Question

I am new to GPStk. I am trying to measure differential carrier phase between two antennas which are, ideally, sub lambda apart. I envision two orthogonal baselines which are aligned North-South and East-West. I don’t really care what the absolute location of the array is, I only am interested in the measured differential phase across the two baselines. ( the third element is the reference element and is common to both baselines. See below. N

R E

The quantities of interest are carrier phase difference between N-R and E-R. I will know the spacing of the baseline to sub mm, and I am assuming I can lay out the array so that the baselines are precisely orthogonal. (included angle 89.95 ≤ angle ≤ 90.05 degrees. I am trying to do this with SiRF Star IV receivers. I have the ability to collect data from the three receivers and produce RINEX 2.1 files from it. I can use the Double difference technique, but what I am trying to measure is the single difference for ALL the spacecraft every second. I have been unsuccessful in calculating single differences for satellites which make any sense. SiRF provides the clock bias for each receiver at each epoch to a truncated nanosecond. However, when I convert that to RINEX, I only get six decimal places of time, which seems to me to be way too course for what I am trying to do.

In the toolkit, there is mention of the DDBase function, and I have read about the DDGen function. One of the questions on the forum was how to get the documentation for the DDBase? The answer was from before 2010 and suggested downloading the source code for DDBase, and that there was documentation for using DDBase in the source. I cannot find the source code anywhere. I have the executable for windows 7 (64 bit), but don’t know how to use it because I can’t get the documentation.

Can you enlighten me?

-- ThomasJaeeckle - 01 Oct 2013

Answer

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Hello Thomas,

As you mentioned, the documentation can be found in the source code, which is located in Files section of our Sourceforge repository, as gpstk-2.2.src.tar.gz.

In order to save you time, I've attached the four DDBase documents currently available.

If you have further questions, please feel free to ask.

Thanks for your interest in the GPS Toolkit, and take care.

Bryan

-- BryanParsons - 02 Oct 2013 No such template def TMPL:DEF{PROMPT:supportquery}

Topic revision: r2 - 02 Oct 2013, BryanParsons
 

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