Instantaneous Ambiguity Resolved GLONASS FDMA Attitude Determination
Authors: Teunissen Peter , Khodabandeh Amir , Zaminpardaz Safoora 
Published: March 2020

&lt;p&gt;&lt;strong&gt;G1 &amp;#8211; Geodetic Theory and Algorithms&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;G1.3 High-precision GNSS: methods, open problems and Geoscience applications&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;&amp;#160;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Instantaneous Ambiguity Resolved GLONASS FDMA Attitude Determination&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;&amp;#160;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;PJG Teunissen&lt;sup&gt;1,2&lt;/sup&gt;, A. Khodabandeh&lt;sup&gt;3&lt;/sup&gt;, S. Zaminpardaz&lt;sup&gt;4&lt;/sup&gt;&lt;/p&gt;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;GNSS Research Centre, Curtin University, Perth, Australia&lt;/p&gt;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt;Geoscience and Remote Sensing, Delft University of Technology, The Netherlands&lt;/p&gt;&lt;p&gt;&lt;sup&gt;3&lt;/sup&gt;University of Melbourne, Melbourne, Australia&lt;/p&gt;&lt;p&gt;&lt;sup&gt;4&lt;/sup&gt;RMIT University, Melbourne, Australia&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;In [1] a new formulation of the double-differenced (DD) GLONASS FDMA model was introduced. It closely resembles that of CDMA-based systems and it guarantees the estimability of the newly defined GLONASS ambiguities. The close resemblance between the new GLONASS FDMA model and the standard CDMA-models implies that available CDMA-based GNSS software is easily modified [2] and that existing methods of integer ambiguity resolution can be directly applied. Due to its general applicability, we believe that the new model opens up a whole variety of carrier-phase based GNSS applications that have hitherto been a challenge for GLONASS ambiguity resolution [3]&lt;/p&gt;&lt;p&gt;We provide insight into the ambiguity resolution capabilities of the new GLONASS FDMA model, combine it with next-generation GLONASS CDMA signals [4] and demonstrate it for remote sensing platforms that require single-epoch, high-precision direction finding. This demonstration will be done with four different, instantaneous baseline estimators: (a) unconstrained, ambiguity-float baseline, (b) length-constrained, ambiguity-float baseline, (c) unconstrained, ambiguity-fixed baseline, and (d) length-constrained, ambiguity-fixed baseline. The unconstrained solutions are computed with the LAMBDA method, while the constrained ambiguity solutions with the C-LAMBDA method, thereby using the numerically efficient bounding-function formulation of [5]. The results will demonstrate that with the new model, GLONASS-only direction finding is instantaneously possible and that the model and associated method therefore holds great potential for array-based attitude determination and array-based precise point positioning.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;[1] P.J.G. Teunissen (2019): A New GLONASS FDMA Model, GPS Solutions, 2019, Art 100.&lt;/p&gt;&lt;p&gt;[2] A. Khodabandeh and P.J.G. Teunissen (2019): GLONASS-L. MATLAB code archived in GPSTOOLBOX:&lt;/p&gt;&lt;p&gt;https://www.ngs.noaa.gov/gps-toolbox/GLONASS-L.htm&lt;/p&gt;&lt;p&gt;[3] R. Langley (2017): GLONASS: Past, present and future. GPS World November 2017, 44-48.&lt;/p&gt;&lt;p&gt;[4] S. Zaminpardaz, P.J.G. Teunissen and N. Nadarajah (2017): GLONASS CDMA L3 ambiguity resolution&lt;/p&gt;&lt;p&gt;and positioning, GPS Solutions, 2017, 21(2), 535-549.&lt;/p&gt;&lt;p&gt;[5] P.J.G. Teunissen PJG (2010): Integer least-squares theory for the GNSS compass. Journal of Geodesy, 84:433&amp;#8211;447&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Keywords: &lt;/strong&gt;GNSS, GLONASS, FDMA, CDMA model, Instantaneous Attitude Determination, Integer Ambiguity Resolution&lt;/p&gt;