> How much latency is there when someone observses (sic) the crosshairs and yells "mark!".
>
> A lot more than if the observer simply pushes the lap button on the stopwatch themselves.
Yeah, for best results, if you're doing solar hour angle observations, you'll want to use a digital stopwatch as a comparing watch. The observer handles the watch so the same personal lag time is present in all stopwatch times and the effect is to nearly cancel out.
Once the instruement is set up, at ambient temperature, and leveled with extreme care. The observer starts the stopwatch on the minute mark given by the time signal. Then stopwatch time (using the lap time function) is noted on the next minute to make sure that there is no surprise.
Stopwatch times are recorded for pointings on the Sun and at the end of the observation, the stopwatch time of the minute mark is recorded again. Typically, you'll probably want to use the stopwatch readings of the second minute and the final minute of the time signal to calculate the equation between stopwatch time and time signal. The seconds fraction of both should usually agree within a few hundredths of a second unless it's a Monday. Naturally, if the time signal is UTC, you'll need to correct it to UT1 by looking up dUT from some online source if you aren't using the WWV broadcast signal that has it coded into it.
I don't think it's huge overkill to record time to 0.01 second if you're trying to do top-quality hour angle observatons.
Mr. Land Ho
> You are interesting.
>
> For starters, you apparently have invested in survey equipment.
>
> And, you want to recoup that investment.
It would be nice, but not necessary.
>
> And you are a developer/Realtor/Landowner/Investor.
>
> And, you want information, of the sort that indicates you don't really know how to USE that equipment.
I don't know why you would assume that. I want to figure out where North is based on surveys that have already been done. None of the equipment I have does that and apparently from what I gathered from reading this entire thread, there is no one piece of equipment that will do this. It is a skill I came here to get more info on. Who better to ask than those who actually have the knowledge.
>
> You are walking a fine line. Usually, either the REALTOR wins, or the SURVEYOR, but not both!
I don't follow. What's the game that you are implicitly referring to that there is a winner and a loser? And what in my post even brought that up?
>
> There are actually a few Realtor/Surveyors here. But, that is not the usual.
>
> As a surveyor, there is more to this business, than meets the eye. It's just not a situation where all the products that are sold as a survey, are truly a survey. Some are not.
I absolutely agree.
>
> Keep learning.......
>
That's why I follow and joined this group.
LandHo, You Misquoted Me
I absolutely agree with you about having a LLS do a survey before building/installing a septic for the very reason you imply - the LLS now has the liability for the boundaries. I have ALWAYS hired an LLS for these purposes.
My response was specifically to the part of your statement "budgets are not unlimited". As I pointed out, there are professionals out there (any profession) that will cut corners and not do the "professional" or the "right" thing because "I'll lose money if I did that." I don't doubt for a minute that those types of folks are not participating on this forum. They just don't care enough. And yes, I've taken significant loses on projects because *I* underestimated the time/effort needed - but the job got done right and I sleep fine.
> Find three trees with moss growing on one side of the stump (this will be north in the granite state), locate with GPS (preferably consumer grade handheld), perform least squares adjustment (freeware, don't worry about what it does), go with it.
Yes. Thanks. I TA'd graduate level courses on numerical methods I and II - got A's on both as well. I know about least squares and a couple of others as well. As I indicated, I wanted to maintain an accuracy of 1 minute of angle. My GPS can't do that - it's only a smartphone which probably uses correction factor tables anyway.
> No monuments? Seller looking for lowest price survey to satisfy the purchase agreement is certainly not going to pay for that.
Huh?
> Don't complain about poor business decisions you made based on not understanding the business or market you deal with.
Double Huh?
> Kent is amazing, but you want to know something about a parcel for a particular use, then you must include it in the contract and pay for it.
>
Again, Huh?
> Just a contrary opinion, no disrespect intended.
