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Re: [RFI] RFI Susceptibility of DTV?

To: W2RU - Bud Hippisley <W2RU@frontiernet.net>
Subject: Re: [RFI] RFI Susceptibility of DTV?
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Sat, 24 Jan 2009 01:33:01 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Sorry, this one got a little long.

W2RU - Bud Hippisley wrote:
> On Jan 23, 2009, at 5:32 PM, Roger (K8RI) wrote:
>
>   
>>> 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 can't agree with this.  Here in the central Adirondacks of upstate  
> NY, during a sunspot minimum I get very useable analog pictures from  
> Syracuse, Utica, and Watertown on channels 2, 3, 5, 7, 9, and a few  
> UHF channels (16, 20, 24, 33, 68), too.  The UHF channels tend to be  
> "snowy", as does Channel 2 from Utica, but the other VHF channels are  
> almost as clear as satellite, despite the mountainous area tending to  
> add multipath to everything.  My antenna is a 10-year-old Radio Shack  
> "fringe" VHF/FM/UHF design with a mast-mounted preamp and coax into  
> the room directly below it.  The antenna is about 30 feet over the  
> lake I'm on, but probably 60 feet below the tops of the pine trees all  
> around me.  Utica is 60 miles away, Syracuse perhaps 90, and Watertown  
> 30 -- all in different directions.
>
> Using the same antenna, the same preamp and the same feedline, but  
> adding a top-rated DTV converter (the Zenith), I get only channel 7  
> out of Watertown. 
That is more likely do to several other items. One is the channels are 
not the same.  IF you have a digital TV set it will show the digital 
version of channel 7 as 7-1, or 7-2.  where 7 is high VHF and the dash 
something is likely to be UHF.
Second, many if not most of the interim stations are not running full 
power so you are trying to find a version of the station that was 
already weak when running full power.
Third, the interim digital station my not be at the same location as the 
analog. It may even be considerably farther than the analog.

Currently there is absolutely no way to directly compare the digital 
reception of a station to the analog version of the same station. Unless 
they are at the same height on the same tower, running the same ERP.

Also, *Unfortunately* I've not found an up-to-date site listing all 
current,  and final digital assignments and that includes the table put 
out by the FCC.  Many of the stations I can currently watch are not even 
listed on their current assignments..  About a third of the lower 
Michigan stations I can watch are not listed in the tables and that 
includes  the Detroit and Kazoo areas. I found one chart that shows Ch 2 
moving from Detroit to Kalamazoo. 
However, *EVENTUALLY* the thought is the low VHF stations will migrate 
to either high VHF or to UHF to get away from band openings.  There is 
absolutely nothing in the works to reallocate low VHF as yet.

As to which antenna, I'm watching stations well outside the area they 
list as usable such as Northern Detroit, Lansing, East Lansing, Jackson, 
Kalamazoo, Grand Rapids, Cadillac, and Traverse City..  All but a couple 
of  these are not occasionally good, but rock solid,  as good and 
reliable/consistent as the local stations. Also as I said before I'm 
using two "fixed" or non rotatable UHF Yagis with antenna mounted 
preamps for reception.     Tropo openings will bring in stations from 
Southern Ohio and even Kentucky but these are easy to identify as they 
may be part of the lineup tonight and not even there tomorrow.  Sporatic 
E on low bands can be seen as a signal varying widely in strength.  Go 
into set up and find the signal strength on some of the newer sets and 
you can watch the strength. 

Another point is we should not be considering propagation based on the 
sunspot cycle for a comparison, as it's effects on Low band VHF are 
irregular and unpredictable. High band VHF as well as UHF are likely to 
be tropo openings, but not E, or Sporatic E, let alone F layer with the 
exception of channel 2 and maybe 3.   When the transition is complete, 
the digital stations are at their final location and running full power, 
THEN we *might* be able to compare what we used to get. Unfortunately we 
don't know what they will be running for power on the new assignments.  
Oh! There's one other variable too.  How many channels are the stations 
going to run on digital. No, it's not going to be just one because some 
will be squeezing two or more SD channels into the space of one analog.  
We have one PBS/College station about 20 miles from us that changes the 
number of channels it runs depending on the time of day.  At night it 
may run two SD, but they have at times run 3.  Each of those stations is 
running less power than the old analog. IIRC all three total are running 
*about* the same.

