Since yesterday (March 9th) several DBOX have their LEDs switched off:

• SDB2: rtpc 5 - DBOX SN07, DBOX SN09, DBOX SN11 (switched off since ~09h05 utc)
• LNFS: rtpc 6 - DBOX SN26 (switched off since ~09h23 utc)
• SIB2 : rtpc7 - DBOX SN08, SN03, SN01 and SN02 (switched off since ~13h20 utc)
• SPRB : rtpc6 - DBOX SN05 and SN06 (switched off since ~13h20 utc)
• SNEB : rtcp8 - DBOX SN04 and SN13 (switched off since ~13h20 utc)
• SWEB: rtcp8 - DBOX SN14 and SN15 (switched off since ~13h20 utc)

The first plot show, for the whole tests sequence related to 5Hz comb investigation,

• The ITF state (META_ITF_LOCK_index)
• the spectrum time of the +12V power supply related to the DBox hosting the camera mezzanine board (SDB2_POWERSUPPLY_DBOX_RIGTH_DOWN_p12V)
• and the one of the B1p QD2 quadrant horizontal signal demodulated at 56MHz (SDB2_B1p_QD2_H_56MHz_I)
• according the following states:
  • Camera ON or OFF
  • Mezzanine Camera ON or OFF . When the mezzanine camera is OFF the connected cameras becomes OFF too .
  • and DaqBox LED ON or OFF

Note:

• the camera trigger signal is a square signal at 5Hz: so only  the 5Hz odd comb(1*5Hz, 3*5Hz, 5*5Hz, ..)
• it seems that time axis of the spcetrum time plot is shifted related to the real one

1:  From 7h00UTC  to 9h15UTC

• During this test sequence, the 5Hz comb remains present in SDB2_B1p_QD2_H_56MHz_I spectrum until the ITF unlock, as there is no more signal
• From the SDB2_POWERSUPPLY_DBOX_RIGTH_DOWN_p12V spectrum, one can see that
  • the 5Hz odd comb amplitude reduction when stopping one by one the different cameras but the 5Hz comb remain present
  • the 5Hz even comb amplitude disappears only if the Camera mezzanine is OFF
  • Around 8h55UTC the DBOx LED were switched OFF on all the SDB2 DBox: the 5Hz comb disappears on all the SDB2_POWERSUPPLY_DBOX_XXX_p12V  signals

2: From 10h00 UTC to 11h00UTC - ITF back in low_noise_3

• The DBx LED are OFF on all the SDB2 DBoxes
• when the CAMERA are OFF and the Camera mezzanine OFF too(from 10h20UTC to 10h30 in the spectrotime plot), there is no more 5Hz odd comb in the  SDB2_B1p_QD2_H_56MHz_I spectrum and  in the  SDB2_POWERSUPPLY_DBOX_RIGTH_DOWN_p12V one
• from 10h30UTC to 10h50UTC the cameras were set to ON one by one with only one enable each time. One can see that the 5Hz odd comb reappears in the  SDB2_B1p_QD2_H_56MHz_I spectrum.

This plot  (zoom) compare the spectums of B5_QD2 DC and RF at 56MH channels, and the ones of the B1p_QD2 DC and RF at 56MHz in the following conditions:

• Blue: DBox LED ON , mezzanine camera ON and  camera ON,
• Purple: DBox LED OFF , mezzanine camera ON and  camera ON,
• Brown: DBox LED OFF , mezzanine camera OFF as consequence  camera OFF,

with:

• for the B5_QD2  photodiode
  • the DC signals are acquired by a ADC2378 located in the SDB2_DBOX_RIGTH_DOWN DBox
  • the RF@56MHz signals are acquired by a DemodMezz located in the SDB2_DBOX_LEFT_UP DBox
• for the B1p_QD2 photodiode
  • the DC signals are acquired by a ADC2378 located in the SDB2_DBOX_RIGTH_UP DBox
  • the RF@56MHz signals are acquired by a DemodMezz located in the SDB2_DBOX_RIGHT_DOWN DBox

The plot (zoom) related the SDB2 +12V power supplies in the same conditions

One can see that

• for the B5_QD2 the 5Hz odd comb disappears on most of  the DC and the RF channels once the DBox  LEDs are OFF
• for the B1p_QD2, the 5Hz comb are still present but  are reduced if there is only the DBox LEDs off . They disappeared only if  everything is OFF : mezzanine camera(cameras ) and  DBox LEDs.
• for B5 and B1p quadrants, the 5Hz even comb remains at the same level whatever the conditions.
• related the power supplies:
  • for the SDB2_DBOX_LEFT_{UP,DOWN} and SDB2_DBOX_RIGTH_UP  the 5Hz odd comb disappears when the DBox LEDs are OFF
  • for the SDB2_DBOX_RIGTH_DOWN the 5Hz comb (odd and even) disappears only  when the  camera mezzanine is OFF (cameras OFF too)
  • idem for the Quadrant power supply, the 5Hz comb (odd and even) disappears only when the  camera mezzanine is OFF(cameras OFF too)

SDB2 power supplies

These plots show the spectrum time plot of the SDB2 +12V power supplies between [30Hz-60Hz], [90Hz-120Hz], [150Hz-180Hz] . One can see

• some moving lines around 40Hz, 100Hz and 150Hz on all the channels monitoring related to the SDB2 power supplies
• and a line moving from 30Hz to 42Hz  in the SDB2_POWERSUPPLY_DBOX_{RIGTH,LEFT}_UP_P12V channels during the ITF relock at ITF state 124 (LOCKING_OMC1_B1s2_DC) . This does not occur at each lock sequence

Conclusion

The 5Hz comb in the SDB2 quadrant signals seems to be due a combination of  the cameras readout and the DBox LEDs.

Today only the SDB2 and SPRB power supplies are monitored .

The follwing plots show the spectrum time of the  SDB2_LEFT_DOWN +12V and the SPRB_LEFT_DOWM +12V channels in the [80Hz-110Hz] and in the [130Hz-160Hz]  frequencies bands.

On can see :

• that the 1Hz  comb  disappears when the SPRB DBox LED were switched off around 13h20UTC
• The presence of some moving lines on both SDB2 and SPRB power supplies
  • for SDB2 around 95Hz and 150Hz
  • for SPRB around 86Hz with some jump upto 92Hz , and 142Hz with some jumps upto 149Hz