[time-nuts] Eureka, no more Cs, active or passive H-masers or GPSDOs needed
magnus at rubidium.dyndns.org
Wed Sep 10 17:12:07 EDT 2014
If you run SFN you need phase-coordination between transmitters. This is
typically done via GPS or distribution network. Rubidium isn't really
needed anyway, it's more about having a good enough crystal.
The ETSI SFN spec's seems to be miss-interpreted quite often, but the
+/- 1 ppb spec is about correct. Phase errors could very well be several
microseconds without great effect for the user, given that gap
configuration is done correct.
The reference side of DVB-T transmitters isn't well standardized.
On 09/10/2014 09:53 PM, Azelio Boriani wrote:
> Rb sources are considered too expensive here in Italy for the TV
> broadcast market. The patent was issued by a small company that
> produces digital TV transmitters able to exploit the single frequency
> network specifications of the ETSI standard and so a stable and
> accurate time and frequency source is needed: usually a GPSDO with an
> OCXO at its heart. Very rarely do we see a disciplined Rb.
> On Wed, Sep 10, 2014 at 9:18 PM, Dr. David Kirkby (Kirkby Microwave
> Ltd) <drkirkby at kirkbymicrowave.co.uk> wrote:
>> On 10 Sep 2014 17:36, "Brian Lloyd" <brian at lloyd.aero> wrote:
>>> On Wed, Sep 10, 2014 at 9:42 AM, Azelio Boriani <azelio.boriani at screen.it>
>>> I skimmed through the patent but did not read it in
>>> detail. There may be some nugget in there that represents something new
>>> nothing jumped out at me.
>> Maybe that is the trick to make money out of a good patent - make 99% of it
>> rubbish, with the nugget well hidden. Then sue when people breach your
>> I looked but it is so boring and so badly written. I did learn one though -
>> I thought Rb sources were used commercially, but according to that patent
>> they are too expensive for that.
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