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In the process of being updated

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.

For now, we only consider sources of noise for MAG. the best approach to catalouge and aggregate noise for RPW won't be clear until EMC tests are complete.

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.
  • Command Sequences: The command sequence IDs that put instruments into certain operational modes, swith on mechanisms and so on. these will be used by SOC to identify when noisy events happen from instrument IORs.
  • Max Change in Current draw at transition: The worst case change in current draw on transitioning to this operational mode. TBC how useful this is given the large number of possible transitions for some instruments.
  • Transition Duration / Event duration: The time that a mode transition takes or the duration of an event (for example a door opening).
  • Minimum current draw: Minimum current drawn while the mode is operating (not the mean).
  • Peak to Peak Current Variation: A numeric scale measuring how much variability in current draw there is while this mode is operating / event is occurring, measured in mA. Split into contributions that are defined as EMC quiet (e.g. Transients as defined in EIDA R-681) and those that aren't. 
  • Direct B changes: Similar to the current variations but for direct changes in magnetic field, for example from a motor.
  • Notes: Could include characteristics of heaters or other information that may be useful in diagnosing problems and.or quiet status.
  • 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. 

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.

Note: Instrument power is delivered at nominally 28, worst case 29 Volts.

Source

Sensor

Event / Mode /

Mode Group

Command Sequence(s)

Max Change in current draw at Transition (mA)

Mode Transition Duration /

Event Duration (sec)

Min Current Draw (mA)Peak to Peak Current Variation (mA)

Direct B changes (pT)

NotesQuiet?
 QuietNoisyTotalQuietNoisyTotal(tick)(warning)(error)
MAG OFF   03210321000SC controlled heater switching at 1min boundaries (Quiet variations)


 
MAG SAFE 368 18932118339000 
MAG NORMAL 0 18932118339000 
MAG BURST 0 18932118339000 
RPW OFF           
RPW SAFE   16001010     
RPW STANDBY   18001010     
RPW SERVICE   56001010     
RPW NORMAL   64002020     
RPW BURST   63006060     
RPW DETECTION   64002020     
RPW BACKUP   62002020     
EPDEPT-HETHousekeeping   40405252   

1 second periodicity

Aggregate of EPT-HET 1 and EPT-HET2

 
EPDEPT-HETNominal Mode   40604848   

No obvious periodicity

Aggregate of EPT-HET1 and EPT-HET2

 
EPDSISNormal Mode   12530030330   

Question about actual variation in tests.

Quiet variations are iris motions tagged in HK

 
EPDSTEP             
EPDICU             
STIX SAFE   75044     
  CONFIGURATION   18501818     
  BACKGROUND   185044   NOMINAL Science mode consists of background and flares 
  FLARES   18514070210   Attenuator tagged and therefore quiet. Noise comes from power variations driven by changes in flux (TBC) 
SoloHI MAINT (HOT)            
  OBSHK (HOT)            
  OBSRV (HOT)   3275450104     
  SURVIVAL (HOT)            
  MAINT (COLD)            
  OBSHK (COLD)   39223150281     
  OBSRV (COLD)            
  SURVIVAL (COLD)   00577577    (error)
  ANNEALING (COLD)   8271540154     
SPICE STANDBY            
  ENGINEERING            
  OPERATE   96436089449     
               
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1 Comment

  1. Questions for PHI:

    Can you stay in obs mode the entire time rather than dropping to obs idle? Cf. UDP_Science Operation_Mode

    Are switches between obs idle and obs tagged in HK? Will we still get that information if the data are discarded on board?