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| Home > Products > Bistatic GPS for ISR |
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| Bistatic
GPS for Intelligence, Surveillance, and Reconnaissance (ISR) |
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GPS bistatic signals
have applications for remote sensing in collecting
data such as soil moisture content, surface altitude,
or wave speed. Prior research using these signals
has been limited by the low signal power of the
bistatic GPS signals. NAVSYS Corporation has developed
an advanced bistatic GPS receiver that uses a
96-element GPS antenna array and digital beam-steering to provide gain to increase the ability
to detect the weak bistatic GPS signals. This
provides up to 20 dB of gain over previous receivers
which use single element tracking.
Because of the extremely low power level of the
returned bistatic GPS signals, this previous research
has focused primarily on the strong specular
static signals. NAVSYS has developed a digital
beam-steering GPS receiver, the High-gain Advanced
GPS Receiver (HAGR), which can be used to increase
the received signal/noise ratio from these weak
bistatic signal returns allowing improved detection
of both specular and diffuse GPS signals thus
increasing the coverage as shown in the figure in the upper right.
Digital beam-steering GPS
receiver
The NAVSYS HAGR is a digital beam-steering receiver designed for
GPS satellite radio navigation and other spread
spectrum applications. This is installed in a
rugged Compact PCI chassis suitable for aircraft
flight tests. The signal from each antenna element
is first digitized using a Digital Front-End (DFE).
Each DFE card includes the capability to sample
signals from 8 antenna inputs. These can be cascaded
together to allow beam steering to be performed
from a larger antenna array. The complete set
of DFE digital signals is then used to create
the composite digital beam-steered signal input
by applying a complex weight to combine the antenna
array outputs. The HAGR can be configured with
a variable number of antenna elements up to a
total of 96-elements. Through the HAGR digital
control, these beams can be directed at any point
on the surface of the Earth for data collection.
The area they cover is a function of the beam
width and the aircraft altitude. Up to 5 beams
each, with +20 dB gain, can be independently
directed by the HAGR signal processing.
96-element antenna
The 96-element antenna is configured in a symmetrical
pattern on its ground plane as shown at right. |
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| GPS bistatic
geometry with specular reflection points |
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| High-gain
Advanced GPS Receiver |
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| Test
aircraft |
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| 96-element
antenna mounted on aircraft |
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| ISR flight tests
Land and maritime flight test data has been collected, processed
and analyzed. The simulation of the 96-element array was verified.
The data demonstrates the ability of the HAGR/Array Antenna
to improve the GPS bistatic remote sensing capability by using
digital beam steering to allow the weak diffuse bistatic GPS
signal to be detected over a larger area. The following figure
shows the results of the analysis when the target was a barge
in the Gulf of Mexico.
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| Characteristics |
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| Antenna elements |
96 |
| Center frequency |
1575.42 MHz (L1,
L2 could be added |
| Code |
C/A
or P(Y) |
| Other applications |
Soil moisture measurement, surface altitude,
wave speed, anti-jam, interference rejection,
and multipath mitigation |
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Related Information
| Papers |
07-01-002 |
Test Results from a Novel Passive Bistatic
GPS Radar Using a Phased Sensor Array
Proceedings of the ION National Technical
Meeting 2007, San Diego, CA, Jan. 2007 (PDF:
312k) |
05-09-004 |
Remote Sensing Using Bistatic GPS
and a Digital Beam Steering Receiver
Proceedings of ION GNSS
2005, Long Beach, CA, Sept. 2005 (PDF:
543 KB) |
05-07-001 |
Remote Sensing using Bistatic GPS and a Digital
Beam-Steering Receiver.
IGARSS 2005, Seoul, Korea,
July 2005 (PDF: 475 KB) |
05-01-002 |
Bistatic Sensing and Multipath Mitigation with
a 109-Element GPS Antenna Array and Digital Beam
Steering Receiver.
ION 2005 National Technical
Meeting, San Diego, CA, Jan. 2005 (PDF: 946 KB) |
03-09-005 |
Bi-Static Sensing with Reflected GPS Signals
Observed with a Digital Beam-Steered Antenna Array
Proceedings of ION GPS/GNSS
2003, Portland, OR, Sept. 2003 (PDF: 250 KB) |
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| Brochure |
Bistatic GPS for Intelligence,
Surveillance, and Reconnaissance (ISR) (PDF: 170 KB) |
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| Contact |
Debbie Westra
info@navsys.com
toll free: 866.4.NAVSYS (866.462.8797)
or 719.530.0600 |
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