Community Forum

Phantom 4 Pro Snap PPK Emlid Reach no Solution

(Gareth O'reilly) #1

Hi All

I have purchased a snap ppk from tuffwing and conducted a test a few days ago.
The flying went well, yet the processing is giving me hassles.
There seems to be no solution, no matter what settings I try. Please help. Here is a link to my files.


(Michael Lambert) #2

Downloading now. What constellations did you use?

(Gareth O'reilly) #3

Thanks, Just GPS

(Hunter) #4

What is your base coordinate and how was it derived?

(Gareth O'reilly) #5

Base Co ord - Lat 29.528814383
Long 31.192123199
Height 94.5860

It was derived from a here position off a spectra receiver.

(Hunter) #6

WGS84 and height above ellipsoid?

(Gareth O'reilly) #7


(Hunter) #8

I don’t know how this happened but your base and rover times do not match. Your rover is in correct epoch 2019/04/12 while your base is showing as 1999/08/27. I stacked a screenshot of each units time interval.

(Hunter) #9

You need to correct your base RINEX file to the right date and it will process. I do not know the best approach to this without a script, I played around a little but no time. Not being an Emlid base can you describe how you you process the Spectra raw logs to RINEX?

EDIT: I think this has to do with the GPS rollover…

(Michael Lambert) #10

What were your base and rover heights? On RTKPOST now.

(Michael Lambert) #11

Can you please look at the RTK Settings on your rover and tell me what constellations you were using so I can post-process the data you shared?

(Hunter) #12

I may be wrong but this will never process without a corrected base RINEX to account for the GPS rollover change (see base date in year 1999).


Potentially need to upgrde firmware on the Spectra for sure. Re-download the data from the receiver (if it’s stored on the receiver) Try the Spectra or Trimble office software to try to correct the file maybe?
Maybe try to download(if accesible) a VRS network nearby station data? or try the CORS webpage if you’re in the USA?
GPS time on rinex are very sensitive, so any second you don’t account for, might change the position of your base.

(Matt Bodnar) #14

There is a “change week” tool in the Teqc program from Unavco…


This may help your rinex file.

(Matt Bodnar) #15

Agree, this is also a well known issue with legacy Trimble gear such as the long retired 5700 gps receiver. If the device firmware is too old, the roll-over cannot be managed.

This means the device wont work for RTK but base logging is ok as long as you manually change the week # on the Rinex file.

EDIT: Trimble charges around ~600 USD for firmware updates on legacy gear… Regardless of unit age. This is arguably more than the device is worth.

(Michael Lambert) #16

You will want to check with a local GPS reseller (if you have a relationship with whoever you got your Trimble from) to see if there is a patch available. We use Topcon and were potentially going to have 4 of our receivers go down after the rollover, but it became known after the fact that a firmware patch could be applied to solve the problem. Unfortunately anything earlier than that was not capable of firmware updates.

(Gareth O'reilly) #17

Hi Guys, sorry for the late reply. I had to leave early this morning for the field.
I have managed to contact my local re-seller and they have sent a link for the upgrade. It seems the issue is a result from the rollover. I will sort it out tonight.
Thanks so much for the advice/help, really appreciated.

(Michael Lambert) #18

Nice that it worked out. We ended up have two units that were older that could not be patched, but that better than the original 6 we were told. We’ll see what happens when the new Galileo and L5 constellations start kicking in…