Qam?

msu2k · 09-13-2006, 01:35 PM

Just when I thought I understood everything about the Series 3, QAM support is confusing me. I'm a DTV subscriber looking to switch to my local Comcast cable and a Series 3. I currently get my HD locals via an OTA antenna but would ideally like to get them with cable. So what exactly is QAM, and am I understanding correctly that if my HD locals on cable use QAM, my soon to be purchased S3 will be crippled dealing with them?

jfh3 · 09-13-2006, 01:47 PM

If you can get your HD locals OTA, just hook your antenna to the Series 3 and use that for your local network source - in many cases, better quality than you will get from cable (and certainly not worse).

Hook your cable to the other input for the other channels.

If you have good OTA, you don't need to worry about mapping the QAM frequencies from the cable feed.

The Series 3 can handle QAM mapping fine, just that to do so it requires CableCards at the moment. Those that have basic cable packages where the broadcast network feeds are also provided in the clear want a way to map the QAM frequency to the channel guide. The Series 3 doesn't have that feature in the initial release.

bap · 09-13-2006, 01:48 PM

QAM = Quadrature Amplitude Modulation. (Aren't you glad you asked?)

In a nutshell it's the protocol the cable companies use to deliver digital content to you. QAM can be scrambled, and indeed that's what cable companies do in order to protect premium content (HBO, ESPN, etc) from piracy. Your STB descrambles the encrypted QAM in order to display it on your TV.

CableCards are the way QAM decryption is provided to TV's that support them. As a customer, your cable company is required to provide you with a CableCard upon request (there are some exceptions). So all you should need to do is contact your provider and request two CableCards (since the S3 supports 2 of them). If you don't have an STB then there should be no additional charge for the CableCards. If you do then your cable company will probably charge you an additional outlet fee (unless you return the STB). Whatever you do make sure they don't charge you two outlet fees since you're getting 2 CableCards. Explain to them that they're going into a single device, so at most a single outlet fee should apply.

terryfoster · 09-13-2006, 01:48 PM

From what has been said from reviews the S3 can tune in any QAM channel but at this time you cannot map the channel to any guide information (without a CableCARD) so season passes cannot be created. What I haven't heard is if manual recordings or manual repeat recordings can be setup for QAM channels.

QAM is a type of modulation for ATSC signals that are carried over cable lines. QAM has nothing to do with encryption of the datastream. Remember Modems (modulator/demodulators)? Your cable provider modulates the datastream at the head end and then your QAM capabile tuner demodulates the datastream.

vman41 · 09-13-2006, 02:08 PM

It uses a lot of higher mathematics I no longer understand, IIRC using the phase relationship between the 2 sidebands so at the sample instant the 'signal' is at 1 of 64 (QAM-64) or 256 (QAM-256) values which then map to a bit pattern that becomes part of the bit stream.

thechiz · 09-13-2006, 02:11 PM

Splitting up your cable lineup like this:

A Analog channels

all the rest use QAM I guess...............

B "digital" SD channels

C "digital" SD premium channels

D Digital/HD LOCAL (on cable but got from OTA by the cable company)
supposedly unencrypted and "in the clear"

E Digital/HD Plus Tier eg ESPNHD, DISCOVERYHD etc....presumably encrypted ?

F Digital/HD Premium eg HBO HD, Starz HD certainly encrypted.....

Without CableCARDs and without paying your cable company
for "digital" or any "Digital/HD" channels what can the TiVo Series 3
record, one way or another ?

terryfoster · 09-13-2006, 02:15 PM

The S3 (from what has been said in reviews) without a CableCARD can tune in any unencrypted QAM channels (so any unencrypted B,C,D,E,F) and it can certainly record analog cable. Like I mentioned earlier recording QAM channels w/o CableCARD is questionable and season passes are out of the question.

Stephen Tu · 09-13-2006, 02:24 PM

Without cablecards, for cable currently you get full Tivo abilities only on A (analog). Additionally, you can manually record shows by time/channel, no guide data, on D (unencrypted QAM, typically local HD, a small % of digital tier chs, possibly ADS (digital simulcast of analog tier) depending on area), you'd have to check frequently if they shifted the channels around.

Cablecards will give you back full Tivo capabilities on D & the rest if you get the channels. Typically have to pay for digital cable tier to get B&E. Paying for premiums gets you C&F.

