Questions about QAM? [Text View]

W Auggie H

09-11-2006, 02:21 PM

Could someone explain QAM to me? I have Comcast Digital Cable in ATL and I do not subscribe to any pay channels. I do get my local "FREE" HD channels and have to use a Comcast box to view them. Does the QAM support in the S3 TiVo mean that I don't have to have that box anymore? Will I still be able to view the broadcast stations stations that I currently get in HD?

I guess I am trying to figure out the difference between QAM and CableCard?

Dan203

09-11-2006, 02:39 PM

QAM is the modulation technology cable uses to put multiple digital stations onto a single frequency. CableCARD is a device used to decrypt the encrypted QAM channels.

As for your actual question... There is no doubt you will be able to view the unencrypted QAM channels with a S3. Any device with a QAM tuner can do this. You should also be able to do basic date/time based manual recordings from these channels, as current TiVos support this for any channel they can tune. So basically the only question mark is whether or not you'll be able to setup Season Passes on these unencrypted channels. If you have a CableCARD then these channels are automatically mapped so that the host (i.e. TiVo) knows that NBC-HD channel 785 is actually on QAM frequency 82.5, so you'll be able to record Season Passes from these channels no problem. However without the CableCARD the only way you'll be able to tell the TiVo to map the data from channel 785 to frequency 82.5 is if TiVo includes some sort of manual interface for doing so, since these mappings are not reported to Tribune and change frequently. If TiVo does not provide such an interface then you will need a CableCARD for the automatic mapping, otherwise all you'll be able to do is manual recordings.

I hope that make sense.

Dan

Bierboy

09-11-2006, 02:41 PM

QAM is the modulation technology cable uses to put multiple digital stations onto a single frequency. CableCARD is a device used to decrypt the encrypted QAM channels.

As for your actual question... There is no doubt you will be able to view the unencrypted QAM channels with a S3. Any device with a QAM tuner can do this. You should also be able to do basic date/time based manual recordings from these channels, as current TiVos support this for any channel they can tune. So basically the only question mark is whether or not you'll be able to setup Season Passes on these unencrypted channels. If you have a CableCARD then these channels are automatically mapped so that the host (i.e. TiVo) knows that NBC-HD channel 785 is actually on QAM frequency 82.5, so with a CableCARD you'll be able to record Season Passes from these channels no problem. However without the CableCARD the only way you'll be able to tell the TiVo to map the data from channel 785 to frequency 82.5 is if TiVo included some sort of manual interface for doing so, since these mappings are not reported to Tribune and change frequently. If TiVo does not provide such an interface then you will need a CableCARD for the automatic mapping, otherwise all you'll be able to do is manual recordings.

I hope that make sense.

DanExcellent explanation, Dan. Even an old guy like me can understand it! Now, if TiVo would just TELL us if the S3 will support manual channel mapping. I know, I know...in a few days (hopefully), we'll know.

cymage

09-11-2006, 02:47 PM

I also have Comcast in Atlanta, and recently hooked up a HDTV that can decode QAM. You can get the broadcast channels in HD, and get some of the basic cable channels in digital cable. Some of the basic channels are missing, and the channel numbers are all different (Example: 108-10 is NBC HD, if I recall correctly). Cablecard will allow you to get the encrypted channels you are signed up for in HD (TNT, ESPN, HBO, etc) as well as have the channels numbered properly so that Tivo can tune properly to record shows. I am planning on turning in my current cable box and get two cablecards as well as get HD from Comcast when I get my Tivo S3.

W Auggie H

09-11-2006, 02:54 PM

That does help, thanks Dan. I guess there are still a good bit of unknowns that we just need to wait to see for ourselves.

thechiz

09-11-2006, 03:07 PM

bkdtv

09-11-2006, 03:46 PM

Right now, when you subscribe to digital cable as well as giving you
the digital STB do they have to turn on the digital channels
at their end ?
Yes.

Virtually all non-local digital channels are encrypted.

You won't get any encrypted channels unless they authorize it on their end. A CableCard provides channel mapping, but beyond that, it does nothing more than provide the means to decrypt the channels. Your cable company still has to give you authorization to decrypt those channels using their computer system.

In that respect, it's just like satellite. You can buy a satellite receiver or a new access card for a satellite receiver, but it doesn't give you access to the encrypted channels until you call to order/enable service.

MScottC

09-11-2006, 06:45 PM

Yes.

Virtually all non-local digital channels are encrypted.

