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why do HD cards suck compare to my TV's HD Tuner?

post #1 of 19
Thread Starter 
i've tried a few different cards (A180, HD Wonder & i have some low profile card in there now) and none of them seem to pick up signals as well as my TV tuner. really freakin bizarre. anyone have ideas/input?
post #2 of 19
Quote:
Originally Posted by freeeeeman View Post

i've tried a few different cards (A180, HD Wonder & i have some low profile card in there now) and none of them seem to pick up signals as well as my TV tuner. really freakin bizarre. anyone have ideas/input?

You probably have a lot of multi-path in your situation. can you describe your antenna type & placement as well as any obstructions you might have (trees otehr houses etc)?

The tuner cards you mentioned are older cards and don't utilize a 5th gen tuner that is beter for multipath situations. The most recent DVICO fusion line have these types of chips, you may want to check into them. Not all tuners were created equal. I am guessing your TV is newer & has a better tuner. What type of TV do you have?
post #3 of 19
Quote:
Originally Posted by sterno3 View Post

The tuner cards you mentioned are older cards and don't utilize a 5th gen tuner that is beter for multipath situations. The most recent DVICO fusion line have these types of chips

1. Generations are applicapable only to a manufacturer's product -- there is no industry wide accepted generation level ... i.e. there is no such thing as a "5th gen" tuner (despite what the forces of marketing wish to tell you and I)
2. In the vast majority of cases, "5th Gen" marketing claims are in reference to the product using the LG DT3303 demodulator ... it is a single chip...it's LG's 5th generation of demodulator IC's for DTV.
post #4 of 19
PC tuners have genericly less RF sensitivity because they are much more cheaply manufactured than the tuners used in TV sets, set top boxes, and VCRs. You can compensate by using about a 10db inline antenna amplifier. Run the amplified signals only to the PC tuners to avoid overloading the frontend on the other devices.

Gary
post #5 of 19
Thread Starter 
all this good info! thanks! btw, i have a vbox cats eye. should be pretty new. and i have a decent sized antenna on the roof and beyond TV claims the signal strength is between 95 & 100. seems like that ought to suffice. there are trees, sure, but w/ that signal strength, i think i should be good. not too mention my DLP tv (Samsung HL-R5078W) gets the picture fine. i'll hunt around for a 10db inline amp to see if that helps...
post #6 of 19
Your problems may be caused by the capabilities of your graphics card and the different operations that take place in your PC during the transfer of the antenna signals to your graphics card output.
What make model card are you using, what decoder are you using and what resolution are you sending to your 1080p TV over what interface?
Are the problems as severe with 720p programs (ABC, FOX) as they are with 1080i programs (CBS, NBC, and the rest)?
post #7 of 19
Thread Starter 
i have a fanless 7600GT. and i use a HDMI w/ the res of 720p. (tv is technically 720p). and the problem only sometimes happens. it seems to be more tuner related than anything else. some channels stutter sometimes, and then not. sometimes everything works great, and then for no reason, a channel will stutter...
post #8 of 19
Quote:
Originally Posted by freeeeeman View Post

i have a fanless 7600GT. and i use a HDMI w/ the res of 720p. (tv is technically 720p). and the problem only sometimes happens. it seems to be more tuner related than anything else. some channels stutter sometimes, and then not. sometimes everything works great, and then for no reason, a channel will stutter...

What you are describing is most likely multipath distortion. This is caused by the reception of multiple overlapping signals in the RF front end of the tuner. There are three ways to address this:

1) Swap your antenna for one that has a higher gain. The antenna gain (measured in db) is simply a ratio of the signal strength of a station the antenna points at as compared to other signals (other stations AND reflections of the station you are tuned to). Thus a higher gain antenna has the ability to better reject the signals not on the exact compass bearing it is pointed at.

This is THE key factor in multipath - you cannot simply assume that because you have plenty of signal strength, you are golden. It is purely the ratio of the main signal to the reflected signals that matters. If the signal strength starts to overload the front end of the tuner it will reduce amplification using the AGC (Automatic Gain Control).

There is a limitation in gain which is that the higher the gain, the fewer stations will be within the narrower "beam width" of the antenna. The higher gain antennas which are the very best at multipath rejection will require that you point precisely at the station using an antenna rotor.

2) Swap your tuner with one that has better multipath rejection. In fact another of the exact model you own may work as well as another brand of tuner - there is considerable variation in inexpensive PC tuners. Few stores balk at "even exchange".

3) All else being equal, the higher you get your antenna, the better the multipath situation. The best antennas are high above the rooftops, and performance degrades the lower you go right down to an indoor antenna, the worst type for rejecting multipath signals that might be due to reflections off a neighbor's metal roof or aluminum siding.

Gary
post #9 of 19
Quote:
Originally Posted by freeeeeman View Post

all this good info! thanks! btw, i have a vbox cats eye. should be pretty new. and i have a decent sized antenna on the roof and beyond TV claims the signal strength is between 95 & 100. seems like that ought to suffice. there are trees, sure, but w/ that signal strength, i think i should be good. not too mention my DLP tv (Samsung HL-R5078W) gets the picture fine. i'll hunt around for a 10db inline amp to see if that helps...

I'm not familiar with BeyondTV, but in general those signal strength indications don't really mean much.

