Issues getting a Fix

Nate The Surveyor

Well-Known Member
I am getting a sense that our enthusiasm is giving the wrong impression about the capability of this equipment with new or potential users.
I have some prospective buyers that I have to remind that this is still GPS equipment, the BEST GPS equipment but still has limitations
Sean is probably right.
Although there are few places I can't get a shot, with verify, etc. It still can take it a while, to get, with 100% satisfaction.
To date, I have been on a point 2 hrs, or slightly more. Sat config was poor, covered up w pines, and oaks, etc. But, it was 100% when i was done.
 

Phillip Lancaster

Active Member
I am looking to bid on a 400+ acre mountain ground with cover and a double tower(side by side) power line running through it, should I be concerned about too much interference from the power lines?
Not with the LS. I work all the time under a 500kv transmission line with zero problems. Sometimes I cannot hold the rod. Now the T1 will shut down while under one but just a few feet either right or left of the line and it comes back in. It even happens when I'm under a single pole distribution. But the T1 is using a decade old technology. Javad put some great filters in the LS. I would guess that the T1M is like the LS but I have never checked to be sure.
 

Sean Joyce

Well-Known Member
Sean is probably right.
Although there are few places I can't get a shot, with verify, etc. It still can take it a while, to get, with 100% satisfaction.
To date, I have been on a point 2 hrs, or slightly more. Sat config was poor, covered up w pines, and oaks, etc. But, it was 100% when i was done.

Nate; I am not backing down 1 mm from my enthusiasm, I have yet to survey a point that just could not be obtained with the L.S. and VERIFIED given enough time.
Like you I will occupy it, and re-occupy it with more favorable sat coverage, and I am still saving a lot of time.
My comment is making reference to expectations in comments made to me about the L.S. that are just totally unreasonable.
I have also run into those that bail out on a point too soon, in one case I believe just before a fix would have been obtained.
(but he still had the data for PPK):)
 

Matt Johnson

Well-Known Member
5PLS
We often work in Marin County which generally consists of steep terrain and heavy to moderate tree cover. It has been my understanding that JAVAD should have no problem in such terrain.

Your typical expectations in these type of locations should be 10 to 30 minutes to collect a point. Set the LS up with a bipod, use the Boundary Action profile and let it work. Then post-process the base-rover data with DPOS.

How much time did you wait before you gave up?
 

Jim Frame

Well-Known Member
Your typical expectations in these type of locations should be 10 to 30 minutes to collect a point.

A reasonable approach, though it's not delivering real-time results of the desired reliability. It's rapid-static, not RTK, and any modern receiver can do the same.
 

Matt Johnson

Well-Known Member
5PLS
You should typically end up with RTK coordinates (although it takes some time) and a static solution. I know of no other receiver that automates the process of processing base-rover static vectors inside the receiver or in the cloud. Post-processing use to be cumbersome process: connect cables and download the data from base and rover to PC, import data into PC software, setup coordinate system in PC software, process data, export coordinates, import coordinates into CAD and/or field software. Now this is all automated in J-Field and only requires a couple button presses.
 

Jim Frame

Well-Known Member
From my perspective, the ease of post-processing is a collateral benefit rather than a distinguishing feature. Being able to obtain a reliable position in real time is what makes the LS a better value than other receivers.

I make this point only to caution enthusiasts who might be tempted to tout the ability of the LS to get a good position with 10 to 30 minutes of data. I wouldn't want to see them get laughed out of the room.
 

Duane Frymire

Active Member
I am looking to bid on a 400+ acre mountain ground with cover and a double tower(side by side) power line running through it, should I be concerned about too much interference from the power lines?
I would be concerned. I have logged what should have been good positions that turned out to be 0.5-2 feet off. Only common denominator is under power lines. There was nothing to indicate the positions would be bad at the time but post processed did not match rtk very well on one, and the other didn't agree with a previous survey so I checked it.
 

Matthew D. Sibole

Well-Known Member
5PLS
I would not be concerned. Take multiple shots on your property corners. Redundancy is key to being able to get good reliable data. If you can shoot that property corner 3 times with the safe guards built into JField and they all come back within a few hundredths or even a tenth and you can also use DPOS to check those RTK shots you should have enough data to prove your position.
 

Nate The Surveyor

Well-Known Member
Well, having been one of the early guys, of "GPS ABUSED PROPERLY", I do have this to say.
GPS in the woods, DEGRADES the position. You get your best data in the open field. You get your best data, with redundancy. Static GPS, in the field, is some of the best data ever. (Kent McMillan is a fan of this approach). Then, ANYTHING in the woods, gets shot in, from "in the clear" control. This is your highest form of data. It's the best.
From this "Gold Standard", we go "downhill".
We now have RTK gps, in the edges of the woods... and it still works. But, we recognize a little error coming in. So, we mitigate it, with REDUNDANCY and TIME. Ok, we are pretty good now.
Then, we take RTK GPS, deep into the woods. Now, we find more trouble. 2' to 7' errors are common. So, we mitigate this with REDUNDANCY, this brings us BACK to the 0.2' accuracy. Then, we add more time, and we are down to around 0.10' accuracy.
In the thick woods, one shot, with "normal" gps, this level of confidence takes between 30 minutes, and 3 hrs. If it takes longer, we give it up. When we give it up, we have 2 paths to go....
1.) Accept the un verified coordinate.
2.) Go back to the wide open, get good control, and use conventional equipment, and bring our control in from the wide open areas, to the thick woods.
Now, for some persons, option 1.) above is ACCEPTABLE. (I am seeing this with some start-up solo guys, with used gear, or a LACK of experience, and a desire to put the business side above the quality side)
For me, it is NOT acceptable.
Javad LS has subroutines, in the data collection process, to mitigate the 5' and 7' and 2' errors.
And, a mechanism to bring the data back to the 0.10' area, and even tighter, when desired.
So, I am a Javad Fan.
Nate
 

Matt Johnson

Well-Known Member
5PLS
I make this point only to caution enthusiasts who might be tempted to tout the ability of the LS to get a good position with 10 to 30 minutes of data. I wouldn't want to see them get laughed out of the room.

