As high-speed digital signal processing has become a reality taking an increasing place in telecom satellite payloads for today, Thales Alenia Space has introduced the most advanced and disruptive technologies in his new generation of onboard digital transparent processor (DTP). DTP namely Spaceflex is an advanced repeater sub-systems having analogueto- digital (ADC) and digital-to-analogue (DAC) channelizers on their input and output accesses and making extensive use of digital processing to support channel routing with fine bandwidth granularity.
 
The mechanical architecture of such advanced digital processor is based on input/output routing channel modules and switch modules interconnected together thanks to optical interconnect technology already implemented in a breadboard developed under the ESTEC contract Optical Inter-board Interconnects for High Throughput on-Board Processors (OI2) but showing higher performances requested by the application.
 
The optical interconnect is supported by optical transceiver, by optical connectors for inside and outside equipment interconnects, by optical cables and flexes. This optical interconnect solution is scalable to an overall throughput in excess of 15 Terabit/s with 150’s of optical links.
 
In the frame of this development, Thales Alenia Space has identified and tested 3 different optical transceivers working at high speed data rate higher than 10 Gbps, compatible with GEO and LEO environment whose reliability is compatible with a lifetime of 15 years.
 
The paper will present in detail the tests on selected transceiver (radiation behaviour and temperature) as well as the overall architecture of such advanced digital on board processing equipment.

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11180/111804B/Spaceflex-onboard-digital-transparent-processor--a-new-generation-of/10.1117/12.2536074.pdf

Spaceflex onboard digital transparent processor: a new generation of DTP with optical digital interconnects

We have evaluated the performance for space applications of commercial off-the-shelf fiber coupled optical switches with no-moving parts, based on different technologies. The technical requirements of several space applications of optical switches were defined. After the technology selection, a tradeoff was performed to select the final optical switches to be tested, which are based on three technologies (Magneto-Optic MO, Bulk Electro-Optic B-EO, and Waveguide Electro-Optic W-EO) and fabricated by four different manufacturers. Other potential technologies (acoustooptic, liquid crystal, thermo-optic, micro/nano photonic waveguides) were not selected due to the lack of commercial products. A test campaign was carried out, consisting of thermal vacuum cycles, mechanical tests (vibration and shocks) and radiation tests (gamma radiation). The main performance parameters were the insertion loss, crosstalk, and switching speed. After the final electro-optical characterization, a destructive physical analysis was made to some optical switches. The results of the tests indicated that B-EO and MO technologies are excellent candidates for the analyzed space applications. They respond very well under typical space conditions as radiation, vibration, shocks and thermal vacuum; B-EO technology presents lower switching time but its crosstalk is worse. WG-EO technology is very fast, but a mechanical failure in one device was observed, the insertion losses are very high and the crosstalk is very low.

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11180/111807H/Evaluation-of-optical-switches-for-Space-applications/10.1117/12.2536188.pdf

Evaluation of optical switches for Space applications

The key element of the next generation high-speed intra-satellite serial data communication link are the optical transceivers. Not only should these meet the high-reliability requirement for space with regard to thermal vacuum, mechanical vibration and shock, but also survive reliably in a radiation environment. At VTT the SolidOpto SPFI-(003)-6G 6.25 Gbps optical transceiver has been specifically engineered for this space environment. This device has successfully passed mechanical vibration and shock, thermal vacuum and total dose radiation up to 100krad. The first SEE radiation tests on this device have been performed and are the topic of this paper. The radiation tests demonstrate that this device is free of destructive radiation events. With a dedicated state-of-the-art high-speed radiation test set-up the BER as well as the SET rate as function of LET and flux could be determined for the optical transceiver operating at 5Gbps. Threshold and cross-section both for receiver and transmitter could be determined as well as the SET pulse-width distribution. The analysis of these results allows the predicted performance of this optical transceiver in space as a function of the implemented transmitted data encoding. Furthermore the result of this work demonstrates the viability of the operational use in space of the VTT SolidOpto SPFI(003)-6G 6.25 Gbps optical transceiver as one of the first of the devices of its kind.

Radiation Tolerant 6.25 Gbps 850nm Optical Transceiver

The ESCC has published new optical fiber connectors standards destined to simplify procurement of such components. A summary presentation is given, but more importantly, how to use them, the lesson learned from Diamond’s perspective is presented. The latter cover the fiber lot management, the radiation and a few other parameters necessary for projects. Three main application categories are presented: A) Generic-Sensing, B) Satellite external communication, C) Satellite internal communication. Their products range and covered solution is presented, with potential new development proposed

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11180/111807E/Optical-fiber-interconnect--standards-procurement-lesson-learned-and-future/10.1117/12.2536185.pdf

Optical fiber interconnect: standards, procurement, lesson learned and future applications

The satellite telecommunication sector is continuously facing new challenges. Operators turn towards increasing capacity payloads with higher number of beams and broader bandwidth, in order to cope with exhausting orbital positions and to lower the cost of in-orbit delivery of bit. Only satellites able to provide high data rate connections to numerous users are expected to achieve affordable communication prices. On the other hand, as the telecom market grows and the range of offered services (HDTV, Video On Demand, Triple Play), operators call for more versatile solutions to quickly grasp new markets and to adapt to these evolutions over the average 15 years of a satellite lifetime. Flexible payloads have found an increasing interest for a number of years. Flexibility is considered as a means for a better commercial exploitation of a satellite fleet and a better allocation of resource in response to traffic evolution and/or changing business plans, with potential advantages such as a wider range of applications, less customization for specific missions, increased production runs of equipment, enhancement of reliability, reduction of equipment cost, reduction of program schedules [1]. Flexibility is expected to be offered in spectrum management and frequency plan, in coverage, or in the repeater power allocation. The industry is taking up the challenge both by improving current telecom satellites and offering new payload technology, more flexible and able to address the new markets. From a system integrator perspective, flexibility is as an opportunity to design more generic payloads, that can be customized during or after fabrication only, thus shortening the design-to-manufacturing cycle, and improving the industry competitiveness.

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10563/1056337/High-throughput-optical-inter-board-interconnects-for-next-generation-on/10.1117/12.2304235.pdf

V. Foucal

Papers

High-throughput optical inter-board interconnects for next-generation on-board digital transparent processors