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Old 19th Apr 2010, 18:30
  #792 (permalink)  
Join Date: Oct 2004
Location: Europe
Posts: 483
The question was put if the inertial navigation system aided by GPS (IRS / GPS unit), the GPS unit installed in the Tu-154M did work or did not work?

In the case of CASA 295M in Mirosławiec the GPS block IRS / GPS not working with this very prosaic reason that the Polish mechanics did not know that the GPS unit in the system INS / GPS used in military aircraft, need additional crypto module, which is required for decode the code P (Y) which is encoded accurate GPS signal (P-code) on both the L1 frequency and (especially) L2.

INS / GPS anyone can buy and install. But only the army, and it is not all, have access to navigation by using P-code.

The module needed to decode coded cipher P (Y), which protects the P-code is probably a secret, and it changes regularly Combination Lock keys are probably top secret. These things are no longer need to receive channels from the U.S. military, by NATO. Maybe not every ally in NATO may get a piece of electronics?

Nay, I would also not be surprised if after receiving an order that the plane has to fly to Russia the order was to remove all the secret material, dismantle the crypto module in the block IRS GPS navigation system / GPS. Or module lies somewhere in the safe and was never installed, as in CASA-295M. Or it has never been and will not.

If the GPS unit with the military P (Y) Code does not work, because there was no crypto module in the receiver, the GPS and precise altimeter were not necessarily operational...
Ptkay is offline