Not always true. I get almost ALL the analog signals as a Digital Simulcast on QAM as well. And my Panasonic HDTV does find them... and a few bonus channels that aren't on my analog lineup that I get unencrypted as well. There are many more that are encrypted, an I assume cablecard or an STB is needed for them.

smark

09-11-2006, 06:50 PM

A quick question...

If you did not subscribe to digital cable, only analog,
(say mandatory through a homeowners association)
would you be able to view and manually record digital channels
with CableCARDs in the TiVo Series 3 ?

Right now, when you subscribe to digital cable as well as giving you
the digital STB do they have to turn on the digital channels
at their end ?

I know that you cannot see the encrypted channels like HBO
or HBO-HD unless you pay for them and they enable them somehow.

Well, 1 you could possibly get what is unencrypted (we in this market tend to encrypt them) and 2, when you say you do not subscribe to digital, is that because the HOA doesn't allow it or just that you get analog as part of being in the HOA?

thechiz

09-11-2006, 07:03 PM

With respect to ONLY the local digital/HD unencrypted channels:

If you have analog cable and do not subscribe to digital cable and
do not have CableCARDs

Will the Series 3 TiVo record those local digital/HD unencrypted channels ?

Do you get something for nothing by not using the cable company digital STB ?

thechiz

09-11-2006, 07:06 PM

Basic cable is included in the quarterly HOA fee.

Most people do upgrade or get satellite service in addition.

But the HOA fee still remains the same in any event.

Dan203

09-11-2006, 07:13 PM

Will the Series 3 TiVo record those local digital/HD unencrypted channels ?

You'll be able to do manual date/time recordings for sure. However it is not yet known if TiVo will provide an interface for mapping these channels to the guide data required for Season Pass & Wish List functionality. If they don't then you'll only be able to get that functionality by renting a CableCARD from your cable provider.

Dan

thechiz

09-11-2006, 07:43 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 for "digital" or any "Digital/HD"
channels what would the TiVo Series 3 be able to record, one way
or another ?

miimura

09-11-2006, 08:10 PM

You'll be able to do manual date/time recordings for sure. However it is not yet known if TiVo will provide an interface for mapping these channels to the guide data required for Season Pass & Wish List functionality. If they don't then you'll only be able to get that functionality by renting a CableCARD from your cable provider.

DanThere's yet another twist here. Even if a CableCARD is required for proper and fullly functional channel mapping, can you get just one and still record 2 unencrypted channels or one encrypted and one unencrypted simultaneously?

- Mike

Phantom Gremlin

09-11-2006, 08:14 PM

Without CableCARDs and without paying for "digital" or any "Digital/HD"
channels what would the TiVo Series 3 be able to record, one way
or another ?
That's a good way to break up the choices. Makes it clear what is being talked about.

I won't buy S3 unless it does B and D without Cablecard (unless Cablecard is free). However, there is one other possibility. I would consider F (HBO only) if it meant free Cablecards for B and D.

HDTiVo

10-06-2006, 07:33 PM

Any handy links to lists/indexes of digital channel mappings?

Thanks.

P.S. I recommend we create a place where such info can be easily accessed on TCF.

moyekj

10-06-2006, 07:59 PM

Any handy links to lists/indexes of digital channel mappings?

Thanks.

P.S. I recommend we create a place where such info can be easily accessed on TCF.
AVS Forum is your best chance to find what you need:
Local HDTV Info and Reception
http://www.avsforum.com/avs-vb/forumdisplay.php?f=45

In my case I have an Excel spreadsheet of Cox, Orange County, CA headend mappings which you can get to from here:
http://replayguide.sourceforge.net/dct6412/DCT6412_Passport.html#Cox_Orange_County_Headend_Map
One problem though is for certain channels they tend to move around quite a lot so the information can quickly get out of date. For many channels, however, such as the HD locals they have not moved around in a long time so a lot of the information is useful.

HDTiVo

10-07-2006, 06:59 AM

AVS Forum is your best chance to find what you need:
Local HDTV Info and Reception
http://www.avsforum.com/avs-vb/forumdisplay.php?f=45

In my case I have an Excel spreadsheet of Cox, Orange County, CA headend mappings which you can get to from here:
http://replayguide.sourceforge.net/dct6412/DCT6412_Passport.html#Cox_Orange_County_Headend_Map
One problem though is for certain channels they tend to move around quite a lot so the information can quickly get out of date. For many channels, however, such as the HD locals they have not moved around in a long time so a lot of the information is useful.
There is some terrific info. It is mostly OTA related.

