Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Precise Real-Time Navigation of LEO Satellites Using a Single-Frequency
  GPS Receiver and Ultra-Rapid Ephemerides   Precise (sub-meter level) real-time navigation using a space-capable
single-frequency global positioning system (GPS) receiver and ultra-rapid
(real-time) ephemerides from the international global navigation satellite
systems service is proposed for low-Earth-orbiting (LEO) satellites. The C/A
code and L1 carrier phase measurements are combined and single-differenced to
eliminate first-order ionospheric effects and receiver clock offsets. A
random-walk process is employed to model the phase ambiguities in order to
absorb the time-varying and satellite-specific higher-order measurement errors
as well as the GPS clock correction errors. A sequential Kalman filter which
incorporates the known orbital dynamic model is developed to estimate orbital
states and phase ambiguities without matrix inversion. Real flight data from
the single-frequency GPS receiver onboard China's SJ-9A small satellite are
processed to evaluate the orbit determination accuracy. Statistics from
internal orbit assessments indicate that three-dimensional accuracies of better
than 0.50 m and 0.55 mm/s are achieved for position and velocity, respectively.

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The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio