AIDJEX Bulletin #40 - Polar Science Center - University of Washington

POSITION MEASUREMENTS OF AIDJEX MANNED CAMPS
USING THE NAVY NAVIGATION SATELLITE SYSTEM
Pat Martin, C. G. Gillespie, Alan Thomdike
AIDJEX
D. Wells
Bedford Institute of Oceaxography
Dartmouth, Nova Scotia
ABSTRACT
The Navy'Navigation Satellite System was used during AIDJEX to make
precise measurements of the positions of the four manned camps.
Satellite signals were acquired under computer control to standardize
and maximize data collection. Single-channel (400 MHz)
translocation (relative positioning) was used to measure changes
in distance between camps and a reference azimuth at each camp.
Special attention was given to the frequency and time references
for Doppler counting, and an efficient editing algorithm was used
to ensure that translocation Doppler data matched. Statistical
filtering after the experiment produced smoothed and evenly spaced
estimates of position, velocity, acceleration, and aeimuth.
An ensemble of 500 fixes from a period of virtually no ice motion
was examined for position errors. Of these, 68% from a single
station had errors of less than 75 m. For translocation between
two stations separated by 100 km, 68% of the errors were less than
20 my and between two receivers separated by 100 m at the same
station 68% of the errors were less than 5 m.
INTRODUCTION
During AIDJEX, precise position measurements were needed to determine
large-scale sea ice deformation. These measurements were taken from March
1975 through May 1976 with the Navy Navigation Satellite System (NavSat)
at four manned camps in the Beaufort Sea, which were deployed at approximately
73'N, 156OW. (NavSat measurements made at unmanned buoys are
described by Brown and Kerut [1975 and this Bulletin, pp. 15-20].) Following
the field experiment, time sequences of the position of each camp and the
distance between the camps were used as input to a statistical filter, which
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