GPS World, February 2016

FIGURE 9 Bearing error as a function of distance for cross correlation technique The proper characterization of the antenna is vital to the performance of the POMDP localization algorithm Using the results presented with the max3 and cross correlation methods the POMDP model can be updated to better reflect the measurements in order to improve the flight profile for localization Max The max method is the simplest method used to calculate the bearing to the signal from a given set of measurements This method is also the reason for the poor performance in calculating the bearing This method can too easily pick a wrong estimate if there is a spike in what should be a smooth main lobe as depicted in Figure 11 These spikes cause a large spread in the errors in calculating bearing seen in FIGURE 8 Cross Correlation Cross correlation is the most complex of the methods used and in the ideal range is one of the best performing methods on par with the max3 method The overall performance of the cross correlation suffered from the poor performance near and far from the router Since this method requires a known truth pattern when the experimental measurements dont yield enough results to create a full pattern the cross correlation can mistakenly identify the partial pattern for a side lobe instead of a main lobe as was seen in Figure 6 In the ideal range it greatly outperforms the max method as expected When looking at the bearing error shown in FIGURE 9 it can be seen that the errors are much more tightly grouped near zero than those seen in Figure 8 for the max method The outliers for the far measurement caused by a failure to match the partial patterns to the truth can also be clearly seen in this figure The increase in performance from near to ideal can clearly be seen in Table 1 where the standard deviation of the error is significantly smaller for the ideal case Max3 Max3 is the strongest of the three bearing calculation methods tested overall it performed the best and max3 has the advantage of simplicity over crosscorrelation FIGURE 10 Distribution of errors for crosscorrelation technique for different distance classifications It can perform on par with cross correlation in the ideal range as can be seen by the similarly close error groupings in FIGURES 12 max3 and 9 cross correlation and by the similar standard deviations seen in Table 1 The benefit over the cross correlation method of not requiring a known truth pattern allows max3 to perform well when the number of measurements is very small and the gain pattern is mostly incomplete However max3 has difficulty making accurate bearing calculations when close FIGURE 8 Bearing error as a function of distance for max technique WANG ELECTRO OPTO CORP WWW WEO COM A GLOBAL LEADER PIONEER IN ULTRAWIDEBAND ANTENNAS AND PHASED ARRAYS SINCE 1991 GNSS Antennas GPS GLONASS Galileo BeiDou Also miniaturized versions using Slow Wave technology D J J H Wang Antennas for GNSS Proc IEEE July 2012 Opportunities available for TOP R D and production engineering talents to advance WEOs recent break throughs under 25 fundamental patents For more information and to submit your resume online visit WWW WEO COM or email to resumes@ weo com a succinct email without attachment ANTENNA SOLUTIONS FOR BROADBAND WIRELESS CUSTOM SOLUTIONS MULTIFUNCTION GNSS Cell Satcom CRPA STANDARD SOLUTIONS See WEO COM or GPSWORLD COM In Metro Atlanta GA USA An Equal Opportunity Employer U S citizenship preferred FEBRUARY 2016 WWW GPSWORLD COM GPS WORLD 53