[time-nuts] Satelles PNT from Iridium satellites

[Tom Van Baak]

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. 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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