None taken, but clearly I have been misunderstood and you have read a lot into my post that simply isn't there. I have many survey maps that I have paid LLS's to do for 10's of thousands of dollars. Is it too much to ask that they make a notation of how the heck they found North? Since they did not, I have to. So I came here to find an answer. I have read the articles on Solar/Polaris observations and how to use a stop watch and sun filters - yadda, yadda, yadda. But none of the articles I found details it well enough.
Basically, I have had many occasions to actually blaze a trail along a boundary (which was supposedly done by the hired surveyor's field assistant) but was not, or not done so that anyone else could find it (so what was the point). I have one starting monument and one bearing and a 700 foot or more traverse through a swamp (really) and I want to make sure I get to the bound at the other end of the line. So how do I find North so I can point my instrument on the angle the surveyor told me to? Or more simply, how do I find where North is and how do I adjust for the fact the original survey was done at a known particular point in time? I know it can be done. It may be involved trig-wise, but that's just math by another name. I figured the guys (and gals) here should have a ready answer.
LandHo,
Half your problem here is you're dealing with Registered Land Surveyors.
Anytime they have to go out in the field it turns into a week's worth of posting, and a long opera of whining and wailing that nobody else is any good, there aren't any monuments to be found, somebody set a monument off by 0.1' yada..yada..blah..blah.
What you need to do is hire a Professional Land Surveyor that employs an actual field crew. We're the guys that make it happen. We routinely get sent out with a tax map, couple dollars for gas and a half six-pack of warm beer and put an entire survey together.
Anytime we take registered out into the field its an entire day of having to help him over the fences or ditches, getting him untangled from the 100' cloth tape, listen to the same old war stories that we've heard two dozen times previously.
Get an actual field crew out there, leave registered at the office.
> LandHo,
>Half your problem here is you're dealing with Registered Land Surveyors.
I'll bite, R.J. What's the other half of his problem?
"I'll bite, R.J. What's the other half of his problem?"
I was sure that would've been fairly obvious, not having a field crew out there.
> "I'll bite, R.J. What's the other half of his problem?"
>
>
> I was sure that would've been fairly obvious, not having a field crew out there.
>
>
>
>
How is the field crew going to help LandHo determine how North on a plan relates to either astronomic or grid North?
"How is the field crew going to help LandHo determine how North on a plan relates to either astronomic or grid North?"
There's endless literature on making astronomic observations, and with an engineering degree he should be reasonably qualified to undertake that learning process.
I was reading something about running 700' worth of line through a swamp. That sure sounds like a field crew type of deal there. He should have a field crew out there.
> I was reading something about running 700' worth of line through a swamp. That sure sounds like a field crew type of deal there. He should have a field crew out there.
In that case, R.J. I think what you meant to post was this:
Actually this is what I use for recon:
https://surveyorconnect.com/images/uploaded/2013010204213150e3b5cb333d1.jp g" alt="" />
The whole point is NOT to have to hire anyone, much less a crew. To me, that would be like suggesting you hire me - a professional electrical engineer - to change a light bulb simply because I know how to compute the inductive reactance of said light bulb. Nonsense. Besides, for that particular exercise the crew was hired and paid. All they did was label the survey plan with "meandering blazed line" back in 1986. Guess what? Those blazes ain't there no more and the line is straight on the plan - with an actual bearing to a precision of 1 minute of angle.
I agree that there is a lot of resources out there that I can avail myself of - and I have. This forum is one such resource that I thought someone might actually be able to help me avoid wading through countless hours of futile effort. After all, if as one poster claimed, it is a simple 15 minute exercise, then why haven't I found the YouTube video yet? I think it is because it is NOT as simple as that. Further, I think I would have had a straight answer by now, rather than the responses I have gotten.
Indeed, I was very deliberate in stating in my original post that I work regularly with 6 or so top-notch surveyors and hold them in high regard. But, they are paid for a job. The stuff I am doing now is not worth their while - even if they were available - which they are not - something about the holidays - imagine that.
Anyway, I'll figure it out and when I do I'll be the one to post that YouTube video.
> Anyway, I'll figure it out and when I do I'll be the one to post that YouTube video.
