Laser ranging distomats
Replacements for distomats:
1991:How much vertical motion do we
have with the DI1001 distomats at 157 meters.
azimuth to use when vertically aligning
monitoring the distomat
dropouts and the modification log
- Datataking program runs on dos pc. host : lrpc on aonet
- It writes to /home/lprc/lr_data/dyy_mm.dat once every two
- The meausurement starts on the even minutes. it takes about 15
- If the file xfer doesn't work, then check that the pcnfs
server is running on mofongo.
wild di1001 specs: ( I think this was one of the orignal distomats).
- 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
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
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
* show hours that had at least 1 valid distomat
measurement for that hour
- red *
shows hours that had no valid distomat measurement for the
- 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
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:
distomat 6 measurements failed whenever the za got less than 6 deg.
Corner 12 was at a low point when this occurred, so distomat 6 is
pointing too high.
- Az =180 degrees
- za 2 to 20 degrees and back all night
When this occurred,the platform height was close tot he correct
position (1256.22 feet)
The plots show the az,za and
distomat measurement times (.ps) (.pdf)
Distomat 6 needs to be realigned.
- 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
- 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)
The easiest way to align the distomats is to
position the azimuth arm perpendicular to the corner where the
distomat is pointing. This should leave that corner at the average
platform height. It does not matter where the dome/ch is.
Try and center the distomats vertical range on this position.
- distomats 1,6 (corner T12) move the azimuth to 92.87,
272.87, or 452.87 degrees (whichever is closer)
- distomats 2,3 (corner T4) move the azimuth to 32.87, 212.87,
or 392.87 degrees (whichever is closer).
- 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.
- 30dec15 distomat 3 & 6 window replaced.
14:00 distomat 4 mounting screw was not secure. Also had
trouble with power supply. Fixed these and lr4 stopped
- 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
- 05apr12: windows on all distomats changed from plastic to
- 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
- 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.
- 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
- 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
- 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
- 17mar06:d1 window cleaned inside,out with anti fog spray
- 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
- 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.
- 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...