We receive COMCAST digital cable in suburban MD, near Washington, DC.
I have amplified the cable signal (using an eLabs 2-way antenna amplifier with lower noise characteristics than what you usually see in consumer electronics stores, to cut the funny noise I had with them), split it, sent one half to the RNG110 set-top-box, and one half to an HDTV. I am feeding the box to the TV both through a composite video cable (NTSC, 480i) and through an HDMI cable. All the cables are shielded and reasonably short.
The HDTV is a $280 32" Westinghouse VR-3225, strictly bottom of the line by most of your standards. For example, some TV's have better noise filtering, and have better options for using the whole screen for NTSC signals, and can see the Internet. But the picture can be adjusted to be bright, detailed and colorful, supports 1080i and 1080p, and it looks nice as a computer monitor, which are all we cared about.
I looked at channels that are available on the cable box in HD form, and are available in both NTSC and HD form as clear (unencrypted) QAM channels when the box is bypassed.
The results are really quite intriguing! I expected the set-top-box to yield the best results, but that isn't what happens.
The set-top-box, fed to the TV in NTSC on a composite video cable (480i), is fairly clean, but is blurred, and it is hard to see details like pictures of text, such as when the picture contains a hand-written letter. (Interesting: many advertisements are not blurred, but appear quite sharp. I bet they use edge enhancement.)
The box doesn't look any better when it is fed to the TV through an HDMI cable, though the TV says it is receiving 1080i, and the picture is a wider.
The direct feed analog NTSC form looks far worse. In particular it is both very low detail and very noisy, pixel-to-pixel and frame to frame. The TV's noise filter can mostly clean the noise up, but it is still blurred. I wonder if the digital data impinges on the frequency range of the normal NTSC signal, and is somehow distorting the analog signal...
The direct feed clear QAM form (1080i for the channels I was looking at) is overwhelmingly cleaner and more detailed than anything else. It is easy to read pictures of text.
Does this make sense to anyone?
It does not make sense for a cable box to appreciably degrade the signal! Given that there is local competition from Verizon, as well as satellite competition from DISH TV and DirectTV, Comcast should be creating the best signal possible from its boxes, and I assumed they would do so.
The one thing I am not sure of is that the cable box was not leased as an HDTV-capable box. (Comcast doesn't charge any more for boxes that are, but this is what we have now. My TIVO can't handle HD, so I'm reluctant to switch to an HD box, in case it can't also deliver SD.) It does not look like the modern Comcast HD RNG110 boxes - but it does have the HDMI port, and that port does deliver some channels in 1080i. Is it possible the box down-samples the QAM signal, then upsamples it again to produce HDMI?
I have tried disconnecting the composite video cable from the cable box, on the assumption that producing that signal might put the box in a weird mode, and disconnecting and reconnecting the power plug to reset the box, but that changed nothing.
Can anyone give me reasons for what I see? For those with similar setups, is it consistent with what you see?
We would like to get an HD recorder, either TIVO or lease a COMCAST DVR.
But if Comcast boxes in general deliver poor signals, paying for an HD DVR, from TIVO or Comcast, is a complete waste of money.
(We can't limit ourselves to clear QAM channels, because that doesn't include several channels we like.)
I'm also wondering - do any of you use Verizon, Dish TV or DirectTV in the same geographic region? How good is the HD from these? Comcast is the most expensive, once the introductory offers have expired, as they have for us, so other options can be considered. (Though I think HD TIVO's don't work with DishTV or Direct TV.)
Thanks for any help!
I have amplified the cable signal (using an eLabs 2-way antenna amplifier with lower noise characteristics than what you usually see in consumer electronics stores, to cut the funny noise I had with them), split it, sent one half to the RNG110 set-top-box, and one half to an HDTV. I am feeding the box to the TV both through a composite video cable (NTSC, 480i) and through an HDMI cable. All the cables are shielded and reasonably short.
The HDTV is a $280 32" Westinghouse VR-3225, strictly bottom of the line by most of your standards. For example, some TV's have better noise filtering, and have better options for using the whole screen for NTSC signals, and can see the Internet. But the picture can be adjusted to be bright, detailed and colorful, supports 1080i and 1080p, and it looks nice as a computer monitor, which are all we cared about.
I looked at channels that are available on the cable box in HD form, and are available in both NTSC and HD form as clear (unencrypted) QAM channels when the box is bypassed.
The results are really quite intriguing! I expected the set-top-box to yield the best results, but that isn't what happens.
The set-top-box, fed to the TV in NTSC on a composite video cable (480i), is fairly clean, but is blurred, and it is hard to see details like pictures of text, such as when the picture contains a hand-written letter. (Interesting: many advertisements are not blurred, but appear quite sharp. I bet they use edge enhancement.)
The box doesn't look any better when it is fed to the TV through an HDMI cable, though the TV says it is receiving 1080i, and the picture is a wider.
The direct feed analog NTSC form looks far worse. In particular it is both very low detail and very noisy, pixel-to-pixel and frame to frame. The TV's noise filter can mostly clean the noise up, but it is still blurred. I wonder if the digital data impinges on the frequency range of the normal NTSC signal, and is somehow distorting the analog signal...
The direct feed clear QAM form (1080i for the channels I was looking at) is overwhelmingly cleaner and more detailed than anything else. It is easy to read pictures of text.
Does this make sense to anyone?
It does not make sense for a cable box to appreciably degrade the signal! Given that there is local competition from Verizon, as well as satellite competition from DISH TV and DirectTV, Comcast should be creating the best signal possible from its boxes, and I assumed they would do so.
The one thing I am not sure of is that the cable box was not leased as an HDTV-capable box. (Comcast doesn't charge any more for boxes that are, but this is what we have now. My TIVO can't handle HD, so I'm reluctant to switch to an HD box, in case it can't also deliver SD.) It does not look like the modern Comcast HD RNG110 boxes - but it does have the HDMI port, and that port does deliver some channels in 1080i. Is it possible the box down-samples the QAM signal, then upsamples it again to produce HDMI?
I have tried disconnecting the composite video cable from the cable box, on the assumption that producing that signal might put the box in a weird mode, and disconnecting and reconnecting the power plug to reset the box, but that changed nothing.
Can anyone give me reasons for what I see? For those with similar setups, is it consistent with what you see?
We would like to get an HD recorder, either TIVO or lease a COMCAST DVR.
But if Comcast boxes in general deliver poor signals, paying for an HD DVR, from TIVO or Comcast, is a complete waste of money.
(We can't limit ourselves to clear QAM channels, because that doesn't include several channels we like.)
I'm also wondering - do any of you use Verizon, Dish TV or DirectTV in the same geographic region? How good is the HD from these? Comcast is the most expensive, once the introductory offers have expired, as they have for us, so other options can be considered. (Though I think HD TIVO's don't work with DishTV or Direct TV.)
Thanks for any help!
