NorthStar 8700, Technical Reference Manual

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Section 4 - GPS receivers
05/01/97 REV H PAGE 11
Section 4 - GPS receivers
4.1 Northstar 8700
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.
4.1.1 Features
•
12-channel correlator for “all-in-view” reception
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External antenna
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Code and carrier tracking of L1 GPS frequency (1,574.42 MHz) for
increased accuracy
•
Very fast signal reacquisition after signal obscuration
•
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).
4.1.2 Technical
specifications
Power requirements
•
10 to 40 VDC
•
6 watts power consumption
•
0°C to +55°C temperature range of operation
•
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
•
Jerk: 2 m/sec
3
Position accuracy
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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