I'll bite. What particular problems are you having with making solar observations for azimuth?
Well for one, I don't really want to spend $500 or so on the special solar filter for my Theodolite that I'm told I need for solar observations. I can do Polaris observations, which means I'll only need a right angle eyepiece adapter, which is more affordable.
I've read the white paper "The Advantages of Polaris Observations in Land Surveying" by Fink et al, as well as the "Astronomical Observation Handbook".
First I don't know if the Lat/Long coordinates my smartphone gives are accurate enough. (I am at about 43.21.34N/72.03.53W according to whatever chip/algoritm is inside my HTC phone.) What is accurate enough for a 1 minute observation accuracy? How is this usually done? My understanding is that Lat has to be accurate to 10 seconds of angle. Is that the case for real? How is this achievable? Doesn't seem that using a USGS map can get you there, as is suggested in the literature I've read.
I am aware I need to reference www.cadastral.com for what is known as "Ephemeris" - whatever the heck that is (haven't got to the etymology of it yet). In any event it's basically a look-up table keyed off of time.
The time element seems critical. How does one sync Universal Time to do this? I mean a stopwatch is suggested, but reaction time is on the order of 30-100 milli-seconds for the average person. That seems like a lot of slop to me. I know CO and HI have atomic clock signals broadcast over the radio, but I don't have a radio that receives those bands, and even if I did there's propagation delays in the radio waves - they are not at the speed of light contrary to what anyone says. So is there a special procedure for doing this or what?
I think I'm getting close, but need to tie it all together. Whatever pointers or suggested reading lists you could provide would be welcome.
Your cell phone / handheld GPS position is fine for the purpose. EDIT: 1 second of latitude is roughly 100 feet on the ground at our northing, so a lat/long "good to 10 seconds" is a spot 1000 feet across. Your cell phone /handheld, even under canopy, if probably giving a 6-10 foot WAAS augmented position, or if not, at least a 30 foot circle. So you are good there. Average a few readings over time if you want to be sure.
If the theodolite has no EDM or electronics, you can skip the solar filter and the angle eyepiece and project the sun's image onto a piece of paper to chase the leading or trailing edge
For time, I have used one of those wind-up emergency SW receivers and listened to WWV on 15.00mhz
(or whatever frequency of WWV you receive best where you are (and when)).
I skip the whole stopwatch thing and chase the sun in the scope until WWV comes around to the click one second after the top of the minute, stop chasing when you hear the click and record the horizontal angle. If you miss one, relax and get ready for the next minute. Record six or eight of those and run the math. Being as they are taken at a regular interval (exactly one minute apart) this will help show the outliers, if any, better than shots at random times.
Remember from rifle practice that a minute of angle is about an inch at 100 yards. To run 700 feet across a swamp, assuming you get everything else right, if you can get the solar azimuth good to a minute of angle you will only miss the other end by 2.33 inches. Guessing that is good enough for a swamp and blazing a line.
Hope this helps!
>I have one starting monument and one bearing and a 700 foot or more traverse through a swamp (really) and I want to make sure I get to the bound at the other end of the line. So how do I find North so I can point my instrument on the angle the surveyor told me to? Or more simply, how do I find where North is and how do I adjust for the fact the original survey was done at a known particular point in time? I know it can be done. It may be involved trig-wise, but that's just math by another name. I figured the guys (and gals) here should have a ready answer.
Does the surveyor you're trying to follow by any chance give the datum upon which North is based?
You can establish an astronomic direction if you like, but if the survey you're trying to retrace was on an assumed basis of bearings it's not likely you're going to hit the bound on the other end.
700 Feet Through a Swamp ?
I have followed 20 year and older cut lines through all kinds of terrain. If you cannot see how the surveyor traversed through the swamp then follow in his footsteps and walk around the swamp.
Paul in PA
> So how do I find North so I can point my instrument on the angle the surveyor told me to? Or more simply, how do I find where North is and how do I adjust for the fact the original survey was done at a known particular point in time? I know it can be done. It may be involved trig-wise, but that's just math by another name. I figured the guys (and gals) here should have a ready answer.
