[opendtv] Re: Italian mobile TV provider has signals covered

I think John Shutt is correct, particularly with regard to E-VSB.  A 1/2 or
3/4 reduction in code rate is just too high. E-VSB and A-VSB are not
backward compatible, since no part of them is usefully received by legacy
receivers.  Legacy receivers merely tolerate their presence.

A 1/3 reduction in code rate might be acceptable, since you can send 720P
robust HDTV with training wheels.  Legacy receivers usefully receive pairs
of regular data segments that are preceded by a segment of additional parity
info.

The problem with E-VSB and A-VSB is that they steal data space from 8VSB and
no part of them is usefully received by legacy receivers.  I suspect that
EVSB was proposed to poison the well for reasonable proposals.

A-VSB was originally proposed just to make the least significant bits of
8-VSB determinate, so you could lock together a multiple-transmitter system.
After that an exaggerated view of its possibilities driven by marketing
personalities seemed to have set in.

Al
----- Original Message ----- 
From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Thursday, June 29, 2006 1:22 PM
Subject: [opendtv] Re: Italian mobile TV provider has signals covered


> John Shutt wrote:
>
> > DVB-T works just fine in portable and mobile uses,
> > as demonstrated by the myriad of portable DVB-T
> > products.
>
> Yeah, right, John. Are you going to wear the UHF loop or rabbit ears on
> your hat? I don't do that with my cell phone, do you?
>
> Last I saw, for mobile DVB-T you need a C/N ratio of 25 dB or so. That's
> a pretty good signal, John.
>
> > ATSC never will work in mobile applications without
> > help from A-VSB or E-VSB.  And the data hit is so
> > great that NOBODY will adopt either one.
>
> Wanna bet? All it takes is clever training.
>
> Bert
>
>
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