Augmenting the DGPS Broadcast with Emergency Information
Hartnett, Richard J.
Swaszek, Peter F.
Gross, Keith C.
MetadataShow full item record
Differential GPS, or DGPS [ Differential Global Positioning Satellite], is a medium frequency radio system that is used worldwide for the broadcast of differential corrections to users to improve the accuracy and integrity of the GPS. This communications system works by digitally modulating radio signals broadcast from a network of marine radio beacons operating in the 283.5-325 kHz radio band. The modulation scheme called Minimum Shift Keying (MSK) is used to transmit the correction data at typical data rates of between 50 and 200 bits per second. The U.S. Coast Guard has pioneered the use of MSK for transmission of differential GPS corrections, and has provided over ten years of worthy service with the system. In this paper we suggest that the DGPS system has significant capability for use beyond that of its current mandate; specifically, there exists the potential for concurrently transmitting a second information-bearing signal on the beacon signal. We believe that this simultaneous transmission of the current navigation correction information (the primary channel) and additional messaging (perhaps DHS emergency messaging or other relevant information) could be accomplished at very minimal cost, and with minimal impact on current users, using a technique we have called phase trellis overlay.
This article appeared in Homeland Security Affairs (March 2011), Supplement no.3
Showing items related by title, author, creator and subject.
Krener, Arthur J.; Kang, Wei; Chang, Dong Eui (2004-08);A parametrized nonlinear differential equation can have multiple equilibria as the parameter is varied. A local bifurcation of a parametrized differential equation occurs at an equilibrium where there is a change in the ...
Krener, Arthur J.; Kang, Wei; Chang, Dong Eui (2004);A parametrized nonlinear differential equation can have multiple equilibria as the parameter is varied. A local bifurcation of a parametrized differential equation occurs at an equilibrium where there is a change in the ...
McKaughan, Michael Eugene (Monterey, California ; Naval Postgraduate School, 1970-12);Omega, a world-wide, VLF, CW, all-weather navigation system offers one mile resolution, but suffers in accuracy due to propagation anomalies which have been found to be relatively constant over differential areas. ...