[time-nuts] advice: frequency calibration to 1 ppm possible without GPSDO?

[Bob Q]

If you're interested, I have a page that shows what all the M12 test points 
are.  I used those, not the connector.  Used to be on the Synergy site, 
along with lots of other info on the M12.
Bob

-----Original Message----- 
From: paul swed
Sent: Friday, February 18, 2011 11:58 AM
To: beale ; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] advice: frequency calibration to 1 ppm possible 
without GPSDO?

As a heads up. I picked up a M12+ from fluke.I. Working well. But the little
pins are a sun of a gun to work with. They are really small. So you may need
to order a connector and pins. Since that would cost more then the M12 I
soldered directly to the pins and added some leads.Now I can use any
connector or none at all.
Regards
Paul
WB8TSL

On Fri, Feb 18, 2011 at 2:51 PM, beale <beale at bealecorner.com> wrote:

> Hi Kasper,
>
> Thank you, your nft program looks very interesting! It turns out the local
> ISP that provides my DSL, sonic.net runs a GPS-driven NTP server and I
> have a pretty low and stable latency, so this may work well.  To measure a
> relative frequency offset, I presume that what limits accuracy is the 
> total
> length of time of the test. So with a stable latency, I should not need to
> poll the server very often.
>
> Meanwhile I have a M12+ timing GPS and antenna on order, and am assembling
> some glue logic, case, 3.0V power supply etc. I may not ever manage a
> long-term GPS installation, since my apartment is surrounded by tall
> obstructions, and my workplace has metallized-film window panes which 
> block
> all GPS signals, and no roof access.  It has a big open parking lot,
> though... I imagine using a car-mount GPS setup and sending a 1 Hz or 100 
> Hz
> LED or laser pulse up through the window to a telescope / photodetector at
> my workbench on the 2nd floor.... or maybe sending a frequency-locked 10 
> kHz
> tone through a FM wireless mic system would be adequate.
>
> -John Beale
>
> > I did a piece of software to provide calibration to equipment-deficient
> microcontroller-hobbyist frequency counter builders (think 100ppm crystal
> from the bin) over ntp:
> > http://n1.taur.dk/nft/nft.pdf
> > /Kasper Pedersen
>
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