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Backsight set-up checking weird
Posted by abw on September 11, 2013 at 9:43 pmEquipment: Leica 1203+ robot, Leica RX1250 data collector, 360 prism
At 8:00 am, set up on control point 2 and backsight 1…horizontal error= .03 feet
11:00 am, re-backsight .04 feet
Go to lunch.
11:30 am, set up on control point 1 and backsight 2…6.9 feet error.
2:00 pm, set up on control point 2280 and backsight 2…6.9 feet error.
3:00 pm, set up on control point 1 and backsight 2… .03 feet error.
4:00 pm, set up on control point 2 and backsight 1… .03 feet error.
You’ll notice on 4 set ups that 2 are the exact same scenario. So why does it as one time check at 6.9′ and another time at .03′? Note there was nothing in the vicinity for the robot to latch onto (something other than the prism). Note that I check the data with the bad backsight with a “good” setup. There was no significant difference in horizontal location. Also verified with GPS…again, no significant difference.
Has anyone else experienced a similar scenario?
surveythemark replied 10 years, 8 months ago 7 Members · 9 Replies- 9 Replies
> Equipment: Leica 1203+ robot, Leica RX1250 data collector, 360 prism
>
> At 8:00 am, set up on control point 2 and backsight 1…horizontal error= .03 feet
>
> 11:00 am, re-backsight .04 feet
>
> Go to lunch.
>
> 11:30 am, set up on control point 1 and backsight 2…6.9 feet error.
>
> 2:00 pm, set up on control point 2280 and backsight 2…6.9 feet error.
>
> 3:00 pm, set up on control point 1 and backsight 2… .03 feet error.
>
> 4:00 pm, set up on control point 2 and backsight 1… .03 feet error.
>
>
> You’ll notice on 4 set ups that 2 are the exact same scenario. So why does it as one time check at 6.9′ and another time at .03′? Note there was nothing in the vicinity for the robot to latch onto (something other than the prism). Note that I check the data with the bad backsight with a “good” setup. There was no significant difference in horizontal location. Also verified with GPS…again, no significant difference.
>
> Has anyone else experienced a similar scenario?The check from 2280 to 2 was a good idea. Since you’re getting a constant 6.9′ error it would seem to disprove any theories about getting returns from a distant car window or the like, unless 2280 -> 2 was in the same general direction as 1 -> 2.
I haven’t had an issue that was that extensive unless it was my own error of using the wrong prism constant; any way you can export your setup log from the DC?
The prism constant was correct. I’ll take a look in CAD tomorrow morning. I verified quite a few topo shots and they all check…even though there was a 6.9′ error in the backsight. That just baffles me that there weren’t any incorrect locations from that. I kept on shooting figuring the 6.9′ was a constant error and I could adjust…and aghast was I when later that error just disappeared on the later afternoon set ups.
I have found that with certain firmware versions, our Trimble 5600 series will measure a distance off a painted white wall, even when it’s not in reflectorless mode.
Kind of made me nervous, but I have never had a problem with distances with this particular inst.
Was the line on a slope? Could the DC be comparing a slope distance to a horizontal distance because of a bug?
I/we had something inexplicable sort of like that happen once.
Nothing robotic at all.I was on the gun and we just simply traversing through the mountains enroute to a corner to locate.
We were doubling our angles or “collect sets” depending on what your DC calls it and everything was going just fine all day.
All of sudden a backsight check simply would not hit within our allotted error – by a LOT.
I mean several minutes on angle and a foot or two in distance. I was easily the best angle turner in the company at the time so no one questioned my abilities.
I turned about 6 sets before giving up and got one of the other guys to try. Same result. The 3rd guy tried with the same results. We each broke it down and re-setup so as not to re-use each other’s setup. Actually, their’s checked worse than mine. In fact it seemed to get worse with each try.We began to suspect the gun must have gone out of calibration on us. A call to the office left them stumped as well and just said to box it and we would test it on some known good points there. We checked all the rods as well.
We did and everything checked out fine there.
Came back the next day with a backup gun just in case.
The weather was the same, same crew, same equipment.
I turned the first set and it checked just fine – back to my usual excellent results.As relieved as we were it left us completely baffled so I turned another set. Again with excellent results.
We just shrugged it off and kept on going.
No one could ever explain it except for “sometimes that just happens”.
It never happened to me before or since.Abw,
This is definitely a strange one…
When I first read it it seemed that Pt 1 would be the proble with the setups after lunch but his is not the case. Also when you looked at the data from the bad backsight check you mentioned that it was good in XY. I was thinking that there may have been a change in the settings for the setups at 11:30 and 2:00 but if the XY checks for the backsight measurement that could not be the case.
When you are checking the data for the bad backsight … say the one at 11:30 with instrument at 1 backsighting 2…. are you looking at all of the measurements recorded in the job database by changing your data filter to show all the measurements and looking at the time stamp? Do you have the data filter set to – No Filter?
I’ve had the robotic eye of a Trimble 5600 lock on the diode of the target and measure to a reflective hwy sign 40′ closer than the prism because the bottom of the sign was splitting the target, diode below and prism blocked from sign above. Sure keeps you honest and looking for error possibilities in this new era of surveying. Jp
Do you reckon that maybe the results got toggled and it was showing vertical difference?
I have narrowed it down to what I happened from the raw file. Seems it backsighted with an offset of 7′. Here’s how that happened:
*was going to offset a tree 7′ behind me
*as you know, once an offset shot is taken with a Leica, the offset distance would go back to “0.00” after the offset shot was taken*However, I never took the shot. We turned everything off and went to lunch.
*Somehow, when we set up again and turned everything on, that offset still carried over….even into the backsight setup. The raw file clearly stated that.What is baffling about all this is not only how or why…but why the collector at no time displayed during the “set-up” sequence that an offset distance would be included.
We had talked to Jeff Posey about this and he is currently trying to recreate our scenario and see what happens.
Abw,
I have never run across this one…. and yes… I would have always assummed that if you exited the survey application even if you never took the shot or a distance that the offset values would return to zero. This is a bug in the software. I can test this and send it up the line to be fixed.
Can you send back to me the firmware version on the RX1250??? Even if it is an older version this may still be in the latest version of firmware….
1. From main menu select the USER key
2. Then select F3 (STAT)
3. Next select 3 System Information…
4. Select F6 (PAGE) once so that you are viewing the Firmware page
5. Send me the firmware version that is listed on the first line — Firmware: (Firmware Version Value)
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