I'm using the "hold" feature on the TS to double angles. I turn an angle, press "hold", go back to the BS, press "ok" or whatever, then turn it again.
For example:
130-53-30, and
261-47-40
Then, using my HP11c, I change 261-47-40, using the H.ms>H button, into:
261.7944 (the decimal equivalent).
Then divide by 2:
130.8972,
And turn back into degrees, minutes, seconds with H>H.ms:
130-53-50
or more than 20 seconds greater than the original angle. It should be much closer than that.
I've been analyzing a lot of my readings, and many seem higher than they should be.
Either the math is wrong, or my second readings are higher than the first for some reason.
> I'm using the "hold" feature on the TS to double angles. I turn an angle, press "hold", go back to the BS, press "ok" or whatever, then turn it again.
>
> For example:
> 130-53-30, and
> 261-47-40
>
> Then, using my HP11c, I change 261-47-40, using the H.ms>H button, into:
> 261.7944 (the decimal equivalent).
>
> Then divide by 2:
> 130.8972,
>
> And turn back into degrees, minutes, seconds with H>H.ms:
> 130-53-50
>
> or more than 20 seconds greater than the original angle. It should be much closer than that.
>
> I've been analyzing a lot of my readings, and many seem higher than they should be.
>
> Either the math is wrong, or my second readings are higher than the first for some reason.
right off the bat, 130-53-30 doubled is 261-47-00, not 261-47-40. That is apparently where things are getting screwy. Sounds like some procedure issues.
just a guess
Are you reading numbers off of a cold LCD display?
Things can appear different..as you approach zero. 😉
>
> right off the bat, 130-53-30 doubled is 261-47-00, not 261-47-40. That is apparently where things are getting screwy. Sounds like some procedure issues.
I'm seeing that.
If I SUBTRACT the first reading from the second (I assumed the instrument was just adding them), I get 130-54-30.
Something is definitely wrong with how I'm doing this.
I would normally say (per the next post about cold instruments) that I mis-read the instrument, or wrote it down wrong, but the numbers look like this through out the measurements I took that day (and maybe other days too...I'm looking).
Is this an HP function H>H.ms mis understanding? Backlash in the tangent screw/encoder disk? I thought I read somewhere that you should always move in one direction and keep going, but that may be moot with digital instruments...there is still a mechanical screw and optical disk.
"If I SUBTRACT the first reading from the second (I assumed the instrument was just adding them), I get 130-54-30"
It should be 130-54-10 not 30
Or are you misreading the first number such that what you think reads 30 is actually reading 50?
> I'm using the "hold" feature on the TS to double angles. I turn an angle, press "hold", go back to the BS, press "ok" or whatever, then turn it again.
>
> For example:
> 130-53-30, and
> 261-47-40
>
> Then, using my HP11c, I change 261-47-40, using the H.ms>H button, into:
> 261.7944 (the decimal equivalent).
>
> Then divide by 2:
> 130.8972,
>
> And turn back into degrees, minutes, seconds with H>H.ms:
> 130-53-50
>
> or more than 20 seconds greater than the original angle. It should be much closer than that.
>
> I've been analyzing a lot of my readings, and many seem higher than they should be.
>
> Either the math is wrong, or my second readings are higher than the first for some reason.
Is 130-53-30 the first turn of the angle, or is it the reported average. In the Topcon repetition mode, two angles are shown, the total and the average and average will change as you turn more angles to reflect the new average. It appears from your post that 130-53-30 is your first turned angle, in which case it would appear that your second turn was 130-54-10 (40" from your original turn), which would sum to 261-47-40. Forty seconds could be a lot or maybe not, depends on how far you are sighting. Short sights could easily have that kind of difference.
> I'm using the "hold" feature on the TS to double angles. I turn an angle, press "hold", go back to the BS, press "ok" or whatever, then turn it again.
Why in the world are you doing that? It's an idiotic way to measure angles with an instrument that is a direction instrument, not a repeating instrument (meaning: the circle doesn't rotate separately from the alidade).
>
> Is 130-53-30 the first turn of the angle, or is it the reported average. In the Topcon repetition mode, two angles are shown, the total and the average and average will change as you turn more angles to reflect the new average. It appears from your post that 130-53-30 is your first turned angle, in which case it would appear that your second turn was 130-54-10 (40" from your original turn), which would sum to 261-47-40. Forty seconds could be a lot or maybe not, depends on how far you are sighting. Short sights could easily have that kind of difference.
Oh, Good Grief! If that's the case, then I've been "averaging the average"!
I'm not using the "REP" function though. Perhaps I should. I'm doing this:
Except, I'm swinging the first observation, pressing HOLD, turning back to the BS, pressing "Yes", and measuring again.
Using the REP function would certainly eliminate a lot of this error prone math though.
One thing's sure: I'm doing something wrong. No wonder my traverses aren't closing.Argh!
Your math looks correct to me, it looks like you are accumulating angles. I'd just say its your gun. There are some calibrations you can do on the gun, look in the manual. This may help.
