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Re: [RFI] RFI Susceptibility of DTV?

Subject: Re: [RFI] RFI Susceptibility of DTV?
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Fri, 23 Jan 2009 17:32:54 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>

Andy wrote:
>> Given the reduced power of ATSC, ...
>>     
>
> Is the reduced power permanent?  Or is this just during the interim period
> when both ATSC and NTSC are in use?  (I thought the temporary DTV
> assignments were at lower power.)
>
> The lower VHF channels are MOSTLY going away / being reassigned to other
> services, except in some areas.
There's a lot of channel switching around, but I think you'll find the 
low VHF including channel 2 will still be widely used and are not going 
away. They certainly are not being reassigned to other services.  The 
only reassignments to other services are channels 56 and up.
> There's a 
>   
> I read that huge areas of rural residents will find themselves without any
> TV after the transition.  Currently they live with watchable snowy pictures.
> With DTV they are out of luck.
>   
There is a small possibility that this may happen in some areas due to 
the channel switching, but in rural areas you rarely find people using 
rabbit ears for antennas.  Generally you find some good, or not so good 
outdoor antennas.
When going to digital and the temporary channels I find I get over 
double the number of channels I did on analog.

IF the channel is snowy with a "watchable" picture it will be crystal 
clear in digital. I've found that currently I get perfect reception from 
stations in the Lansing and Northern Detroit area that were basically 
unwatchable in analog.  Although my two antennas are high, they are 
fixed in position. Again that is something I couldn't do with analog.  
I'm also using only UHF antennas instead of the VHF/UHF combo as the 
stations on VHF (high and low) are strong enough that this works.

 The problem is the analog and digital are currently on different 
frequencies.  Some stations will switch to digital on their original 
channel assignment and some will keep the current digital  channel 
instead.  In the state of MI I only found a couple that will remain on 
the original channel.  It looks like a game of "musical channels" with 
all the switching around.  At least it appears we still will have only 
one channel 2 which will be moving from the SE side of the state to the SW.
> I don't think people won't be able to pin the blame on hams.  If their
> reception goes out every evening when you fire up your rig, and at the same
> time your voice or CW comes through on their stereo, then they will connect
> the dots.
>   
There  is no doubt there will be some problems, but in the long run I 
think interference problems will be considerably less.  More than likely 
they will come from those in densely populated areas still trying to use 
rabbit ears. One thing digital TV doesn't do is ghost.  Instead of 
ghosting,  multipathing does cause the same symptoms as weak signals 
which under certain conditions can cause any thing from mild pixelation 
to complete loss of the desired station. In the case of a marginal 
signal, just strong enough to give a lock which gives picture perfect 
reception, a slight case of interference might be enough to push it over 
the edge.

I have one big UHF antenna that is pointed due South which picks up 
stations (Low VHF through UHF) from SE through SW reliably to a 100 
miles plus a tad. I have one big UHF TV antenna pointed NW which does a 
good job in that direction , but all stations in that direction are 
within 20 degrees

73

Roger (K8RI)
> Andy
>
>
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