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Positioning Application: Why is the vehicle personality file max limit for angular rate 7 rad/s when the simulator dynamic limits are much higher?

  • PosApp (SimGEN / SimREPLAYplus / SimREPLAY)
  • The vehicle personality file limits are very much unchanged since the early designs of the Spirent's GPS simulator
    • When simulations were run at a mere 10Hz    (1kHz is the modern-day Spirent simulator capability!)
    • Simulation data had to be pre-processed and as such the amount of data generated had to be kept to a minimum
  • However the limits were also adopted in order to reflect real-world dynamic limits of a typical fighter aircraft
    • Such as the Harrier (a common fighter plane at that time) 
  • This was based, in part, on the paper* by S J Gale provided an analysis of Roll rates, Lever Arm and Simulation update rate and minimisation of errors.
  • The Dynamic Limits proposed at the time were:
    • Velocity: 100,000 ms-1
    • Acceleration: 150 ms-2
    • Jerk:  500 ms-3
    • Roll rate: 6.3 rads-1  (1.5m lever arm)
  • Here then is where the personality file limit of 7ms-1 was established
  • Compare with Spirent's current simulator dynamic limits (GSS8000 / GSS9000):
    • Velocity: 120,000 ms-1
    • Acceleration: 192,600 ms-2
    • Jerk:  890,400 ms-3
    • Roll rate: 60pi rads-1  (1.5m lever arm)
  • Of course, the RF dynamic limits account for more than just the motion of the vehicle
    • The RF signal changes are a reflection of the total modelled simulation environment - vehicle, satellites, atmosphere, undeclared errors, etc.


*   Reference: GPS Simulator, by S J Gale, STL Harlow, 23rd Sept 1985


Product : SimREPLAYplus,SimREPLAY,SimGEN,PosApp