Tom Van Baak
tvb at leapsecond.com
Sun Nov 12 18:25:44 EST 2006
> Hi Tom,
> The plot from the brochure that you are looking at is
> one you had measured for us on the FireFox GPSDO
> predecessor, which did not have Temperature or aging
> compensation, and had a much coarser TIM, DAC,
> and DAC reference etc but used the same OCXO as
> the Fury. The Fury improves upon this previous product
> very significantly. We are still preparing the ADEV plot
> of the final Fury using a Cs standard.
OK, that's good news. I thought that TSC plot looked
familiar even if it wasn't very good. If your new offering
is better than the early prototype, you will be in good
shape. Looking forward to seeing your updated data
> According to Symmetricom, the performance of the
> 58503b between 100s and 1000s is about 3E-011
> typ and 5E-011 max. according to page 3 of this
> Symmetricom datasheet:
When dealing with competition it's ok to compare
their spec with your spec; just dangerous to compare
their spec with your actual measurements.
Still, given the older design and implementation of
the 58503 I think there's a good chance you will beat
it by quite a bit. It's a great benchmark since many of
us are familiar with the 58503/Z3801 family.
> Our spec is typical, and measures about <5E-012
> on the PDF ADEV plot. That is almost an order of
> magnitude better than the Symmetricom datasheet
> for 100s to 1000s. Of course as you mentioned every
> oscillator is different, and improves over time just as
> red wine :)
Unless you're talking lost-GPS holdover performance
the "red wine" aging improvement will have almost no
affect on the performance of your GPSDO.
That's why when building a GPSDO it's much more
important to pick an OCXO that has good short-term
stability than one with good long-term stability. The
GPS engine and FLL/PLL algorithm can make up for
long-term drift but there's nothing you can do about
short-term stability if it isn't there in the first place.
> Also, our phase noise is about 10dB (or more) better,
> while our power is almost an order of magnitude lower
> than the 58503b.
> Our price is also about $3000 less I believe.
This all sounds very good.
More information about the time-nuts