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Maa-6.3289 GNSS-technologies (5 cr) Course work assignment, “Performance Analysis of a GPS software defined receiver” In this course work, you are asked to use an open source software-defined GPS receiver developed by Prof. Kai Borre and his colleagues [1], [2]. You are asked to carry out certain tasks with the receiver. The software receiver is developed in Matlab, and a brief description of the software can be found in [2]. Please read through the article carefully for a better understanding on the receiver. Live data collection A 60 seconds long raw GPS data in the form of In-phase and Quad-phase (I/Q) is provided to you for analysis. The data was collected on December 01, 2014 via an RF front-end from Nottingham Scientific Limited [3]. The front-end configuration for this data set is provided in Table 1. Parameters GNSS signal Intermediate frequency Sampling frequency Front-end bandwidth Signal type No. of Quantization bits Values GPS 6.39 MHz 26 MHz 4.2 MHz Real 2 The receiver was static for the whole data duration, and the true WGS84 coordinates are: trueLatitude = 60.1610902666670 N; trueLongitude = 24.5454277833330 E; trueHeight = 54.1970000015572 [meters]; You need to use the true coordinate of the receiver as a reference when comparing the performance with the estimated position solution. Task 1 Plot the frequency domain spectrum of the received GNSS signal. What is the approximate 3-dB bandwidth of the received signal? You may find spectrum plot in probedata.m function. Task 2 How many satellites were acquired with the given data set? What is the number of coherent integration time used for acquisition? Make a three-dimensional acquisition plot of one acquired satellite, for example, a 3D acquisition plot for PRN 8. (hint: you may use ’mesh’ command in Matlab for 3D acquisition plot). You need to use debug option in order to step into the acquisition file. You can have a break point in line 178, when the satellite is acquired. Use ‘mesh’ command with the variable ‘results’ in order to see the acquisition metric. In Xaxis, you can see the code delays in samples, and in y-axis, you can see the frequency steps with respect to intermediate frequency and in z-axis, you can see the correlation value of all the possible code delay-frequency combinations. Make a table of the acquired satellites with the following information filled: Acquired PRN Number PRN 8 ? ? ? Estimated Code Delay in Chips ? (a/26000)*1023 ? ? ? Estimated Doppler in Hz ? ? ? ? Task 3 Plot the tracking result for PRN 8. Describe each of the sub-plots in your own words. Task 4 Plot the positioning error in local East-North-Up (ENU) frame at 1 Hz rate. Task 5 Compute the tracking error variances of PRN 8 in the following three cases: i. ii. iii. with correlator spacing 1 chips with correlator spacing of 0.5 chips with correlator spacing of 0.25 chip Which of the above three cases has the least tracking error variance? Compute also the 3D Root Mean Square Error (RMSE3D) of the position solution in the above three cases. You may need to save the trackingResults.mat file for three different cases. Task 6 Plot a sky-plot of the satellites which are used in the navigation solution. Are all the GPS satellites acquired? Compare the sky-plot you have with the sky-plot of Trimble GNSS planner given in the following site: http://www.trimble.com/GNSSPlanningOnline/#/Settings ). You have to look for sky-plot of December 01, 2014 at around 17:30 o’clock. Select GPS satellites only with elevation mask of 10 degrees. How can you acquire more satellites in a GPS receiver? Task 7 Describe the logical flow diagram of the GPS software-defined receiver. Mention the basic functionalities of the following three processes in the context of the receiver: i. ii. iii. Acquisition Tracking Navigation Task 8 What code discriminator (i.e., DLL) is used in the receiver? What other code discriminator based algorithms exist in the literature? You may look at tracking.m function for the required information. Task 9 What carrier discriminator (i.e., FLL/PLL) is used in the receiver? Mention the key properties of the used carrierphase discriminator. You may look at tracking.m function for the required information. You need to send a detail report with the above tasks completed to [email protected] Mention your student ID in the subject of your email. For any further questions, please contact [email protected] References [1] K. Borre, D. M. Akos, N. Bertelsen, P. Rinder, S. H. Jensen, A software-defined GPS and Galileo receiver: a single-frequency approach, 1st ed. Applied And Numerical Harmonic Analysis, Birkhäuser Verlag GmbH, Boston, USA, 2006. [2] K. Borre, D. M. Akos, A Software-Defined GPS and Galileo Receiver: Single-Frequency Approach, Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005) September 13 - 16, 2005, Long Beach, CA, pp. 1632-1637. [3] Nottingham Scientific Limited. Available online: http://www.nsl.eu.com/datasheets/stereo.pdf (accessed on February 16, 2015).