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Cable vs. Sat vs. OTA - tech info
Posted: 06 November 2008 05:54 AM   [ Ignore ]
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Can anyone tell me the frequency bands and spectrum allocations for the satellite TV companies vs. OTA (digital TV, not analog), as well as the actual bandwidth available from cable?

I don’t sell any delivery mechanism, but my clients often ask for my opinion. I have an opinion on which is technically best, but that’s not really based on technical data (I think cable has more bandwidth to play with, but I’m not really sure).

Can anyone help out?

Thanks -
  Rob Schultz
  Inspired Electronics, Inc.
  http://www.inspired-electronics.com

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Rob Schultz
Inspired Electronics, Inc.
Palatine, IL
http://www.inspired-electronics.com
847.471.4420

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Posted: 07 November 2008 11:45 AM   [ Ignore ]   [ # 1 ]
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Can anyone tell me the frequency bands and spectrum allocations for the satellite TV companies vs. OTA (digital TV, not analog), as well as the actual bandwidth available from cable?

OTH digital is most often UHF but some stations use VHF for their digital signals but still within the same VHF (54-216 Mhz except for 88.1 to 173.9 Mhz which is where FM radio, Some public safety, marine radio and aircraft bands are located) and UHF bands (470-890 Mhz but the top 100 Mhz or so was taken away if I remember correctly and is used for public safety and other radio services) originally used for analog TV.  After the analog cut-off I believe the stations have a choice of permanently moving to the extra channel they have been temporarily assigned for digital transmission or going to digital on their originally assigned analog channel.  The bandwidth of the digital signal can be used for an HD channel and a non-HD digital channel (ie 5-1 and 5-2—note that these channels are “mapped” in the TV tuner and are not really on channel 5—see http://www.titantv.com for your local stations and their actual digital frequencies).  Some stations chop the same bandwidth up even more and have 3, 4, or even 5 “splinter” channels.  Doing this reduces the bandwidth available for each channel and can reduce the quality of the picture.  Cable uses a different modulation method and usually more compression than OTA.  The OTA method is called ATSC and the cable method is called QAM.  Within QAM in the US 64-QAM and 256-QAM are used in digital cable television.  As far as the bands and allocation for cable since it is (theoretically at least) confined to their cable network there are a number of bands available to them that cannot be used for OTA broadcasting.  Go to this link http://www.jneuhaus.com/fccindex/cablech.html for information on the cable bands.  Also, the analog cut-off next year does not apply to cable.  They have until 2012 to change to all digital.  Satellite is already digital and uses microwave bands such as 12 - 18 GHz Ku Band and 27 - 40 GHz Ka Band.  A good place to get very useful information on both DirecTV and Dish is http://www.dbstalk.com.  This may be way more than you wanted but this is just an overview.  Gene (WOW Factor)

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Posted: 07 November 2008 12:01 PM   [ Ignore ]   [ # 2 ]
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Oops—left out answers to your second question.  As far as bandwidth and quality of picture, OTA with a good outside antenna is usually best but only gets the local channels.  For other channels I think that satellite (I use DirecTV at my house) has a better picture than our local cable.  This is a function of how much compression the cable company uses and the quality of the cable and amplifiers in their “plant” but typically each amplifier can introduce a tiny bit of noise in the signal where the satellite signal comes directly to your house.  Also with cable companies, quality may vary from company to company and even from neighborhood to neighborhood within the same company.  Another delivery system that is getting good reviews but is not available in my area is FiOS which uses fiber optic cable rather than copper coax.  Some companies are using fiber to the home and others are only fiber to the neighborhood and then coax to the home.

Gene
WOW Factor
http://www.isfcalibrations.com

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