CompuServe Messages

#GPS Error

    18-Dec-94 19:56:36
Sb: #GPS Error
Fm: Guy Hammer 72315,465
To: Lanny R. Ream 73512,1163
Hi, Lanny I found the following in the 4X4s, Trucks and Vans section of the automobile forum tonight. Item 2 might be a possible explanation for the two mile error your Scout gave you in the field last summer… ===================================================================== Alistair, WRT the Coast Guard undoing the error the DOD introduces into GPS signals: 1. Even without the injected error, GPS accuracy would not be good enough for blind harbor entries, which the differential GPS system would permit. 2. The differential GPS system also tells the user when a satellite is broadcasting bad data. It can be up to several hours before a satellite can be "turned off", thus causing positional errors to unknowing users for that time There are some other reasons differential GPS would be used even without the DOD injected error ("Selective Availability"), but you're right we would be much better off without this error. Chip ===================================================================== Are you planning to return to site of the error any time soon? (Well, after things thaw out anyway?) I'd be interested to see how the next fix compares with the first. Happy Holidays, Guy