[BC] FCC Deletes digital report from today's meeting

[Stan Tacker]

These are all valid observations, but I want to chime in by adding to the
comment which prompted Mike's statement regarding the D/U ratio.

No matter how you cut it, we are still operating in an analog universe.
There is no mandate to convert to digital operation.  As long as analog and
hybrid stations are operating side by side (no pun intended), the hybrid
operation must protect existing service.

My point was this...At night, interference adds up.  Thus, nighttime
interference from IBOC operation is not a local issue. It impacts everyone
on the center frequency and each adjacent channel. 

BTW, the article by Barry McLarnon in the 7/19 issue of Radio World is worth
reading.

Stan


-----Original Message-----
From: broadcast-bounces at radiolists.net
[mailto:broadcast-bounces at radiolists.net] On Behalf Of Mike McCarthy
Sent: Monday, July 17, 2006 7:10 PM
To: Broadcasters' Mailing List
Subject: Re: [BC] FCC Deletes digital report from today's meeting

I didn't suggest that as being the number which Ibiquity uses.  I used it 
as an example of how there is a HUGE difference between acceptable IX for 
analog and that which occurs with digital before degradation of service
occurs.

And as I said before, the measured D/U needs to consider worst case 
(strongest) signal strength when defining the overlap.

MM

At 10:42 PM 7/16/2006 -0700, Chuck Hutton wrote
>6 dB? Where does that value come from? It's a little hard for me to
>interpret the iBiquity documents, but 6 dB for a QAM system would be
>phenomenal and - given what I know of the error correction and interleaving
>- not possible. My guess: add roughly 10 dB to that but please accept that
>as a rough guess.
>
>As for "16 - 17 dB (any flavor)", the SINR needed to decode depends greatly
>on the modulation (QPSK? 16QAM? 64QAM?), coding gain, interleaver, sync
>algorithm, etc. Additionally, the audio coder plays a role: some codecs
like
>to know when an uncorrectable frame is seen by the error correction block
>and then attempt to conceal the error. Others don't, and it makes a notable
>difference. The efficacy of the concealment algorith is also a variable.
Add
>it all up and no one answer is possible as there is quite a range.
>
>Chuck
>
>
>From: Robert Meuser <Robertm at broadcast.net>
> > The D/U for digital (any flavor) is around 16 - 17 db.
>
>
>
>Mike McCarthy wrote:
> > In an analog world where the D/U ratio is something like 40dB, your
> > argument is correct.  In a digital world, the D/U ratio could be as
> > little as 6 dB and there would be no problem receiving/decoding the
> > signal. I can see where a NUMBER of arrays would be able to go omni
> > with digital...day AND night..
>
>
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