So, with Chris's help, I think I have most things worked out with this old 4400 ATS and have a couple more questions before I take it to the field. I got the internal batteries swapped out. Not much fun but also not too bad either. I don't recommend the DIY methods unless you have very sound electronics experience because all you have to do is short the battery and you may lose all memory. We were VERY careful and had no issues.
I did some testing with the gun and RMT in a controlled indoor area. I was trying to determine the basic length of a line by shooting the first point, obtaining its HD, then using F21 to zero the Href, then jog to the next point on the baseline, shoot that to get the second HD, and obtain the angle between them.
With this method, My manually measured line length was 2.400ft, with the gun and calculator, I got 2.225ft. I live in a world of inches so at first I was thinking "hey, I am 15thou off, that could easily just be operator error" but then I realized I was shooting in feet that was more like 3/16" off. My shots HD was about 31ft, and angle was only 4* or so. I am wondering if I just did not rotate enough to really get a good figure on this or if this seems concerning?
*recording points*!!
I had no idea it would be this hard just to record some points once I went through P20 station est. I have been setting as free station for now. I don't have hardly any programs in this gun but one of the UDS or user programs has been created as "topo", P6. I tried it once I was established. It asks some basic questions then asks for a pt# and I hit REG and it seems like it records the pt. I thought I was on my way, but when I go back through menu/editor to review the data under that job file, it just says "P20" and no points are logged.
Now, Chris has tried to walk me through the procedure for creating a program but I am dense and it takes a couple tried to get through my wall. I figured at first that I could just create a job file and drop points in there at will and assign a pt#. Not really. Geodimeter is odd like that. We need a program?
So.....what is going to be my easiest route to just get some points recorded in the gun for later review? I am thinking about this like a topo map. I don't need to go to defined points, I just want to plug some points of interest for later plotting. I don't care where they are.
I'm a longtime Geodimeter user, but am having trouble coming up with a solution for you. There is a reason the programs were written for the CU's.
regarding your results... perhaps checking a line longer than 2 feet would be a better test?
Andy J, post: 407339, member: 44 wrote: I'm a longtime Geodimeter user, but am having trouble coming up with a solution for you. There is a reason the programs were written for the CU's.
regarding your results... perhaps checking a line longer than 2 feet would be a better test?
Trying to read very short distances is problematic and often throws up errors. It's to do with the return signal from the prism being too strong. At one stage Geodimeter used to sell a rubber ring which fitted over the prism and held a plastic circle with a central cut-out. You can make one yourself by just cutting a suitable size cardboard ring and then making a hole in the centre. Start with a hole about 3/8 in diameter and gradually enlarge it until the instrument gives a reading. That should give you an accurate answer up to about 12 ft. range, after which its OK to use the prism normally.
Bob - I'll e-mail you about setting up a few simple programmes - might be next week as I've a lot on over the next few days.
Chris, sorry if my post was misleading but the distances shot were about 31ft. the separation between two points was 2ft. I would think 31ft is a reasonable distance?
I am also realizing that I have yet to take the gun outside and do a real collimation test. I did a rather basic test at only 20-30ft. Hoping that is where I find my error? I really don't need to be ultra precise with my work but I want to make sure my gun is up to stuff and it really should be. I did notice after the fact that my baro pressure was off. I had 28.80 and pressure was 30.10. I doubt at that distance it made any difference but just need to make sure.
I might have to setup an outdoor controlled test to make sure things are on.
bob james, post: 407376, member: 12050 wrote: I might have to setup an outdoor controlled test to make sure things are on.
Take it to a Calibrated Base Line
Hi Bob, do you have a barometer? The reported barometric pressure is adjusted to sea level which might explain the 30.10 pressure. Generally, for each 1000 feet of elevation, you lose an inch of pressure. So if your elevation is 3000', you will have 3" of barometer which you take off of the 30 inches of sea level pressure, which would get you about 27 inches of barometric pressure. I notice you are in Kansas so maybe about 2000' or less, so the 28.80" might be about right. Some instruments have their own thermometer and pressure sensor built into them. I have a Topcon 301 and I enter the information into the setup and it corrects for the pressure and the temperature. If you can find a Calibrated Base Line to take it to and check it, that would be a good thing. The data for the calibration line would likely have the elevation for each monument on the report. You can check the NGS website for these. They are very handy and enlightening. Good Luck, Jerry.
