Issues getting a Fix

[Shawn Billings]

These are two different things, and I think it's important to distinguish between them. Rapid-static isn't real-time, so I don't think it belongs in this discussion, DPOS or otherwise. My comment about getting laughed out of the room pertains to implying that a good RS solution is something only the Triumph-LS can deliver.

I agree that *if* you can get a verified RTK solution you'll save time over having to set rapid-static points and returning to the site, if that meets your comfort level. (I don't trust a single RTK shot for control work, so I generally get two or more, preferably on different days and at different times of day.) The times I've tried for 10 minutes or more without getting a verified shot, I've chosen to cut my losses and get the shot by other means. But I can usually drive to my control points; if I had to pack very far, I'd likely change my approach.

Jim raises a good point here. We all typically find a niche within which to work. I currently do not have a robot because my current work would not justify owning one. I have had a robot in the past and it is extremely efficient in many environments and under varying project requirements (i.e. incredible vertical accuracy). If I were surveying numerous small sites with a lot of sky obstructions, RTK would not be the most efficient tool to use. I've used my total station entirely on four or five jobs in the past year because RTK simply wasn't the best tool. All were fairly small in size. Two required vertical accuracy under canopy that I didn't believe RTK could do as quickly and reliably as the total station. I've also surveyed several large acreages (100+ acres) in the past year (by myself) that I simply could not have done without RTK (specifically the Triumph-LS). And there have been several jobs that were a compromise. RTK made the most sense for most of the job and the total station would have made more sense for part of the job, but I did it all with RTK because I didn't want to switch gears in my workflow for a small number of points. And there have been times that I've used a mix of RTK and the total station with great success.

My point is that surveying is so diverse that there isn't yet a single tool that does it all. This makes surveying fun though, in my opinion. Every day you size up your job and determine the procedure you'll take based on the project needs and the tools at your disposal. A ten, or even thirty, minute observation on every point may seem ludicrous or may seem like cheating depending on what's between here and there. This week, I've been working on a topo of a future industrial site (approximately 20 acres), a survey of a heavily wooded 200+ acre tract, and a cut-out of 5 acres around a driveway, house and barn from 29 acres of mostly pasture. I've used the LS exclusively on each one. While there isn't a complete do-it-all tool yet for surveyors, the LS comes really, really close for my niche.

 

[Jim Campi]

This is slightly off topic but certainly related to getting a fix.

I noticed quite some time ago that the orientation of the LS is critical if a fast fix with maximum engines is important. When doing a topo with a large number of points it becomes clear that the azimuth of the LS impacts the total number of engines and the time to max engines fixed. I looked at this carefully on Tuesday when collecting precise topo data on a small rural site with what I consider a small number of overhead obstructions. In most areas I could reach 6 fixed engines within 5-10 seconds with the correct orientation of the LS. There was a 5-10 second difference to fix and as well as a difference in the total number of fixed engines. For example in the NE corner of the property I could reach 6 fixed engines with total occupation time of 12-15 seconds at 225 degrees. At 45 degrees it took an additional 6-10 to reach a total of 3-5 engines plus the additional occupation time associated with fewer engines. After collecting 10-20 points it becomes obvious that the LS's efficiency is based on orientation when doing topo work and the total occupation time is small. It's also apparent that the most efficient bearing changes based on location. The greater the overhead obstructions the more obvious is this attribute.

I have not tested this however; the time to fix may decrease when the azimuth of the LS and T2 are equal.

Does the quality of the data change if the LS is rotated while collecting point data? Any other thoughts?

 

[Matt Johnson]

Does the quality of the data change if the LS is rotated while collecting point data? Any other thoughts?

Both the base and rover should be aligned to north (record button the T2 to the north and display of the LS on the north) especially for processing with DPOS which uses azimuth dependent phase center variations. I'm not sure if it might reduce the time to fix but it would be an interesting experiment.

 

[Jim Campi]

Hi Matt,

Are you saying that when occupying a point, the LS should be pointed North if post processing via DPOS? I always set up the T2 to point N.

 

[John Evers]

technically yes...the display of the LS faces north,the compass will read due south.

 

[Ron Booher]

The job I am bidding on is all moderate to heavy canopy with the high voltage towers cutting almost halfway through the property, the property has a township road to be located and subdivided with a 1700' mountain to be the dividing line. i am wondering if i set my receiver up on the power line clear-cut can i reach my LS in the woods?

 

[Matthew D. Sibole]

Too many variables to say. What I can say is that your base needs to have as unobstructed sky as possible (the whole horizon if at all possible). As far as range is concerned it depends a lot on vertical relief and your radio. How high is your base? How high can you get your radio antenna? How many watts are you transmitting? How dense is the tree cover etc. Radio range is much harder to diagnose than whether or not your LS will work in that environment.

 

[Matt Johnson]

The job I am bidding on is all moderate to heavy canopy with the high voltage towers cutting almost halfway through the property, the property has a township road to be located and subdivided with a 1700' mountain to be the dividing line. i am wondering if i set my receiver up on the power line clear-cut can i reach my LS in the woods?

If you are asking if the radio signals will reach the rover, the best way to answer this is to calculate the viewshed from the base location. http://www.heywhatsthat.com/ is the best site I have found for this.

 

[John Evers]

My method to not worry about radio range is to use the internet for cell corrections. It does not require a strong signal...just a signal.

Is there any cell service available in that area? The LS makes doing this rather simple.

Also...do not forget that you can still accurately measure points beyond the range of your radio system by taking advantage of DPOS.

 

[Ron Booher]

My radio has 1 watt but if i locate a stone pile for 3 setups, then DPOS them I should be confident of the reading?

 

[Phillip Lancaster]

What's the reference to face the T1/T1M to north. I cant remember but i think that the future cut out ports face north. Is this correct?

 

[Adam]

What's the reference to face the T1/T1M to north. I cant remember but i think that the future cut out ports face north. Is this correct?

Its the triangle above the lights.

 

[John Evers]

My radio has 1 watt but if i locate a stone pile for 3 setups, then DPOS them I should be confident of the reading?

I need a little help with your question. Are you referring to three DPOS solutions?

 

[Ron Booher]

Yes may at different times of day and this is central Pa. bad cell cell service so I'm kinda limited with valleys and mountains.