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Discussion Starter · #1 ·
I just had Comcast out to hook up their HD cable box so now I can finally get HBO in HD. When the cable guy was out he said since I am using the normal cable out of the wall for my connection from the cable box to my HiPix card, I will not be able to get 1080i, the best I can get is 480.


As far as I can tell, the only input option I have for my HiPix card is the normal video cable. I have been using this for the OTA HD and it works, but I am sure the picture could be better.


Am I missing something? How is everyone else hooking up their HiPix cards? Is anyone else using it with Comcast cable HD?
 

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The HiPix and other PC HDTV tuners only support 8VSB modulation, which very few cable providers use. So no, you can't use a HiPix or any PC HDTV card with your cable-provided HDTV.
 

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Quote:
Originally posted by MentholMoose
The HiPix and other PC HDTV tuners only support 8VSB modulation, which very few cable providers use. So no, you can't use a HiPix or any PC HDTV card with your cable-provided HDTV.
When we can get QAM capable tuner cards you should be able to tune non encrypted cable delviered HD.


Encrypted content of course will not be accessible.
 

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Quote:
Originally posted by jmhays
...Am I missing something? How is everyone else hooking up their HiPix cards? Is anyone else using it with Comcast cable HD?
Where are you currently viewing the HD content you get with your HiPix board? Are you viewing it on your computer monitor or an HD ready set? (Sorry, I'm not sure of the capabilities of HiPix since I use a Fusion board). If you are using an HD set then you just need to either swap input cables or buy a switching device to choose the source for the screen. If you are using your computer monitor you are just about out of luck. I think I have read somewhere about a device that allows you to use any computer monitor as an HD set which is a box with DVI or component inputs and VGA connector for the monitor. If this isn't just a figment of my imagination it would probably provide a way to switch between cable and your PC (which would include the HiPix signal). The entire discussion assumes you have a Comcast set top box (STB) that will decrypt the HBO HD channel and output an uncompressed HD signal on either DVI or component.
 

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Quote:
Am I missing something? How is everyone else hooking up their HiPix cards? Is anyone else using it with Comcast cable HD?
You're not. As was stated before, the MSO's in the US have reached an agreement with CE manufacturers to use QAM modulated on the cable network instead of 8VSB which is used for OTA. This has been in the works for some time. Any card that supports 8VSB will not be able to tune and demodulate the QAM signal.


Part of the reason that I think the Fusion style architecture is the future of HDTV cards, as it looks likes the hipix and accessdtv, etc... aren't going to field QAM tuners and that means the center of gravity for software development will shift to these new architectures that use software decoding.


BTW, in our area, Comcast isn't encrypting any of it's HD programming, though that will likely change in the future for things likes HBO HD...


Thanks,

Mike
 

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Discussion Starter · #7 ·
"BTW, in our area, Comcast isn't encrypting any of it's HD programming, though that will likely change in the future for things likes HBO HD..."


Same here, I can actually watch the HD programming using my HiPix card. The issue for me is that I can only view it in 480 instead of 1080i.


Is there a daughter board for the HiPix card? I only have the single card, no remote or anything else, so I may be missing something (parts or ??).


I guess this means that everyone is using the HiPix just for OTA? Is there a better way to hook it up other than the coax cable?
 

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No, there isn't a better way. One way to view the problem you face is compressed versus uncompressed. Your HDTV signal whether it is OTA or cable is delivered in a highly compressed state (about 100:1). Both the HiPix board and your Comcast STB change that to an uncompressed signal. Once it is uncompressed the only non-pro method for getting it into your computer is to throw away most of the detail. There are cards for capturing uncompressed HD signals but they are pro gear and cost in the thousands of dollars. Both composite video and S-video extract an NTSC signal from the source which as you have noted is nowhere near an HD signal. Heck, there isn't even a way to input a 480p signal into a computer that I know of. If there were then some of the games for PS2, GC, and XBox would be more fun to play on your computer monitor.
 

