Show us why the public should always call a land surveyor

Where are you surveying?

Land Surveyor


I am a budding surveying professional and am trying to troubleshoot my old Nikon DTM A20lg total station. Currently riding the struggle bus as the original manual is pretty slim and not comprehensive. Most of my work is in water resource sciences, performing topographic and bathymetric surveys for river engineeirng projects.


I'm only trying to use this (old, inexpensive) TS for simple local surveys in very rugged, WET, accident prone locations, thus why I have gone with the obsolete, vintage tool. I do not have a data collector. Really just trying to get local coordinates and topographic survey scratched into a notepad and put into CAD/HEC.

I have poured through the manual and have figured out how to reset the horizontal reference angle (zenith) to 0 degrees for a local survey and set the XYZ of the TS origin/station point to 1000,1000,100. I input target height & instrument height no problem. Sokkia prism constant is set to 0mm.Ā 

My problems arise when I shoot the prism for topo shots. When I sight the prism and take a shot, it goes through the motions with the EDM (I can hear it whirring), but it doesn't spit out the horizontal distance (HD), vertical distance (VD), or calculated XYZ coordinates of the ground shot. Instead, the output reads that the prism/target is located on the station point (1000,1000,100.83 - that extra 0.83 is weird). This happens regardless of where I move the target. When I check the measured distances of a shot using the keyboard buttons, it reads the slope distance (SD) - which appears to be accurate - but a horizontal distance (HD) of 0. Vertical and horizontal angles (VR, HR) appear to be consistent and accurate when I re-position the target back on the same ground shots.

Whats weird is it is calcuating the slope distance but not registering any horizontal or vertical distance. The slope distance appears accurate when I pull a tape from the EDM to the prism.Ā 

Other forums have suggested trying longer and shorter distances for ground shots, rebooting, re-set initial settings, pulling the batteries and letting the unit sit overnight, then trying again. Nothing changes.

I'm going to send it in for calibration (been stored 10 years) and service, but wanted to see if folks know of anything else I should try. Its a fun little unit - when it works! The last time I know it worked well was 2 winters ago..Ā 


You need to be a member of Land Surveyors United - Global Surveying Community to add thoughts!

Join Land Surveyors United - Global Surveying Community

Votes: 0
Email me when people reply –


This reply was deleted.

Answer As your Facebook Page

Global Surveyor Forum

Latest Discussions by Category

How to Utilize Surveyor Forums

How to use Forums
Our forums on Land Surveyors United are here to be used as much for finding help with problems in the field as the are for you to express your opinions on anything that has to do with land surveying in general. Feel free to share anything that is on your mind, as long as it isn't meant to damage another member's reputation. Please keep it clean and help insure that everyone has the opportunity to enjoy the benefits of being part of a community that grows together.

We are committed to allowing freedom of expression for all of our members, and that includes maintaining a safe space for people with opposing views to express themselves. We get posts from all over the country and even the globe, so needless to say, people come with different viewpoints on lad surveying practices and processes. We see this diversity and variety as a real strength-- dialogue and debate are an integral part of the educational process, as well as an important tool in exploring different sides of complex issues.

All Community Hubs inside the community have their own forum for asking specific questions to other surveyors, by location, equipment type, etc.

Topics by Tags

Monthly Archives

Global Forums

Add Your Expertise

šŸŒ Explore Forums Based on Location

Blog Topics by Tags

Monthly Archives