LS+ Action Profile Settings

Tyler

Member
It's been a while since I've seen any updates on recommended action profile settings. I'm hoping to get some recommendations on what I should change in my boundary profile and what other profiles people are using. Here are the settings that I use for locating boundary evidence (3 measurements in the AM and 3 more in the PM):
20220404-15.04.20_00907_Action_Setup__TLS__Min1Eng_Medium_.png


20220404-15.03.15_00907_How_to_Stop_.png

20220404-15.03.24_00907_Verify_Settings.png
20220404-15.03.41_00907_RTPK_Usage.png
20220404-15.03.54_00907_What_To_Record.png
20220404-15.04.02_00907_Options.png
 

Shawn Billings - Javad

Active Member
JAVAD GNSS
Just a couple of general notes for Triumph-LS Plus users with RTPK.

1. A variety of 1.3 with an RTPK session of 60 seconds or longer appears to be very reliable.

2. Sixty second observations produce very good precision. I was an advocate of 180-240 second sessions for precision with the Triumph-LS with GPS and Glonass. I ran several tests that showed diminishing returns in precision beyond four minutes. I saw a screen capture from an NGS seminar on the Surveyor Connect website that suggested the same. However with the Triumph-LS Plus with multi-constellation, I think the point of diminishing returns will be more along the lines of 60 seconds or so.

Point 1. relates to accuracy and Point 2. relates to precision. Developing a profile that incorporates both of these with the least amount of time required will yield great results and improved efficiency (profitability).

As Adam points out, the new canopy and open profiles in version 4 do just that.
 

Tyler

Member
Just a couple of general notes for Triumph-LS Plus users with RTPK.

1. A variety of 1.3 with an RTPK session of 60 seconds or longer appears to be very reliable.

2. Sixty second observations produce very good precision. I was an advocate of 180-240 second sessions for precision with the Triumph-LS with GPS and Glonass. I ran several tests that showed diminishing returns in precision beyond four minutes. I saw a screen capture from an NGS seminar on the Surveyor Connect website that suggested the same. However with the Triumph-LS Plus with multi-constellation, I think the point of diminishing returns will be more along the lines of 60 seconds or so.

Point 1. relates to accuracy and Point 2. relates to precision. Developing a profile that incorporates both of these with the least amount of time required will yield great results and improved efficiency (profitability).

As Adam points out, the new canopy and open profiles in version 4 do just that.
In your workflow, how many repeated measurements do you take? I assume you try to take measurements after satellite geometry changes still too?

I normally do 3 measurements in a row and then wait 4 hours and do another 3 measurements. Is this excessive in your opinion?
 

John Evers

Well-Known Member
5PLS
Tyler,

The fact that you observe points four hours apart puts you in the top 1%.
In my own work, I do not normally make that a part of my practice.
The main thing I would add to your profile is reset engine at start. The reason I do this is to separate fixes from one observation, from being involved in the next observation. I usually collect 5 points on a stone in the woods.
Your profile is 5 epochs longer than my normal, your Confidence level of 5 is two less than I do which is 7. I also use the 60 second time frame for benefit of PPK while in the woods. One big difference is that I do not use Validate. I achieve the next shot to Validate the previous shot. (I happen to dislike validate)
 

Shawn Billings - Javad

Active Member
JAVAD GNSS
Is this excessive in your opinion?
Yes and No.

From a functional standpoint, yes, I think it is overkill. Repeating the observation a few hours later will improve precision, but repeating back-to-back probably won't have any practical benefits over simply running a single session that spans the same duration. And, as I noted before, with the firmware/constellations, sessions longer than 60 seconds appear to offer diminishing returns.

But there are other considerations. Matt Sibole has shown that with our software, adding multiple sessions in cluster average will reduce the error estimates of the point dramatically. This can be useful in demonstrating some prescribed positional tolerance requirement (e.g. ALTA/NSPS Land Title Survey requirements). I don't know that the resulting point is actually any more precise, but it reports to be more precise.

