Leica Backsight Error

I've came to the conclusion the 1203 and 1203+ are dud models.

Aaron,

What are the distances between points? Anything over 500 feet and a one-way vertical is never very reliable. That being said, I can take reciprocal measurements at 1200 feet and the adjusted elevation are flat.

As for the 1203 being a dud, ours has performed remarkably well over the years.

When you did the checks, did you do the vertical index after the combined adjustment?

> I know there was a thread on this earlier but I could not find it so I apologize in advance if this has been answered.
> The other day I was set up on CP #1, Backsight, CP #2. I turned and tied a couple of additional points 20,22. Moved to CP 20 and backsite CP #1. Horizontal flat, vertical -.05'. Hmmm..... Turned to 22 to check it. Flat on both. okay. So I moved back to #1, backsight again to #2 and did a stakeout to #20. Hit flat. At this point I'm stumped. Set back up on #20 and backsight #1 again. -.05'. Called my Leica rep and we ran thru a check and adjust, still had same issue. Ended up taking it in and having them run a calibration on it. Vertical was right on. This has happened several more times and I know that other people were running into this same problem. Its ALWAYS on the backsight.
>
> Equipment:
>
> CS15 w. Viva v4.60 controller
> TCRP 1203 Instrument
>
> Thanks!

Hello Aaron23,

By 'flat' I assume you mean a good check? ~0.000m?

How far and how steep are the sights? Manual or ATR? 1 or 2 faces? How long since your l,t calibration? distance from 20 to 22?

If they were long sights (>300m) I'd guess it's a combination of refraction, l,t index error and residual V index. Depending on the geometry of the stations then you could easily get a 'dud' looking backsight check but ok side check to another station.

If they are were all short sights then I'd be perplexed too.

short sights - appx 300'. Did the full meal on the check and adjust and when I took it in they put it on their equipment and measured the high to low vertical check and it was right on.

short sights appx 300' and pretty flat. Was just shooting down a road. no heat wave, it was a fairly brisk morning and instrument had been outside for about an hour so I think it was pretty well acclimated.

forgot to mention, I tried ATR, Manual, both faces etc. all the same result. Stakeout to the point was good. then when I set up on it, my backsight off. Its perplexing.

I've had good luck with mine, until this issue popped up.

I had a similar problem several years ago with my 1205, after I sent it to Phoenix for a check and calibration. When it came back I had obvious problems with the backsight elevation check. It turned out there was a Phoenix area coordinate system file in memory, and the total station was trying to warp to it from Tucson (yes, I know that sounds weird). I deleted that file, and it reappeared. Numerous times I went back and forth between the total station and the GPS rover, always deleting that coordinate system file, and it came right back. After perhaps ten tries I finally got rid of it, and then the total station elevations were correct.