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Introduction

When managing EMC in the mission planning process, we will have to consider operations at (at least) two granularities. At mission level and long term planning we'll have to consider (on average) how noisy various instrument modes (e.g. SPICE dynamics mode) are, then at medium term and short term planning, once we receive instrument IORs we will have to assess discrete operations  - i.e. the effect of instrument command sequences (e.g. move the EUI filter wheel) - for EMC quietude, and whether or not these operations can be considered 'Movable' according to the definition in the E-FECS ICD.

This table is a first attempt to capture the broad EMC behaviour of various different instrument modes, based on the results of EMC characterisation of instrument EMs and platform elements. We can thus start to produce the EMC noisy events catalogue that will form the basis of EMC management during operations. See the E-FECS ICD for details of the proposed EMC management scheme. The discrete operations that make up each mode and will be assessed at IOR level will be summarised in the details page for that mode. It is expected the SOC and the EMC working group will collaborate to first map the instrument modes listed here to various aspects of the EMC characterisation (and hence identify any gaps that can feasibly tested at spacecraft level either on the ground or in flight - i.e. we will not request any further testing of individual payload units as the result of this exercise) and second fill in the various columns for each mode to the extent possible given current information.

EID-A Requirements and Aggregate Noise

The EID-A requirements concerned with defining an EMC quiet phase give limits for levels of EMC noise that need to be respected in order for an interval or operation to be considered EMC quiet. These limits are defined for the entire platform and payload. Different instruments and platform units will be operating simultaneously, so a combination of operations that individually meet all of the EMC quiet criteria might easily break one or more EMC requirements when considered in aggregate. Thus, aggregate EMC noise needs to be taken into account during the science planning process. For this reason, the table below, as well as cataloguing events and instrument modes as quiet and noisy, can also catalogue them as maybe. Noise from events that are maybe quiet will need to be considered in aggregate with other 'maybe quiet' events that are operating simultaneously to determine whether or not an interval will be EMC Quiet.

 Definition of Columns

  • Source: This column is the instrument or platform subsystem. Platform subsystems are in blue-shaded cells. In the case of instruments the text links to the SOC's summary page of that instrument and its various operating modes.

  • Mode, Mode Group or Event: The operating mode of the instrument or subsystem (where appropriate for the latter). Scientifically different modes that are equivalent in terms of EMC characteristics can be collated in a Mode Group. Discrete events, for example filter wheel movements, that are common to several modes are also treated individually and have their own row in the table (for the time being). Events that meet the EID-A definition of a transient should also be included but these will be classed as quiet.
  • Quiet: Whether the mode in question is quiet (tick), noisy (error), or maybe (warning). Note we do not distinguish between fixed noisy and movable noisy at this level. If necessary a note can be included next to the symbol specifying whether a mode or event will be noisy for MAG, RPW (E/H) or both. 
  • Current variations: A numeric scale measuring how much variability in current draw there is while this mode is operating, measured in mA. Note transients as defined in EIDA R-681 don't have to be accounted for here. 
  • Broadband H field: Similar to power variations in that it is a numeric scale quantifying how much broadband H field noise a given mode generates. Broadband noise will also be treated in aggregate. The 3 (TBC) sub columns refer to different frequency ranges over which the aggregation will be done. How these ranges will be defined is also TBC, but could be decades of frequency or based on 'aggregation groups' where only those units that are empirically determined to need aggregation are included in a given group.
  • H Field Spike Density: As well as broadband noise we need to worry about narrow band spikes, specifically how much of a given frequency range is filled with them. This field attempts to capture that. Details TBD.
  • Broadband E field: Equivalent to broadband H field but for electric field. It would be nice if the frequency ranges were the same as for H, but this isn't strictly necessary.
  • E Field Spike Density: Equivalent to H spike density but for electric field. Again, we'd prefer common frequency ranges but this isn't strictly necessary.
  • Details page: A link to the page containing the details of the lower level characterisations that will inform SOC constraint checking at IOR level. Details of which events that can happen during a given mode are considered movable for the purposes of planning will be listed here.

A mode will be considered noisy (error) if it breaches the relevant EIDA requirement in any of these columns. It will be considered maybe (warning),  if, when operating concurrently with other maybe (warning) modes (from any platform or payload element), on aggregate an EIDA Requirement might be breached. The aggregate noise will be considered when determining whether or not a period will count as EMC quiet during planning, and if this falls during a mandatory quiet window the SOWG must collectively decide how to resolve this situation (i.e. whose mode to change or move). The method of calculating the aggregate is TBD and will be decided in collaboration with the EMC working group.

Source

(Inst. / PF Subsytem)

Mode, Mode Group, or event

Quiet
(tick) (error) (warning)

Current Variations

(Peak to Peak, mA)

Broadband H FieldH Field Spike DensityBroadband E fieldE Field Spike DensityDetails Page
f range 1f range 2f range 3f range 1f range 2f range 3f range 1f range 2f range 3f range 1f range 2f range 3
                 
                 
                 
                 
                 
                 
                 
                 
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