Hi Oddly enough, the two share a direct connection:
"Report on NBS Dual Mixeer Time Difference System (DMTD) Built for Time-Domain Measurements Associated with Phase 1 of GPS" https://tf.nist.gov/general/pdf/84.pdf <https://tf.nist.gov/general/pdf/84.pdf> Came out in Jan 1976 Starting in 1980, they had at least one paper a year on one or another aspect of GPS timing. The first one: ACCURATE TIME AND FREQUENCY TRANSFER DURING COMMON-VIEW OF A GPS SATELLITE https://tf.nist.gov/general/pdf/192.pdf <https://tf.nist.gov/general/pdf/192.pdf> Was the one that got a lot of people to sit up and notice GPS as a time source. Bob > On Aug 10, 2020, at 12:10 PM, ew <[email protected]> wrote: > > I did attend those conferences, it was my first ex poser to Dual Mixer, NIST > presented it for high precision frequency measurements. Still have copies of > the proceedings.Time is and was key but I do not recall any papers addressing > using GPS for time distribution as we know it today, and that is what I was > responding to the question that I answered to. Also writing the proposals and > attending all project reviews it was never covered. > > Bert Kehren > > > > In a message dated 8/10/2020 10:48:12 AM Eastern Standard Time, [email protected] > writes: > > Hi > > From what I saw as the system was developed, the people doing it realized > that timing > was at the core of the design. If there was a timing problem, nothing was > going to work. > There were GPS (and before that other sat-nav) presentations at the Frequency > Control > Symposium for many years. The “big boys” in timing all were involved in GPS > one way > or the other. > > NIST was doing time transfer work on GPS before the system was fully up and > running. > Their results are (to a great degree) what got everybody believing that GPS > *could* > be a good source of time. Those papers started early and kept on flowing …. > Until they > put their “stamp of approval” on the technique, I don’t think anybody was > ready to call it > a super time source. > > This is by no means to imply that NIST was the only outfit involved or that > the others > who also evaluated GPS somehow did not contribute. That’s far from the case. > The only > point is that NIST got out there early. > > Bob > > > On Aug 10, 2020, at 5:09 AM, ew via time-nuts <[email protected] > > <mailto:[email protected]>> wrote: > > > > Attached are two pictures from my TI days as program Manager of the first > > GPS. There was no discussions of consumer use or timing application. Focus > > was on military application being able to guide a bomb in to a chimney. The > > cost per device was $ 300 000. Because of my high security clearance I was > > asked to brief the NSA and CIA on the future of GPS equipment. With my > > semiconductor background Moores Law and previously involved in consumer > > calculator development I predicted the size of a brick and $ 3000. I was > > declared the company Idiot lost all credibility as a strategic thinker ans > > subsequently left TI. When Magellan came out with there handheld unit they > > remembered me and send me one. Still have it. When two years later the > > units the size of a cigarette pack came out and where given away if you > > took a Cadillac test drive the asked for it back. I refused. History.Bert > > Kehren In a message dated 8/9/2020 11:23:33 PM Eastern Standard Time, > > [email protected] <mailto:[email protected]> writes: > > I've done some quick research. I do not see timing as one of the services > > provided. I wonder if it can be achieved by just listening into what's > > already transmitted (like GPS) and do some math on our side. > > > > On more broader sense, was GPS originally designed to provide timing > > service? Or is it a byproduct of needing to measure location and speed, > > thus it needed a constant signal, and that using it to sync reference > > signal is just an ancillary and after-thought use cases? > > > > --------------------------------------- > > (Mr.) Taka Kamiya > > KB4EMF / ex JF2DKG > > > > > > On Sunday, August 9, 2020, 9:21:23 PM EDT, Bob kb8tq <[email protected] > > <mailto:[email protected]>> wrote: > > > > Hi > > > > > > > >> On Aug 9, 2020, at 7:03 PM, Tom Van Baak <[email protected] > >> <mailto:[email protected]>> wrote: > >> > >> Hi Stu, > >> > >> There's no problem with a semi-commercial posting here. You've been a > >> member for a decade and frequent contributor plus the subject matter is > >> exactly on-topic. So thanks for posting. > >> > >> I spent a while on your web site and didn't uncover a trove of white > >> papers. If you could post some URL's that would be appreciated. You don't > >> have to worry about being less accurate than GPS. I mean, there are often > >> far more important factors than nanosecond precision. > > > > To that point ( as accurate as GPS ) ….. GPS is simply a convent comparison > > system. Saying that > > this or that is better or worse at this or that tau is *not* the same as > > saying it has more or less value. > > It’s simply a system that is out there to be compared to. > > > > Bob > > > > > >> You didn't mention pricing; it's hard to imagine it's as free as GPS so > >> that seems like another disadvantage to me. > >> > >> Your comment about fewer satellites is spot on. That will be taken care of > >> if you give SpaceX / Starlink a call and join that bandwagon. There are > >> already 597 Starlink [1] satellites up there vs. 82 Iridium [2] > >> satellites, yes? > >> > >> If you have entry-level / hobbyist grade evaluation kits I'm sure a number > >> of us would be very interested to try it out. > >> > >> Thanks, > >> /tvb > >> > >> [1] https://en.wikipedia.org/wiki/Starlink > >> <https://en.wikipedia.org/wiki/Starlink> > >> > >> [2] https://en.wikipedia.org/wiki/Iridium_satellite_constellation > >> <https://en.wikipedia.org/wiki/Iridium_satellite_constellation> > >> > >> > >> On 8/9/2020 2:53 PM, Stewart Cobb wrote: > >>> Taka Kamiya and Forrest Christian both asked recently about the > >>> alternative > >>> satellite PNT system using the Iridium satellites. That system was > >>> developed by my company, Satelles. It has been commercially available for > >>> more than a year now. > >>> > >>> The biggest advantage is that our signal is at least 30 dB stronger than > >>> GNSS signals (the exact numbers depend on whether you're talking to > >>> engineering or marketing :). You can easily get a usable signal in deep > >>> jungle, or a data center in the middle of a building's basement, or even > >>> inside a locked shipping container. The stronger signal is correspondingly > >>> more difficult to jam or spoof than GNSS, and our signal has anti-spoofing > >>> features as well. > >>> > >>> The biggest disadvantage is that it is not quite as accurate as GPS, > >>> because there are fewer satellites in view at any given time. > >>> > >>> I don't want to quote exact timing numbers here, because they depend a lot > >>> on system integration details, but you can easily steer an OCXO within a > >>> few hundred nanoseconds of USNO time. With a rubidium, you can do > >>> considerably better. > >>> > >>> If you want to know more, our website is www.satellesinc.com. > >>> > >>> (If this message has been too commercial, I apologize in advance. The > >>> boundary between information and salesmanship is not always sharp.) > >>> > >>> Cheers! > >>> --Stu > >>> _______________________________________________ > >>> time-nuts mailing list -- [email protected] > >>> <mailto:[email protected]> > >>> To unsubscribe, go to > >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >>> <http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> > >>> and follow the instructions there. > >>> > >> > >> _______________________________________________ > >> time-nuts mailing list -- [email protected] > >> <mailto:[email protected]> > >> To unsubscribe, go to > >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >> <http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> > >> and follow the instructions there. > > > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > <mailto:[email protected]> > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > <http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> > > and follow the instructions there. > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > <mailto:[email protected]> > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > <http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> > > and follow the instructions there. > > <First GPS.jpg><Side view > > GPS.jpg>_______________________________________________ > > > time-nuts mailing list -- [email protected] > > <mailto:[email protected]> > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > <http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > <mailto:[email protected]> > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > <http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
