[time-nuts] Chinese GPSDO 10 MHz error

[Bob Benward]

So how does a frequency lock work?  How is it implemented? Can someone sketch a schematic?

And what equipment or technique is used to measure a 2hz error at 100GHz?

Bob

>>> -----Original Message-----
>>> From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Tim
>>> Shoppa
>>> Sent: Wednesday, August 26, 2015 5:18 PM
>>> To: Discussion of precise time and frequency measurement
>>> Subject: Re: [time-nuts] Chinese GPSDO 10 MHz error
>>> 
>>> Full KE5FX evaluation of BG7TBL GPSDO here:
>>> http://www.ke5fx.com/gpscomp.htm
>>> 
>>> I'm wondering out loud if it might, like many hobbyist GPSDO's, be
>>> frequency-locked rather than phase-locked and thus susceptible to last-digit-
>>> counter bobble in some long-averaging counter.
>>> 
>>> Tim N3QE
>>> 
>>> On Wed, Aug 26, 2015 at 3:18 PM, Perry Sandeen via time-nuts < time-
>>> nuts at febo.com> wrote:
>>> 
>>> > Hi,
>>> >
>>> >
>>> >
>>> > On the EEVBLOG  (http://www.eevblog.com/forum/index.php)
>>> >
>>> >
>>> >
>>> > They mention that the "2014-11-06"version GPSDO that was “most
>>> > extensively tested, so far (by ke5x and others).
>>> >
>>> >
>>> >
>>> > (Has a) known bug, outputfrequency is not exactly 10mhz
>>> > (9,999,999.999,800 Hz). This translates to ~2hzerror at 100ghz.”
>>> >
>>> >
>>> >
>>> > A question is if this bug isjust for this particular model or all
>>> > other versions suspect?
>>> >
>>> >
>>> >
>>> > I realize that in and of itsself it is very small error, but errors
>>> > tend to multiply or cause incorrectconclusions to testing.
>>> >
>>> >
>>> >
>>> > Another question is will the LHdisplay unit they offer work with other
>>> > Trimble units such as are offered byRDR?
>>> >
>>> >
>>> >
>>> > That said, these models seem tobe a very nice turn-key systems.
>>> >
>>> >
>>> >
>>> > Regards,
>>> >
>>> >
>>> >
>>> > Perrier
>>> >
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