Last Friday I was attempting to finish 35ac retracement. On our second to last setup we started to get large distance errors (16.5') This error was precise/repeatable in both direct and reverse (able to pass tolerances set in data collector).
In the field I changed batteries/reshot/etc but distances were still seemingly arbitrary.
avg. temp was 15deg F +/-
Due to the cold the electronics on the instrument were noticeable slower as the day progressed (7ish hrs).
What I am thinking is the cold (and instrument age) was affecting the vertical compensator enough to vastly change the zenith angle ~ horizontal distance.
Anyone had experience with a similar situation / or other ideas? I have surveyed bunches in the cold before but never had a problem like this.. instrument seems fine today.
Detz
16.5' sounds very close to 5 meters. Probably not a compensator problem, but an EDM problem.
We had an occasional problem years ago with a Sokkia that would now and again give us a 2000 meter error. We never could figure out why, though....
A zenith angle error cannot give a consistent distance error. The only way to get a consistent distance error is an incorrect prism constant. 16.5 feet is 5 meters, so look for that error range in your prism offset setup, i.e. 5000mm.
Paul in PA
The error was not on all observations, it would shoot 72' in one set both direct/reverse than 55.5 both direct/reverse than 72' direct / 55.5 reverse.
Remember all the frequency nulling from the old Geodimeters?
There was a round number that would pop up on long distances ... I forget what it was ... back in the early to middle 1970s.
Remember all the frequency nulling from the old Geodimeters?
Needed to know the distance to within 2000 meters to get the proper readout, seems that the wave length repeated every 2000 meters so there was a switch with a position for less than 2000 meters and for shots more than that, you could scale the data from a quad if you were shooting very far, took one shot to 3 prisms at about 5 miles on cold clear winter day with an AGA 76 but the EDM only displayed the distance of less than 2000 meters, had to add the rest to that readout. Still have it and it works. Used the laser in it once to aim a TV reflector with a flat mirror taped to it while occupying a point on line from the reflector to the repeater at The Dalles while on a ridge line and adjusting the reflector until the laser was seen at the ranch, then fine tuned without the laser, worked good, a little snowy until the cows started using it as a scratching post.
jud
Remember all the frequency nulling from the old Geodimeters?
Bingo! Now that you mention it, I do remember the 2,000 meter factor. The one I used was a Model 6 - no laser, just a itty-bitty flashlight bulb.
Remember all the frequency nulling from the old Geodimeters?
That white light AGA 6A was a heavy old beast that preferred to work at night, go through the routine and take the notes to the office to compute the distance. There were times when it saved a lot of work but we were still using the 300 foot chain most of the time.
jud
That doesn't seem all that cold.
I did have a gun once that would not come on at all except for a few seconds and it would shut down.
If it would stay on for a little while it wasn't long enough to get a shot on anything. The PC thought I was just BS'ing and wanted to get out of the cold. Well, sure who didn't that day! I finally convinced him to come watch. We boxed it and headed back to the office. Even the bulldozer lost traction trying to get us out of there. I've never seen a dozer slide before or since.
But it was near about 0 F the day I'm thinking of.