Activity Feed › Discussion Forums › GNSS & Geodesy › Test Drove a GPS system
Test Drove a GPS system
Posted by lanceboyle93101 on February 22, 2021 at 12:22 amLocal vendor HUBS Hawaii brought the Spectra Precision 85 w/ Ranger7 into real world conditions. Using a base/rover setup, for RTK.
Cut a x-section in partial canopy w/ 8ft cane grass. Fix maintained entire way.
Another section thru full canopy. Fix maintained, then lost and re-acquired. Good RMS and PDOP values.
Took them to an area that we could not get fix w/ our SP80’s. The 85’s fixed after a bit of coaxing.
The 85s have same housing as the 80’s (bad) but more channels and can process the newer L5 frequency. (Good)
Tracking 38 satellites, and using 20 of those for position in the canopy.
I was skeptical on the Ranger7: Big screen lugged thru the jungle seemed like a disaster. But it balanced nicely on the rod. Plus running W10 (Survey Pro) w/ that color screen was so fast and responsive to finger taps, makes up for extra weight and size.
Our Trimble R8v4 or Spectra E50’s would have never worked in those conditions. The Spectra 80s maybe…
Trimbles are more robust in the housing dept and produce tighter positions in clear open conditions. But we rareley do const layout and parking lot topos. Boundary in the bush 75% of the time.
Curious about other users of this system. Comments?
dooryardsurveyor replied 3 years, 1 month ago 14 Members · 19 Replies- 19 Replies
A fun good unit if it fixes in that terrain!
Mahalo.
I don’t know if the SP85 does better in heavy canopy than the SP80, however both receivers do track L5.
It was the SP60 that did not track L5; I clipped these from the online brochures:The cases are an issue. Especially the battery doors and seals. And since water that gets in the battery compartment is in the receiver, it is a big deal if you work in the rain. But the SP8x display is really useful when debugging RTK that won’t fix and battery issues.
When comparing to R8’s you need to make sure the R8 has current/latest firmware installed. Probably not reasonable to compare latest SP85 FW to 2 year old R8 firmware. Also, if the R8 is ‘s’ then make sure it has EVERYTHING enabled or not apples to apples comparison.
Another difficulty in comparison is the Street price difference might be close to 45%.
It’s very likely you were getting good fixes when the unit reported a fixed position. I’m not disparaging the system you tested by what I’m about to say. I am challenging your evaluation (and most other surveyors in your shoes). Your statement that PDOP and RMS were good is meaningless. I see a lot of surveyors point to those values to demonstrate QA/QC, but I would recommend relying on a repeat observation over time as a better indication of a good fix until you are confident in the reliability of the system’s reported status. Set nails at a few points in the boogers that would represent normal field conditions for jobs you encounter and then come back to those points several times at different times and compare the repeated observations to really prove that when the receiver says it is fixed it is really fixed. Bad fixes can produce good RMS for several minutes. Precision vs. Accuracy.
My previous employer purchased this same setup. They did a Boundary survey on a 10 acre wooded parcel with both the GPS and robot on state planes. Each survey was within a tenth at all corners. Pretty cool if you can trust it. The tsc7 is too large for the woods in my opinion but would be great for construction staking. Also, it is too much like a computer. I don’t want to be reminded of virus protection updates in the middle of surveying. Tsc3 is the better option to me
I run Windows 10 on my Panasonic fz-m1 tablet and keep the internet connection off when I am not using it. That should keep it from doing anything virus protection or update related while your surveying.
The other advantages like receiving files via email directly on the tablet, emailing the download back to the office etc, or even just easier file transfer via flash drive make me not like the older stuff like the TSC3 and its lack of functions. Even finding points on the screen is like night and day difference compared to the old resistive touch screen.
- Posted by: @350rocketmike
The other advantages like receiving files via email directly on the tablet, emailing the download back to the office etc, or even just easier file transfer via flash drive make me not like the older stuff like the TSC3 and its lack of functions.
I liked the size of the TSC3, but the TSC7 is worth lugging around if you’re doing anything other than rough woods work. With SIM cards installed on them, we push data directly to and from the controllers, no email necessary.
