GPS RTK vs. GNSS post processing

Why not do both? I think the 4 extra birds will be very helpful to you in canopy.

Bryce, with all due respect, it sounds like you have OLD GPS units.
So, I'd suggest newer equipment, if that is the case.
What do you have, and how is it configured?

There are circumstances when RTK will be more accurate, and there are circumstances when PPK is better.

So, I suggest that you consider the concept of MORE TIME on each shot, will bring your accuracy up, on an immediate way, and do both. With older equipment, I'd prefer PPK, or PPS. (PPK = Post Processed Kinematic, and PPS = Post Processed Static)

For a PPS shot, 5 mins, will generate alot of data. At a 1" data rate. I know a surveyor, who strictly ran control for other surveyors. He'd do 8 to 10 minute shots, 1" rate, and over 1/2 of them were on offset shots, (not the actual item that needed tied), because he wanted good sky view. Set 2 control nails, and give the data to his client. They would do the additional work.

Nate

Nate The Surveyor, post: 376258, member: 291 wrote: Bryce, with all due respect, it sounds like you have OLD GPS units.

I'm thinking it more likely that he has an RTN that's GPS-only. That's the situation I usually deal with (CRTN).

Thanks Jim... I am not not RTN literate!

The only RTN around here, is the calling of barbecue, from a local feed stop, in Kirby AR

N

I would say 6 GPS and 4 Glonass will not get you accuracy with either RTK or post processed. I generally do not even start collecting data until I have 6 GPS in view and know more are coming.

It does sound like you have older receivers with a limited number of channels. If that is the case you are better off using all available channels for GPS, 8-10 in view can now be expected on a regular basis.

Paul in PA

Yes the base correction servers that I have access to are all trimble netrs stations and only do gps. I use a trimble 6000 xh and will have 12-15 satellites in view, then if I use real time corrections it drops to 4-6 being used and Terrasync shows a 10cm accuracy but this realtime is just using gps all the glonass data is doing nothing. If I just turn off the correction and get back to my pc then I can use the glonass and post process the data from a local cors station. I just don't know which is the best to use at this point with just the 2 choices. I will be setting up my own ntrip server soon and will have gnss correction and this will not matter but it will be a month or two. On a side note one of the things I was looking up was rinex from ssf file correction and could not understand why I had no L2 corrections after I used the Trimble rinex converter so no oppus was possible. Then I learned that trimble strips out the l2 on purpose because I have pathfinder office and they did not want the gis stuff crossing over to the survey stuff, I felt a little cheated since I thought I had a pretty good system going on with the 6000xh and the terrasync etc. But after reading here I see that an R8 version 2 might be what I really want down the road so I can get away from The SSF format I am stuck with.

Suggestion, don' use Trimble to convert to RINEX. Send the Trimble file as is to OPUS and get an L2 solution.

Paul in PA

We do not have the same format as Trimble Business Center, I only have SSF and I don't think it worked on opus last time I tried that is why I will probably move away from using Pathfinder Office.

How would you use the receiver to do stakeout or to take you to a particular point without RTK?

Paul in PA, post: 376310, member: 236 wrote: Suggestion, don' use Trimble to convert to RINEX. Send the Trimble file as is to OPUS and get an L2 solution.

Another non-Trimble user who is somehow an expert on Trimble?? I use Convert to RINEX on an almost daily basis; as long as you have the most current version and understand the options there's no problem.

Post processed is always more accurate and the number of measurements is not as important as the number of measurements over time as the constellation changes. That is why when a specification is written for a HARN or densification network the observation times are long and the record interval is 10-15 seconds. PP Static will always be more accurate than RTK (more precise and accurate). I've surveyed 100,000s of static vectors and worked on HARNs, densification networks and local networks both conventionally and with GNSS.

GPS only RTN would be fine as long as you have a minimum of 5 SVs- many states are still running GPS only networks and surveyors are doing fine. I have seen when a full GNSS box will not resolve ambiguities and not provide a fix solution on a GPS only network- because the unit is set to only provide a GNSS (G & G) solution and it can't find anyone to speak russian with. It's always reduced to the least common denominator.

Sometimes, in deep woods, with rtk GPS, in beast mode, 5 corrections per second, I have seen rtk be correct, and post processed static be wrong. I don't think this is your normal circumstance. But, with redundant shots, you figure out what is right. 3 rtk shots in the woods, that agree within less than a tenth, AND have a time separation, are good. This is not your normal procedure, for most GPS users.

N

Lee D, post: 376373, member: 7971 wrote: Another non-Trimble user who is somehow an expert on Trimble?? I use Convert to RINEX on an almost daily basis; as long as you have the most current version and understand the options there's no problem.

Lee,

Brice complained about his Trimble conversion to RINEX. It appears Brice does not share your software.

One does not have to be a Trimble owner or user to know that OPUS will accept and use a Trimble format file for an OPUS solution without having to convert it to RINEX.

If Trimble labors to defeat the full use of their equipment by the equipment owners, that is not my cross to bear.

Paul in PA

Trimble, at various times (such as when they went to GNSS), has changed their file format and NGS isn't generally in a huge hurry to catch up. And you can't send the native receiver file to OPUS, you never could. You have to convert it to a DAT file, which NGS may or may not handle correctly. The Convert to RINEX utility has always worked flawlessly IF you pay enough attention to keep it current. Trimble has outstanding tools, you just have to trouble yourself to learn about them, which apparently must be too much to ask of some folks.

I don't work for Trimble and I don't have any vested interest in defending or promoting them; I'm just sick of clueless blowhards badmouthing an outstanding product that they know nothing about.

Bryce, you may want to try to find a used Geo 6000XR. It's the survey version of the device you currently have. It will use the same zephyr antenna, but it has Access software instead of Terrasync. NEI in Lafeyette, LA has a couple for sale. http://www.ebay.com/itm/Trimble-GEO-XR-6000-with-Trimble-access-/151895355970 . Perhaps they would just sell the XR by itself, since you already have the antenna, pole, case, etc. You can then purchase a base license for Trimble Business Center for $500. The GIS module is an additional $500, which you only need if you want to import geodatabase schema into TBC to load into Access.

Thanks! I had been looking at some 6000xr units but I started planning out my future direction and decided it was best for me to just break down and buy a trimble netr5 unit so I can use the glonass in realtime and for pp the data. And if I need to the netr5 can be taken into the field as a temp base. IN my area the cost is $1800 a year for access to the gnss corrections and I will have $2500 into this netr5 so it was the direction I went.