Of course one can put up an antenna & get all available OTA w/o cablecards.

thechiz · 09-13-2006, 02:49 PM

Just suppose you live out in the boonies.
Too far for most HD OTA channel reception without a huge antenna in the attic or on the roof. Also, you don't want to mess with satellite as they supposedly compress HD a lot,
(even if they actually give you local network HD stations).

You currently pay for analog cable (no digital channels at all) only.

Without upgrading to digital service can you just get CableCARD's
from the cable company ?

If so would you not then be able to do Series 3 TiVo season pass recordings on category
D, the local Digital/HD stations like ABCHD, CBSHD, FOXHD and NBCHD ?

terryfoster · 09-13-2006, 02:59 PM

Yes the cable card provides the mapping TiVo needs to allow you to create season passes. It is up to your provider for whether or not they would provide CableCARDs w/o subbing to digital cable.

It has been said on this forum that you might be able to sub to digital cable to get the install of the CableCARDs and then cancel your digital cable subscription while keeping the CableCARDs.

msu2k · 09-13-2006, 02:59 PM

So WITH CableCards (which I'll need for HBO HD anyway), I should be able to map all of my HD Locals just fine and be able to set Season Passes, etc.

The people that were upset were the ones who could get HD locals w/o a CableCard and they didn't want to pay for digital cable.

theone · 09-13-2006, 03:04 PM

[quote=thechiz]
Without upgrading to digital service can you just get CableCARD's
from the cable company ?
QUOTE]

Probably depends on your cable company. I called my TWC customer support and was told I could get a cablecard without digital cable. I went to pick it up and was told I would have to sign up for digital cable to get one.

thechiz · 09-13-2006, 03:10 PM

Quote:

Originally Posted by msu2k

The people that were upset were the ones who could get HD locals w/o a CableCard and they didn't want to pay for digital cable.

Some people are just cheap.

Probably the same ones that bitch about the $799 box price ?

GoHokies! · 09-13-2006, 04:31 PM

OK, here's what I see - I just got my S3 and it looks like QAM mapping works without cablecards.

Hooked up cable and antenna (don't have cable card), and tell it to scan for channels.

When I look at the channel list I see for Channel 2 (Baltimore ABC channel that I receive OTA and Comcast offers in HD)

2 cbl WMAR
2 ant WMAR
2-1 cbl *WMAR-HD
2-1 ant WMAR-HD
2-2 ant WMARDT2
2-3 ant WMARDT3

Over on the side the note by the * says "CLEAR: delete scanned (*)"

Looks like it found the HD feed of Channel 2 over the cable just fine!

When I tell it to use the cbl version of 2-1 I still see guide data, so I'm assuming that season passes DO work with the QAM mapping that's going on.

Anyone have any questions or anything, let me know - I'm not an expert on the technology, but I'll be glad to mash buttons and tell you what I see....

I'll also post some pics sometime this evening (I hope, it's gonna be a busy night - so much for getting my grad school homework done tonight!!!).

moyekj · 09-13-2006, 04:35 PM

Looks like perhaps the S3 does read PSIP information which contains channel number and station name. That's the 1st encouraging piece of news about the S3 I have heard since the release...

Cue-Ball · 09-13-2006, 04:36 PM

Quote:

Originally Posted by thechiz

Some people are just cheap.

Probably the same ones that bitch about the $799 box price ?

It doesn't seem cheap to me at all. They already get the stations for free. Why would they suddenly want to pay for what they have been getting for free all along?

bap · 09-13-2006, 04:38 PM

Quote:

Originally Posted by moyekj

Looks like perhaps the S3 does read PSIP information which contains channel number and station name. That's the 1st encouraging piece of news about the S3 I have heard since the release...

When I tinkered with building up a MythTV box I found that my provider (Comcast outside Boston) wasn't including PSIP information in the QAM streams. I did write to them as did a bunch of other people over on the MythTV forums, but I have no idea if they started supplying that data or not. That was about a year ago so I'm hoping they have. In any event, we'll find out soon enough!

rainwater · 09-13-2006, 04:39 PM

Quote:

Originally Posted by thechiz

Some people are just cheap.

Probably the same ones that bitch about the $799 box price ?