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Carl Romanik writes:

Quote:
Here you go:

http://www.twinhan.com/visiontv-1_4.htm


But I believe that most American cable is encrypted.
That card is simply one of the many DVB QPSK cards. What the poster is asking for is a QAM-capable tuner card which, as yet, is unavailable. But as I posted elsewhere a couple of weeks ago, DViCo is do to release their FusionHDTV III QAM-capable card sometime around the end of October.
 

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Quote:
Originally posted by edmc
Carl Romanik writes:

quote:

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


Here you go:

http://www.twinhan.com/visiontv-1_4.htm


But I believe that most American cable is encrypted.


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






That card is simply one of the many DVB QPSK cards. What the poster is asking for is a QAM-capable tuner card which, as yet, is unavailable. But as I posted elsewhere a couple of weeks ago, DViCo is do to release their FusionHDTV III QAM-capable card sometime around the end of October.
This card is a DVB-C card (C means cable) that can indeed receive QAM

over cable. These types of cards are in use mainly in Europe where they adhere strictly to the DVB-C standard. The US standard that has been adopted is slightly different and I don't know if this card would work or not. But it is moot point anyway since I believe that american cable companies are encrypting their signal, at least for premium content, and they would also likely not authorize such a device, even the ones with a CAM card.
 

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> This card is a DVB-C card (C means cable) that can indeed receive QAM over cable.


I believed the card demodulates via QPSK which is different than 8VSB (the OTA modulation scheme used in the US and supported by the popular HDTV Tuner cards discussed here and on AVS) and different than QAM64/QAM256 (the Cable modulation scheme used by Comcast).


But I see where one can get the idea that the TwinHan card supports QAM in the following text:


QPSK & FEC

Symbol rate: 7Msps max

QAM size: 16,32,64,128,256, Auto

Roll-off factor: 0.13;0.15

FEC: Annex A & C


I've always understood that QPSK and QAM were different and so was confused by the QAM reference on the WebSite. From my perusing, QPSK is somehow "translated" to QAM for transmission over Cable which seems to confirm Carl's statement - but then I don't know why a DVB-C card would mention QPSK.


Can anyone explain how these are the same or different than the HD Cable standard here in the US?


Regarding the encryption fear, this does appear to be in our favor. Various rulings have held that if the signal is carried on the Cable (a big "if" as it turns out as there is no "must carry" for HD on Cable) and is also "in the clear" OTA, then it must be "in the clear" on Cable.


For those that would poo-poo receiving "just" the OTA stations and not being able to receive HBO and the like - I say that would be good enough for me. I'm very jealous of those that actually have the option of OTA. Alas, my location is not so lucky. Hence, I'd be more than happy with even a subset of those OTA-broadcast stations being transmitted on Cable in such a way that a QAM-capable card could tune those not encrypted.


As for my local cable (Comcast - Bay Area), FOX and CBS are not currently carried :-(. NBC & ABC are, but I rarely watch anything on those networks.

But it's a start...
 

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> Can anyone explain how these are the same or different than the HD Cable standard here in the US?


Let me offer one such difference. Apparently, the DVB-C standard uses 8MHz spacings while ATSC (US) Cable uses 6MHz. Of course this means the ATSC standard is more miserly of frequencies allowing for more stations I suppose. But this likely means the TwinHan DVB-C card mentioned above won't be able to tune ATSC Cable despite both systems using QAM :-(
 

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After a little more research, I found that this card should not work in the US because it does not support the type of FEC / interleaving used in the US.


But, as has been mentioned, it looks like compatible cards are coming soon.


If anyone is interested: the DVB-C documentation is: ETSI EN 300 429


US cable standard is described in ITU-T J.83, Annex B. There is also documentation on the scte website (Society of Cable Television Engineers).


Also, the reference to QPSK in the data sheet must be a typo, since I don't think that QPSK is used over cable anywhere.
 

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Quote:
Originally posted by edmc
But this likely means the TwinHan DVB-C card mentioned above won't be able to tune ATSC Cable despite both systems using QAM :-(
ATSC over cable uses 8VSB or 16VSB. But few cable systems use them.


what Carl said
 

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> ATSC over cable uses 8VSB or 16VSB. But few cable systems use them.


