[MOIMS-NAV-EXEC] FW: CCSDS Events for Nav, CSS, and MO

[Berry, David S (3920)]

All:

Second of 2 emails related to event definitions for the CCSDS.

David



From: "Barkley, Erik J (3970)" <erik.j.barkley at jpl.nasa.gov>
Date: Tuesday, September 6, 2016 at 5:20 PM
To: Sam Cooper <sam at brightascension.com>, Colin Haddow <Colin.Haddow at esa.int>, Mehran Sarkarati <Mehran.Sarkarati at esa.int>, "Berry, David S (3920)" <david.s.berry at jpl.nasa.gov>
Cc: Mario Merri <Mario.Merri at esa.int>, Dan Smith <danford.s.smith at nasa.gov>
Subject: RE: CCSDS Events for Nav, CSS, and MO

Dear Sam,

There has been a bit of development/refinement on the CSSM side with regard to the event definition.  Please see below.
The key items to note are the ability to make the uncertainty window around an event asymmetric and the ability to allow for agency specific extensions in a controlled/flexible manner while retaining a core inter-operable data format.  This is essentially what is addressed via the abstract parameter definition with several simple types for simple extensions and a complex type should an agency really need to state something involved.

With regard to your observation that this is aimed at future/predicted event definitions that is correct.  In general I suspect that when dealing with a stream of actual events, there really would no longer be an uncertainty window (then again, on board clocks often drift – especially for spacecraft in deep space).

The Rome meetings for me are rather difficult to arrange as I have other unmovable commitments such that I will only be attending from Wednesday on of the technical week.  Nonetheless, perhaps you, Colin, and David (whom I have asked via separate email), could get together for a joint session at the Rome meetings.  Alternatively, considering that planning for various working groups/agendas is already likely quite advanced, we could arrange to have a telecon, post Rome, leading to a joint session at the San Antonio (spring ’17) meetings.

Best regards,
-Erik



[cid:image001.png at 01D221FF.93D3E400]

From: Sam Cooper [mailto:sam at brightascension.com]
Sent: Monday, July 04, 2016 4:21 AM
To: Barkley, Erik J (3970) <erik.j.barkley at jpl.nasa.gov>; Colin Haddow <Colin.Haddow at esa.int>; Mehran Sarkarati <Mehran.Sarkarati at esa.int>; Berry, David S (3920) <david.s.berry at jpl.nasa.gov>
Cc: Mario Merri <Mario.Merri at esa.int>; Dan Smith <danford.s.smith at nasa.gov>
Subject: CCSDS Events for Nav, CSS, and MO

Dear All,

I took the task in Cleveland to review the information sent out on the definition of an Event from joint sessions between Nav and CSS. This was with respect to how MO defines and uses events.

The diagram I am working from is this one:

[cid:image002.png at 01D221FF.93D3E400]

The first thing that occurs to me is that these events seem to be focussed on predicted, future, events (which is understandable) whereas MO events are things that have happened as it is event reporting rather than event prediction.

Using a similar approach, our events contain (this is a simplified view):

  *   Timestamp of event (absolute)
  *   Source of Event
  *   Event type number
  *   Event instance number
Then the body of the event is specific to that event type.

So our definition of event is a little lower level than either of the existing event definitions. We also have a specific "type" of event called an Alert which extends the event specification to have a body which contains a set of Name/Value argument pairs (whether you call them arguments or parameters is moot, they achieve the same effect).

So, for me the next step is probably for you to send me any more information you have on any more work done by you in this area. If this is still the current state then I think it would be interesting to have a short teleconference to discuss what we think the next steps could be. It looks like we all have a basic similar outlook on events ( a timestamped "thing") but probably have different ideas on their usage (MO is for reporting, whereas Nav is probably more predicted?).

I would also encourage the MOIMS Planning WG to have an opinion on this as they are certainly going to be a heavy user of both any Nav events but also CSS events for tracking any contact information.

How does this look to everybody?

Best regards,
Sam.
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