I'm trying to use some CORS data in my Project Manager (post processing software) and I have to specify the antenna. From the coord. report and the site report, I'm not sure where the info is that I need. I'm given the type of antenna (Trimble 5700) but I do not know where to get the antenna radius, slant height measurement point vertical offset or the L1 phase center vertical offset. I basically have to enter the specs for the new antenna and I don't know where to get that info.
I have 3 ProMark2 antennas and am given the info (which I will hold as a control site) on an NGS monument. I trust that info, but I want to double check it with some CORS info. Without specifying the antenna height and phase offsets etc, I get nothing even close.
Any help would be greatly appreciated.
NGS Calibrated The ProMark2 Antenna, Even If It Is L1 Only
http://www.ngs.noaa.gov/ANTCAL/Antennas.jsp?manu=Ashtech
First on the list is the ProMark2, 110454. Take a look at the "drawing", ANTEX and ANTINFO.
Just pick antenna 110454 in Ashtech or GNSS Solutions, I am unfamiliar with Trimble software.
When you look at the antenna data, be aware that the 5° increments are opposite how they would be in the Ashtech antenna.inf file. One is zenith to horizon, the other horizon to zenith, but it was so long ago I do not know which is which.
Then you have to determine if your software wants the old NGS calibration format or the new international absolute format.
Paul in PA
NGS Calibrated The ProMark2 Antenna, Even If It Is L1 Only
I'm ok with the ProMark antenna specs. Those are built right into the software. It's the remote CORS antenna that I need info for. Having a hard time deciphering the site notes and such. It's gotta be there. Trimble is not listed in my options. If it is, I don't know which one it is. Trimble 5700 or some such.
NGS Calibrated The ProMark2 Antenna, Even If It Is L1 Only
Additional for my info post:
The following is from the offset data decal on the bottom of my ProMark2 antennas.
Units in meters
R=0.0921
SMP=0.0516
L1=0.0694
The following is from the antenna.inf file which can be found in the Solutions BIN folder:
[110454]
Description=ProMark2 external antenna
Radius=92.1
SHMPOffset=51.6
L1Offset=0.0 0.0 69.4
SMP = SHMPOffset = Slant Height Measurement Point
Radius is at the SMP
Offset is from the ARP = Antenna Reference Point
The [square root of (Slant Measurement squared minus Radius squared) minus the L1 Offset] equals the vertical antenna height to the ARP.
Paul in PA
Go To ANTCAL Main Page, Select Trimble
http://www.ngs.noaa.gov/ANTCAL/
In the Trimble list I do not see a 5700 antenna.
Most other antennas are in my antenna.inf file. Years ago I had to edit my antenna.inf file to add CORS antennas, but not lately.
What exactly do you have?
BTW open the CORS RINEX file in a word editing program like WordPad and read the antenna model, right under the receiver model.
Paul in PA
I believe the 5700 is a receiver-only model. You'll have to find out from the CORS info which antenna was used, most likely one of the Zephyr models.
CORS Antenna Models
The antenna model is listed in the header of the CORS RINEX file.
In addition you can find the antenna model in the NGS CORS Position Text file which you can request when you make a ufcors download.
Open the CORS.pos.txt file with WordPad and print it out. It gives the CORS ARP position and the CORS L1 phase center position. If you use the L1 phase center position enter the antenna type as "none". Alternately if you already have the CORS coordinates in the program, enter antenna type "none" and use the L1 phase center offset as the antenna height. Antenna model is less critical with the L1 only processing that you get CORS to PM2.
Paul in PA
NGS Calibrated The ProMark2 Antenna, Even If It Is L1 Only
Howdy,
As Mr Chyko indicates, the 5700 is a receiver NOT an antenna. Determine the site ID for the CORS you will use. Choose the Site Log option from the menu. Look at section 3 of the site log. Section 3.1 has receiver information, section 3.2 antenna information. Note that receivers and antennas change. The date of the change is included in the log. Of course some sites don't keep them up.
Use the antenna model you found to find the dimensions you need in the Antenna Calibration page in the NGS site.
Note as well that the physical dimensions provided by manufactures may differ from the NGS values which are the result of signal NOT physical measurements. The magnitudes are probably not significant enough for your work.
I do not know anything about the software you are using. If it only accounts for the distances if the L1 and L2 phase centers from the antenna reference point that is easy to determine, entering the azimuthal and zenith corrections is another matter.
HTH,
DMM
Correct, there is no 5700 specific antenna.
SHG
CORS Antenna Models
A word of caution, sometimes the RINEX header can be wrong, it is only as good as the person creating the header 🙂
The safer place is the station log and safer yet is an up to date photo, no wondering if somebody screwed up that way.
SHG
NGS Calibrated The ProMark2 Antenna, Even If It Is L1 Only
Be careful mixing manufacturer antenna models with NGS models, safest bet is to import ALL the NGS models and use those with both your gear AND the CORS data, using antenna models from the same source for all the data that way.
In addition this will allow you to use the new absolute values which is the correct thing to do with the current epoch of CORS data and satellite orbits.
If your software won't allow import of the NGS calibration files then you will have to settle for something less than optimal...
SHG
CORS Antenna Models
I need antenna radius, Slant Height Measurement Point Vertical Offset, L1 Phase Center Vertical offset and L2 phase center vertical offset ... all in meters. My ProMark antennas are already in there. This is where I give up and just use my small point network and hope for the best.