[time-nuts] Satelles PNT from Iridium satellites

[Bob kb8tq]

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
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com
>> To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>> and follow the instructions there.
>> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.