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4.1 Northstar 8700
4.1.1 Features
4.1.2 Technical
specifications
05/01/97 REV H
Section 4 - GPS receivers
The Northstar 8700 GPS position sensor decodes satellite radio signals,
and provides three-dimensional position, velocity, time, and other status
information at a maximum rate of once per second.
Each of the 12 parallel channels continuously tracks a GPS satellite signal.
To support faster acquisition of GPS signals, the sensor makes provisions
for external initialization of data. Further, the sensor can use exter-
nally-provided differential corrections to reduce inherent GPS inaccura-
cies; WGS-84 (World Geodetic System) is used as its reference datum.
12-channel correlator for "all-in-view" reception
•
External antenna
•
Code and carrier tracking of L1 GPS frequency (1,574.42 MHz) for
•
increased accuracy
Very fast signal reacquisition after signal obscuration
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Two serial input/output data ports: One to transmit navigation data,
•
another for differential data input or other needs. Either one can be
used for maintenance (reprogramming mode).
Power requirements
10 to 40 VDC
•
6 watts power consumption
•
0°C to +55°C temperature range of operation
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Internal, two-amp fuse
•
Electrical requirements
The 8700's power supply is protected against reverse-polarity power
inputs, and features a remote turn-on ability. The 8700 turns on when-
ever power is applied to pin 25, ground to pin 13, and remote-on pin 12 is
connected to a source of +5 to +40 VDC.
Dynamics
Velocity: 1800 km/h
•
Acceleration: 4 g
•
3
Jerk: 2 m/sec
•
Position accuracy
3 m horizontal, with DGPS, 95 percent confidence
•
30 m horizontal, without Selective Availability (SA) imposed, 95 per-
•
cent confidence
100 m horizontal, with SA imposed, 95 percent confidence
•
Section 4 - GPS receivers
PAGE 11
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