20 



FISH AND WILDLIFE TECHNICAL REPORT 30 



3 3,500i 

 E 3,000- 



0) 



2,000^ 



~ 1,500 



O) 



o 1,000 



500^ 

 



200 400 600 800 1,000 

 Location Elevation (m) 



Fig. 13. Relation between mean longitudinal 

 error and FIT elevation for PTT's at four 

 locations. Number of location estimates (and 

 number of PTT's) at each site were, in order 

 of increasing elevation: 113 (4); 48 (3); 101 

 (5); 140 (5). 



Fig. 14. Schematic representation of location 

 error resulting from a PTT being at a higher 

 elevation than that assumed by Argos when 

 making calculations. The PTT is estimated to 

 be at the intersection of the cone with the 

 earth surface (vector B), when in fact, it is 

 farther from the satellite in the longitudinal 

 direction but above the assumed earth sur- 

 face in elevation (vector A). Vectors A and B 

 are of equal length. The resulting error is 

 generally along a direct line from the true 

 location to the satellite at its closest 

 approach. 



360 

 300 



60 120 180 240 

 Error Azimuth () 



300 360 



Fig. 15. Relation between the azimuth of the 

 satellite at its closest approach and azimuth 

 of error in the estimated location of 44 known 

 positions of elk in Yellowstone National 

 Park. PTT's were assumed to be at sea level 

 in Argos 's calculations. Data courtesy of 

 D. Vales, University of Idaho. 



