GPS chip speed/altitude restrictions?

1.
Does anybody on this list know if it is possible to obtain GPS-chips
without the 512 m/s and 18000 meter ristrictions?

2.
How fast do restricted chips usually resume reporting when returning
to within the limits?

3.
Do all restricted chips have the same logic ( "and" versus "or" )
regarding the restrictions?
For example, will some units resume reporting when the speed goes
below 512 m/s even it is still above 18000 m?


Best regards,

Niels Foldager

wrote:

1. Don't know.
2. This depends on the receiver. And note that you could have problems
with consumer GPS receivers before reaching the limits (especially if
you have application with very strong dynamics)
3. They should have the OR logic implemented. But seems that some
manufacturers disables tracking if just one of the limits is reached

If just one limit is reached? Isn't that the "OR" logic? If either
one OR the other is reached?

Best regards

Niels

wrote:

Sorry: I explained not correctly. :)

To disable tracking, you must reach both limits.
But some receivers disables tracking if just one limit is reached.

N. Foldager wrote:

Many GPS receivers are restricted in dynamics for military
reasons--dynamics not exceeding--

Dynamics:
Acceleration 4g (39.2 m/s^2)
Motional Jerk 20 m/s^3

Operational limits
Altitude < 18,000 m or velocity < 515 m/s
Either limit may be exceeded but not both (in non-military GPS
receivers).

These restrictions do not apply to the Space Shuttle or LEO satellites
making use of GPS signals. You can always build your own receiver
without restrictions of any kind.