First PPP Questions

I am wondering what version of rinex, and what hz rate to use for submission to nrcan.

Trying to get my latest cellular base location for farming dialled. I know i do not need absolute accuracy for farming, but I am having fun learning about surveying.

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I would think 5Hz for 45 minutes should get you enough. Use v3.03 Rinex.

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I read the reach instructions and it said only use gps and glonass, so i take it nrcan just does not track beidou and Galileo.

It also said to use 1hz observations, is there any benefit faster or slower rate? How much more accurate does longer observation time make the measurement?

Of course when I want to do this a big storm rolls through will start making logs tomorrow.

Any reason ubx logs at the same time as Rinex on the RS2?

Hi @PotatoFarmer,

We’ve tested PPP in NRCAN and have some recommendations:

  • NRCAN uses GPS and GLONASS only for calculations
  • CSRS-PPP support says that the 30s data interval is the best. We’ve got good results with 5s logs as well

We’ve updated our Logging tab in 26 firmware version, so you can set the needed interval right there:

The antenna name will be saved in RINEX file as well. Please let me know if you need more info regarding any of these recommendations.

UPD. I’ve edited my post a bit since decided to add the screenshot for better understanding.

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Thank you for all the help I will start logging tonight after work. The junk weather we are having looks like it will calm down by then. And post the step by step progress, for other PPP newbs.

I’ll link the post I made a few minutes earlier:

If you’re doing static, PPP now decimates to 30sec. interval for dual frequency so I guess you can safely log at the slowest refresh rate.

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I sent off my Rinex file.

Picked Static, IRTF, and uploaded my rinex.zip like the tutorial.
That was really super easy unless I am missing something.

I took 24hrs of data, though i read rs2-with-different-observation-times and it looks like 12hrs is extra good enough to be accurate.

There was no choice I could find on NRCAN PPP for Final, Rapid, or Ultra Rapid. So guessing 2 weeks is the wait?

I am also surveying in the reach for the 30min standalone base average just for fun to compare the coordinates.

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NRCAN sent me a report extremely fast, took a couple hours.

So how I think I Interpret this is my data is in IRTF14, to that datum it is this position, with sub centimetre accuracy to a 95% confidence level. Wow that was fast. So onto getting this entered into the base station.

The base is a Trimble BD970, there is no way I can find to change it from WGS84. It also has a setting for ITRF 2014 in it. I also did some reading on WGS84 vs IRTF 2014, and for the most part it sounds like its apples to apples.

I read myself to sleep last night learning about geoid vs ellipsoid.

I also just surveyed in the reach position as an average single using all constellations to see how accurate that was vs PPP. I only have a Data set of 1 but it was very precise other than height.


pppcompare

So other than the math of the different antenna height of the base vs the RS2 i think i might be in pretty good shape.

**edit i also entered the irtf coordinates into google maps and the position is pretty much exact with the satellite imagery :exploding_head:

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Wow, that average single is closer than I would expect horizontally. Overall tolerance would be +/- 0.6-0.7m. Does anyone know if that is typical for a 30m average?

Great job Po!

The reach always is pulling off magic tricks for me!

Thank you everybody for the help. This is so cool.

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Just remember that this means the PPP solution has 95% of the points in the solution within that error-ellipse.
It doesn’t say much about the absolute accuracy, but something about the precision.

I have seen height differ up to 10 cm. It also down to a few millimeters, usually depending upon the quality of the raw-file. The ambiguity fixing percent seems to be important here. I have seen some very accurate solutions when the percent was 70% and some that were off by 10 centimeters when the percent was 40% (transformed from ITRF14 to ETRS89 in this specific case)

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My ambiguities are sitting at 65%, so is this good or is it grounds for a re-do?

Swapped the Trimble Antenna to the mount this morning so I will see how accurate it averages vs the PPP as well.

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Just chiming in so I get updates.

My machinery barn looks just like yours - even the same colour and window style. I’d love to locate my base just like yours, but I have 150ft high maple trees right behind it, so I don’t think it’s a good place for my base.:pensive:

If only your base was an rs2 (or weatherized M2) you wouldn’t have to worry about the format. I just plugged in my LLH and antenna height directly and good to go. I have zero experience but my limited work suggests that the reach is awesome too!

Any chance you have a maintained monument nearby? NRCan maintains a database for these monuments with exact locations that you can use to walk back to your location. It worked like a charm for me. You already posted on that thread but here is a link for your convenience. If you use their database, make sure you access it with a pc - not a smart phone.

I have not played with uploaded files or post processing yet. But I sense that we are a lot alike. It will happen soon enough.

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Couldn’t resist trying to help. You have helped me immeasurably. Apparently, there is a maintained marker a few miles from you at 53.571240 -112.104270 near Royal Park. Maybe your radio can reach it without any hops? Although if it necessary a hop or two isn’t a big problem. If the method works, it is foolproof and takes away any and all doubts.

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Since this is a cellular base I could verify my base by taking the RS2 to that monument and hang out for a bit. I would need to use RV3 surveying in NAD83, since Canada is based off of it.

The Trimble base is WGS84 which is super close to IRTF 2014. The Emlid also desires WGS84 corrections. The biggest Learning gained in doing this project was Ellipsoid vs Geoid and keeping your datum versions straight.

You can fix off a wrong datum and still do pass to pass guidance, wildly enough. I also learned from reading if your base position is too far in error of absolute position or using the wrong datum it increases the error due to ppm dilution as you travel further from your base drastically.

It seems I read one page, and always find a whole extra book of stuff to learn behind it.

I think we are to its fun to tinker.

PPP is way easier than i thought it would be.

Your trees might not be an issue, I can keep a fix in some gross areas with the m2. But its best to have your base in the open.

I see. So distance isn’t a problem for you. I had been hoping LoRa might reach. Nice thing about using the Emlid products is that you can go straight to LLH and skip all the datum complications. You might consider doing that anyway. All you really want is an exact location for your Base - trimble or emlid.

Yes, I am enjoying the learning experience.

I spent most of my day making a mounting bracket for my row crop tractor and fixing a hydraulic oil leak. I’ll make a similar bracket for my loader tractor next.

Btw, I spent a long weekend in your neck of the woods a dozen years ago. I judged a dog test at a farm not too far from yours. I don’t remember exactly where, but I remember it was held at a farm that was an easy drive east of Edmonton.

I’m not worried anymore. Now that my base isn’t getting so much multipath, things are working ok where it is on the light post.

I just liked your location.

Its a handy place to put it, thats the second install like that. Seems to work well.

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