Being able to get a reliable RTK position in difficult locations is an invaluable feature even if it does take long observations times to accomplish. I don't see why anyone would get laughed out of the room for getting good RTK solutions where other receivers can't.

Consider this scenario which I have encountered quite often. You are trying to set a missing monument deep in the woods. It takes a 30 minute hike through the rough terrain to get from the car to this location. With reliable RTK positions you can the monument set with one trip to the location. Now compare this to trying to set the monument with rapid-static. The first trip you measure two rapid static position that you believe are close to the location of the missing monument, setting nails at the recorded points. You then go back to the office, connect cables, download data, process data and upload coordinates to data collector. Then you drive back to the site, set up the base station again, hike back to the location and do a distance-distance intersection to the stake coordinate. You drive the pin and record rapid-static data on its location, walk back out of the woods, drive back to the office, connect cables, download data and process data again. If you are very lucky your distance-distance intersection got you close enough to the stake coordinate that you don't have to go back out again and move the pin closer.
 

Darren Clemons

Well-Known Member
From my perspective, the ease of post-processing is a collateral benefit rather than a distinguishing feature. Being able to obtain a reliable position in real time is what makes the LS a better value than other receivers.

I make this point only to caution enthusiasts who might be tempted to tout the ability of the LS to get a good position with 10 to 30 minutes of data. I wouldn't want to see them get laughed out of the room.
Laughed out of the room? Really? I can guarantee that that is the last thing any of us using and "touting" the abilities of the LS are concerned about. The LS CAN and will get a, not only good, but extremely good, position on almost any point deep in heavily covered wooded areas - period.
Some people just simply will not accept and therefore will never truly trust GPS - period. This LS gives us so, so many ways to validate, check and re check our data it's virtually impossible not to be 100% certain of it if the proper procedures and parameters are used.
 
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Nate The Surveyor

Well-Known Member
Matt, I like how you think.

There's even other options.

If you are beyond radio range, from the base... And need to set a corner...

You can field ppk, with a cell phone, mifi.

Your temporary ctrl. Nail is gonna be real close... Typicly 6' or less, compass and box tape it in, after field ppk. If you know how to use a compass... You will be in the gold, with one ctrl nail...

I can go on.....

N
 

Jim Frame

Well-Known Member
You should typically end up with RTK coordinates (although it takes some time) and a static solution.

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.
 

Matt Johnson

Well-Known Member
5PLS
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.

Yes, I definitely agree that other brands are certainly able to deliver good RS results under tree canopy with good post-processing software.
 

Matt Johnson

Well-Known Member
5PLS
I'd add that where J-Field RS processing differentiates from other brands the most notably is:
  • The ease to post-process data as I discussed before.
  • An association between field data and the GNSS raw data file is kep intact. Instead of just ending up with a raw data file with a random file name and no point description, J-Field links the raw data file with the user defined point name, description, photos, etc. The user then does not have to try to remember what each point was and enter it in the post-processing software. No other field software package that I'm aware has this ability.
  • The ease to compare the RTK coordinates with the post-processed solution and then choose the desired solution.
 

Jim Frame

Well-Known Member
Instead of just ending up with a raw data file with a random file name and no point description, J-Field links the raw data file with the user defined point name, description, photos, etc. The user then does not have to try to remember what each point was and enter it in the post-processing software. No other field software package that I'm aware has this ability.

My mid-1990s Trimble 4000SSx receivers allow field-entered point name, antenna model and antenna height. (They don't have cameras, so no photos.) I believe that firmware was written by Javad Ashjaee.
 

Shawn Billings

Shawn Billings
5PLS
From my perspective, the ease of post-processing is a collateral benefit rather than a distinguishing feature. Being able to obtain a reliable position in real time is what makes the LS a better value than other receivers.

I make this point only to caution enthusiasts who might be tempted to tout the ability of the LS to get a good position with 10 to 30 minutes of data. I wouldn't want to see them get laughed out of the room.

From a fast static perspective, I would add to Jim's caution that you should not rely on a single DPOS solution in heavy canopy. If you find it impossible to get an RTK solution in heavy canopy and decide to use DPOS to obtain a position, always get at least two shots on the point. The heavier the canopy the more time is required, minimum 30 minutes per shot if it is too heavy for RTK. A single DPOS solution may yield a fix status but not be correct. Without a second agreeable solution, you have no way of knowing if the DPOS solution was truly good.

In the open, I've had tremendous success with very short DPOS observations. Two days ago I was shooting boundary monuments in a road a mile from my base. I was collecting for 20 seconds. All processed in agreement with the RTK solution. The need for 10-30 minutes is for moderate to heavy canopy.
 
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