RFC, you are turning the angles the same way I do. I use the hold function also. If your first angle is 90-00-00, you second angle should be 180-00-00, your third angle should be 270-00-00.
Kent it must not be completely idiotic, since that's the way I do it also, and I have a Topcon gun.
I never thought to do that. With Kent calling it idiotic, it certainly bears consideration in my mind now!
In seriousness, Repetition mode is handy because it doesn't affect your zero on your backsight. So once you finish the repetition, you can take single turn sideshots without wondering what your backsight angle is related to, and it handles the averaging for you, as you say. The only downside is that it doesn't really show how well each individual turn compares to the average.
> > I'm using the "hold" feature on the TS to double angles. I turn an angle, press "hold", go back to the BS, press "ok" or whatever, then turn it again.
>
> Why in the world are you doing that? It's an idiotic way to measure angles with an instrument that is a direction instrument, not a repeating instrument (meaning: the circle doesn't rotate separately from the alidade).
If that's the case, then how in the world is it ANY different than using the REP function? In both cases, you're swinging the instrument back and forth, "pressing buttons". Nothing would be different with the glass. The only thing different I would think is that the REP key keeps track of, and updates the average.
If what you're saying is true then, there's absolutely NO advantage to "doubling angles" with a digital Total Station.
Not so?
> RFC, you are turning the angles the same way I do. I use the hold function also. If your first angle is 90-00-00, you second angle should be 180-00-00, your third angle should be 270-00-00.
>
> Kent it must not be completely idiotic, since that's the way I do it also, and I have a Topcon gun.
Oh, it's completely idiotic. All you dudes are doing is repeating the measurement over the exact same part of the circle. There is no improvement as there is with a repeating instrument.
Much better practice is to use the instrument as the direction instrument that it actually is, i.e. point at BS F Lt and F Rt, point at FS F Lt and F Rt, compute angle.
You can just repeat that procedure if you want to improve results or you can add multiple pointings if for some reason you're having problems with pointing the instrument at a target.
> > Why in the world are you doing that? It's an idiotic way to measure angles with an instrument that is a direction instrument, not a repeating instrument (meaning: the circle doesn't rotate separately from the alidade).
>
> If that's the case, then how in the world is it ANY different than using the REP function? In both cases, you're swinging the instrument back and forth, "pressing buttons". Nothing would be different with the glass. The only thing different I would think is that the REP key keeps track of, and updates the average.
>
> Not so?
I've never owned a Topcon instrument, so I have no idea what the REP function does. I do know that if you are just measuring the same angle over the same part of the circle, all multiple measurements get you is some averaging of pointing errors. If you are using high quality targets and taking care about minimizing heat shimmer, pointing errors should be smaller than the least count of your instrument.
> I'm using the "hold" feature on the TS to double angles. I turn an angle, press "hold", go back to the BS, press "ok" or whatever, then turn it again.
>
> For example:
> 130-53-30, and
> 261-47-40
>
> Then, using my HP11c, I change 261-47-40, using the H.ms>H button, into:
> 261.7944 (the decimal equivalent).
>
> Then divide by 2:
> 130.8972,
>
> And turn back into degrees, minutes, seconds with H>H.ms:
> 130-53-50
>
> or more than 20 seconds greater than the original angle. It should be much closer than that.
>
> I've been analyzing a lot of my readings, and many seem higher than they should be.
>
> Either the math is wrong, or my second readings are higher than the first for some reason.
You did the math right. Turn first angle, hold, flip, backsight, release, turn second angle.
Divide the second angle by two by hand. It should be within 10 seconds, depending on the distance, i.e. if it's 30' away and 20", who cares, but on a control point several hundred feet, well, you need to re-turn that angle.
The 48 allowed for this method, but the nomad and recon don't, so unless we are manually turning the double, we turn first angle, flip, backsight, turn second angle, subtract 180, and look at the difference and mean it from there.
Edit: If you can't get the instrument to double, then you're out of level, period. If it says it's level, it's time to colluminate (sp) the gun, check the spirit levels, and adjust. Then, you'll hit it. The purpose of doubling and flipping was to take the error in plate out. Since we don't use plates anymore, it catches errors in leveling.
> You did the math right. Turn first angle, hold, flip, backsight, release, turn second angle.
This thread just made my life easier. No need to "double" at all on each face. Double using BOTH faces; TWO readings not four.
For now, I'm going to run Starnet on my traverse using just one measurement from each face and see what it looks like.
As for being "idiotic", That doesn't bother me at all. I've got an excuse!:-D
"idiotic"
> As for being "idiotic", That doesn't bother me at all. I've got an excuse!:-D
Coming from Kent, I wouldn't take the term "idiotic" personal either. I think he uses it as an endearing term of affection...:pinch:
"As for being "idiotic", That doesn't bother me at all. I've got an excuse!:-D"
Don't EVEN think of trying to usurp me as the Surveyor Connect village idiot! 😉
"idiotic"
:good:
> >
>
> As for being "idiotic", That doesn't bother me at all. I've got an excuse!:-D
I wouldn't sweat it. About once a month he gets like this and needs some summers eve.
