[time-nuts] Alternate frequency sources : DVB-T and ISDN & OT comment

[paul swed]

Kit,


On Mon, Nov 23, 2009 at 6:30 PM, Kit Scally <kScally at bytecan.com.au> wrote:

> Guys,
>
>
> Don't get confused with (a) recovering the transmitter's carrier
> frequency and (b) recovering the colour burst and/or data stream in a
> DVB-T signal for use as a "house frequency standard".  They're not one
> of the same !
>
> Most TV carrier frequencies here in Sydney, Aust (analogue & digital -
> we've got both running at the present time) are bog-standard xtals
> (possibly ovened).    As noted by others, this crude approach isn't good
> enough for SFN's
>
> Attempting to recover any part of a RAW MPEG data stream from a "$49
> digital STB" may be doomed to failure. Most STB of this ilk use a single
> jungle-chip with RF in and various flavours of video out.  The data
> streams you need to access for any clock recovery strategy is
> unfortunately buried in silicon....
>
>
> OT - Happy Thanksgiving holiday to all those in the USA & Canada.
>
>
> Kit
>
> VK2LL
> Sydney
>
> Christian Vogel wrote:
> > Hi Alan,
> >
> > at least here in Germany the digital TV transmissions (DVB-T) are
> > using (in some areas) Single Frequency Networks[1]. I live near one of
>
> > the transmitters and when I visited the facility, they had Meinberg
> > GPS receivers in the racks housing the TV signal generators.
>
> SFN requires synchronisation of frequency (10 MHz) and phase (PPS).
> DVB-T transmitters using SFN will broadcast pilot-tones. See ETSI EN 300
> 744, accessable through:
>
> http://www.dvb.org/technology/standards/
>
> >>snip
>
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