Yes WAAS is geosynchronous On Tuesday, August 11, 2015, Bill Prince <part15...@gmail.com> wrote:
> Except for the WAAS satellites ( > <https://en.wikipedia.org/wiki/Wide_Area_Augmentation_System> > https://en.wikipedia.org/wiki/Wide_Area_Augmentation_System). > > bp > <part15sbs{at}gmail{dot}com> > > > On 8/11/2015 5:20 PM, Mike Hammett wrote: > > GPS isn't geosynchronous. > > > > ----- > Mike Hammett > Intelligent Computing Solutions > http://www.ics-il.com > > <https://www.facebook.com/ICSIL> > <https://plus.google.com/+IntelligentComputingSolutionsDeKalb> > <https://www.linkedin.com/company/intelligent-computing-solutions> > <https://twitter.com/ICSIL> > > Midwest Internet Exchange > http://www.midwest-ix.com > > <https://www.facebook.com/mdwestix> > <https://www.linkedin.com/company/midwest-internet-exchange> > <https://twitter.com/mdwestix> > ------------------------------ > *From: *"Jaime Solorza" <losguyswirel...@gmail.com> > <javascript:_e(%7B%7D,'cvml','losguyswirel...@gmail.com');> > *To: *"Animal Farm" <af@afmug.com> > <javascript:_e(%7B%7D,'cvml','af@afmug.com');> > *Sent: *Tuesday, August 11, 2015 5:54:49 PM > *Subject: *Re: [AFMUG] GPS Timing > > Hum ? So geosynchronous is just a suggestion? > On Aug 11, 2015 12:25 PM, "Sean Heskett" <af...@zirkel.us > <javascript:_e(%7B%7D,'cvml','af...@zirkel.us');>> wrote: > >> the satellites are constantly moving tho and since they are moving faster >> in orbit than we are here on earth you need to account for relativity. >> knowing where you are doesn't give you enough information to know where >> the satellite is and therefore you can't accurately calculate the >> relativity offset. once you have 3D lock with 4 satellites you can >> accurately calculate the relativity offset and therefore calculate the >> accurate time for where you are on earth. >> >> shoulda taken the blue pill ;-) >> >> -Sean >> >> On Tue, Aug 11, 2015 at 12:08 PM, Bill Prince < >> <javascript:_e(%7B%7D,'cvml','part15...@gmail.com');>part15...@gmail.com >> <javascript:_e(%7B%7D,'cvml','part15...@gmail.com');>> wrote: >> >>> That's what I thought too. Once one of these little beggars has been >>> online for a half hour or more, the location should be "set" so to speak. I >>> would then expect them to hold time sync even with 1 satellite in view. >>> Knowing that the location is static and unmoving, I would expect that >>> maintaining time lock would be gravy. >>> >>> Sadly, this does not seem to be the case. >>> >>> bp >>> <part15sbs{at}gmail{dot}com> >>> >>> >>> On 8/11/2015 10:48 AM, Chuck McCown wrote: >>> >>> Interesting, I guess you need to know where you are to calculate the >>> delay. Had not considered that. But if you know where you are and have >>> ephermis data, you should be able to calculate the delay and arrive at a >>> pretty accurate timing pulse with one satellite. >>> >>> *From:* Forrest Christian (List Account) >>> <javascript:_e(%7B%7D,'cvml','li...@packetflux.com');> >>> *Sent:* Tuesday, August 11, 2015 11:39 AM >>> *To:* af <javascript:_e(%7B%7D,'cvml','af@afmug.com');> >>> *Subject:* Re: [AFMUG] GPS Timing >>> >>> >>> You need an accurate 3d position to get accurate timing. To have an >>> accurate 3d position using GPS alone, you need four satellites. Three >>> only gets you a 2d lock, and less than that you don't get a lock at all. >>> >>> There are receivers out there which will survey a position and then use >>> that position to be able to continue to provide a timing signal if you >>> subsequently lose lock but still have sats in view. As far as I know, >>> this type of receiver is not in use in any commercially available timing >>> product for the cambium radios. In fact I think we've almost all ended up >>> using the exact same GPS modules, at least for any recently designed >>> product. >>> >>> Some of the earlier products would attempt to preserve the sync signal >>> across a GPS lock loss with various levels of success. For instance the >>> cmm micro in early releases provided a wildly incorrect sync pulse even >>> without a lock. Same with early syncpipes. The CTM has a holdover >>> timer. And so on. I think most of us have moved away from this in newer >>> designs. >>> On Aug 11, 2015 8:36 AM, "Dan Petermann" < >>> <javascript:_e(%7B%7D,'cvml','d...@wyoming.com');>d...@wyoming.com >>> <javascript:_e(%7B%7D,'cvml','d...@wyoming.com');>> wrote: >>> >>>> What is the minimum amount of satellites needed for a proper GPS sync >>>> pulse? >>>> >>>> And does that differ across products (CMM, CTM, SyncPipe, etc.)? >>>> >>> >>> >> > >
