A 600m sight is throwing a 25mm vertical error compared to a closed level run (good practice on the level run).
It seems as if the C&R corrections are being applied twice.
Does anyone know for sure if the S6 applies them itself?
If so it seems a bit silly to have the corrections offered in Access as well (for this instrument).
> A 600m sight is throwing a 25mm vertical error compared to a closed level run
Are you confident that the refraction coefficient accurately reflects (pun intended) actual conditions? 600m is a long way to hop and still achieve reliable vertical results.
Not Silly, Just A Choice
C&R corrections as well as prism offsets can be set within most instruments and also within most data collectors. It is operator error to have both set. Some data collectors can ignore the instrument corrections and use the instrument raw observations.
Are you doing D&R observations?
When was the last time you set your vertical compensation?
Paul in PA
Squowse,
Here's an old thread on that subject:
https://surveyorconnect.com/index.php?mode=thread&id=162107
According to North Dakota DOT, you can turn off C&R in the S6:
Dave
All settings and corrections for the S6 are driven from the data collector if running Access and applied once.
You have to enter temperature yourself for the S6, but it gets a pressure reading from the instrument.
25mm isn't horrible at that distance without knowing your equipment and procedure. It may be great depending on how you did it. At 600m each second vertically is about 3mm. Most S6s are 3" instruments. S6s are finicky about how you perform the collimation also.
Not Silly, Just A Choice
> C&R corrections as well as prism offsets can be set within most instruments and also within most data collectors. It is operator error to have both set. Some data collectors can ignore the instrument corrections and use the instrument raw observations.
>
> Are you doing D&R observations?
>
> When was the last time you set your vertical compensation?
>
> Paul in PA
Agreed. 0.08' in 2000' isn't too shabby. We'd be happy being that close every time.
Yes I see reference to having corrections on the instrument in the Access manual but I can't find how to switch them on or off on the S6 so I can only assume that the observations are sent to the data logger raw.
The error is consistently worse with distance and I get a much closer answer if I switch C&R off. Bit strange but maybe I am just being too fussy.
To answer others questions yes I am measuring direct and reverse, 2 second instrument. The instrument has just come out of dealer calibration but I did run the collimation routine again and got rid of a few seconds vertical angle difference face to face. I also ran the compensator calibration and am interested in how the "S6 is finicky". Maybe I'm not doing it as well as I should?
Yeah, that's only 8.5" error in that distance. Generally speaking vertical is only half as good as horizontal with a TS. Meaning if you want 1" vertical accuracy the best practice would be to D&R 36 times. Wouldn't take that long with a robot.
Also remember 3" is one sigma! Unless you have an S6HP.
So very true, the vertical collimation is something to keep after on an S6. We've had one go out on us, and it had to be replaced.
I usually check ours every couple of months during construction season, more often if I notice any "drift" in our control checks.
Agreed 600m is a long shot for trigging in elevations, vertical angle doubling is definitely called for at those kinds of distances.
