In this paper we will detail the hypothesis of how we intend to alter a valid GPS navigation data message in order to produce a perceived receiver position which is shifted a few meters from the actual (calculated) position. What we propose is that by altering the parameters by which the receiver corrects for satellite clock error characteristics we can essentially introduce a bias into the pseudorange calculations to each satellite in such a way that the calculated position can be shifted in any given direction from the original. To test this hypothesis, we developed a Matlab simulator that parses Receiver Independent Exchange Format (RINEX) navigation and observation files to calculate the receiver position and then plot the perceived positions based on the proposed alterations, thus proving the viability of the concept and allowing us to establish a range of values which produce the most efficient results.

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