Thursday, March 13, 2014

Source of rumor of no antenna needed with converter box?




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Can anybody tell me where the rumor came from that no antenna is needed if you use a digital converter box. I'm seeing this all over the technical areas of Y!A. People complaining that they don't get a good picture with their converter box unless they have an antenna hooked up and they were told that you wouldn't need one. One person just said in an answer that he saw it on the news. What news? Any other engineers out there seeing this same issue have any clue where it started?


Answer
I don't think it's possible to determine the source of the "no antenna needed for the digital converter box" rumor, but I suspect it is uneducated or misinformed people who do not understand RF transmission/reception principles. All it takes is one person who appears (or is believed) to be 'an authoritative source' to say something, and as it gets repeated and embellished from one source to the next, it takes on a life of its own. This is the nexis of the human communication principle "A lie told often enough becomes the truth."

As tomtom and Roland L. have correctly pointed out - it is not true that you do not need an antenna to receive over-the-air digital TV broadcasts. Anyone with a modicum of technical knowledge knows that some sort of antenna is required to receive any type of broadcast RF signal. This is especially true for over-the-air digital broadcast signals, which are fed to the digital converter box in order to convert the digital signals to analog signals that can be viewed on older TV sets (those without an ATSC tuner).

The specific type/quality/placement of antenna required (such as outdoor amplified, outdoor, indoor amplified, indoor, 'rabbit ears' or even a length of bare wire) depends on how close the antenna is to the transmission source, the source signal strength, and sources/amounts of interference in the line of sight between the transmitter and receiver (such as large buildings, high voltage electrical transmission lines, topography, etc.). The overall determining factors are signal strength and quality.

If the signal strength is weak, or if there is a large amount of interference, the amount of signal received will be insufficient to be demodulated into a usable signal. Thus a good quality antenna (possibly amplified) would be required. If you're sitting on a hill very close to and in the line of sight of the broadcast antenna, then it's possible that you could use a coat hanger for an antenna. But you obviously don't need to spend a lot of money for a "specially designed" HDTV amplified antenna.

Digital Converter & Digital Antenna Questions?




Steve S


Okay, I bought my parents a Dynex Tube 32' tube tv a couple of years ago from Best Buy. They dont watch much tv so I bought an inexpensive model. They live out in the country and cant get cable, satellite is the only option, but they dont want to spend the money.

Their TV currently gets digital channels in WITHOUT any converter box, like its built in or something. The problem is that one day they'll get 10 channels, the next they get 2. They really want to be able to watch at least a couple of channels. Their friend bought them a Digital TV Antenna to get more channel reception and a higher quality signal. However, from what they told me, they had to return it because there was no spot for them to plug the antenna into in the back of the TV. I think that they only make those antennas to fit into the back of Digital Converter boxes themselves, and since their digital converter is built into the tv they are out of luck.

My question is, will buying another actual digital converter box and plugging it into the tv and then buying a digital antenna for better reception solve this problem? Any ideas? Thanks!



Answer
>gets digital channels in WITHOUT any converter box, like its built in or something.

Any TV made for the US market after Feb 2007 has a digital tuner built into it.

>Their friend bought them a Digital TV Antenna....no spot for them to plug the antenna into in the back of the TV..

Unless it was a extremely rare "smart antenna", they just didn't understand the directions.

But, in North America all TV antennas are "Digital Antennas", even 30 year old antennas. What type of antenna will work best has to do with their location. Having "Digital", "HD", or "HDTV" slapped on the antennas box is just marketing BS and tells you absolutely nothing about how well it will work at a specific location.

Indoor antennas are always a hit & miss kind of thing because the materials in a building interfere with TV signals. The best spot for reception is probably not the top of the TV. On one end of the house I'm in a paper clip stuck in the antenna socket will pick up all the local stations; for the other end of the house we had to install an outdoor antenna in the attic because no indoor antenna would give good enough reception.

Start by going to http://www.tvfool.com/index.php?option=com_wrapper&Itemid=29 and find out the info on their local TV transmitters. Pay particular attention to the direction, distance, and "real" channel numbers of stations they really want.

The next step is to get a length of coax cable (maybe 10-15 feet) and hunt for a signal "sweet spot". Pay attention to what direction the signals are coming from and what might be reflecting or absorbing the TV signals.

If you find that you can't find a good enough spot, ask a question about what antenna might be best. Include the ZIP code, distance to transmitters, and what kind of antenna was tried and what the results were.

Quite a few people found that they needed to go to an attic or outdoor antenna after the DTV transition.

While their TV already has a digital tuner, chances are that a good converter box will have a better tuner than the one built into the Dynex. It would certainly be reasonable to buy a used/refurbished Zenith or Insignia model converter off of ebay and give it a try. The tuner in the Zenith/Insignia is probably as good as the ones in new HDTVs, so if it doesn't give good reception, you have to improve the antenna situation.

As for the other answers you got:

Can't use a converter box - Just plain wrong

Basic rabbit ears the best indoor.. - Sometimes that's true but certianly not all the time. If you don't have any local VHF stations, it is certainly not the best choice.

Outdoor antenna.... - Outdoor antennas almost always give better results than indoor ones and in some cases is the only option. Installing an antenna in the attic is a compramize, but it avoids problens like drilling holes in roof, weather damage, and need for lightning protection.




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