Not true. Certain Cable systems have chosen to serve the existing 8VSB tuning capabilities included in certain HDTVs, but the OpenCable agreement (see ITU-T J.83 mentioned by Carl) indeed specifies QAM64 and QAM256.


8VSB was chosen for OTA due to the ability to more easily correct for multi-path - a problem Cable obviously doesn't have.


As I recall, COFDM was the best of the three considered for ATSC at dealing with multi-path but lost out (partially) due to its less efficient use of bandwidth.


Meanwhile, QAM64/256 is more bandwidth efficient but insufficient for dealing with multi-path.


Nevertheless, for most Cable Systems - particularly Comcast mentioned in this thread's title - have either adopted or are adopting the OpenCable standard. In addition, many TV/Tuner manufacturers are busy readying sets with built-in QAM64/256 tuners - as well as addressible decoders which theoretically will allow us to get rid of those cable boxes once and for all.


Alas, this (the "addressible decoder") likely will never make it to a PC despite the "trusted computer" DRM attempts by microsoft and HTPC-ers desires :-(
 

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Gear> 8-VSB at 19.34 Mbps

Gear> COFDM at 19.76 Mbps.

Gear> ...

Gear> Where is that a more inneficient use of bandwidth?


Your memory of what transpired is obviously better than mine - thanks for updating us. As for the answer to your question, 1st off I'd point out that the 19.xx Mbps figures you quote are the bit rate of the demodulated signal. I believe while that bears some relationship to the portion of the frequency range needed to actually carry the stream, I think the number is quite different.


In other words, I think I actually answered your question though, again, my memory may not be totally accurate - specifically, I think I recall that COFDM was criticized for needing 8MHz of bandwidth per station rather than the 6MHz used already in the US. What this means is that the station layout would have to be changed. 8VSB, on the other hand, was able to fit the ATSC stream within the 6MHz alloted frequency range of each station.


Does this ring a bell? Mind you I definately am not defending the 8VSB choice over COFDM. The politics of that decision are well beyond me :)


Interestingly, though, I read thru the datasheets of several DVB devices and learned that several are able to be adjusted for 6, 7, or 8MHz channel spacings. At first blush, this would seem to suggest that DVB could use the channel spacings here in the US. But then maybe it wouldn't be carrying the necessary 19.xx Mbps?
 

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Quote:
In other words, I think I actually answered your question though, again, my memory may not be totally accurate - specifically, I think I recall that COFDM was criticized for needing 8MHz of bandwidth per station rather than the 6MHz used already in the US. What this means is that the station layout would have to be changed. 8VSB, on the other hand, was able to fit the ATSC stream within the 6MHz alloted frequency range of each station.
I thought that Congressional demo was already using 6 MHz ranges for COFDM also.


In any event it seems COFDM may be better for highly populated areas and indoor or portable antennas due to the multipath issues. But 8VSB may have a power advantage in areas where you want a big antenna to reach a large area over long distances. The USA tends to have more of the latter than Europe.


But all this is just the impression I've gotten by readiing a lot of these discussions here and elsewhere. And I think it is forum policy not to open any more of these COFDM/8VSB debates here as they tend to cause flame wars. ;)


- Tom
 

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Quote:
Of late I only respond to misinformation. Don't want to debate.

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Good points! ;)


- Tom


PS - I think it's maybe just the HDTV Forums where they have limited debate on the 8VSB/COFDM issues. I guess maybe it has not been as much of a problem here in HTPC but I forgot where I was due to the topic.
 

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Quote:
Originally posted by Gear
Of late I only respond to misinformation.
:rolleyes:


Ha Ha Ha Ha Ha Ha! I must admit Bob, you really do give me a good laugh sometimes. Funny though, I have noticed that your posts generally contain the greatest concentration of misinformation and "spindoctoring" that I have seen anywhere :p
 
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