[Grovenet] digital TV question

Jamsm at aol.com Jamsm at aol.com
Wed Nov 11 19:04:07 PST 2009


 
Most people that bought antennas for their analog TV bought  an  antenna 
optimized for VHF and lower UHF frequencies  and many of those  had no upper 
UHF antenna rods or had very poor  reception of the  upper UHF signals.  With 
the old analog signals could you receive  TV channels under the UHF section 
of the tuner? I  think chanel 22 or 24 (analog) was one that was available  
out of Salem and Beaverton had another that was broadcasting before I left  
the area.  Channel 49 (analog) also comes to mind.
 
The new digital signals are primarily used in the UHF bands and are  highly 
directional. (see notes below)
Most of the better antenna being sold  for the digital signals are highly 
directional - think V shaped. Thus, if you  want good reception you need a 
new antenna optimized (high gain) for the  UHF band.
 
For optimal reception you want an antenna to gather only the signals you  
are interested in.
If you had a VHF/UHF antenna (for all the old TV stations 2 - 12) and  had 
low gain on the UHF channels then you should buy an antenna optimized  for 
the UHF signals (marketed today by many as a digital antenna) - a  
directional antenna is far better than one that is willing to accept signals  from 
various directions. Meaning - the more directional the antenna the cleaner  
your signal should be.  {think of ghosted signals of analog signals  that were 
a result of reflected signals}  [When I first  moved to the  Portland area I 
lived in the Water Tower district; we had very poor reception of  the  
analog signals and the best signals we could get  were  reflections off the 
hills in East Portland. Yup, snowy to no picture.  I  learned to go to a 
friend's home to watch TV.]
 
Please read !   Also search and read up on antenna  design!
http://en.wikipedia.org/wiki/North_American_broadcast_television_frequencies
 
 

The following was extracted from above link

 
In the U.S., all channels from 7-36 and 38-51 are frequently used for  
digital TV broadcasts. However, _VHF 2 - 6_ 
(http://en.wikipedia.org/wiki/Band_I)  are rarely used by DTV  broadcasters due to ongoing problems with 
_impulse noise_ (http://en.wikipedia.org/wiki/Impulse_noise_(audio)) , and  channel 
6 being an _adjacent channel_ 
(http://en.wikipedia.org/wiki/Adjacent_channel)  to the  _FM broadcast  band_ 
(http://en.wikipedia.org/wiki/FM_broadcast_band) .
 
 
 
(http://en.wikipedia.org/wiki/North_American_broadcast_television_frequencies)  
This link has some wild ideas and interesting notes
http://www.tvtower.com/Commercial%20Television%20Frequencies.html
 
The following was extracted from above link - an interesting note for those 
 that use wireless mics
 
** March 15, 2001:   The Federal Communications  Commission took its first 
steps to auction airwaves used by television  broadcasters on _Channels 52 
through  59_ (http://www.newsfactor.com/perl/story/8277.html#story-start) , 
sought by mobile-phone carriers such as Nextel  Communications.   The agency 
proposed rules to make the TV spectrum  available for mobile or other 
wireless services. It is seeking comment on  whether it should help broadcasters 
relinquish the frequencies. The FCC plans to  let broadcasters and phone 
companies work out agreements to clear the spectrum.  
This Spectrum will become available as broadcasters switch to  
higher-quality digital signals and shut off analog signals. The move will occur  when 
_85 percent_ (http://news.cnet.com/news/0-1005-200-5148343.html)   of 
consumers have digital TV receivers, or by 2006, whichever is later. 
Almost all wireless mics operate on the same  frequencies as TV stations. 
The TV stations are licensed by the FCC and are  running at very high power 
levels. Virtually all wireless mics are not licensed,  and must accept any 
interference they get from TV stations. For this reason, a  wireless mic that 
works fine in one city, may not work in another. 
As new stations go on the air, your wireless mic may become  useless. It is 
important to understand this, because every TV station in the  country is 
getting a new frequency for digital TV broadcasting. Only some of  these new 
transmitters are on the air yet, but in the 2006,  they should  all be on 
the air. Check with all your local TV stations to determine what new  channels 
have been assigned to them for digital broadcasting, and when they  expect 
to be on the air. Most manufacturers can switch your existing wireless  mics 
to different frequencies if needed. It would be wise to determine today if  
your existing mics will have problems so you can get them changed at your  
leisure, and not in a panic after they fail.
 
Yup, I have no idea what I am talking about and am an idiot for having  
posted anything  here.
Having worked in electronics and computers for almost  40 years and I  
still don't know anything.

 
 
 
In a message dated 11/11/2009 4:05:01 P.M. Eastern Standard Time,  
edavie at verizon.net writes:

They  give them different names but they are still the same antennas as 
before.  The technology may have improved but they are NOT digital  
antennas!
Ed





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