Timing for AP: introduction Javier Serrano AB-CO-HT 15 September 2006.
6
Timing for AP: Timing for AP: introduction introduction Javier Serrano Javier Serrano AB-CO-HT AB-CO-HT 15 September 2006 15 September 2006
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Transcript of Timing for AP: introduction Javier Serrano AB-CO-HT 15 September 2006.
Timing for AP: Timing for AP: introductionintroduction
Timing for AP: Timing for AP: introductionintroduction
Javier SerranoJavier SerranoAB-CO-HTAB-CO-HT
15 September 200615 September 2006
Plan for the morning
Intro, context, hardware. Javier. General timing concepts. Julian. Central Timing. Jean Claude. Distributed Timing. Ioan. Visit of central timing and BA3
Faraday Cage. Hands-on demo.
The timing team One of the 3 broad activities of the HT section. Three SW FTE:
Julian: activity leader, low level software. Jean Claude: central timing, libraries. Ioan: distributed timing.
Broad mandate: sync services for all accelerators at CERN, both HW and SW.
Strong ties to operation, many installed systems -> very visible activity.
Big inter-dependencies with all layers of control system -> need to communicate a lot.
Many clients with different (sometimes conflicting) requests -> continuous evolution, sometimes causing unavoidable instability.
Overall though, very successful system. Injectors can change function completely every 1.2 seconds!
GPSOne pulse per Second
GPS
Smart clockPLL
PLLOne pulse
per Second
Phase locked10MHz
Basic Period1200/900/600 ms
Advanced (100us)One pulseper Second
Synchronized 1KHz(slow timing clock)
Phase locked10MHz
Phase looked40 MHz Eventencoding clock
40MHz PLL
CTSYNC
RS485Timing
CTGU
The newgenerationlowjitter <1nsVMEbasedMTGmodule
UTC time (NTP or GPS)
Eventtables
External events
General Machine Timing (GMT) Hardware Architecture
CERN UTC Time
Set once on startup & on Leap Seconds
RS485Timing
CTRP
40 MHz
10 MHz
1 KHz
1PPS
Delay
Control SystemCERN UTC Time
25ns steps
Timing receiver
UTC: the basis for GMT at CERN
Very precise atomic time standard. Uniform seconds defined by International Atomic Time. Leap seconds added every ~18 months to compensate
for the Earth’s slowing rotation. Warning 1: Subtraction of two dates must in principle
consult a table of leap seconds. Warning 2: other time scales (like UNIX time, GPS time
and TAI) do not use leap seconds. UTC is nevertheless the most used system because all
legal time is referenced to it. All leap seconds happen at midnight on June 30 or
December 31.
GMT cards CTG: Controls Timing Generator.
Runs “event programs” in a dedicated CPU. Its output drives one GMT network.
CTR: Controls Timing Receivers. They produce pulses and interrupts in response to GMT events. CTRV: VME format. CTRP: PMC format. CTRI: PCI format.
