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Date: Thu, 3 Dec 2015 21:07:09 +0000
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From: Andy Talbot <andy.g4jnt@gmail.com>
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: EbNaut 137.777
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Status: O

You have no control over the phase of the reference - only the frequency.

GPS derived PPS signals, these days, are typically within a few tens
or 100ns.  This is still a complete cycle of 10MHz so you can't rely
on that to sync its phase either.

Also, as soon as you lock any other frequency to a reference, except
for direct multiplication of it, you lose the phase relationship.

Phase is one parameter that is meaningless on its own, and cannot be
transferred.

You can only refer to teh phase of a signal when compared to another
local reference.  (In the case of I/Q signal channels, that reference
is DC)

Andy


On 3 December 2015 at 20:57, edgar <edgarjtwining@virginbroadband.com.au> wrote:
> Hi Paul and Andy,
>
> My question on the use of GPSDO for EbNaut was to improve my limited
> understanding of the equipment required.
>
> It was not intended to directly compare Rubidium Oscillators vrs GPSDO.
>
> I had considered that a GPSDO had the advantage of providing a PPS.
>
> Also the frequency, and possibly the phase of the reference signal, would be
> known and be similar at both locations.
>
> Thank you for your feed back.
>
> Regards, Edgar
> Moonah, Tasmania.