Global Positioning System (GPS) User Equipment (UE) Time Aiding Using WWV/WWVB

A dismounted soldier or airman who turns on his GPS receiver on the battlefield depends on a quick and accurate navigation solution, even in areas where the GPS signals may be degraded. The intent of this SBIR program is to address this requirement by providing military GPS receivers with an external timing signal precise enough to allow direct P(Y) acquisition, greatly reducing the time-to-first-fix (TTFF) even during"cold"starts in GPS-degraded or denied environments. Under this Phase II effort, NAVSYS will design the software applications required, exportable to a Software-Defined-Radio (SDR) platform, to receive an external timing broadcast, extract the 1-pps signal, and use it to initialize a"cold"DAGR receiver within"warm"start specifications. NAVSYS will develop these applications on a software development kit for the JTRS HMS radio to allow easy transition in a Phase III effort. In order to provide a timing signal where no external broadcast is available, NAVSYS will also design a Tactical Transmission Station (TTS) which will transmit its own timing signal (TWWV) using the 1-pps data from an internal GPS receiver. The reduced TTFF results will be demonstrated using network (NTP), common-view (CV) and Tactical (TWWV) broadcast signals. BENEFIT: With an external timing signal precise enough to allow direct P(Y) acquisition, TTFF could be greatly reducing even during"cold"starts in GPS-degraded or denied environments. This capability will allow the warfighter to more quickly identify his position to others in order to avoid friendly fire or to locate enemy forces. Any ground force unit which deploys into a combat zone with SAASM GPS receivers could benefit from this application. Stand-alone and embedded military GPS receivers are widely used in every theater of operations but there is no guarantee that a particular device will not be issued in a"cold start"condition, having been powered down for a significant period of time. This application will give the warfighter confidence that his GPS receiver will come to full function quickly even in areas where GPS signals may be impacted. Future implementation could also include applications for intelligent munitions and unmanned ground and aerial vehicles using a JTRS waveform.