Pseudorandom Noise Codes(PRN) What is PRN? Operating Principle: The generation of the PRN sequences in the codes is based on the use of hardware devices called tapped feedback shift registers Storage cells Number of Cell 3 4 5 ( bit) Clock pulseInitial state Clock puls Successive state output The new value of the leftmost cell is determined by the binary sum of two defined cell The chose of the defining cells is arbitrary and determines the property of the resulting code 電 Principles of the Global Positioning System 2005-3-18(17 Signal modulation L1 CARRIER 1575.42 MHZ ∞⑧ CA CODE 1.023MHZ Mixer NAVISYSTEM DATA 50 Hz 「L「「「 P-CODE 10.23 MHZ mutt wuuI L2 CARRIER 1227.6 MHZ MWwMWmWW990WWM XX>L2SIGNAL GPS SATELLITE SIGNALS Principles of the Global Positioning System 2005-3-189 Principles of the Global Positioning System 2005-3-18 17 Pseudorandom Noise Codes (PRN) Principles of the Global Positioning System 2005-3-18 18 Signal modulation