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TBC- Static solution to get my base Coordinates

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(@therock003)
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I want to set up a GPS Base on a fixed location. I have constructed a rod into a terrace and placed the unit and i now want to give it its permanent location coords. For that i will use my local CORS network to get the corrections. Here in Greece its Called HEPOS (Hellenic Position System). You can buy the log files at a cost per hour of reference station of your choosing. Closest to me are 3 stations (25-35-45kms). Of course i will be buying the data from the one located 25kms from my position. So lets say i log my unit for 4-6 hours (5sec intervals) and i buy the respective period of the CORS data files and i now need the silution to get my fixed location.

Trimble R8s my unit produces a .t02 and data can be purchased as RINEX .17o

After i set units and my projection system settings and import both files into project, how do i set the CORS as my base?

I set my units location to "unknow quality" since it is a here reading, but what do i do with the known coords?

I have a list of their locations on ECEF format.

 
Posted : 28/03/2017 12:09 am
(@squirl)
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imo...not knowing the accuracy you're trying to achieve or the tolerances of your project, can't you send the Rinex file to OPUS for a fixed position?

If that's not an option, you can process the baselines of the static to known CORS stations and adjust the HERE position to a fixed point based on the CORS. Just a couple thoughts based on the information you provided. Good luck!

 
Posted : 28/03/2017 4:34 am
(@moe-shetty)
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First, I do not use Trimble software, so I hope someone else can help with that. Your Trimble software might convert the native data language to RINEX, so use that for your processing, or process in Trimble by importing the CORS RINEX into your project.

The station ISER (are you using this?) has some data available, but appears to not be continuous data. ZAXO and ISSD do not have available data, so it is my guess that this is why you have to purchase RINEX.
Set ISER's antenna reference point as this:
***IGS 08***
IRAQ SURVY ERBIL (ISER), IRAQ

Created on 31Aug2011 at 10:14:12.
_____________________________________________________________________________
| |
| Antenna Reference Point(ARP): IRAQ SURVY ERBIL CORS ARP |
| ------------------------------------------------------- |
| PID = DL3893 |
| |
| |
| IGS08 POSITION (EPOCH 2005.0) |
| Computed in Aug 2011 using data through gpswk 1631. |
| X = 3708161.232 m latitude = 36 09 35.46813 N |
| Y = 3582297.943 m longitude = 044 00 39.37543 E |
| Z = 3742781.381 m ellipsoid height = 431.332 m |
| |
| IGS08 VELOCITY |
| Predicted with NNR-MORVEL Aug. 2011. |
| VX = -0.0299 m/yr northward = 0.0324 m/yr |
| VY = 0.0035 m/yr eastward = 0.0233 m/yr |
| VZ = 0.0262 m/yr upward = 0.0001 m/yr |
| |
| L1 Phase Center of the current GPS antenna: IRAQ SURVY ERBIL CORS L1 PC C |
| ------------------------------------------------------------------------- |
| The Zephyr GNSS Geodetic II - RoHS compliant antenna |
| (Antenna Code = TRM57971.00 NONE) was installed on 14Jun2009. |
| The L2 phase center is 0.009 m below the L1 phase center. |
| PID = DL3894 |
| |
| |
| IGS08 POSITION (EPOCH 2005.0) |
| Computed in Aug 2011 using data through gpswk 1631. |
| X = 3708161.271 m latitude = 36 09 35.46816 N |
| Y = 3582297.980 m longitude = 044 00 39.37542 E |
| Z = 3742781.421 m ellipsoid height = 431.399 m |
| |
| The IGS08 VELOCITY of the L1 PC is the same as that for the ARP. |
|_____________________________________________________________________________|

 
Posted : 28/03/2017 4:58 am
(@lee-d)
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Are you just going to do a single baseline from the 25Km station? This is pretty straightforward. Import the T02 from the R8 and make sure that the position is set to Unknown quality. Then load the RINEX file; make sure that the position that came in is in fact the true control position, then set it to Control quality. I would wait a day or two and get the IGS Rapid orbits - the easy way to do this is with the Internet Download tool - and make sure in Project Settings that Ephemeris is set to Precise or Automatic. Then just process the baseline.

 
Posted : 28/03/2017 5:10 am
(@bradl)
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My process would be to import all data as RINEX files. I have had issues where TBC wants to assign a base station to trimble files (.T01 & .T02). This could be your issue.

Also, if you are observing multiple locations, TBC will import redundant vectors that will not show if importing strictly RINEX. If you want to get better solutions, use PAGE-NT from the NGS. It will require getting the precise ephemeris and broadcast ephemeris, both obtain from IGS. https://igscb.jpl.nasa.gov/components/prods_cb.html

 
Posted : 28/03/2017 5:13 am
(@mark-mayer)
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therock003, post: 420599, member: 12282 wrote: Of course i will be buying the data from the one located 25kms from my position.

For best results I recommend that you use at least 3 of these HEPOS stations in your solution.

therock003, post: 420599, member: 12282 wrote: i log my unit for 4-6 hours (5sec intervals)

more
For best results occupy your point 2-3 hrs. Wait a couple hours, then occupy again another 2-3 hours. Doing static, 15-30 second intervals will be more than sufficient.

