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.
Cheers,
Magnus
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) <[email protected]> wrote:
On 10 Sep 2014 17:36, "Brian Lloyd" <[email protected]> wrote:
On Wed, Sep 10, 2014 at 9:42 AM, Azelio Boriani <[email protected]>
wrote:
I skimmed through the patent but did not read it in
detail. There may be some nugget in there that represents something new
but
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
patent.
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.
Dave
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