I hope this isn't stating the obvious, I hope you're comparing apples and oranges. What I mean by that , for example, is comparing what the PC card will receive with a direct connection, and what the TV will receive with a direct connection, not what one receives with a direct connection and one with the use of a splitter. And I'd go even further and if you are using a splitter, reverse the cabling in case it's a problem with the cable you're running to the pc card.

Also, assuming this is multipath, you're probably better off with an attenuator than an amplifier. That is probably cheaper too. I think Radio Shack has one for about $10.00.
post #10 of 19
Again what MPEG2/DVD decoder are you using and do you have hardware acceleration enabled with it since stuttering is normaly caused by your video or audio not being able to keep up with the decoder or by the decoder running in software mode. What is your CPU utilization?
Also 1080i programs are much more likely to stutter then 720p programs due to all of the extra power requied to de-interlace the video and apply motion compensation.
post #11 of 19
Quote:
Originally Posted by freeeeeman View Post

i have a fanless 7600GT. and i use a HDMI w/ the res of 720p. (tv is technically 720p). and the problem only sometimes happens. it seems to be more tuner related than anything else. some channels stutter sometimes, and then not. sometimes everything works great, and then for no reason, a channel will stutter...

If your TV is an Samsung HL-R5078W then its a 1080P TV that can except 1080i via component and HDMI and 1080P 60 via the VGA adapter. Don't run signals into it at 720P.

Maybe its the 720 channels that look OK (ABC and FOX) but the 1080 channels look bad? If so thats because of all the conversions you are forcing.
post #12 of 19
The two cards you listed are not known for having good reception.

In the proven category I'd recommend the Fusion 5 series cards or the VBox 150.

There are a couple of new cards that people have been talking positively about but I tend to wait a bit before jumping in.

btw... the Fusion 5 card in my Media Center has better reception than the Tuner in my Mits DLP.
post #13 of 19
Thread Starter 
thanks everyone!

i have a vbox 150 in it now.

for the decoder, i used the snap stream video decoder. i've also tried cyberlink which came w/ my DVD player, i believe.

i have swapped cables & the TV & PC are each using one of the splits from the antenna. i'll try the attenuator. sounds interesting. i tried not using a splitter, but i just tested the signal strength, i didn't watch TV. tough to test b/c it only stutters sometimes.

and i'm sure my TV is only 720p. i may have pasted the wrong model#. but i only paid for a 720p, so i'm sure that's what i have.

we aren't supposed to have antennas on the roof, so mine is low. that maybe an issue.

and so far, i haven't noticed a difference in reliability between 480, 720 or 1080 broadcasts. so i don't think that's the issue. not too mention that some 720 and 1080 broadcasts will work flawlessly for hours. (namely, NFL football. i've waited 12 years for the chargers to give me something to cheer about!) so the video card was able to keep up then. it more seems like a tuner issue to me.

i'll also try to see if there's a better place for my antenna that won't get me in trouble.
post #14 of 19
The reason HD cards suck compared to TV's HD tuners is interference from the computer.
You have a tv signal that is orders of magnitude smaller than all the various clock signals
that are required to run the computer, confined in a small physical space. The computer
was not designed to have TV signals within its the physical enclosure. it is shielded to
prevent interference to TV and radio signals external to the enclosure. The way to
minimized the effect of the interference is to amplify the TV signal external to the
computer. If you read the specs on most tuner cards for computers, they usually specify
cable or amplified antenna for the input signal.

If the computer tuner shares the antenna with the tv, you will have to put the amplifier
after the splitter , otherwise you run the risk of overloading the TV. By the way,if the TV
works without any issues on the same antenna, you pretty much can rule out multipath
as the cause of your problem. To the best of my knowledge, all the card manufacturers
use standard commercial tuners from such sources as LG or Phillips Electronincs.


wb
post #15 of 19
Just my 2cents worth I in dvb-t land and from what i've tried most cards have a reception issue except for the "Twinhan" card its rock solid.
Here the link to ATSC ver http://www.twinhan.com/product_D%2BA_2.asp
post #16 of 19
Quote:
Originally Posted by Bignickfly View Post

Just my 2cents worth I in dvb-t land and from what i've tried most cards have a reception issue except for the "Twinhan" card its rock solid.
Here the link to ATSC ver http://www.twinhan.com/product_D%2BA_2.asp

Thanks for the link, very limited distribution in the US and no digital cable (QAM).

wb
post #17 of 19
Thread Starter 
looks like sterno3 seems to have hit the nail on the head. i built an antenna stand that raises the thing off my roof, but not high enough to be visible from the street (against the rules) and that seems to clear everything up. heck, i get channels from los angeles (100 miles away) now! thanks all!
post #18 of 19
Quote:
Originally Posted by freeeeeman View Post

i built an antenna stand that raises the thing off my roof, but not high enough to be visible from the street (against the rules)....

In general, such rules are illegal.
FCC Preemption of Restrictions on Antennas
post #19 of 19
Quote:
Originally Posted by SpaceCadet View Post

In general, such rules are illegal.
FCC Preemption of Restrictions on Antennas

Unless your wife is imposing them, nothing the Federal Government can do to exempt you from those rules...

-Suntan
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