I guess I am one of those people who is cheap. I am going to get a S3 when/if they add QAM channel mapping. I can not get all of the major networks OTA in my current location but can get them with unencrypted QAM. I am not going to pay for the HD and digital package just to get a few more HD channels. Maybe when there is more HD content I will add the package but at this point I don't have any need.

AVSman · 09-13-2006, 04:39 PM

Quote:

Originally Posted by GoHokies!

OK, here's what I see - I just got my S3 and it looks like QAM mapping works without cablecards.

Hooked up cable and antenna (don't have cable card), and tell it to scan for channels.

When I look at the channel list I see for Channel 2 (Baltimore ABC channel that I receive OTA and Comcast offers in HD)

2 cbl WMAR
2 ant WMAR
2-1 cbl *WMAR-HD
2-1 ant WMAR-HD
2-2 ant WMARDT2
2-3 ant WMARDT3

Over on the side the note by the * says "CLEAR: delete scanned (*)"

Looks like it found the HD feed of Channel 2 over the cable just fine!

When I tell it to use the cbl version of 2-1 I still see guide data, so I'm assuming that season passes DO work with the QAM mapping that's going on.

Anyone have any questions or anything, let me know - I'm not an expert on the technology, but I'll be glad to mash buttons and tell you what I see....

I'll also post some pics sometime this evening (I hope, it's gonna be a busy night - so much for getting my grad school homework done tonight!!!).

You are lucky. I'm sure someone will correct me if I'm wrong, but if your HD locals over QAM happen to have the same channel number as the OTA HD channel number, you should be able to get the guide data. For me, only some of my (cable) HD locals happen to have the same channel number/frequency as the OTA ones.

AVSman · 09-13-2006, 04:45 PM

Quote:

Originally Posted by Cue-Ball

It doesn't seem cheap to me at all. They already get the stations for free. Why would they suddenly want to pay for what they have been getting for free all along?

Exactly. I get them now, paying $13.50/mo. I'd have to spend $41/mo more to get the lowest-tier digital package in our area. That's almost $500 a year!

By spending so little a month on my cable bill, I was able to save up enough over the past year or so to buy the S3 yesterday. Without bitching.

thechiz · 09-13-2006, 05:30 PM

Quote:

Originally Posted by rainwater

I can not get all of the major networks OTA in my current location but can get them with unencrypted QAM. I am not going to pay for the HD and digital package just to get a few more HD channels. Maybe when there is more HD content I will add the package but at this point I don't have any need.

Rainwater, I was wondering..

Do you currently have a HDTV with a CableCARD in it so
that you can tune in to the cable QAM local HD channels ?

Or do you just know that you would be able to receive them if
you had a QAM tuner ?

*** Or do you have a TV with a QAM tuner integrated in it perhaps ?

TiVoToo · 09-13-2006, 07:09 PM

Quote:

Originally Posted by terryfoster

From what has been said from reviews the S3 can tune in any QAM channel but at this time you cannot map the channel to any guide information (without a CableCARD) so season passes cannot be created. What I haven't heard is if manual recordings or manual repeat recordings can be setup for QAM channels.

I am setting up my S3 even as I type this. No CableCards as yet, but have both Cable and OTA attached. I do a Channel Scan. S3 finds a bunch of QAM channels. All of the unencrypted QAM channels are Channel 0. My channel list shows about 2 dozen channel 0. All of the other 200-300 encrypted channels use the standard XXX-YYY channel numbering. Since ALL of the unencrypted QAM channels are listed as Channel 0, I can't tell which one to pick to set up a manual recording. Cable is with BHN in Central Florida.

What's interesting is that my Sony 60A2000 also has a QAM tuner. When it scans Cable, it finds the unencrypted channels at XXX.YYY. However, the XXX.YYY channel assignments used by the Sony appear to be different than those assigned by the S3.

jfh3 · 09-13-2006, 07:12 PM

Quote:

Originally Posted by GoHokies!

OK, here's what I see - I just got my S3 and it looks like QAM mapping works without cablecards.

Hooked up cable and antenna (don't have cable card), and tell it to scan for channels.

When I look at the channel list I see for Channel 2 (Baltimore ABC channel that I receive OTA and Comcast offers in HD)

2 cbl WMAR
2 ant WMAR
2-1 cbl *WMAR-HD
2-1 ant WMAR-HD
2-2 ant WMARDT2
2-3 ant WMARDT3

Over on the side the note by the * says "CLEAR: delete scanned (*)"

Looks like it found the HD feed of Channel 2 over the cable just fine!

