These are the minutes of the System Design Team Meeting, held at MSSL on 8 July 1999 (SDT-10)

Present: MWT (Chair), LKHM, AJM, RAG

Apologies for CJM

No significant events other than those detailed elsewhere.

Information about the Solar-B command system had been received and distributed to Alec and Rob. It was noted that there were 'only' 32 commands stored in the DHU timeline. This led to a discussion of the power-up condition of EIS. Alec assuming for the present that some small amount (e.g. 1W) of power would be available at all times. This would be used to supply the circuits which would manage the transition to full power. There were a number of possible modes or states of the instrument.

The criteria for mode definitions included: power consumption, safety (e.g. contamination), thermal stability, preservation of software state (variables), observing table protection/configuration.

Alec stressed the need to include test modes in the instrument, both in hardware and software. Rob advised some caution, as any modes, including test modes, would be required to be tested themselves. There was a discussion about this tradeoff area which was not resolved, although it was agreed that it would be beneficial to have a mode of real-time control (or minimal latency) accompanied by maximum status information. There was a discussion of methods for preservation of state information, such as may be required be rapid resumption of operation following a power-off (intentional or otherwise).

Two methods were apparent:

Keep-alive RAM (requiring a small amount of spacecraft power) or use of EEROM. It was decided that the baseline ICU should incorporate both mechanisms. The details, such as how much data would constitute the "state" need to be worked out in the future.

MWT had circulated an updated system hierarchy EIS-sys-des-hierarc and this was discussed. Some of the ground-segment items need further elaboration (test facilities ? lifting gear). Or clarification (EGSE components). Note the EGSE acronyms are derived from a draft EGSE equipment list that will soon be circulated.

ACTION: MWT/SDT elaborate ground-segment elements 26 July (A/SDT-10.2)

ACTION: MWT correct EGSE acronyms 26 July (A/SDT-10.3)

ACTION: MWT circulate EGSE equipment list 19 July (A/SDT-10.4)

No progress on shutter definition.

Chris McFee was continuing to study CCD shielding requirements, temperature effects. Analysis of change spreading was also in program. He had also been working on a specification for a CCD/camera development system, including PC and data acquisition cards.

A more detailed software development schedule had now been worked out. Although not final, this had shown the need for more manpower on on-board software, and for the requirements at the PM delivery to be further defined. It was certain that the PM functionality will be a small subset of the FM, some key features will have to be omitted at PM - data compression and other advanced data manipulation being obvious candidates.

Duncan Self and Alec are developing an ICU architecture. A block diagram will be available soon. Since there are no known plans for a rad-hard implementation of the ADSP21060 processor the baseline CPU is now the ADSP21020. The Virtuoso RTOS is also baselined. Some benchmarks need to be run on this processor family so that table loads can be scaled from after platforms.

ACTION: AJM consider benchmark strategy 22 July (A/SDT-10.5)

The ICU functional breakdown was discussed.

ACTION: AJM/DGS to elaborate that shown in EIS-sys-des-hierarc 22 July (A/SDT-10.6)

Since the ICU and far MHC must perform thermal control of the instrument, the thermal control approach must be known. The number of sensors heater points was particularly desired.

ACTION: SMM at BU to specify baseline number of nodes 29 July (A/SDT-10.7)

At present the number is thought to be >3 and <20.

MWT was preparing to elaborate the schedule and will be seeking inputs from the team, particularly for the electronics development.

Review of existing actions

A/SDT-9.3 HH/MWT communication - ongoing.

A/SDT-9.4 Update system hierarchy - complete.

A/SDT-9.6 CJM has 'defective' CCD images. He will show to LH, CPD - complete.

A/SDT-9.9 JLC still considering this.