Hi The pseudo random spreading / looks like noise / buried signal thing is the most common way people piggyback low level signals on a bent pipe.
Bob On Jul 11, 2013, at 12:00 AM, David I. Emery <[email protected]> wrote: > On Wed, Jul 10, 2013 at 07:40:50PM -0400, David I. Emery wrote: >> >> But if the satellite radiates what a local GPS package would and >> transmits ephmerides defining its position and motion it could be >> included in a GPS solution and could be used for timing and frequency >> purposes the same as any other GPS satellite subject to whatever degree >> of relative accuracy the bent pipe clock obtains and the degree to which >> the ephemerides in the format transmitted allow an accurate position to >> be determined. >> >> And from what I have read it seems very likely the WAAS birds >> meet these criteria.. > > Thinking some more about the bent pipe repeater aspect of > WAAS, aside from allowing any kind of WAAS like signal someone might > invent in the future to be retrofitted to existing satellites without > a long replacement cycle and expensive launches being involved - there > are some interesting properties of the design. > > One is that one COULD bury in the WAAS uplink cryptographic > (eg essentially random to users not in possession of the key) spreading > sequence transmissions that would be radiated globally and could be > received with "unique" GPS hardware... such a covert channel in civilian > GPS could have various purposes... and would look rather noise like > to the rest of the world. > > > -- > Dave Emery N1PRE/AE, [email protected] DIE Consulting, Weston, Mass > 02493 > "An empty zombie mind with a forlorn barely readable weatherbeaten > 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in > celebration of what could have been, but wasn't and is not to be now either." > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
