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Topcon GTS 301 help?  

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Posts: 47
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I am testing a new to me Topcon GTS 301d on my property today

A146C82F 7C62 43AC 80A7 28414F84046C

.  As I was taking a side shot, This appeared on my screen (the letter “b” in place of the horizontal and vertical angle display, along with the occasional “-c”) (See not so clear image) and I was not able to log the shot on my Data Collector (Topcon Ranger 200-Running Survey Pro 3.8).

I rotated to another side shot, and then the issue seemed to disappear and was able to complete my shots. 

It was a chilly, windy day in Wisconsin. (36 degrees at time of use with wind gusts out of the NW of 15 mph).

Anyone experience this before? My best guess was that the cold and wind was affecting the total station? Maybe this Total station is getting sensitive in its older age?

The Data Collector slowed down a bit, but still worked well in the cold.

I hope to get out and do some more testing tomorrow (as time and weather permits). Any help, info, guidance and encouragement is appreciated.


7 Replies
Posts: 276
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I don't think those temperatures had anything to do with it but I cannot help you beyond that.

Jim Frame
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"b" means the instrument is out of level beyond its tilt correction range.  An instrument leveled near the tilt limit could go out of level briefly in response to a gust of wind.

"-c" means the EDM return is poor.  Something blowing in between the gun and prism?


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Jim has your answer, but FYI, the manual states that the operating range goes down to -4 F. In my experience that is very accurate. You can operate it colder if you keep it warm with hand warmers, or quickly pull it out of a warm truck, but I can't vouch for its accuracy in those situations.

The wind will not affect it, unless it is blowing enough that it won't keep level. It doesn't "feel" the wind chill.

Posts: 47
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Thank you for the input. Makes sense.  I will give it another whirl and seee what happens.

1 Reply
Bill C
Joined: 3 years ago

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@drratiug-survey here's a PDF of the manual for that instrument. If the attachment doesn't work, let me know if you (or anyone else) would like me to send it to you.

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