Single Epoch GPS Orientation Determination Method And Realization With Baseline Constraint

Satellite orientation, as one of the main technologies in modernnavigation field, has many advantages, such as low cost, quickinitialization, high precision and no accumulates error and no geographicalposition influence. The study of orientation determination using GPScarrier phase becomes an interest area in the applications of GPSBased on the theory of relative positioning using Carrier phase, thealgorithm of single and double frequency’s carrier phase only using singleepoch was studied and proposed, and the system was designed andachieved. The main content describes as follow：the principle of the GPS pseudo-range and carrier phase measurementwas presented, also the error source which influence the orientationaccuracy in the GPS measurement was discussed in this paper, and thedouble difference measurement equation of the GPS orientationdetermination was derived. In addition, the base theory of two antennasorientation method and some problems in the direction angle solvingprocess was discussed.According to the reference methods, which using GPS carrier phasedifference technology to orientate determination at home and abroad, someclassical methods of the calculating integer ambiguity have beenintroduced in the paper. Based on relationship between the accuracy ofpseudo-range and carrier phase in the short-baseline condition, theleast-square-search method with baseline constraints was proposed. For thesingle frequency receiver，the dual-difference integer ambiguity possible solutions were determined using know baseline length and low accuracyangle sensor auxiliary method. For the dual-frequency receiver, thedual-difference integer ambiguity possible solutions were calculated by theknow baseline length and wide-lane wave length method. Because of onlyusing single epoch information, the method has the immunity to the carrierphase cycle slips, reduced the initial time significantly. Finally, thecomplete integer ambiguity can be confirmed by the residual constraintmethod and then got the carrier’s orientation.According to the least square method under the baseline constraint,the GPS satellite data acquisition and directional calculating program havebeen completed by PC/104PMI2in the Vx-Works environment, andorientation of the carrier have been measured in real time. Moreover, theproblems of the main satellites selection and ambiguity’s confirming werealso studied and discussed in the actual measurement.Finally, the double GPS antenna orientation determination experimentwas carried out using the proposed method. Both the static and dynamicexperimental results proved the speediness and efficiency of this method,which is characterized by high success rate (>99%) and high accuracy(<0.2°/baseline length) in the orientation determination.