[Grovenet] digital TV question

Ed Davie edavie at verizon.net
Wed Nov 11 19:30:04 PST 2009


Have to agree with all that! Although all of the antenna's are and were directional to a certain extent. There is/was a front and back etc.
But you are correct that the newer ones are more directional. It wasn't as important with the lower frequency, analog, channels. As a radio amateur I built a number of antennas for the much lower bands but even they were directional. The more elements you added the more directional they became.
Ed

--------------------------------------------------------------------------------


----- Original Message ----- 
From: <Jamsm at aol.com>
To: <grovenet at rdrop.com>
Sent: Wednesday, November 11, 2009 7:04 PM
Subject: Re: [Grovenet] digital TV question


> 
> 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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