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GPS Pseudo random code

Asked by: 2472 views Instrument Rating

Im not really sure what a pseudo random code is in the first place; nextly im confused on a coarse acquisition and a precision code. what little i do know makes me ask the question do you have to have a precision code for a precision GPS approach? Thanks so much

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  1. Best Answer

    John D. Collins on Dec 29, 2012

    No, the precision code is encrypted and only available to the military. There are up to 32 Pseudo Random Numbers assigned to satellites. In effect, it is the name of the satellite. The actual pseudo random code is 1023 bits long. It is called pseudo random because although it appears to be random, it has a fixed value for each satellite. The short name is PRN 1 thru PRN 32.

    Technically, there are no GPS precision approaches available to general aviation users, even though many of the latest LPV approaches have exactly the same minimums as an ILS Category I precision approach. The WAAS RNAV (GPS) approaches that have vertical guidance such as the LNAV/VNAV or LPV procedures are termed APV (APproach with Vertical) approaches. The current instrument PTS (Pilot Test standard) permits pilots to use a LPV approach with a DH of 300 feet or lower to be used to accomplish the precision approach task on an instrument check ride, even though it technically isn’t a precision approach.

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  2. wes eads on Jan 01, 2013

    thanks john, your answer helps alot!!!!

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