LandHo,
In the interest of sharing general knowledge I would like to share my opinion on the matter. First, be advised that I am not a registered or licensed surveyor, but being an equal professional on a related field (im a civil/structural engineer) and having keen interest in surveying, I presume that atleast I have a minimum amount of knowledge to be part of this forum. So here it goes;
Finding North as expressed on a surveyor's plan generally depends on which method you want to employ. The more common way to do it is to refer to existing survey markers or monuments which is tied to a specific reference grid system. From the technical description of your property (the bearings & distances of the points of the polygon) you could calculate the coordinates of each point. Assuming that you can setup your survey equipment directly over Point-A, entering the bearing(or azimuth) of Point-A to Point-B and taking a backsight at B will now orient you to the bearing system used in that grid. North is simply azimuth = 0 deg (or 180 deg in my country).
However, often times it is difficult to setup your equipment directly over Point-A, so what one do is to setup the equipment in a Point-C (unknown coordinates) where you have a line of sight to Points A & B, take the azimuth & distance readings from Point C-A and Point C-B, calculate the "assumed coordinates" for A & B with respect to C, and finally compare the "assumed bearing A-B" against the "true or grid bearing A-B", the difference is what you call the angular (or magnetic, depends on how you orient your initial direction) declination, apply this correction to your initial reading from Point C-A and presto, you're now back in the bearing system used in that grid. This method is commonly called Resection, if you have one of the newer total stations you could do this automatically.
The above method sounds easy but in reality there's a lot of factors complicating it, primarily the decision on when to say that your reference points (A & B) is in their actual correct position is the critical one. Please don't rely on consumer-grade handheld GPS to locate boundary points, it is not intended for that purpose and it might bring you a lot of trouble. Furthermore, surveying is a fun and worthwhile activity, but bear in mind that it is also a regulated profession and should people like us want to practice surveying, we should do so under the guidance and supervision of a duly registered professional surveyor.
Happy New Year!
yep - having an RLS in the field is SUCH a PITA, all that knowledge and book-learnin
slowing the crew down 😉
so I wonder who signs+seals the survey?
> Well for one, I don't really want to spend $500 or so on the special solar filter for my Theodolite that I'm told I need for solar observations. I can do Polaris observations, which means I'll only need a right angle eyepiece adapter, which is more affordable.
The solar filter you should be looking for is the least expensive one, an eyepiece filter, not an objective lens filter with all sorts of jazz. Is a simple eyepiece filter that slips onto and off of the eyepiece really $500?
If all you want is an accuracy of +/-1 minute, then I'd recommend not bothering with a solar filter and just doing solar altitude observations, projecting the image of the Sun onto a white card or field book page to observe the Sun in relation to the reticle.
Timing is not critical for altitude observations and neither is longitude. If you have an handheld GPS device that displays NAD83 (aka WGS84), that latitude should work fine for reducing observations.
Awesome! It does help a great deal. It shows what I suspected: reading from books presents the theoretical best practice, but nothing beats years of field practice. I confess I never took rifle practice, but at the beginning of the summer I got a new sight system, and never got to the range to dial it in. I completely forgot about the moa relationship - doh!
For anything I'm doing, inches of accuracy is way accurate.
Thanks also to Kent who made the post about UT1 from NIST broadcast UTC Time Signal - at midnight no less! I confess I already was familiar with this as I was working on an embedded atomic clock with my kids using the Arduino at the beginning of the summer and had to learn the embedded coding of the digital broadcast stream.
I'm actually quite surprised by the accuracy that is had using these techniques. They honestly seem so convoluted, tedious, and error prone.
Thanks so much again, even to those who took a little bruising by my little rant. I really wasn't looking to stir the pot, I was just responding the "Joe Homeowner" dig without exercising my usual restraint.
Now I gotta go out in this frigid NH weather to do this!?
