Re: [IRCA] Another Boston Acoustics Receptor HD Radio Review

["Bob Foxworth" <rfoxwor1@xxxxxxxxxxxxxxx>]

Rene writes, while reviewing the BA HD Receptor,

>On the AM side, I was very disappointed.  I have several AM IBOC
>stations nearby that I used for testing:  WIP, WPEN, WDAS, and WOR.
>What disappointed me the most is that "static" and other noise is still
>an issue on AM, even with IBOC.  (I would be curious is Scott Fybush
had
>the same experience with his).


>being demodulated along with the digital audio.  My gut feeling about
AM
>IBOC, now having experienced it, is that AM stereo was much better.
>
>73,
>René
>
>Rene' F. Tetro,


I have to go out on a limb and guess that one of the
issues with static being a problem on AM is the
possibility that long duration impulse noise, which
is wide with respect to the digital bit stream, is
punching holes in the digital data stream, and causing
momentary dropouts. I have no idea how the receiver
would behaves in this circumstance. I would guess
that the impulse noise is somewhat stronger than the
desired bit stream. I am pretty sure that the receiver
is not sophisticated enough to replace the missing bit
stream with an analogue of the recovered data that
came just before it, and that which was cleanly decoded.

In TV, this can be done because it is only done once,
in a studio setting, when rebroadcasting a link
from somewhere else that is noisy. But I doubt
it is cost effective to do in each receiver.

My best guess is that the receiver "mutes" during
a loss of data due to masking by noise, and this
would punch a momentary "hole" in the audio you
hear.  Or perhaps it just outputs the actual noise
pulse for that momentary period.

I'd guess this is worth trying to get a handle on,
as obviously the marketing claim of "noise free"
HD reception - on AM - is suspect.

Scope traces of the recovered analog (HD) audio during
noise-filled HD reception, and similar traces of the same
frequency, on a standard analog set, are called for, I
would think.

Unfortunately, no hardware here for me to try it, or
else I'd be doing it now. My home QTH is certainly
noisy enough !!

- Bob



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