Comcast Digital Feed: OTA Format?

I know somebody who has Comcast cable - basic service, no box...
just the wire.

Over the past week or so, they had been losing channels.

Turned out that the lost channels had been converted to digital,
but nobody had told him.

Comcast support fixed him up with a box for each (analog) TV and
now all is well.

The Questions - which probably boil down to one or two actual
issues:

- If he had attached a digital-capable TV to that wire - no box
involved - would he have seen the missing channels?

- Would plain OTA-type converter boxes worked just as well?

- Is the digital signal coming over Comcast's wire the same
signal as what comes in via a rooftop antenna?

- Do digital-capable TVs have tuners that can handle multiple
signal standards...?
--
PeteCresswell

(PeteCresswell) wrote:
The Questions - which probably boil down to one or two actual
issues:

- If he had attached a digital-capable TV to that wire - no box
involved - would he have seen the missing channels?

Yes, though probably on the wrong channel numbers.

- Would plain OTA-type converter boxes worked just as well?

No. They only receive OTA signals; Comcast uses a different standard. (see below)

- Is the digital signal coming over Comcast's wire the same
signal as what comes in via a rooftop antenna?

No. Comcast uses a different transmission standard. (the cable standard makes more efficient use of the spectrum available but is less tolerant of
noise, interference, and weak signals.)

- Do digital-capable TVs have tuners that can handle multiple
signal standards...?

Yes.

--

Doug Smith W9WI
Pleasant View, TN EM66

They should be encrypting the cable channels very soon though.

(PeteCresswell) wrote:

- If he had attached a digital-capable TV to that wire - no box
involved - would he have seen the missing channels?

Depends on if Comcast is encrypting them or not.

- Would plain OTA-type converter boxes worked just as well?

No. They are for 8VSB modulated ATSC. Cable uses 256QAM modulated ATSC.

- Is the digital signal coming over Comcast's wire the same
signal as what comes in via a rooftop antenna?

No. See 8VSB versus 256QAM answer above.

- Do digital-capable TVs have tuners that can handle multiple
signal standards...?

Yes. They do ATSC and NTSC. In addition, they handle 8VSB as well as
256QAM modulated ATSC.

UCLAN wrote:
(PeteCresswell) wrote:

- If he had attached a digital-capable TV to that wire - no box
involved - would he have seen the missing channels?

Depends on if Comcast is encrypting them or not.

- Would plain OTA-type converter boxes worked just as well?

No. They are for 8VSB modulated ATSC. Cable uses 256QAM modulated ATSC.

- Is the digital signal coming over Comcast's wire the same
signal as what comes in via a rooftop antenna?

No. See 8VSB versus 256QAM answer above.

- Do digital-capable TVs have tuners that can handle multiple
signal standards...?

Yes. They do ATSC and NTSC. In addition, they handle 8VSB as well as
256QAM modulated ATSC.

A small caveat on the above:

They do ATSC OR 256QAM - in other words you have to choose between
"antenna" and "cable".

On Sat, 07 Nov 2009 11:06:16 -0500, RickMerrill wrote:

UCLAN wrote:
(PeteCresswell) wrote:
- Do digital-capable TVs have tuners that can handle multiple
signal standards...?

Yes. They do ATSC and NTSC. In addition, they handle 8VSB as well as
256QAM modulated ATSC.

A small caveat on the above:

They do ATSC OR 256QAM - in other words you have to choose between
"antenna" and "cable".

Also, not all digital capable TV's support QAM. Some only support ATSC
8VSB and NTSC.

--
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(PeteCresswell) wrote:
I know somebody who has Comcast cable - basic service, no box...
just the wire.

Over the past week or so, they had been losing channels.

Turned out that the lost channels had been converted to digital,
but nobody had told him.

Comcast support fixed him up with a box for each (analog) TV and
now all is well.

Actually they only give you 2 convertors. You have to pay for additional
boxes.


The Questions - which probably boil down to one or two actual
issues:

- If he had attached a digital-capable TV to that wire - no box
involved - would he have seen the missing channels?

Yes, if the channel is unencrypted and is in QAM format.


- Would plain OTA-type converter boxes worked just as well?

No


- Is the digital signal coming over Comcast's wire the same
signal as what comes in via a rooftop antenna?

No


- Do digital-capable TVs have tuners that can handle multiple
signal standards...?

They should handle OTA and cable QAM

RickMerrill wrote:

Yes. They do ATSC and NTSC. In addition, they handle 8VSB as well as
256QAM modulated ATSC.

A small caveat on the above:

They do ATSC OR 256QAM - in other words you have to choose between
"antenna" and "cable".

A small caveat on your caveat: Cable's 256QAM *is* ATSC. It's just 256QAM
modulated ATSC. [Similar to saying "They have grapefruits and pink
grapefruits. Pink grapefruits *are* grapefruits. 256QAM modulated ATSC *is*
ATSC.]

Wes Newell wrote:

Yes. They do ATSC and NTSC. In addition, they handle 8VSB as well as
256QAM modulated ATSC.

A small caveat on the above:

They do ATSC OR 256QAM - in other words you have to choose between
"antenna" and "cable".

Also, not all digital capable TV's support QAM. Some only support ATSC
8VSB and NTSC.

Perhaps true, but since 8VSB and 256QAM demodulation are now both handled by
the same IC, every HDTV set I've seen sold in the last couple of years did
both. Do you know of a particular model that doesn't? Some older Samsung
units were the last ones I know of that didn't support QAM.

UCLAN wrote:
RickMerrill wrote:

Yes. They do ATSC and NTSC. In addition, they handle 8VSB as well as
256QAM modulated ATSC.

A small caveat on the above:

They do ATSC OR 256QAM - in other words you have to choose between
"antenna" and "cable".

A small caveat on your caveat: Cable's 256QAM *is* ATSC. It's just 256QAM
modulated ATSC. [Similar to saying "They have grapefruits and pink
grapefruits. Pink grapefruits *are* grapefruits. 256QAM modulated ATSC *is*
ATSC.]

I LIKE pink grapefruits. But they tell me that ATSC is 64QAM for OTA.

Exactly where this distinction/rubber meets the road is probably too far
removed from us consumers to make any difference whatsoever. :-)