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Spirent KB Article
Doc ID: FAQ15523
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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?
Environment/Versions
PosApp (SimGEN / SimREPLAYplus / SimREPLAY)
Answer
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
Version
3.0
Publish Date
2016-07-12
Categories
Product : SimREPLAYplus,SimREPLAY,SimGEN,PosApp
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