Topo and set out are very separate things in the old Geodimeter world. We had UDS's for topo that established the user as UDS 1
UDS 1
343 ADM
79 10
51 0
52 0
53 0
56 0
74 0
79 7 2
and then ran into UDS 2 which was station establishment.
UDS 2
343 ESTAB
79 10
2 1
3 1
62 1
21 1
79 7 3
Which then rolled into UDS 3, which started recording topo shots
UDS 3
343 TOPO
5 2
4 2
6 2
79 7 4
and then UDS 4 repeated shooting topo
UDS 4
343 REPEAT
5 4
4 3
6 3
5 8
4 8
6 8
7 0
8 0
9 0
79 5
Then there was the traverse program, which memory tells me we went through Prog 2 again and when Prog 3 came up we hit program 5 (sorry it has been many, many years ..)
UDS 5
343 TRAV
5 1
4 1
6 1
17 0
18 0
24 0
25 0
9 0
79 5
We also had a variation of the Prog 3 and 4 which collected line work as Func 86 (started out as func 85, but, GPS didn't allow 85 so we grabbed the next unused func)
UDS 13
343 ACAD TOPO
5 2
4 2
86 3
6 2
79 7 14
UDS 14
343 ACAD OVER
5 4
4 3
86 3
6 3
4 8
86 8
6 8
7 0
8 0
9 0
79 5
We did keep the topo separate files from the control for easier processing. Attached is some sample data from 1996
Prog 20-39 were written for staking and are completely separate from the UDS 1-19 programs in operation
"Chris, sorry if my post was misleading but the distances shot were about 31ft. the separation between two points was 2ft. I would think 31ft is a reasonable distance? "
That makes a bit more sense! that error is way too large for sure. What did you point at? the actual marks you set out? or a range pole? (if so, was it hand held or with a bipod?) Or two tripods next to each other??
OK, here is where I am at with this testing. While I don' technically have a "calibrated base line", I know that once I am close'r', I can mount the RMT in one of our cnc machines and jog it, knowing the exact horizontal movement down to .0001". However, I know my even my crude methods are not producing results that are acceptable. No need to further qualify the gun until this part is rectified.
I checked my temp and pressure. Indoor temp at 70F, press at 30.10hg. I then collimated the gun again. deviation from previous test was .0006, now at .004 for horizontal. Actually, I might want to take a closer look at VA because that can affect all this too.
I have a line on the floor with points placed with a precision tape measure. While not perfect, easily within .0625 or 1/16" accuracy. I have a baseline length of 2.2422', I gun measured the line at 2.2264. I am pretty repeatable. Done this test several times. First on a pole with measurements of 2.220-2.225, now I am just setting the RMT on the floor so it is very repeatable aside from visual alignment tolerances.
I tried angling the RMT towards to gun or roughly 'normal' to the gun, then I just kept the RMT perfectly straight along the baseline, both tests returned about the same results. While on the pole, the RMT was roughly even height with the gun. While on the floor, I have not angled the RMT 'up' towards the gun, just dead plumb. I do notice that the crosshairs are not centering on the yellow triangles but I assume the gun may be projecting that point due to the angle error?
NOTES: I have ONLY tested this in autotrack mode ONLY! I am not using D mode or two faced, just STD. I have also NOT set my RMT or gun heights as I do not think this will make any difference in the HD? The gun calculates the SD and VA to determine the HD?
So.... out of curiousity, I played with the test values to see how I might end up with the right values. The HD would have to be registered.30' longer than tested, or the HA would have had to be returned at .03* more than tested. Now, .3' is 3.6" so there is no way at all that I missed by that much in my setup. Unless of course the gun is shooting the HD all wrong, in which I have not precisely measured the gun to target HD.
