Hello,
I am testing a new to me Topcon GTS 301d on my property today
. ?ÿAs 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.?ÿ
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.
Thanks!
I don't think those temperatures had anything to do with it but I cannot help you beyond that.
Licensed Land Surveyor
Finger Lakes Region, Upstate New York
"b" means the instrument is out of level beyond its tilt correction range.?ÿ 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.?ÿ Something blowing in between the gun and prism?
?ÿ
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.
Thank you for the input. Makes sense. ?ÿI will give it another whirl and seee what happens.
@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.
Cold weather introduces other variables. Assuming frost in the soil the leg tips may be carrying warmth from the sun to the ground and the southernmost leg may end up settling all day long. If there was snow on the ground we would pile some around each leg base to keep that temperature uniform.?ÿ Having used a 301 for many years I know they are quite sensitive in the vertical. If I looked at the zenith angle from a distance then stepped in to observe I could see the zenith angle change. That meant it would be different as I stood at various spots around the instrument. On the worst such day it may have been necessary to relevel for almost every shot.
As to the distances, you may want to focus though the whole range from instrument to target to look for interference and?ÿ to be observing through the scope when you are taking your distance shots.
In cold weather it was more important to keep the battery and data collector warm than the instrument. If you had to sit in the truck cab to warm up, the batteries and data collector would sit on the dashboard. If it was a long traverse away from the truck the spare battery stayed in an inside pocket with a hand warmer and hand warmers would be rubber banded under the data collector.
I notice you do not have a Topcon tribrach under that 301. The Topcon see through tribrach plumb and the instrument plumb are the best ways to keep a level and steady position. The Topcon tribrachs I bought for my traverse setups are one of my best investement. Not cheap but worth every penny. Until recently I have had no instrument that could keep it's backsight zero like that old 301 could.
Paul in PA
Thank you for the tips. I still have the original Topcon tribrach. I may try using it and see if there is a difference.