[time-nuts] time-nuts Digest, Vol 100, Issue 95

[Fabio Eboli]

Hello Jacques,
what revision of the module do you have?
On adafruit's page, under "Downloads" tab
you can see that they use 3 different GPS units:
PA6B for first revision, built around an MT3329
PA6C for the second and PA6H for the third,
both with MT3339 chipset.
Where did you see the different jitter claims?
Globaltop's site has the most recent datasheets,
but you need to sign up and they dont contain much
info anyway:
http://www.gtop-tech.com/en/category/GPS-Antennt-Module/A01_MT3339.html

Fabio.

Jacques Tiete <jacques at tiete.org> ha scritto:

> About:
> {
> Date: Thu, 22 Nov 2012 22:26:24 +0100
> From: Fabio Eboli <FabioEb at quipo.it>
> To: time-nuts at febo.com
> Subject: [time-nuts] MT3339 chipset in Globaltop's FGPMMOPA6H
> Message-ID: <20121122222624.71854hb9oslingcg at webmail.micso.net>
> Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes";
>    format="flowed"
>
> Hello, while asking info about the FE5682,
> I realized that for another project
> (model plane data logging) I will buy
> some cheap gps modules built around an
> MT3339 chipset.
> In my mind somewhere I stored the fact
> that in the datasheet of these module
> is mentioned the pps output, so I checked
> and the manufacturer is claiming that it
> has "High accuracy 1-PPS timing support
> for Timing Applications (10ns jitter)"
>
> This is the module I'm talking about:
> http://www.mirifica.it/store/gps/342-globaltop-fgpmmopa6h-pa6h.html
> http://www.alcom.be/binarydata.aspx?type=doc/GTop-FGPMMOPA6H-Datasheet-V0A.pdf
>
> Has anybody used this chipset or similar for GPSDO?
> I have no experience with discipled oscillators
> but if there is any hope that the pps out
> of these modules is good for the task maybe
> it's time for me to start reading more about
> the subject.
> The final goal will be to check the timing
> of the Rb I have around.
>
> Thanks,
> Fabio.
> }
>
> Hello TNutters,
>
> I did some test with this module from Adafruit  
> (http://www.adafruit.com/products/746) and it seems not a bad unit.  
> Tested it together
> with my TBolt and the PPS seems quite stable most of the time, I did  
> not do any logging and math on the result,
> just letting the TBolt trigger the scope and apart from the cable  
> offset I guess 80% of the time the module was
> within 10 to 15 ns.
> However the specs are not very clear and it is a typical chip for  
> mobile use in eg. carnav stuff. I also saw some
> other specs where the jitter was specified as 100ns. and even one  
> with a 1 microsec. so I'm a little confused.
> As soon as I have some time I plan to connect this module to a  
> BeagleBone and do some testing for an NTP server
> I think the Beagle is better for this than the RaspBerry because of  
> the "real" ethernet port.
>
> Greetz,
>
> Jacques Tiete
> 0499 99 83 78
> jacques at tiete.org
>
> Op 23-nov.-2012 om 00:19 heeft time-nuts-request at febo.com het  
> volgende geschreven
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