When I tell it to use the cbl version of 2-1 I still see guide data, so I'm assuming that season passes DO work with the QAM mapping that's going on.

Anyone have any questions or anything, let me know - I'm not an expert on the technology, but I'll be glad to mash buttons and tell you what I see....

I'll also post some pics sometime this evening (I hope, it's gonna be a busy night - so much for getting my grad school homework done tonight!!!).

Are you able to see guide data and set a season pass for a program on WMAR if you deselect all the WMAR options except 2-1?

GoHokies! · 09-13-2006, 08:45 PM

Quote:

Originally Posted by jfh3

Are you able to see guide data and set a season pass for a program on WMAR if you deselect all the WMAR options except 2-1?

I can see the guide data, I haven't tried a season pass... I'll get on it and report back.

rainwater · 09-13-2006, 08:49 PM

Quote:

Originally Posted by thechiz

Rainwater, I was wondering..

Do you currently have a HDTV with a CableCARD in it so
that you can tune in to the cable QAM local HD channels ?

Or do you just know that you would be able to receive them if
you had a QAM tuner ?

*** Or do you have a TV with a QAM tuner integrated in it perhaps ?

My TV has a built in QAM tuner. I probably get around 20 channels with about 6 HD channels.

thechiz · 09-13-2006, 09:29 PM

Quote:

Originally Posted by rainwater

My TV has a built in QAM tuner. I probably get around 20 channels with about 6 HD channels.

Ah, I see.

I wonder if there really is anyone out there with CableCARD(s)
in their HDTV but not paying for digital cable service ?

NJChris · 09-14-2006, 11:54 PM

Quote:

Originally Posted by thechiz

Ah, I see.

I wonder if there really is anyone out there with CableCARD(s)
in their HDTV but not paying for digital cable service ?

I'm going to try and see if they will let me not sub to their digitial service (Cablevision, NJ (Oakland) and get the cablecards when I call tomorrow.

I did a scan and it found all the digital channels for the locals(since the additional ones must be encrypted) as well as the HD locals.

I get the channel # (such as 80.40) but no guide info or details for the channel.

I'd rather not deal with putting manual recordings in, so I will be calling for cablecards tomorrow.... hopefully without incident.

GoHokies! · 09-15-2006, 05:06 AM

Quote:

Originally Posted by GoHokies!

I can see the guide data, I haven't tried a season pass... I'll get on it and report back.

I'm sorry, I was mistaken - I was looking at the guide data for the wrong 2-1 (I'm not used to seeing so many different versions of the same channel!).

The 2-1 over cable had no guide data, so therefore was unusable for season passes.

Sorry for any confusion (and getting peoples hopes up) that I caused.

jfh3 · 09-15-2006, 09:48 AM

Quote:

Originally Posted by GoHokies!

I'm sorry, I was mistaken - I was looking at the guide data for the wrong 2-1 (I'm not used to seeing so many different versions of the same channel!).

The 2-1 over cable had no guide data, so therefore was unusable for season passes.

Sorry for any confusion (and getting peoples hopes up) that I caused.

Oh well. I didn't think it would work, but hoping it might ...

theone · 09-15-2006, 10:16 AM

GoHokies! you had me almost buying an S3 based on you getting guide data for clear qam channels!

After being told no I couldnt get a cablecard without upgrading to a digital pkg I email TWC support. I explained that it shows on their website that HD locals are included in the basic cable pkg that I have.

I have been receiving HD channels ever since I bought my TV that has an internal hd tuner.

They decided that I could get a cable card without getting a digital cable package. The catch is I have to upgrade from my current analog basic cable pkg at 16.42 a mo to expanded basic (analog pkg) at 44.99 a mo. Guess what the digital cable pkg costs....45.99. Obviously this makes no technological sense as my TV currently receives the channels fine with no problems.

The cable card would be an addtl 1.75 per mo. I forgot to ask about how much the second one would be.

So just to be able to get channel mapping on the channels I currently receive will cost 48.49 (for 2 cable cards at 1.75ea) a month instead of 16.42. So 32.07 more per mo or nearly $400 a year more forever.

It seems a shame that I will probably have to buy an hd antenna for $100 or so just to get the channel mapping for the S3.