[opendtv] Re: 20050727 Wolfsson's Wednesday Words (Mark's Monday Memo)

Tom Barry wrote:

> >      "This brings us to double conversion tuners like the
> > type Zenith designed for testing its 8-VSB DTV modulation
> > technology.  It was the outstanding interference rejection
> > of that double-conversion tuner that led the FCC to
> > conclude that the UHF taboos did not apply to DTV":
> >
<http://www.tvtechnology.com/features/digital_tv/f_charles_Rhodes.shtml>
>
> I've included that article here in hopes someone can explain
> it better. Does it help or have implications in explaining
> the Zenith mystery boxes tested at Mark's apartment?  And
> will the lack of double conversion tuners mean we have to set
> aside extra channels to avoid interference in some areas?

My speculation has been that the LG prototype boxes had dual
conversion tuners, but that none of the other LG-equipped
boxes did. Also, I pointed to a couple of press releases which
touted new single conversion tuner chips used in their design,
on the basis of lower cost. So we have manufacturers doing
things that might be inconsistent with FCC frequency planning.

That's why I believe that the FCC should establish some
minimum performance requirements in such parameters as
selectivity and sensitivity. The FCC shouldn't have to mandate
use of a particular technical solution (e.g. dual conversion
tuners), but it definitely should quantify the assumptions
they made when they figured their reception contours.

Bert

 
 
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