I anxiously await the day when we can drop the physical screen altogether and get a holographic screen that appears above a small rugged keypad…
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman I’m waiting for the day they can make a good touch screen that can continue working normally in heavy rain and snow. Mine has water mode but that essentially just makes it almost impossible to click anything without taking my gloves off.
@350rocketmike this is a really big issue in my experience too. what do you think about a voice interface? probably not going work.
I barely talk to my Google home so I doubt I’d feel comfortable talking to a tablet in public lol. Actually my Panasonic is better in ice/snowfall then rain, I can leave it in normal touch mode a lot longer before it starts to spaz out and click randomly. Usually it happens when I can’t see and have to wipe the snow and ice off. The rain is a problem because it doesn’t like to work with the rubber stylus in water mode when it’s extremely wet. I’m going to look into a better stylus for that type of work. I lost the original hard tipped stylus that came with it. Not sure if it would have been better.
- Posted by: @shawn-billings
Set nails at a few points in the boogers that would represent normal field conditions for jobs you encounter and then come back to those points several times at different times and compare the repeated observations to really prove that when the receiver says it is fixed it is really fixed.
The only problem I see in that procedure is that he needs to do everything 2x. Waste of time and effort. For control points, I would agree with you. But for topo ground points that is a waste of time. A longer logging time under canopy would be a better approach but still, it won’t guarantee no false fixes. It is what it is I guess.
I’m not talking about using this for production, I’m talking about using this to evaluate an unknown RTK system. Once you’ve repeated this test several times over a period of several hours you can begin to develop confidence in the system that it provides reliable fixes in canopy. Then you can extrapolate that experience to future surveys so that when you collect a point on a future project in similar conditions to those of your evaluation you can have a reasonable expectation that the results are good.
The more you repeat the test for your evaluation the more confidence you gain in how the equipment performs in that environment. This confidence translates into better practices and better results. Until you do this sort of evaluation in environments that mimic your general work environments, you really don’t know what is wasted time and wasted effort. The appropriate amount of time is the bare minimum amount of time required to get a reliable result and the appropriate amount of effort is the bare minimum amount of effort required to get a reliable result. Any less time and effort is negligent and any more time and effort is unprofitable. Both should be avoided, but I would generally hedge against the negligent more than the unprofitable. But again, you don’t know what is appropriate until you strenuously evaluate the system to understand where and when it works and where and when it does not. A surveyor’s best tool for this evaluation process with RTK is repeatability over time.
Try the mesh tip ones…super cheap, you can jonny appleseed them across the county and it wont hurt too bad…work great in wet conditions
The spectra precision receiver is low priced but from what I??ve heard is not that durable. It might be ok as a base station.
- Posted by: @robertusa
The spectra precision receiver is low priced but from what I??ve heard is not that durable.
I have worked for two firms that used them, and they definitely were of lower build quality. The shell was pretty flimsy, and there were frequent problems with both the battery compartment lid and the front face buttons not holding up to repeated use. That being said, they worked about as well as I would expect them too.
It was a relief to make the move to a firm that invested in the good stuff. There’s a night and day difference, in both build quality and performance, between the Spectra stuff and the Trimble stuff.
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman I like the TSC7 whether in the woods or on a construction site. I will admit it’s a little bulky in the woods though. I do agree about it being “too much like a computer” at times. One time I felt the need to restart and had to wait for windows updates to install while I stood in a swamp.
Gregg
YMMV. If you don’t pay for durability up front, you’re going to pay for it in repairs and accessories later, plus the opportunity cost of losing work.
I was tech support for a major Trimble dealer. We also sold Spectra in theory, but we did everything short of removing the gear from our catalog to avoid selling it. The tiny amount of Spectra gear in the field took up an outsize portion of my time and the repair shop time. Not to mention that the vast majority of our customers did remote work and could not afford for a receiver to go down on a two-week bush job only accessible by chartered plane…
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman@350rocketmike try out the grounded stylus for working in wet weather/snow. Not sure if it will work with your DC, but it has been a game changer for our Carlson RT4 tablets in bad weather.
Log in to reply.