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| Advanced GPS Hybrid Simulator
(AGHS) |
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| Key components
Digital Storage Receiver: DSR-220
A key component of the AGHS is the Digital Storage Receiver (DSR).
NAVSYS' latest generation DSR product has the capability of storing
the complete GPS spectrum (20 MHz) with up to 12-bit resolution.
The DSR-220 in one of its configurations can record up to 3 hours
of 8-bit L1 and 8-bit L2 at 56 Msps input data. Up to 3 hours of
single bit data from 16 L1 antenna elements at 56 Msps can be recorded.
The block diagram shows the way the DSR is utilized for system development
and test.
RF Remodulator
The RF remodulator card provides the capability to remodulate the
digital GPS data onto an RF carrier for playback into a conventional
GPS receiver. The remodulator card includes eight channels to allow
simultaneous playback into multiple antenna elements. By configuring
the AGHS with two cards, both L1 and L2 remodulation can be performed.
The RF remodulation capability allows the AGHS to operate as a wavefront
simulator playing back either pre-recorded GPS signals or digitally
simulated signal profiles.
MATLAB Signal Simulation Generation
The AGHS uses MATLAB as the primary
user interface for generating simulated GPS profiles to drive AGHS.
The inputs for the GPS profile can be entered either as a sequence
of waypoints from which a trajectory is interpolated and satellite
range and Doppler is computed using the specified satellite ephemeris,
or as an option, the raw satellite measurements can be provided
instead. User inputs spreading code, signal strength, jamming, etc.,
are input. The satellite to be simulated can be specified by loading
an almanac or ephemeris GPS file. The AGHS MATLAB tools will compute
the visible satellites throughout the trajectory; generate the estimated
range, carrier phase and Doppler observations; and generate a navigation
data file for modulation on the simulated signals. The AGHS will
also compute the spatial offsets for an antenna array (if specified)
based on the user trajectory and the simulated satellite locations.
The simulation files that are used by the AGHS can also be generated
from recorded DSR flights or from a flight simulator, such as the
Microsoft flight program that uses a joystick as input.
MathWorks Simulink Control
The primary interface to the AGHS is the MathWorks Simulink. The
graphical inteface of Simulink has proven to be of great value in
the control of the simulation being performed. NAVSYS is developing
a user interface for our AGHS and High-gain Advanced GPS Receiver
(HAGR) products with the MathWorks Simulink tool. Simulink is a
platform for multidomain simulation and model-based design of dynamic
systems. It provides an interactive graphical environment and a
customizable set of block libraries that let you accurately design,
simulate, implement and test control, signal processing, communications
and other time-varying systems. We are using the Simulink interface
to control and set up our AGHS products and to control the GPS receiver
under test.
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| Simulink
Interface |
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| Advanced features |
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- INS and IMU simulation
- GPS wavefront simulation
- Jammer wavefront simulation
- Integrity failure simulation
- RAIM failure simulation
- Satellite failure simulation
- Digital outputs to support software GPS receivers
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- Open architecture to allow user access for low level
simulation customization
- Sofware interface for insertion of future GPS signals
or simulated jammer waveforms onto composite digital satellite
signal profile
- The AGHS is flexible and designed for research into new
GPS innovations
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| AGHS related info
| Related Products |
| High-gain
Advanced GPS Receiver (HAGR). The HAGR provides a fully
functional, modular, GPS digital receiver architecture that
is compatible with the AGHS digital signal generation interfaces.
In addition to performing the core GPS tracking and navigation
functions, the HAGR also can be configured to perform digital
beam steering for enhanced GPS signal tracking performance.
The AGHS digital data from one or more antenna elements can
be played back into the HAGR for real-time or post-test analysis.
This allows the same data to be replayed using different HAGR
configurations, including alternative tracking loop implementations,
or using different spatial processing. The HAGR can be configured
to operate using preprogrammed weights to allow test and evaluation
of alternative spatial processing algorithms using the same
test data set.
GPS Signal Simulation Toolbox.
This MATLAB toolbox includes functions to generate simulated
GPS signal scenarios and also tools to emulate the GPS tracking
and navigation capability performed in a GPS receiver. This
can be used to create software simulated data files for downloading
to the DSR and playback through the AGHS, or for tracking
and analyzing in MATLAB recorded DSR files either from live
satellite tests or prerecorded digital scenarios. |
| Downloadable Papers |
05-09-001 |
Testing of Ultra-Tightly-Coupled GPS Operation Using
a Precision GPS/Inertial Simulator.
Proceedings of ION GNSS 2005,
Long Beach, CA, Sept. 2005 (PDF:
524 KB) |
04-03-001 |
Architecture and Performance Testing of a Software
GPS Receiver for Space-based Applications.
Proceedings of IEEEAC, Big Sky,
MT, Mar. 2004 (PDF: 797
KB) |
| 01-06-001 |
Advanced GPS Hybrid Simulator Architecture.
Proceedings of ION 57th Annual
Meeting 2001, Albuquerque, NM, June 2001 (PDF: 475 KB) |
| 00-01-006 |
Modeling and Simulation of GPS Using
Software Signal Generation and Digital Signal Reconstruction
Proceedings of ION Technical
Meeting, Anaheim, CA, Jan. 2000 (PDF: 162 KB) |
| 99-09-001 |
Digital Storage Receivers for Enhanced
Signal Processing.
Proceedings of the ION GPS ‘99,
Nashville, TN, Sept. 1999 (PDF: 252 KB) |
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| Downloadable Brochure |
| Advanced GPS Hybrid Simulator
(AGHS) (PDF: 167 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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