Fast acquisition techniques for very long PN codes for On-Board Secure TTC transponders

Next generation of On-Board Telemetry, Tracking and Command (TTC) equipment for Secure Communications, based on Spread Spectrum Systems, shall adopt very long Pseudo Noise (PN) Cryptographic Codes in order to increase the Secure Satellite link Confidentiality and Anti-Jamming performances. This paper presents a new On Board PN Codes Synchronizer Architecture based on the Generalized Zero Padding Algorithm (GZP) and frequency domain Doppler compensation scheme in order to acquire very long PN codes at low Signal to Noise Ratio, large Doppler and large Jammer over Signal Power Ratio (J/S). It is shown that by adjusting the zeros padded to the received signal, the non coherent integrations and the Doppler compensation strategy, the On-Board Code Synchronizer satisfies all different satellite mission scenarios (Geo Stationary Orbit, Low Earth Orbit, Medium Earth Orbit and Launch and Early Orbit phases) requirements for very long PN code synchronization, ensuring very low code acquisition time due to the high parallel searching capability.