I like the little boards at:
http://navspark.mybigcommerce.com/development-boards/
It's a GPS with a fully programmable 32-bit Arduino-compatible
processor. $22
Crowdsourced about 3 yr ago, matured now. Various versions; you can even
have Beidou :-).
Don
On 2016-05-22 19:45, Tom Van Baak wrote:
Can a pure analog design access the sawtooth correction? My GPS
receivers send sawtooth as a digital message on a serial port. I
don't know if saw tooth correction is required to meet his spec.
Hi Chris,
Many GPS/1PPS receivers don't output sawtooth information and yet they
work really well. Sawtooth correction isn't necessary except for
high-end GPSDO. The same is true for zero-D timing mode.
Examples include:
https://www.adafruit.com/products/746
https://www.parallax.com/product/28509
as well as any number of equivalent GPS/1PPS boards at half the price
on eBay. See also:
http://www.leapsecond.com/pages/MG1613S/
In fact many simple GPSDO rely on sawtooth dither to improve their
performance; that is, it's a feature to be exploited, not a bug to be
corrected for.
A dirt cheap GPS receiver these days may have 1PPS error of 20 ns RMS.
Over 1000 s integration that's 2e-11 in frequency stability; far
better than the OP's modest target of 1e-10 at an hour.
Here's another thought. OP wants STS of stability of 1e-10 at an hour.
No mention of accuracy, or long-term performance. So if stability is
all that's needed I would just use a old 10811-class OCXO, perhaps one
that's been running faithfully for a few weeks or months. That will
get you 1e-10 at an hour without any GPS any antenna any analog any
digital any complexity any tuning.
/tvb
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