[time-nuts] GPS Timing Source -- looking at buying

Ed, k1ggi k1ggi at comcast.net
Sun Jul 11 08:23:43 EDT 2010


Keep in mind, SMPTE/EBU is timecode, AES/EBU is digital audio.
3 orders of magnitude difference in the bit rates.
Chris was talking timecode.
Ed

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Bob Camp
Sent: Friday, July 09, 2010 8:38 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] GPS Timing Source -- looking at buying

Hi

The Thunderbolt has a GPS and an OCXO inside it. It's built in smarts align
a PPS created from the OCXO to the GPS PPS. This allows the PPS to be more
stable than a normal GPS PPS (less jitter). It also provides holdover on the
PPS if and when GPS sat's are not available. 

Since your ultimate objective is (I think) AES / EBU timing, jitter is an
important consideration.

Bob


On Jul 9, 2010, at 3:10 AM, Chris H wrote:

> I might go for the Garmin one to start with, and see how it all works..
> and then move up to a more reliable source of timing source in the
> future...
> 
> When you say Reliable, what exactly do you all mean---
> does it loose time? 
> Does it loose lock to the satellites?
> because it's only millisecond accurate, is that your concerns....
> 
> Please correct me if I am wrong: 
> 
> If it's pulsing every second, and that second is generated by the lock
> to the satellite, then should it not be as accurate as the device that
> it's getting it's lock from?
> 
> (Sorry I am new to all this)
> 
> 
> On Fri, 2010-07-09 at 19:02 +1200, Chris H wrote:
>> Yes sorry -- stratum 1 -- brain fart :(
>> 
>> 
>> 
>> On Fri, 2010-07-09 at 06:32 +0000, Paul Nicholson wrote:
>>> Chris H wrote:
>>>> Would be good as a timing source for GPS
>>>> ... make a PC into a Stratum 0 timing device?
>>> 
>>> I think it would count as stratum 1, since you are 1 hop
>>> away from a master time source.
>>> 
>>> This page may be of interest,
>>> 
>>>  http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm
>>> 
>>> Trimble Thunderbolts have been recommended on this list as a
>>> proper timing grade GPS, superior to these EOM Garmin GPS units.
>>> 
>>> There's a reliable source of Thunderbolts on E-bay.  I currently
>>> have one of these on order,
>>> 
>>>  http://cgi.ebay.co.uk/290322053618
>>> --
>>> Paul Nicholson
>>> --
>>> 
>>> 
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> 
>> 
>> 
>> 
>> 
>> 
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> 
> 
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.





More information about the time-nuts mailing list