Minutes of the 11^th Timing Working Group Meeting (TimWG)
Held on Friday the 30^th June 2000

Present:

Excused:

Julian LEWIS.

Agenda

• Approval of previous minutes
• GPS update - Gary BEETHAM
• WorldFip jitter measurements - Quentin KING
• IRIG-B tests at LEP - Andy BUTTERWORTH
• AOB

Approval of previous minutes

There were no corrections on the previous minutes.

GPS update

Gary BEETHAN reminded the decision of the White House to stop degrading the global positioning system (GPS) accuracy. He presented a first set of results showing an improvement by a factor 5 of an absolute position measurement. More improvements in the future can be expected. Measurements of the absolute time distribution stability are in progress.

WorldFip jitter measurements

Quentin KING presented the results of jitter measurements over WorldFip. These results are a factor 3 better than what was expected and a factor 2 better than what SL/PC needed.  In summary, highly precise distribution of synchronized time over WorldFIP has been successfully demonstrated and the possibility to realize a start of a ramp at a specified time has been demonstrated. He reminded that the overall event distribution method has still to be decided and that the "Digital Controller Hardware" design needs to be frozen within 1 year, so a decision on event distribution (at least as far as it affects the bottom layer) is needed soon.

IRIG-B tests at LEP

Andy BUTTERWORTH showed a distributed diagnostics system for LEP RF trips monitoring based on the GPS/IRIG-B for absolute time acquisition. A measurement synchronization mechanism with a resolution better than 30us have been achieved for equipment distributed across 4 different LEP pits.

AOB

John PETT reminded the important dead lines for the design of the converter controls and raised up questions of different timing aspects that have still to be solved:

• Design decisions for the converter controls by end of 2000
• Need to have the OK from the TimWG on the actual propositions
• MTG design and responsibility, event distribution mechanism
• Reminded the networking aspect for event and error processing

Michel JONKER asked to put on the agenda of a future meeting the question regarding the necessity of an MTG mechanism for event distribution taking into account the real time requirements for the LHC control system.

Next meeting

Next Meeting will be held on Friday14 July 2000 at 10:30 AM in 864 1C01.

Agenda

1. Approval of previous minutes
2. TTC Test Beam results, Bruce TAYLOR
3. BI progress with TTC, Jean-Jacques SAVIOZ
4. GPS IRIG-B measurements, Christian ANTFOLK
5. AOB