Sunday, December 13, 2015

GNSS Post Processing Using Trimble RTX (one year free subscription)

Its been a while since the last time I publish geospatial stuffs in this blog. And today I would like to share some free GNSS services available on the internet and how to fully utilize their services to fulfill your GNSS processing needs, mainly if you needs post processing service and you cant get or you cant reach any software available in the market (though I would like to recommend RTKLIB, a freeware/open source GNSS processing software).

Nowadays, doing post processing GNSS measurement data is not only could be achieved using Desktop Software (Trimble pathfinder, Trimble TBC, Leica Geo office, RTKLIB and so on), but also Online Services (Leica Spiderweb, Trimble RTX and may be others). Two main geospatial agencies in my country (Badan Informasi Geospasial/Geospasial Information agency, formerly known as BAKOSURTANAL and Badan Pertanahan Nasional/National Land authority) have developed online GNSS Services using national GNSS Station Network as its core base station data provider. BIG service is called INACORS, while BPN's service is called JSRP CORS BPN. Unfortunately due to unknown reasons, those two services have limiting its online post processing GNSS services. INACORS still providing offline base stations data (as far I know, it is a paid services because they are instructed to support National Non Taxable Income/Penerimaan Negara Bukan Pajak), whereas the BPN's Service JSRP CORS still offline (even the website itself has been died for some time). I dont know if they are restricting their services to only support internal organization GNSS tasks or just simply dead). In my opinion, if we are pretty serious to develop geospatial sectors to be more more widely available and easier to reach by our citizens, these sad offline things shouldnt have happened.

Okay, I dont want to grumbling more, I think INACORS Service when its still openly available is pretty much helpful to me, because I dont needs to set up a base station when I go to the field to do Static GNSS Survey, besides setting up base stations are tedious, pain in the ass, wasting time, sensitive to incorrectness and blah blah blah (grumbling again).  What I want is something like what we do on the Navigational GNSS Survey (turn on the gadget - waiting the devices to find the fix signal from satellites - record the data - go home to sleep). I point out Precise Point Positioning  at my previous post, but it is just does not accurate enough to fulfill some application needs.

So, A friend which is working at UAV Mapping business (thanks to him) tell me about Trimble RTX services (which as far I know is a Paid services). We are arguing each other about the Paid aspect and he keeps insisted me to check it out, and when I check them on their website, wow they are giving one year free subscription (dont know if they are planning something fishy behind this, but fuck it, at least I could post process my GNSS measurements without setting up a base shit station hahah)

So here we go, the first thing first is you must register an account, so just go to www.trimblertx.com, click register, fill the form and submit it.



and then, proceed to post processing service


Choose the coordinate system and tectonic plate you stood on or just simply choose autodetect. Choose the measurement data to be uploaded. Remember it is only support Trimble native format (which means you should use Trimble GNSS devices, they are a company after all), or just convert your non trimble format to RINEX to use the service (beware about antenna support, read the disclaimer and antenna support in the website). Dont forget to read the observation recommendation. Pseudorange and carrier phase (which means your device should be dual frequency L1/L2 at least) is mandatory.



Fill up your email, and the proceed the processing. The post processed static data will be sent to your email.





And the processing has been done in few seconds, awesome, the lovely email coming. there are two identical reports in two format, one is an XML file and the others in PDF format.


The report, there are two version, one in Epoch 2005 ITRF 2008 and the others in Epoch 2015




lets inspect some aspects about the post processing result.

- Trimble claims the RTX technology giving horizontal accuracy up to 2 cm and 4 cm vertical accuracy based on in field 95 percent of performance of the time, I dont know what this statistical thing means, but I trust them, hahaha

- I dont know if RTX processing service is complement with my country current national reference datum (SRGI2013 - Sistem Referensi Geospasial Indonesia 2013) or not, but based on RTX asking about tectonic plate (SRGI2013 is DGN95 with Tectonic Plate Movement Consideration), I think it should complement (needs to clarify it to my friends at BIG).

- It is interesting to compare the RTX result with my current national geodetic reference control network, which it is available all over Indonesian islands (especially in Java island which  has so many of them) as landmark building, consider to do this when I have free time.


thats for now, Cheers,