Measurements:

• 07sep15: using 3 distomats to measure the height.
  
• 11apr14: distomat failure by hour of day.
  
• 08jun12 test distomat mounted on distomat 6. distomat 6 goes out of alignment.
  
• Rfi caused by the distomats

Replacements for distomats:

INFO/Doc

Software:

• Datataking program runs on dos pc. host : lrpc on aonet
• It writes to /home/lprc/lr_data/dyy_mm.dat once every two minutes
• The meausurement starts on the even minutes. it takes about 15 seconds.
• If the file xfer doesn't work, then check that the pcnfs server is running on mofongo.
  

• accuracy: 5mm  + 5ppm
• range: 1km (1prism)
• measurement time: 1,5 sec
• production year: 1989-2001

11apr14: distomat failures by hour of day.

    Distomat 3 has not been working very well for the last month or 2. This  has caused the laser ranging measurement to fail (it needs all 6 distomats to measure the platform position). 

    The tiedown tracking uses the distomat measurements to keep the platform at the correct height. If their is no measurement, then the platform remains in the current position.

    I plotted  distomat failures by hour of day for 12mar14 to 11apr14 (10am). For each hour of each day i marked the hour ok  if there was at least 1 valid distomat measurement during this hour.

    The plot shows the distomat measurements by hour for 12mar14 to 11apr14 (.ps)  (.pdf)

• The horizontal scale is hour of day
• The vertical scale is day number of year
• daynumber 71 = 12mar14
• daynumber 101= 11apr14
• green *  show hours that had at least 1 valid distomat measurement for that hour
• red *   shows hours that had no valid distomat measurement for the entire hour

Summary:

• since 01apr14 (daynum 91) there have been no valid distomat measurements 22:00 to 7:00 hours
• for 9 of the 11 days (01apr-11apr) there have been no valid distomat measurements 17:00 to 7:00hours
• Some days have no valid measurements 15:00 -> 07:00
• The lack of measurements is leaving the platform at a daytime position for the entire night.
• High frequency observing  cband,xband  will be far out of focus during the evenings for these nights.
• If the failure rate of the distomats continues, we'll need to rethink high frequency observing (or at least using something other than the distomats to position the platform

processing: x101/140411/distochk.pro

08jun12: test distomat mounted on dist6. dist6 goes out of alignment

    On 07jun12 a test distomat was mounted on the side of distomat 6 canister. This caused distomat 6 to go out of alignment. Galfacts (as2130) ran from 20:00 to about 2:30 the next morning. Their setup was:

• Az =180 degrees
• za 2 to 20 degrees  and back all night

• Top Azimuth vs hour of day
• 2nd: dome za vs hour of day
• bottom: Time for each distomat to make a measurement. The normal value is 5 or 6 seconds.
• I've offset each distomat time for display,. The dotted line shows the 0 sec line for each distomat.
• A distomat failure will record 0 seconds for the measurement time.
• You can see the times increase for dist6 as the dome approaches  6deg from higher za.

Azimuth angles to use when aligning the distomats.  (top)

1. distomats 1,6  (corner T12) move the azimuth to 92.87, 272.87, or 452.87 degrees (whichever is closer)
2. distomats 2,3 (corner T4) move the azimuth to 32.87, 212.87, or 392.87 degrees (whichever is closer).
3. distomats 4,5 (corner T8) move the azimuth to  152.87, 332.87 or 512.87 degrees (whichever is closer).

Some things to keep in mind.

• Make sure the tiedowns are tracking the average height of the platform before you start the adjustments.  Look at the tiedown Status display in the control room. The mode should be tieTrk for all 3 tiedowns. If it does not say this, ask the operators to do a tietrk command
• The platform should be close to the reference position. Look on the laser ranging display  (the plot of height versus hour of day to the left of the observers workstation). On the upper right it has the time, platform position, and the platform reference position. The time should be within the last 3 or 4 minutes. The last position should be within .05 feet of the reference position.
• If the software tries to take a measurement while you are adjusting the distomat, it may get a no reading. In that case it will switch and use the temperature to position the tiedowns. This is probably not a problem.

