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Does the HD3000 have a poor RF tuner?
PostPosted: Fri Nov 26, 2004 3:11 pm Reply with quote
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Don't get me wrong, I'm enjoying the HD3000, but recently I was surprised to compare it to the ATSC tuner in my HDTV when both were hooked up to the same antenna. I can have cases where the HD3000 can't tune the signal at all, reporting either an unusable 40% signal or no signal at all, and the TV is able to get a clear, dropout-free picture.

This is not a problem for the San Francisco stations which are all in the same direction for me, and for which I can get a fine signal in the 85% range on my porch (rare dropouts, but not unknown) and close to 100% on my chimney once I permanently mount the antenna. However, the San Jose stations while closer come in from different directions. I must point to SF to get 90% of what I want to watch, but I also need NBC from San Jose, and I found it much easier to get the TV to do this than the tuner card.

Of course, when QAM support comes, I may just give up on the antenna, since my TV also has a QAM tuner and I see comcast is providing the local digital stations over QAM.

Anybody else have similar experiences?
Re: Does the HD3000 have a poor RF tuner?
PostPosted: Fri Nov 26, 2004 9:14 pm Reply with quote
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Anonymous wrote:
Don't get me wrong, I'm enjoying the HD3000, but recently I was surprised to compare it to the ATSC tuner in my HDTV when both were hooked up to the same antenna. I can have cases where the HD3000 can't tune the signal at all, reporting either an unusable 40% signal or no signal at all, and the TV is able to get a clear, dropout-free picture.

Anybody else have similar experiences?


I'm running into the same issues -- my Samsung SIR-T351 is doing a better job. Neutral

But, I'm holding out on calling it a useless card until QAM support comes out. I'm really excited to be able to use it with unencrypted cable channels.
PostPosted: Sat Nov 27, 2004 12:38 pm Reply with quote
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Of course, it would be not so catastrophic if tuning to a bad channel didn't cause Mythtv's frontend to crash. Is it the pchdtv's driver that is causing that infinite loop or something in myth? I would be amazed if myth crases any time any tuner card goes to a missing channel.
PostPosted: Mon Nov 29, 2004 6:29 pm Reply with quote
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Anonymous wrote:
Of course, it would be not so catastrophic if tuning to a bad channel didn't cause Mythtv's frontend to crash. Is it the pchdtv's driver that is causing that infinite loop or something in myth? I would be amazed if myth crases any time any tuner card goes to a missing channel.


This happens to me with a plain old bttv capture card. Feel free to be amazed now Smile
PostPosted: Mon Nov 29, 2004 10:12 pm Reply with quote
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does your other hdtv tuner have a preamp built in? That would sure increase quality of the signal. Maybe you should get a LNA (low noise amp) rom radio shack or something
PostPosted: Tue Nov 30, 2004 4:15 pm Reply with quote
spitfire
 
Joined: 09 Nov 2004
Posts: 11
Location: Utah




I don't have alot to compare to the HD3000, however, I do have a HiDTV Pro 2.0 which I purchased because it was noted on the avsforum for having a particularly strong tuner. The HiDTV Pro has a Thompson tuner and it appears that my HD3000 also has a Thompson tuner. And perhaps not so coincidentally they both score nearly identical signal strength values. So perhaps it may not be quite as strong as tuner X or Y, but from my experience I certainly wouldn't call it weak.
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All tuners have preamps
PostPosted: Mon Dec 06, 2004 6:40 pm Reply with quote
Dara
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Anonymous wrote:
does your other hdtv tuner have a preamp built in? That would sure increase quality of the signal. Maybe you should get a LNA (low noise amp) rom radio shack or something

Since the received signal in any communications system (broadcast-only in the case of TV) is usually quite weak, it is ALWAYS amplified using an LNA with automatic gain control inside the receiver before doing almost anything (there may be a low-loss bandpass filter before the LNA). I don't see how adding your own LNA right before the tuner would help (maybe make things worse even). If you add an LNA right at the antenna in the case of long cable runs, that can help quite a bit of course.

But in this case, the signal is obviously plenty strong enough to be received correctly with another piece of hardware. I don't know if there is a standard percentage signal strength you could use to compare 2 tuners. I've seen % signal strength measurements on HDTV tuners, but I never know what that is supposed to mean: % of what? All digital receivers will have a nonzero error rate that decreases as power increases - therefore there is no reference power level to be a % of. (unless there is some standard BER like 1/million).

Digital signals are classically known to work great, or work very poorly depending on signal strength - the zone in between is pretty sharp - hence the term 'waterfall' curves on BER plots. So it might not be that many dB in receiver noise figure that separates the two devices. Another possibility is rejection of multipath - I think some HDTV receivers can do fancy things here (certainly other types of comm systems do).

All in all, this is a bit disappointing - I've noticed my old MyHD 120 card is also vastly inferior to 2 brand new HDTVs I've compared it to, and I was hoping this wasn't the case with the HD3000. Anyone else have comparisons?

Dara
Tuner Comparison
PostPosted: Tue Dec 07, 2004 9:52 pm Reply with quote
rab45
 
Joined: 24 Nov 2004
Posts: 42




I have an RCA DTC-100 connected to the same antenna as the HD3000. They seem very comparable in performance with maybe the HD3000 being a little better (even thought the cable is 25 feet to the HD3000 and only about 6 feet to the DTC-100). I also have an RCA 38" widescreen HDTV with a DTC-100 built-in in a nearby room. This set-up is VERY sensitive and tends to get more interference. I have a Samsung something orther (I don't remember the model number off hand) downstairs and it seems to be very sensitive to antenna direction and signal strength. All in all, the HD 3000 seems to work very well.

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Does the HD3000 have a poor RF tuner?
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