nahhh.. you all got it wrong.... it's all made in china any way ! Faisal Imtiaz Snappy Internet & Telecom 7266 SW 48 Street Miami, FL 33155 Tel: 305 663 5518 x 232
Help-desk: (305)663-5518 Option 2 or Email: [email protected] ----- Original Message ----- > From: "Chuck McCown" <[email protected]> > To: [email protected] > Sent: Wednesday, August 12, 2015 3:21:46 PM > Subject: Re: [AFMUG] GPS Timing > Not to mention that RF was invented by the Soviets... > From: Shayne Lebrun > Sent: Wednesday, August 12 , 2015 11:36 AM > To: [email protected] > Subject: Re: [AFMUG] GPS Timing > Nyet, Tovarich. Superior SOVIET RF works four times as hard as any lazy > capitalist RF, and without exploiting the proletariat photons. > From: Af [ mailto:[email protected] ] On Behalf Of Jaime Solorza > Sent: Wednesday, August 12 , 2015 1:22 PM > To: Animal Farm > Subject: Re: [AFMUG] GPS Timing > not to worry Comrade RF is universal > Jaime Solorza > Wireless Systems Architect > 915-861-1390 > On Wed, Aug 12 , 2015 at 9:52 AM, George Skorup < [email protected] > wrote: > Cambium is using a new receiver on the 450APs that does GPS+GLONASS. I assume > it's from Global-Top, but I haven't opened up a new AP to look. I'm not real > excited about using the Russian signals, but with so many satellites > available, it does acquire lock very fast. Have you thought about doing the > same for your 'Pipes? I think it would be beneficial. > On 8/12/2015 5:34 AM, Forrest Christian (List Account) wrote: > > Ok, if you really want to know, I finally found a (somewhat data) document > > which describes this in semi-understandable terms. > > > And yes, the real time does fall out of the equations (see watch error - > > which is how fast or slow your reference clock is). > > > http://www.maa.org/sites/default/files/pdf/cms_upload/Thompson07734.pdf > > > What I'm hearing from my GPS module vendor is effectively that since they > > don't really have to do any additional work to output a 1PPS signal from a > > 3d lock, they feel comfortable in doing so. Adding the complexity of > > surveying an location to an useful accuracy and then using that to compute > > the time is a lot of additional work with a lot of variability they don't > > want to try to deal with without additional demand. I do know that a while > > back we tried some shortcuts to get there, but they were not all that > > useful. > > > -forrest > > > On Tue, Aug 11 , 2015 at 12:25 PM, Sean Heskett < [email protected] > 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 < [email protected] > > > 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) > > > > > > Sent: Tuesday, August 11 , 2015 11:39 AM > > > > > > To: af > > > > > > 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" < [email protected] > 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.)? > > > > > -- > > > Forrest Christian CEO, PacketFlux Technologies, Inc. > > > Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 > > > [email protected] | http://www.packetflux.com >
