[USRP-users] GPS Constellation Simulator with USRP Beta Testers Wanted

Michael Wade mikew at navlabs.com
Wed Oct 7 10:27:40 EDT 2015

Hi Everyone,

     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
    primitives, like
      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*
and with
*USRP Beta*
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,
Michael Wade
Navigation Laboratories aka NavLabs
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