[USRP-users] GPS Constellation Simulator with USRP Beta Testers Wanted
mikew at navlabs.com
Wed Oct 7 10:27:40 EDT 2015
My name is Michael Wade and I am with Navigation Laboratories, a
GPS Constellation Simulator manufacturer that has been providing GPS
simulators since before there was actually a GPS satellite constellation
:) Yes, we've been in GPS since the Yuma Proving Grounds Inverted
Range. Hmmm! That dates us!
In the past we have provided GPS Constellation Simulators as a complete
package: hardware and software. As technology has changed we believe
that it is more economical for both our customers and ourselves to use
off the shelf hardware in providing a simulation environment, and the
USRP appears to be an ideal hardware candidate. We ported our
military/civilian grade simulation generation capabilities to the USRP
family of hardware and so far it looks fantastic. Using our software
and USRP hardware we can simulate a GPS/WAAS environment of 16
satellites. Users can now completely define the scenario, build a file
and stream it to the USRP over and over again.
Our software is capable of the following:
* 16 GPS/WAAS satellites
* WAAS (yes, a WAAS satellite that actually transmits real
corrections, which if the receiver uses, results in a more accurate
* Simulating any valid GPS Time (Jan 6 1980 to ... how many 10 bit GPS
week rollovers do you want?)
* Includes a very user friendly user motion generator. Not one that
requires the user to calculate the correct linear/angular jerk to
get to the desired position/attitude, but one with real user motion
o Change Speed - Enter terminal speed, the TapVpg program does the
o Turn - Enter final angle and max radial acceleration, all other
calculations done for the user. And, yes, it supports antenna
lever arms and coordinated turns
o Pitch - Changes the vehicle pitch angle to climb of dive
o Climb - Change altitude with a continuously differentiable model
o Orientate - Set a desired attitude, specifying end-of-maneuver
body orientation and desired angular rates. Maximum angular
acceleration and angular jerk not exceeded
* Prefer your own user motion generator? No problem! The software
imports several different vehicle state formats and you can bypass
the built-in Vehicle Profile Generator (VPG) by providing a 10 Hz
file of vehicle center-of-mass position, velocity, acceleration,
jerk, attitude, angular rate, angular acceleration, and the
simulator will take it from there.
* Want a particular GPS constellation? You can import any standard
USCG/Yuma almanac file and the software uses the orbital parameters
to generate satellite motion.
Once all the parameters are entered, the Vehicle Profile Generator
essentially builds a very large file of I's and Q's that can be streamed
using the included streaming program. You can build once and run the
same scenario over and over again. And you can build multiple scenario
streaming file, giving accurate and repeatable results, with the only
limit being disk space.
Even though NavLabs provides GPS Constellation Simulators for all the
GPS codes/frequencies, this version is limited to L1 C/A. We are
currently investigating the practicality of providing L1/L2 P(Y), M' and
True M through the USRP platform. If, in the end, it's not practical on
the software based USRP, we believe it will be practical on the higher
end FPGA based systems, as our native hardware platform is FPGA based.
Our goal with the USRP is to provide the best and the lowest cost GPS
simulation environment. By leveraging our experience and our IP we have
been able to generate accurate and high quality GPS signals using the
USRP to provide a low cost, repeatable test environment.
While we have ported a mature system to the USRP, we do not want to use
paying customers as beta testers. We believe the system is now ready
for beta test and are looking for qualified testers who currently have a
USRP radio, a GPS receiver, and are willing to help make this a solid
and useful product.
If you are interested in being a beta tester please email us at the
following email address:
*info at navlabs.com*
in the subject line.
We apologize for asking for help like this in this newsgroup, but you
all have been so helpful during the long development cycle of this
product and we are both hoping for a little more help and to give back
some by providing the software to beta testers.
Thank you very much,
Navigation Laboratories aka NavLabs
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