Signal and Data Transport



The SADT team attended the Annual SKA Engineering meeting in Stellenbosch and found that it was extremely productive opportunity for discussing and agreeing a number of technical issues with other Consortia. In addition, while still in Stellenbosch, we held our sixth face-to-face Consortium meeting, which was similarly productive and allowed us to re-examine and confirm our internal interfaces between the various SADT sub-elements, and resulted in an agreed diagram capturing the end-to-end physical realisation of the networking and timescales for both the SKA-mid and SKA-low telescopes.


The SADT team in Stellenbosch for the Annual SKA Engineering meeting.

A great deal of our recent work has been to support the SKAO in preparation for System Preliminary Design Review (PDR). This has been primarily in producing Interface Control Documents (ICDs), both Internal to the Consortium (where we have written a total of 46 documents) and External ICDs with other elements. In parallel we have progressed the Detailed Design Documents (DDDs) which capture the design that will be assessed next year at a Critical Design Review. We have also released the first draft of the SADT Failure Mode, Effects and Criticality Analysis (FMECA), which analyses the probability of failure modes against the severity of their consequences. This work has been undertaken through a contract with Frazer-Nash Consultancy, with whom we have had a series of workshops and telecons. This FMECA analysis has allowed us to start work with MMI Engineering Ltd on the Integrated Logistics Support (ILS) analysis that will develop a support strategy for the SADT products.

Electromagnetic Compatibility (EMC) of all areas of the SKA design is critical, since there is a significant risk that self-induced radio frequency interference (RFI) might otherwise limit the performance of the SKA. We have conducted a series of EMC tests at the semi-anechoic chamber, shown in the figures below, at ASTRON in the Netherlands.

We have tested equipment that will be used in the following areas: the Digital Data Back Haul (DDBH) of astronomical data from the receivers back to the Central Processing Facility; the Non-Science Data Network that carries the monitoring and control signals throughout the telescope; the White Rabbit network that carries absolute time. All of these products are located very close to the telescope receivers, in the telescope pedestal (for SKA-mid) and the Remote Processing Facilities (RPFs for SKA-low), and so their EMC performance is critical. Various different hardware configurations and different vendor equipment were assessed. Preliminary assessment of the results is very encouraging, but it is clear that the shielded enclosures being planned to house this equipment is essential to meet the challenging requirements of the SKA.

Report provided by the SaDT consortium