BST timing and BPM triggering

Info from Lars Jensen: Triggering of the BPM acquisition

Info from David Dominguez: BI needs for SPS, BST

Conclusion by Jens Andersson from the discussion with Lars Jensen:

• The BPM acquisition will start when some given BST bit is set. A default set of 1, 10, 100, 1000 Hz is available.
• The acquisition will be over a given number of turns (1-255). A suggested method would be to average over 20 ms (approx 224 turns), to get rid of 50 Hz noise. No such noise has been observed so far though, so it could perhaps be done over much fewer turns. In any case, the acquisition can be performed concurrently with orbit control processing, so the 20 ms does not necessarily add up to the total latency.

Conclusion by Jens Andersson from the discussion with David Dominguez:

• The BST master will not have a main input which is guaranteed to be in absolute synch to UTC during 2004 (or will it? unclear), but later it definitely will.
• The BST master has 8-16 external inputs, one of which could be UTC from a GPS card.
• With a bit of programming and an allocated bit in the BST message, any delay in a whole number of milliseconds between BPM triggers can be produced.
• Also with those conditions, it will be possible to start on a given millisecond number, which will be UTC synched if the main input is.