The PRS10 schematics are available on line from Didier.
See the following link:
http://www.ko4bb.com/manuals/index.php?dir=05%29_GPS_Timing/SRS
Sincerely,
Stijn
Op 02-04-12 09:48, Azelio Boriani schreef:
OK, thank you. I'll collect the documentation you suggest to study it. Yes,
the PRS10 manual available online has no schematic. The paper one does
have. Does this means that Stanford Research want it not to be disseminated?
On Mon, Apr 2, 2012 at 5:06 AM, Said Jackson<saidj...@aol.com> wrote:
Hi Azelio,
its a dual slope interpolator, much like the HP 5334A counter. In fact the
5334A service manual is very nice to go through to get lectured on how this
works. The capture hardware is similar to the Linear Tech app note written
by Jim Williams (mentioned in the time nuts archives). Basically its a very
fast constant current source, and a high quality capacitor. Except Jim
charges the cap, then uses an analog to digital converter to capture the
time difference. We use a micro controller to capture the time difference
on the cap, then capture how long it takes to discharge the cap with about
~1000x slower current than the charge current. Hence we get ~1000x to 1
time dilution, which means the underlying 16.66ns counter resolution
becomes a ~16.7ps resolution. While I have never seen the PRS-10 Rubidium
schematics (anyone have them in PDF format?) I gather from the description
in the service manual that they do something similar to this. The Wavecrest
DTS user manuals floating around on the internet also explain how this
works. So in short, all that is required to build a unit like this is a
bunch of fast analog charge hardware, and an analog comparator that can
trigger a counter capture event, and some software for calibration and
control...
bye,
Said
Sent from my iPad
On Apr 1, 2012, at 4:07, Azelio Boriani<azelio.bori...@screen.it> wrote:
Said,
how complex is your 20pS time interval counter? Is it analog, FPGA,
something else (if you can disclose some info, of course)?
On Sat, Mar 31, 2012 at 11:44 PM, Hal Murray<hmur...@megapathdsl.net
wrote:
mar...@ptsyst.com said:
I’ve seen that the peak to peak jitter is reduced from something like
27
ns
to< 10 ns.
Is this a reduction of just the jitter, or is the actual accuracy to
UTC
also improved by this amount.
Have you read the hanging-bridges paper?
Tom Clark and Rick Hambly: Timing for VLBI
http://gpstime.com/files/tow-time2009.pdf
I think that is the key to understanding this area.
If you could average over many sawtooth cycles, you should get an
accurate
answer.
The problem is that you don't get to pick how many cycles fit into your
averaging time. The sawtooth pattern is the beat between two
frequencies.
One of them is drifting with time/temperature. If you are unlucky, the
beat
frequency can be very very low.
The sawtooth correction lets you correct on a cycle-by-cycle basis. You
don't need to average over many samples.
--
These are my opinions, not necessarily my employer's. I hate spam.
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