History

• 2018
• 
  
• 180629: distomat 5 di1001 replace by di1600 (purchased on ebay)
  
• 2017
• 27jun17: distomat 3 di1001 replaced by di1600
  
• 2015
• 30dec15 distomat 3 & 6 window replaced.
  
• 2014
• 03jun14 14:00 distomat 4 mounting screw was not secure. Also had trouble with power supply. Fixed these and lr4 stopped failing.
  
• 2012
• 07jun12. tsst distomat installed on canister for distomat 6. dist 6 goes out of alignement.
  
• 01may12 distomat 4,5 switched to see if problems with 5 change. Switched all windows back to the plastic. The power levels went up. Looks like glass was not working very well
  
• 20apr12. put new plastic window on distomat 5 (was glass) to see if sun problems decrease.
  
• 18apr12,19apr12 put sun shade on distomat 5 to cut down on failures.
  
• 05apr12: windows on all distomats changed from plastic to glass
  
• 2010
  
• 20sep10: distomat 2 replaced with spare.
  
• 17sep10: distomat 2 has been failing a lot. when window removed rcvd signal goes from 1 to 5. today replaced window with a window that was on the kronos time system in building 1. rcv signal with window on is now 2-2.5.. close to what other distomats have. (but distomat continued to fail). Willy says there is an error registering on the distomat.
  
• 20oct08: new reflectors at 2,3,4,5 installed
• 10oct08: new reflectors at 6,1 installed
• 10jan07: all dists window cleaned. dist2,3 were realigned
• 2007
  
• 24jan07: distomat 5 failed (sn 101115) with error 72. Replaced with spare (sn 101036?).
• apr07: some distomats were covered by the containment for a few days. Probably need to realign the distomats when painting done. For apr07->jul07 data was used even when ch not in stow position. This was needed since the painting did not leave the ch at stow.
• jul07: distomat 4 and 5 were off for a long time because of the painting containment.
• aug,sept.. some distomats covered by painting containment.
• 2006
  
• 13nov06: dist 3( sn xxx) was replaced with s/n 10115) from leica. The external window was replaced with a new one.
• 02oct06: dist5 window cleaned and realigned around 13:45
• 02oct06: dist6 (sn: 101115) was replaced by sn:10037. Cleaned and then realigned.
• 11sep06: all distomat  windows cleaned with fuller anti-fog.
•  07sep06: morning. replaced distomat 5 (sn 100337) with distomat back from maintenance (sn 101036).
• 06jul06: dist 4 (sn 101036) replaced by dist (sn 101075) and then realigned. sn 101036 will be sent back to fab for maintenance.
• 05jul06: all distomat windows cleaned.
• 21apr06: realigned D4. Looks like it got knocked out of alignment by the previous days work. D5 was also realigned.
• 20apr06: d1 switched out for maintenance. It was replaced with the spare that just came back from leica. windows cleaned and fans turned on for distomats: 1,2,3,4 (5,6 will be done tomorrow).
• 17mar06:d1 window cleaned inside,out with anti fog spray 14:00.
• 16mar06:d2 window changed 11:25.
• 14mar06: d1 window changed, realigned. Used a different glue with this window :flexible silicone adhesive silver plate aluminum from chomerics.
• 06mar06: d1,d2,d3 exterior window cleaned with anti fog.
• 23feb06: distomat 2,3  outside window cleaned with EXXENE antifog.
• 07feb06: new windows distomats: 3,4,5.
• 06feb06: new window distomat 6.
• 27jan06: afternoon all fans turned off. lenses cleaned.
• 19jan06: fan installed dist5
• 18jan06: fan installed dist 4
• 17jan06: fan installed dist 3
• 13jan06: fans installed dist 1 and 2.
• 11jan06: put fan in distomat 6 to try and improve temperature circulation inside canister.
• 2005
  
• 30may05 6pm distomat 4 stopped working. When examined, the heater was off. Probably no power getting to distomat. On next day found that the filter for the ac line that is right inside where the acpower enters the distomat canister was toast...
• 31jan05:    all distomats realigned.

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