Re: [chrony-users] gpsd, pps and chrony

[Ed W <lists@xxxxxxxxxxxxxx>]

Hi

> Since an NMEA ntp client is a stratum 1 and since NMEA has an accuracy
> around
> 10ms (yes, ms, not us) there is no such requirement. Ie, the accuracy of
> stratum 1 clocks varies wildly.

By implication are you suggesting that you expect a decent proportion of
current pool.ntp.org stratum 1 servers are only synced to within some
few ms of "correct"?  Seems a bit sad?

There is some info on the ntp.org wiki where servers can volunteer their
hardware setup info.  Quite a few suggest using decent hardware?

I presume it's somewhat moot in that you are bounded by the limits of
the various tcp connections, but still seems like the tech is easily
available and we ought to be trying to get current stratum 1 time
servers to be syncing within some few 10s of usecs?



>> Incidently, while we are geeking out on chipsets, I saw Skytraq
>> mentioned on the gpsd mailing list and they do all kinds of fun stuff,
>> some with fairly inexpensive eval boards, this has 30ns PPS pecision:
>>    http://www.skytraq.com.tw/news20090701.htm
> 
> Remember that the sure board includes usb ( ie power supply) and antenna in
> its $30 price.

Hmm, cool.  Note that I haven't found a supplier doing a simple eval
board for the time sync clock above, but other eval boards with similar
chipsets are going for only a little more than the Sure board (without
antenna though).  They are also generally much smaller boards? Certainly
similar enough that shipping costs will determine which is cheapest.

Cool that very decent GPS chipsets are getting plentiful at very
sensible prices.


> 
>>
>> (They also have a 20hz GPS with decent sensitivity and a GPS/GLONASS
>> hybrid board...)
> 
> And exactly what would a 20Hz buy you?

:-)

Perhaps you want to track your guided rocket?

Actually given that they only appear to be the same kind of pricing as
any other GPS board, if you were into UAVs it could be very handy.  I
guess also anyone tracking "racing" things would also like one?

Cheers

Ed W

---
To unsubscribe email chrony-users-request@xxxxxxxxxxxxxxxxxxxx 
with "unsubscribe" in the subject.
For help email chrony-users-request@xxxxxxxxxxxxxxxxxxxx 
with "help" in the subject.
Trouble?  Email listmaster@xxxxxxxxxxxxxxxxxxxx.