 
Posted : 28/03/2017 5:13 am
(@lee-d)
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Bradl, post: 420618, member: 2848 wrote: I have had issues where TBC wants to assign a base station to trimble files (.T01 & .T02).

This will always be the case if the data was collected using RTK & Logging or RTK & Infill; it's a very simple matter to go to the properties of the coordinate record and change them to Unknown.

 
Posted : 28/03/2017 5:16 am
(@mightymoe)
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To change the quality of the points in TBC, I've found that it's best to pick the point from the list in Project Explorer not from the point on the screen, you should import your CORS point and set it as Control Quality and your new base point as Unknown.

If you import more than one CORS point you can assign them as fixed in the Adjust Network slide after you process the baselines.

I would suggest writing down or printing out your new base points autonomous Lt, Long and Ht. I also do so for each solution for the new base from each vector from each CORS point. Then if I like the resulting numbers I will run it through the adjustment.

I've never needed to do a RINEX conversion to use the processing tools in TBC. After all the R8 is a trimble receiver and should work well for what you need in it's native format.

If you are just using the one CORS point then you don't need to adjust your network after processing, it should move the autonomous point after you accept the processing session and give you the new values for your point.

 
Posted : 28/03/2017 7:17 am
(@lee-d)
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MightyMoe, post: 420650, member: 700 wrote: To change the quality of the points in TBC, I've found that it's best to pick the point from the list in Project Explorer not from the point on the screen

When you open Project Explorer and expand the point you'll see the coordinate record(s) that are associated with it and what they're derived from (JOB file, T02 file, etc.). These are where you would change the coordinate quality. Note that these are strictly coordinate records and don't affect the data in any way - if I have several of them from multiple observations I usually just delete all but one.

 
Posted : 28/03/2017 8:03 am
(@therock003)
Posts: 189
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Lee D, post: 420617, member: 7971 wrote: Are you just going to do a single baseline from the 25Km station? This is pretty straightforward. Import the T02 from the R8 and make sure that the position is set to Unknown quality. Then load the RINEX file; make sure that the position that came in is in fact the true control position, then set it to Control quality. I would wait a day or two and get the IGS Rapid orbits - the easy way to do this is with the Internet Download tool - and make sure in Project Settings that Ephemeris is set to Precise or Automatic. Then just process the baseline.

The here position of my setup is unknown, and the rinex(or .to2) will for sure mention the mean average inside. But how do i know for sure the the CORS station has the exact-price coord location on the RINEX and not an approximation. IF it does in fact include the precise location then i guess it really is a matter of setting point as control quality and simply process said baseline between mine and the CORS station.

Another question is does it really matter and make any difference if i use same day ephmeris or the next few days (rapid-ultra rapid) or if i have to wait until the exact final ephemeris is calculate weeks after the static logs are retrieved?

 
Posted : 29/03/2017 5:26 am
(@lee-d)
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therock003, post: 420786, member: 12282 wrote: The here position of my setup is unknown, and the rinex(or .to2) will for sure mention the mean average inside. But how do i know for sure the the CORS station has the exact-price coord location on the RINEX and not an approximation. IF it does in fact include the precise location then i guess it really is a matter of setting point as control quality and simply process said baseline between mine and the CORS station.

Another question is does it really matter and make any difference if i use same day ephmeris or the next few days (rapid-ultra rapid) or if i have to wait until the exact final ephemeris is calculate weeks after the static logs are retrieved?

The autonomous position of your R8 will come in with the T02 file; depending on how it was collected it could come in with a coordinate classification of Unknown, Mapping, or Control. If it comes in as anything other than Unknown you need to set it to that.

The CORS should come in with the correct coordinates in the RINEX file; I'm assuming that whoever you're buying the data from will be kind enough to also provide the position at the ARP, just check it by viewing its properties. And if it doesn't come in as Control quality you need to set it to that.

Regarding the ephemerides - it's not necessary to wait for the Final orbits unless you're trying to squeeze out every possible millimeter. The Rapid orbits are generally available within 24 hours and are probably worth waiting for unless you're really in a hurry. For short baselines I'm OK with using the Broadcast or Ultra Rapid orbits but for longer baselines I prefer to wait for the Rapid if I can.

 
Posted : 29/03/2017 10:52 am
(@therock003)
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For some reason, when i import files it detects time as the year 1881 and thus i have trouble matching the ephemeris. This happened both by getting rinex sample from ngs servers and when i tried producing my own .t02 files. I tried tampering with the options and on the time column i entered all available options (UTC/UTV OFFSET/GPS/GPS OFFSET) but still it detects 1881 as year of the observations. Why could that be

 
Posted : 30/03/2017 5:32 am
(@alan-chyko)
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The weird dating issue cropped up a few versions back - 3.5 or 3.6 I think - and you'll have to update TBC to fix it.

 
Posted : 30/03/2017 5:55 am
(@lee-d)
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I'm pretty sure running the latest version of the Configuration Utility will fix that:

http://www.trimble.com/Infrastructure/trimbleconfiguration_ts.aspx

 
Posted : 30/03/2017 7:33 am
(@lee-d)
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But you still want to run the most recent version that your license supports. 3.82 is current.

 
Posted : 30/03/2017 7:34 am
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