitally modulated baseband signals (QPSK, 8PSK, etc) These interfacing functions need a differential mode of transmission capable of maintaining high integrity in the process.

3 32006 MAPLD International ConferenceSpaceWire 101 Seminar Four Shielded Twisted Pairs High Performance GoreTex Dielectric Overall braided EMI shield Performance Table Cable Drawing SpaceWire Cable Design

4 42006 MAPLD International ConferenceSpaceWire 101 Seminar Connector Performance Issues Triax Contact Micro D-Sub Commonly used Connector interfaces show strong impedance mismatch

5 52006 MAPLD International ConferenceSpaceWire 101 Seminar Connector Performance Issues Connector performance has a strong impact on the signal transmission at frequencies above 30MHz. Assembly shows non- monotonic attenuation characteristic. Matched Connector interface required. Signal Attenuation vs. Frequency Bulk Cable Assembly

6 62006 MAPLD International ConferenceSpaceWire 101 Seminar Symmetrical Connector Interface Impedance vs. Length 4 and 5-way Twinax Connector

7 72006 MAPLD International ConferenceSpaceWire 101 Seminar Advanced Interconnect Performance Attenuation of 2m long SpaceWire Cable Assembly Insertion Loss [dB/20m] f [MHz] AWG AWG Attenuation of 20m long SpaceWire Cable Assembly

8 82006 MAPLD International ConferenceSpaceWire 101 Seminar Reflection Loss Measurements

9 92006 MAPLD International ConferenceSpaceWire 101 Seminar Skew Measurements

10 MAPLD International ConferenceSpaceWire 101 Seminar Connector NEXT

11 MAPLD International ConferenceSpaceWire 101 Seminar Crosstalk Results SpaceWire cable not significant contributor to crosstalk Crosstalk due to 9-pin Microminiature D-type connector (and connection) -Cross talk between Data and Strobe high (~20dB) -Crosstalk between Strobe pairs high (~20dB)

12 MAPLD International ConferenceSpaceWire 101 Seminar Shielding Measurements Shielding Effectiveness for 1m Assemblies: 100MHz > 1GHz

13 MAPLD International ConferenceSpaceWire 101 Seminar Eye Pattern Measurement Eye 10m, AWG26Eye 10m, AWG28 LVDS requirements: Eye Height: 200 mV,Jitter:1 200 Mbit/s

14 MAPLD International ConferenceSpaceWire 101 Seminar Eye Pattern Measurement Eye 10m AWG28 Eye 20m, AWG28 LVDS requirements: Eye Height: Mbit/s

15 MAPLD International ConferenceSpaceWire 101 Seminar Summary Technical issues with a symmetrical cable interconnect using a Triax contact has been discussed. A new design with a light and compact twinax contact has been introduced. The electrical Performance in terms of Impedance, Insertion Loss, Return Loss, Crosstalk, Skew, Eye Pattern and Shielding has been presented The performance of the new symmetrical cable interconnect is adequate for frequencies up to 2GHz and higher.


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