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    Re: Threats to GPS and introduction of eLORAN
    From: Mark Coady
    Date: 2016 Jan 30, 19:09 -0800

    L-C, while not as chart accurate as GPS, was highly repeatable for those of us who worked with our own recorded coordinate logs. We regularly could exchange and  relocate recorded targets or positions with high accuracy based on logs. As a wreck/recovery diver, with well kept recorded Loran C logs, I could find remote wreck targets on the bottom or lobster traps or other dropped target buoys with high reliability.

    I am not sure of the advances in electronics that might reduce errors and improve chart positioning from C. Later Loran recievers had preprogrammed corrections for specific geographic regions, the "ASF" automatic secondary factors (which could create confusion in vessel to vessel coordinate exchange if on/off or different). 

    As a former devotee of Loran C, and someone who witnessed very effective jamming of local GPS reception with simple technology, I am overjoyed to hear that an improved Loran type system might be reinstituted. Interestingly enough, the referenced GPS jam left the Loran C operational.

    The shutdown of Loran and the lack of any backup system to GPS I considered a folly, given the number of key activities military and civilian that now rides on the integrity of a vulnerable system. 

    In my coastal/near coastal experience, I have maintained a religion like commitment to being able to function without it. I know countless examples all through the technological front where long term GPS loss would create at least the potential of serious accidents and substantial confusion.

     In my now obsolete understanding something like a DGPS terrestrial station broadcast correction on a Loran type system might provide better signal accurizing locally, where chart accuracy is critical. On the civilian front, chart accuracy becomes super critical in piloting waters, less in open sea.   

    Technology is outrunning me daily, so I don't know or claim to know what the limits of an updated system might be. I would also be curious about the signal processing in relation to solar flare interference. 

    In a purely utilitarian sense, I also miss the quick visual and mental position estimates created by a charted hyperbolic crossing grid. 

    If GPS was 100% guaranteed, we might make the case that a vessel and pockets full of waterproof GPS recievers would render celestial obsolete.  I for one am not ready to go that far.  I have embraced celestial for historical and technical interest certainly, but also because it provides continual backup and alternate positioning to GPS. The shutdown of Loran made celestial even more attractive. Its also easier to improvise and calibrate an angle measuring device from wreckage than a GPS reciever. 

    Pre GPS, I lived sailing a vessel into a port on a down coastal voyage in winter with zero functional electricity (except a flashlight or two) and failed electronic communication, due to serious in-journey electrical damage. If I were in open sea, vs coastal piloting, I would have been very desperate in a desire for celestial skills.  

    GPS is now available/cheap/reliable, but not infallable.....so I'll hang onto celestial.........and would bless a new E-Loran.

    MC

       
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