1. Monitoring glitches in the frequency divider
N. Blaskovic
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2. Contents
Monitoring the glitches of the 714-to-357 MHz frequency divider: set-up and results
The effect of the use of Colin’s filter to reduce glitching
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3. SET-UP 1 22/04/12 00:56 (onwards) KEY N. Blaskovic FONT Meeting
Doug’s original set-up
SET-UP 1 22/04/12 00:56 (onwards)
BNC 18 “kicker pre trigger”
fanout
scope CH1 (trigger)
BNC 16
LO box
(In  Out Raw)
scope CH2 20 16
Φ/2 (2008)
scope CH3
Φ/2 (2011)
scope CH4
KEY
Power splitter
1.5 Hz
Amplifier (dBm)
Φ/2
Frequency divider (year)
714 MHz
Attenuator (dBm)
Colin’s filter
357 MHz
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4. SET-UP 1 N. Blaskovic FONT Meeting
Data collection (Doug’s scope DAQ): only the value of CH2, CH3 & CH4 at the sampling index (shown by the circles) are logged for each acquisition (approx. every second)
Voltage of CH2, CH3 & CH4 vs. time for an acquisition:
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5. SET-UP 1 N. Blaskovic FONT Meeting
20 glitches in CH4 (no filter) over the first acquisitions
0 glitches in CH3 (with filter) over the first acquisitions
‘Slipping’ of CH2, CH3 & CH4 relative to CH1 trigger evident for acquisitions
Plot of sampled CH2, CH3 & CH4 voltages vs. acquisition number:
6 h (0.8 acq/s)
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6. SET-UP 2 22/04/12 17:52 (onwards) KEY Freq. dividers interchanged
BNC 18 “kicker pre trigger”
fanout
scope CH1 (trigger)
BNC 16
LO box
(In  Out Raw)
scope CH2 20 16
Φ/2 (2011)
scope CH3
Freq. dividers interchanged
Φ/2 (2008)
scope CH4
KEY
Power splitter
1.5 Hz
Amplifier (dBm)
Φ/2
Frequency divider (year)
714 MHz
Attenuator (dBm)
Colin’s filter
357 MHz
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7. SET-UP 2 N. Blaskovic FONT Meeting
No glitching recorded in either CH3 or CH4 (over around 4 hours)
‘Slipping’ of CH2, CH3 & CH4 relative to CH1 trigger evident
Voltage of CH2, CH3 & CH4 vs. time for an acquisition at 18:17 (FONT PC time):
Sampling close to CH2, CH3 & CH4 peak
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8. SET-UP 2 N. Blaskovic FONT Meeting
No glitching recorded in either CH3 or CH4 (over around 4 hours)
‘Slipping’ of CH2, CH3 & CH4 relative to CH1 trigger evident
Voltage of CH2, CH3 & CH4 vs. time for an acquisition at 18:51 (FONT PC time):
34 minutes later, the sampling point is no longer sampling CH2, CH3 or CH4 peaks!
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9. SET-UP 2 N. Blaskovic FONT Meeting
Possible sources of ‘slipping’ of CH2-4 relative to CH1 trigger:
Phase drift of the 1.5 Hz trigger relative to the 714 MHz
Varying shape of the falling edge of the 1.5 Hz pulse
wobbly CH1 (trigger)
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10. SET-UP 3 23/04/12 01:17 (onwards) KEY CH3 used as trigger N. Blaskovic
BNC 16
LO box
(In  Out Raw)
scope CH2 20 16
Φ/2 (2011)
scope CH3 (trigger)
CH3 used as trigger
Φ/2 (2008)
scope CH4
KEY
Power splitter
Amplifier (dBm)
Φ/2
Frequency divider (year)
714 MHz
Attenuator (dBm)
Colin’s filter
357 MHz
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11. SET-UP 3 N. Blaskovic FONT Meeting
This set-up allows a clear count of glitches. Left running overnight, the number of acquisitions collected was
Number of glitches (in CH4): 2022
Plot of sampled CH2, CH3 & CH4 voltages vs. acquisition number:
13 h (5 acq/s)
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12. SET-UP 3 N. Blaskovic FONT Meeting Zoom in...
Plot of sampled CH2, CH3 & CH4 voltages vs. acquisition number:
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13. SET-UP 3 N. Blaskovic FONT Meeting Zoom in further...
Glitching on occasions occurs between consecutive acquisitions, with an acquisition rate of 5 acq/s
Plot of sampled CH2, CH3 & CH4 voltages vs. acquisition number:
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14. SET-UP 3 N. Blaskovic FONT Meeting
But glitches in CH3 (with filter) are indistinguishable from glitches in CH4 (no filter):
Glitch in CH3
Given that CH3 is set as trigger,
CH2 (714 MHz) is shifted through a whole period
CH3 (357 MHz, filter) does not glitch, as it is acting as the trigger
CH4 (357 MHz, no filter) apparently glitches, due to the glitch in CH3 (trigger)
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15. SET-UP 3 N. Blaskovic FONT Meeting
But glitches in CH3 (with filter) are indistinguishable from glitches in CH4 (no filter):
Glitch in CH4
Given that CH3 is set as trigger,
CH2 (714 MHz) undergoes no change
CH3 (357 MHz, filter) undergoes no change
CH4 (357 MHz, no filter) glitches
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16. SET-UP 4 23/04/12 15:50 (onwards) KEY Initial set-up; no filters
BNC 18 “kicker pre trigger”
fanout
scope CH1 (trigger)
BNC 16
LO box
(In  Out Raw)
scope CH2 20 16
Φ/2 (2008)
scope CH3
Initial set-up; no filters
Φ/2 (2011)
scope CH4
KEY
Power splitter
1.5 Hz
Amplifier (dBm)
Φ/2
Frequency divider (year)
714 MHz
Attenuator (dBm)
Colin’s filter
357 MHz
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17. SET-UP 4 N. Blaskovic FONT Meeting
1 glitch in CH4 (2011 frequency divider, no filter)
0 glitches in CH3 (2008 frequency divider, no filter)
Plot of sampled CH2, CH3 & CH4 voltages vs. acquisition number:
2 h 20 min (0.8 acq/s)
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18. Summary
The 357 MHz signal coming out of the frequency divider does glitch
Glitching occurs as often as every 0.2 s
Rate of glitching varies throughout the day
Colin’s filter reduces the occurrence of glitches: not a single glitch was recorded when using the filter
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19. Epilogue: a single slide on kicker gain matrices
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20. Comparison of kicker gain matrices: December 2011 – April 2012
P2 P3 GainDec* = K K Gain18AprCal2** = Gain18AprCal2 ./ GainDec = * final kicker calibration, as used for fbRun6,7,8_Board1_coupled_ ** kicker calibration 2 on
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