One thing that we seldom discuss is the vertical slope during collection. Javad added this a long time ago and the theory behind it is solid, but I don't think anyone really uses it. The idea is that you want to stay long enough for at least a full cycle of the sine wave that appears in the vertical scatter plot during collection. Please forgive me for not having any context for the following slide. I'm taking it on the word of the person who posted it on Surveyor Connect that it is a slide from an NGS presentation.

AccuracyRTN.jpg


Notice that for their tests, 30 seconds actually provided poorer statistics than 5 seconds. At 60 seconds, it comes back to being on par with 5 seconds and then improves from there. I could be wrong, but I suspect this is because the first 30 seconds is usually biased in one part of that sine wave (think of only having epochs in the peak or the trough) and that the additional time provides epochs in the rest of the phase. Including epochs on both sides of the phase of the wave will result in a mean slope of 0. You need enough epochs to make sure the sample size actually includes the top and bottom of the wave and that you are just catching the top of the wave (which would appear to be a 0 slope line on graph) or the bottom of the wave (which would also appear to be a 0 slope line on the graph). So a very short data set may look horizontal, but in actuality is just not long enough to provide the shape of the sine wave. This may also be why in the above chart that the vertical precision at 180 is above the straight line between 60 and 300. Clearly 180 is better than 60 in this graph, but you would expect it to look more like the shape of the horizontal RMSE, where it falls below the straight line between 60 and 300. Perhaps at 180, the cycles are such that there have been several cycles and then a fractional part of an additional cycle, still biasing the solution a bit, but not as much since one or more full cycles are already part of the average.

This is mostly guesswork on my part, but I can say that the user will probably do well to pay attention to the scatter plot of the vertical plot to see when to stop observing.

Also note that this chart is using GPS and Glonass. I believe the reason we're seeing such great precision with shorter observations is because of the addition of Galileo and Beidou, particularly Beidou, which seems to be providing the most precision of any of the four systems used at present.
 

Tyler

Member
In JField 4.0 there are 2 new default profiles. One for Canopy and one for Open. Copy and rename and use these profiles.
I tested the Open profile default setting and it accepts a shot after 2 epochs without a RTPK solution even though the "Stop Survey When RTPK Solution is Verified" box is checked. The RTPK environment category is set to Open (10 sec). Was this the intent for this action profile?
 

Tyler

Member
I tried switching to "Stop after 10 sec" and it did that for the first shot, then all auto-start shots collected after 2 epochs (~0.2 seconds). I am on the pre-release version.
 

Shawn Billings - Javad

Active Member
JAVAD GNSS
I tested the Open profile default setting and it accepts a shot after 2 epochs without a RTPK solution even though the "Stop Survey When RTPK Solution is Verified" box is checked. The RTPK environment category is set to Open (10 sec). Was this the intent for this action profile?
Tyler,
"Stop Survey When RTPK Solution is Verified" will stop the observation if the RTPK processes and repeats the prescribed number of times. I had a situation last week where I could not get an RTK fix, but RTPK was able to process. It processed several times and even though I had no RTK, the shot stopped and stored with the RTPK solution.

In order to force the RTPK and RTK to agree for the shot to end you need the setting in RTPK Usage "RTPK/RTK Must Agree".

For the open, I don't find this setting to be useful, but I do like for RTPK to be on so that if I happen to venture into less than open points, RTPK is already running to help me out. This is why I also like to have Variety at 1.3 or higher, even for open shots. Variety of 1.3 in the open is easy to get, but if I happen to get a little outside of "open" it's already set to slow me down and check me in more difficult environments.
 

John Thompson

Well-Known Member
I noticed that the Open profile stops after 2 epochs if the Variety target is reached regardless of the Min RTK Time Span or Min Total Duration settings. It would be nice to have more flexibility in setting how to stop. If some of those conditions could be "and-ed" instead of "or-ed".
 
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