The other PBS station shows up on the chart, but they have them 
displaced by about 50 miles when I can see their tower from the top of 
mine. If it wasn't for the trees I wouldn't need to climb.

There are many, many, mistakes and omissions in the charts and tables.  
Maybe when all are put together we could find them all, but we'd still 
have to guess about the ones that have been misplaced.

For a given signal power at a given distance if it comes in on analog it 
should come in on digital.  That also depends on bandwidth and digital 
SD takes up less bandwidth than analog SD for a better S/N ratio. 
Actually HD should take up about the same bandwidth as a full power 
analog SD station.

The problem is as I stated earlier, it's highly unlikely we are going to 
find the digital version of an analog station running the same power 
from the same location.  That means any TVI likely hood will be 
different after the transition than it is now.


>  No amount of fiddling with the TV antenna heading  
> brings anything else in.  My local satellite TV installer says he's  
> not surprised, and expects I won't see any additional channels until I  
> put the antenna and the preamp up above the nearby tree tops -- if then.
>
> The people in the hamlets around here have cable, so they won't care  
> much.  But those of us outside the hamlets that depend on local  
> weather maps (especially in this lake effect snow belt region I live  
> in) are going to be out of luck.  Utica is our "local" metropolis but,  
> because of some arcane FCC or Congressional ruling, neither Utica nor  
> Watertown can be one of satellite TV's "local" options. 
You have some mighty big hills in that area.  I used to get out to the 
Hamonsport (sp?) area about every summer.

I ran into that as well. They just draw a circle on a map. If you are 
inside that circle you are close enough to get the signal...if it wasn't 
for that mountain in the way.  My daughter in Colorado ran into the same 
thing.  There are no stations the get consistently. They are less than 
30 to 40 miles from most of the stations. Unfortunately they are on the 
second range back to the West of Golden with two big mountains between 
them and the stations, so they signed up for satellite.
As to local stations, we watch one for safety (being near several large 
chemical plants), but I get my weather and RADAR off the Internet via 
subscription.  The RADAR is much better than what I can get from the NWS.

>  And, to add  
> insult to injury, in our zip code another Congressional mandate makes  
> it illegal for the satellite TV suppliers to offer Syracuse as our  
> local option!
>
>   
Take heart on that one.  We were in that situation, but I believe both 
DISH and DIRECT TV now offer the local channels. Of course I'd have to 
pay for them. OTOH I think they offer all local stations for something 
like $5.00 a month.  What they don't offer are those 20 plus stations I 
receive from 50 - 100 miles away.  If in a poor reception area that 
might be worth it. I'd bet in the not too distant future you'll also be 
able to get your local stations via satellite.  BTW, they consider if 
you can get a "watchable" signal 50% of the time you are in a good 
signal area. That didn't mean a clear one, but one where you could see a 
picture. With digital you will either get a good picture or you pretty 
much won't and in that case should qualify. It's seems as if some 
stations treat the distance as iron clad, but the rule says 50/50 nor is 
it supposed to be by zip although it might cost money to get that changed.

BTW I *used* to have C-band.  Like now I subscribed to *almost* 
everything but also took the networks. One day they disappeared.   
Apparently the local stations had seen I was getting the networks 
without going through them.  I complained as I had been receiving them 
all along.  Fortunately there is such a thing as the "grandfather 
clause".  HOWEVER when I went to the DISH Network they said I couldn't 
get the networks as I was too close to the local stations even though I 
already was getting the networks on C-band.  So I kept C-band for some 
years, but as the number of subscribers to C-band became less and less 
the cost became more and more until I finally dropped them.   BTW I 
called the local stations, explained the situation and the station 
managers passed me on to the engineers who were downright rude.  So I 
can now watch the same networks from stations outside the area and have 
little need for any of the local network stations.
> Love those politicians!
>   
And it doesn't matter what party as far as I can see.

73 and good luck,

Roger (K8RI)
> Bud, W2RU
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