Cooperative Networked GPS signal acquisition

ABSTRACT: The biggest demand on a military receiver has been from the time required to search and acquire for the military signals when an accurate internal time reference is not available. Prior research by NAVSYS into network assisted GPS approaches used the JTRS network itself to transfer time from another GPS receiver to reduce the initial time uncertainty and speed the acquisition time. This required at least one receiver on the network to have already acquired and tracked the GPS signals. Under this SBIR, we shall develop and implement methods to reduce the direct P(Y) acquisition time under situations where no unit on the network has yet acquired a GPS solution. The cooperative signal acquisition algorithms shall use shared data between network participants to speed direct P(Y) and direct M-code acquisition by distributing the search space between network participants reducing TTFF and allowing for longer correlation times for weak signal and high interference environments. This will be demonstrated under this effort using Software Defined Radio Testbeds to process the received GPS signals and also provide intra-network timing observations for the cooperative GPS signal processing. We shall use a combination of simulated and live satellite signals to show the improved performance. BENEFIT: The NAVSYS cooperative networked GPS signal acquisition technologies will provide reduced TTFF (Time to First Fix) initialization among a networked user groups as well as improved ability to acquire in weak signal or high interference environments. Military applications will be pursued in all major DoD branches by tailoring the implementation of this technology to their specific needs for assured PNT in their networked operations.