OTA vs Satellite Reception

[deepmoz]

I have a samsung tx-r3079wh with a digital tuner that I have hooked up to an antenna to receive OTA programs. I realize not everything on OTA is actually HDTV, but why is it that even SDTV on OTA looks much, much better than images received from my satellite dish?

Can someone explain to me what the difference is between DTV and digital over Dish Network Satellite? Thanks!!

 

[fayrich]

Compression!!!

 

[deepmoz]

I guess let me rephrase my question:

What is the difference between Digital Television (DTV) from OTA and Satellite? Why does SDTV over OTA look better than Dish Network's Satellite reception?

 

[Lorenzo]

I think Dish and Direct both deceided that more channels=more customers. Since they have a finite amount of satellite bandwidth the more they digitally compress their transmissions the more channels they can offer. More compression equals less resolution- a less detailed picture. Beta vs VHS tape recorders was a similiar tradeoff. VHS gave more recording time but less resolution.

 

[deepmoz]

Thanks for a more detailed explanation. Do you guys think any of this is going to change? It's just funny that we're back to using antennas when viewing programming.

 

[Lorenzo]

I don't think it will change as long as the bulk of consumers value quantity over quality.

 

[Van]

Dishnetwork has 9 satellites in use so as to not overload the bandwith on any given satellite. Im guessing that you have one of the hd recievers from dish and your tv is a large screen hdtv around 56 inches. In my opinion it alot of times comes down to the tv itsself with pq on the set, Ive seen incredibly sharp pq on hdtv's even on the sd channels through dish's recievers on some tv's yet on others the pq looks like clear sand under water being washed around on glass. The best pq quality hdtvs on an sd channel that Ive seen has been sony, sharper vision, zenith, and LG, some of the worst has been rca, magnavox, mitsubishi, toshiba, and panasonic, but for both its not all models that they manufacture. But locals over dish tend to look fuzzy on hdtv's, always has and when ever I meet with customer I always warn the customer to the potential that the locals may not be as crisp as what they are expecting and that there will be side bars on all channels other than hd except for espn hd.

 

[bpickell]

More compression equals less resolution- a less detailed picture. Beta vs VHS tape recorders was a similiar tradeoff. VHS gave more recording time but less resolution.

Ok, wait a minute. I tried that argument a couple weeks ago on another thread, talking about the difference between mpeg2 vs mpeg4. I lost the battle miserabley.

 

[john262]

If you are in an area where you can get good line of sight reception with an OTA you are always going to get better reception IMO. Neither satellite nor cable TV can match it. They can come close but that's it.

 

[deepmoz]

If you are in an area where you can get good line of sight reception with an OTA you are always going to get better reception IMO. Neither satellite nor cable TV can match it. They can come close but that's it.

My question, however, is why that is? Why is it that a good line of sight OTA is much better than satellite or cable?

It's just interesting that we've come full circle from going away from bunny ears to now using some kind of antenna all over again.

 

[TuxCoder]

It's because for OTA, each station has a certain amount of bandwidth available via their equipment and licensing. They use all of this bandwidth to transmit one channel, or worst case, a small handful (maybe 5 channels at most). Typically, the HD channel (if present) gets the vast majority of the allocation while their SD digital(s) alongside (if any) will get a small chunk. The bandwidth going to the HD channel (or the single digital SD channel if that's all they broadcast) is usually enough for an excellent picture quality because little or no compression is needed.

On the other hand, the satellite company is like the station mentioned above. Granted, they have much more bandwidth to play with, but they have even more channels--thousands--to send within that bandwidth. Spotbeam transponders help quite a bit, but they still are forced to use a fairly high (or how about unfairly high ) compression ratio to fit all of the stations in their streams.

As MPEG4 gradually replaces MPEG2, they will have the opportunity to relax the compression on their existing channels, or leave the compression at the equivalent same level and add more channels. They will probably do a combination of the two. At least we can hope for some relaxation of the compression ratios.

 

[jergenf]

Understanding analog from a digital prespective:
With analog OTA you have each channel take up 6Mhz of bandwidth. Example channel 2 is 54-60Mhz then channel 3 is 60-66Mhz, etc, etc. Each analog channel presents a standard definition by using part of the 6Mhz to include three separate signals.
One: Sound (FM)
Two: Luminance or Black & White picture (AM)
Three: Chroma or color overlay (PM)

With the analog picture the Luminance is 640x480 (digital equivalent)
The color overlay perhaps at 200x240 (digital equivalent)
If you marry the chroma and luminance together you'll get a analog picture quality of 320x480 (digital equivalent). About half the detail of B&W but yet much better than the color overlay was.
Sound is comparable the FM radio.

Understanding digital OTA:
Now digital OTA channel also uses same TV channels and are 6Mhz bandwidth however it's equal to 19.4Mbits of zeros and ones. But the station may use most of the digital stream to produce for example 1 HD channel or multiple SD channels. In other words it send video files in the data stream simular to the streaming videos you download off the internet. That is they send multiple programs in the same stream or just one that uses nearly all the data. If a station decides to use SD at the full 640x480 they can fit about 4 subchannels and still have space left. Also notice that 640x480 is about double the color detail of analog even though it the same SD.

Applying same concept to digital cable and satellite:
Satellite and cable use the same principle except they sometime squeeze 6 channels in the same 6Mhz bandwidth resulting in a slightly reduced resolution compared to OTA digital but 50 percent more channels. This bit squeeze is done before the regular mpeg2 or 4 compression is even applied. Now with an ordinary analog TV the picture quality of satellite and cable look about the same as ordinary analog TV quality. The problem is more noticeable now that people have digital TV because you can actually see every pixel, where people with the old analog sets see absolutely no difference at 320x480 (digital equivalent).