Or the HA is being returned wrong. I sort of doubt that because I would think the collimation test would have shown backlash or high values and I don't think .004 is unreasonable?
Am I just missing something with my setup?
bob james, post: 407519, member: 12050 wrote: press at 30.10hg
I doubt this is the pressure at your elevation. See Jerry Hastings post above. Although that won't be a problem for short distances.
UPDATE: Ok, on a hunch, I decided to lose the RMT and get a visual. I installed a needle in the floor at each point so I could align the crosshairs with the needles for visual HA confirmation. I had the gun still setup exactly as it was when testing the points with the RMT so I went back to my HA 0.0000 and I could not have been more aligned with the needle. Then I walked over to HA4.0505 and again, I was dead aligned with the other needle. I have no issue with HA performance with either the gun or interaction between the gun and RMT. I walked the HA over to HA 4.0800, which is what it would take to preturn the proper value and it was visually about 3/16" off! Great! We are getting somewhere.
So then I checked the VA collimation value and it is at -.0027. HA was actually .0004! The book indicates values exceeding .02 are an issue so I am easily within tolerances.
So where do I go from here? I am confident that my HD is being returned wrong for some reason. I am sure this either boils down to my rookie mistakes in setting up the gun, or a calibration issue that is fixable. It seems the gun and RMT like each other just fine. I have worked through the collimation for HA but shall I work on VA again? or tilt axis maybe?
You may have covered this earlier, but:
is Autolock turned on?
Is your RMT flashing?
What is your prism constant set to? If Geodimeter prisms, should be zero. if other make??
Have you gone through colummation routines at 300 meters as suggested in the manual?
Ken
bob james, post: 407527, member: 12050 wrote: I am confident that my HD is being returned wrong for some reason.
What is your prism constant set at?
The RMT is the matching Geodimeter unit. PC is set to 0. No, I have not collimated at the recommended distances yet but my reasoning is I would have to be WAY off with my current testing to return such wild measurements.
I think I should take a look at the tilt axis again. I seem to remember not shooting that all that accurately before but again, it seems like I would have been having a real bad day to shoot a 1/2" off.
Let me ask this as a rookie question, they make a device to tilt the RMT so it presents more normal to the gun. When you tilt the RMT relative to the two threaded holes on the side, does that still give you a relative XY center to the pole? Is it possible that since I am not tilting the RMT, but rather keeping it plumb in XY, regardless of height, I could be shooting distance errors?
Well, I decided to apply an SD offset until I can do more testing. With the testing I have done so far, I can pretty much rule out issues with the rotating axis or axis tilt. About the only thing it can be is the EDM. I will probably have to run some tests at different calibrated distances to see if it is consistently off or not. By adding a whopping .280' to the SD, I am hitting about dead on for my baseline length.
In the real world, the prism is rarely at the exact height of the instrument, so I would have been surprised to find the tilt correction take up that much error. Have you checked the longer legs of your setup to see if they are measuring correctly?? Seems like you could do that in house with your skills.. If the EDM is that far off, you'll see it in every shot.
The system is designed to work with the RMT held square to the line of sight. In practice holding it vertical shouldn't make much difference unless you are measuring to high precision and with significant vertical angles. If high precision is required you should be using the target on a tripod and you can calculate the correction needed to the length for any given VA. Most times the RMT would have be used in tracking mode to carry out general surveys, where the distance measurement would only be recorded to 1cm. (or whatever the equivalent setting is in imperial measurement).
Have you done a three point check? Ideally you need three tripods, but with your facilities you could set up three 5/8" bolts to screw the tribrach and target to. Call them A,B,C and set them to be more or less the same height. In Dbar read AB and AC. Then go to B and read BA and BC, finally to C and read CA and CB.
Mean of AC should equal the sum of means AB and BC. The difference is the instrument/prism error constant. This should be Zero, but it will probably be "k"
Then AC+k = (AB+k)+(BC+k)
Enter the value k as the constant F20 (silly question, but you have checked that F20 is set back to zero haven't you?)
