[time-nuts] Satelles PNT from Iridium satellites

[dikshie]

Hi Kamiya san,

I know there is only one company in Japan that uses STL service from
Iridium (via Spectracom as Vendor).
However I cant disclose the information more detail.

Best Regards,

Dikshie

On Mon, Aug 10, 2020 at 12:23 PM Taka Kamiya via time-nuts
<time-nuts at lists.febo.com> wrote:
>
> 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 <kb8tq at n1k.org> wrote:
>
>  Hi
>
>
>
> > On Aug 9, 2020, at 7:03 PM, Tom Van Baak <tvb at LeapSecond.com> 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
> >
> > [2] 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
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> >>
> >
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-- 
-dikshie-