Fix Version/s: None
Component/s: Systems Engineering
A meeting around 9/26/2014 agreed on a set of revisions to LSE-69, with some language still needed from Gregory Dubois-Felsmann. This action is to edit the tracked-changes Word version of LSE-69 containing the notes from that meeting into a final copy that can be reviewed by the Camera team and used as input to editing the SysML version of the ICD.
- has to be finished together with
DM-1310 Create change request for LSE-69
A clean copy, LSE-69_20141005.docx, has been uploaded to Confluence and requested to be uploaded to Docushare by Robert McKercher. This is meant to be the content that is reviewed by the CCB.
Provided comments in HipChat and verbally. The only significant change required is to the wording of the DM Conditions Latency specification.
Pat Hascall has asked DM to look specifically at whether requirement CA-DM-CON-ICD-0004, "Camera Conditions Latency for All Data" can be relaxed or removed altogether. Note that this is a requirement of long standing, and that, although the latency value was stated as TBD, it was also stated to be consistent with the "cycle of delivery of raw data to the Archive Center", i.e., related to daytime operations as they were then conceived.
To summarize cartoons of our positions (Pat, correct me if I'm wrong):
Pat: The Camera already has a generic requirement flowed down from the OSS to publish telemetry. Adding this requirement just creates another very similar one to test, and does not really meaningfully additionally constrain the Camera, unless the latency is short (as in the present draft, 60 seconds), in which case there are worries about some types of infrequently-updated telemetry that simply cannot meet that requirement.
Gregory: The 60-second requirement was introduced in the expectation that it would be trivial to meet by just publishing all telemetry more or less as soon as it's available to publish. We understand the problem with infrequently-updated telemetry. It's difficult to craft a bulletproof text that accommodates that, and we are all under pressure not to write wishy-washy requirements. There is at present no baselined DM requirement for the 60-second requirement. By definition Data Release Production runs at much longer latencies, and the telemetry requirements of Calibration Products Production (which runs, among other times, in the afternoon to generate daily synthetic flats) are not yet baselined.
But I don't want to give up on a latency requirement altogether. DM does have a requirement to make Level 1 data products available within 24 hours, and those include the associated Observatory metadata - which includes Camera telemetry.
So I propose that we compromise on a 12-hour latency. I think that should handle all conceivable cases of low-frequency telemetry, and gives DM plenty of time to do any assimilation of metadata into the release of Level 1 data products.
I will edit this into the next draft.
I am fine with a 12-hour latency, but I think all that is necessary to constrain is that the difference between the measurement/rendezvous timestamp in the telemetry and the publication timestamp be no more than, say, 10 seconds (allowing for lots of post-processing). I think DM is going to have to operate in a reasonable fashion whether this telemetry is present or not and a 12-hour latency from image readout to publication is not going to be particularly useful.
K-T's 10-second suggestion, including the decoupling of this requirement (-0004) from the image data cycle, was acceptable to Stuart.
I have added that to the Word document, uploaded it to Confluence, and asked Robert M. to upload it to Docushare.
Review of the Word draft is now effectively complete and what remains to be done is to update EA.
The change request was recommended for approval at the October 22, 2014 CCB meeting.
Edits have been merged into LSE-69-20141004.docx, uploaded to Confluence.