[BC] Digital Interference

[Robert Orban]

At 04:41 PM 12/19/2005, you wrote:
>From: Rich Wood <richwood at pobox.com>
>Subject: Re: [BC] Digital Intgerference
>To: Broadcast Radio Mailing List <broadcast at radiolists.net>
>Message-ID: <7.0.0.16.2.20051219104221.065d6d50 at yahoo.com>
>Content-Type: text/plain; charset="us-ascii"; format=flowed
>
>------ At 10:35 PM 12/18/2005, Robert Orban wrote: -------
>
> >My Boston Acoustics never mutes as long as I am on the main channel.
> >The crossfades in either direction are smooth. Of course, the HD2
> >digital channel will mute if it loses signal because there is no analog 
> backup.
>
>Why would there be any mode switching in a stationary receiver? If
>the mode switches back to analog doesn't that bring your original
>analog problems back?

I have a very marginal RF situation at my house because of terrain 
shadowing with respect to all San Francisco FM TX sites. (My house is on 
the side of an east/west canyon about 25 miles south of the TX sites.) The 
BA is hooked up to a directional rooftop antenna but a couple of the SF 
stations (KFOG and KITS) do not supply solid HD reception--the BA will lock 
on to their HD signals but not all the time. This is actually a good thing 
because the BA has no way to force an analog/digital switch, so this is the 
only way I can assess the performance of the BA's crossfading.

Anyone who has tried to get good analog or digital TV reception from an 
outside antenna in a terrain disadvantaged or B contour location will know 
what I am talking about. All it takes is an airplane flying overhead to 
change things. HD radio's modulation scheme (COFDM) is more resistant to 
such phenomena than ATSC digital TV but is not entirely immune.

Fortunately, KDFC's (our classical station) HD is solid when it's on the 
air, although the HD went off during a fairly big storm we had in the last 
few days. I have no idea if the storm caused the problem or if it's a 
coincidence. As of this morning, it was not yet restored.

Bob Orban