We need to start accumulating handy links for people so they can easily find their OTAs and their available cable channels w/o cable cards.

Also, I am not sure we have good info in a FAQ here about how to and what you can do with digital channels when not using CC, unless I missed it.

vstone

10-07-2006, 08:36 AM

Pre-cablecard, my S3 assigned all digital channels to detected to channel 0. Did anyone else have this experience?

HDTiVo

10-07-2006, 09:14 AM

Pre-cablecard, my S3 assigned all digital channels to detected to channel 0. Did anyone else have this experience?
No, but my experience has been that 4 detected digital channels are assigned to 0...not 0-1,0-2,0-3,0-4, but just plain 0.

0a-c can be viewed; 0-d is blank.

My ABC-HD affiliate is 0-c. There is no way to record either by channel or manual this station. A Manual recording gets only 0a which is just a commercial for HBO or Cinemax (0b is just a commercial for the other.)

The only way to record 0-c is to manually tune in LiveTV (choose 0 and then up channel twice from 0a to 0c) and then push record button and use record options to approximate length of recording (default is 30min and you can choose stop recording up to 3 additional hrs.)

By contrast, HBO digital is on 85-6, and can be recorded with a Manual recording in the usual way.

moyekj

10-07-2006, 10:36 AM

There is some terrific info. It is mostly OTA related.

We need to start accumulating handy links for people so they can easily find their OTAs and their available cable channels w/o cable cards.
A lot of it is OTA but if you search a few pages you will also see a lot of local cable headend specific threads as well such as:
Seattle, WA - Comcast
San Francisco, CA - Comcast
Norfok, VA - Cox
Houston, TX - TWC
etc.
In my headend thread (Orange County, CA - Cox) for example there are multiple posts concerning unencrypted HD channels and their assignments buried within all the DVR talk.

On another note, Tivo did not pickup any of my unencrypted QAM channels during a scan. Since I know what the frequencies are I tuned to them manually and then recorded a snippet of each one in order to have Tivo add them to my channel list. Most of them ended up being listed by Tivo as the original frequency such as 86-3 cbl, 85-1 cbl, etc. Some containing PSIP info were mapped to the local OTA number. For example, I tuned 99-1 and the channel added ended up being 11-1 cbl.

HDTiVo

10-07-2006, 02:37 PM

On another note, Tivo did not pickup any of my unencrypted QAM channels during a scan. Since I know what the frequencies are I tuned to them manually and then recorded a snippet of each one in order to have Tivo add them to my channel list. Most of them ended up being listed by Tivo as the original frequency such as 86-3 cbl, 85-1 cbl, etc. Some containing PSIP info were mapped to the local OTA number. For example, I tuned 99-1 and the channel added ended up being 11-1 cbl.
Do you think if I redo Guided Setup, then tune the digitals manually, recording a bit on each, I will be able to get some OTA #s mapped?

moyekj

10-07-2006, 05:05 PM

Do you think if I redo Guided Setup, then tune the digitals manually, recording a bit on each, I will be able to get some OTA #s mapped? You don't have to redo guided setup if cable is already one of the inputs. Simply tune the digitals manually and record a snippet of each. Once you do that if you go over to channel list you should see them show up in your list and you can put checkmarks next to them to enable them in the guide listings. Obviously there is no program information for any of them but it's useful to have them in the guide for tuning purposes.

The key is knowing what RF frequencies they are on. In my case once I tuned to 99-1 and recorded a snippet of it the 2 other sub-channels of 99 also showed up. I suppose you could go one by one entering 80-1, 81-1, etc. if you don't know where your unencrypted channels are, but that could get tedious in a hurry since many cable systems go to at least RF 125.

HDTiVo

10-07-2006, 05:36 PM

You don't have to redo guided setup if cable is already one of the inputs. Simply tune the digitals manually and record a snippet of each. Once you do that if you go over to channel list you should see them show up in your list and you can put checkmarks next to them to enable them in the guide listings. Obviously there is no program information for any of them but it's useful to have them in the guide for tuning purposes.

The key is knowing what RF frequencies they are on. In my case once I tuned to 99-1 and recorded a snippet of it the 2 other sub-channels of 99 also showed up. I suppose you could go one by one entering 80-1, 81-1, etc. if you don't know where your unencrypted channels are, but that could get tedious in a hurry since many cable systems go to at least RF 125.
Oh, I did that already with channel scan which found 355 channels. I then hunted through each one to find which had any accessible video and checked those in the channel list by hand.

I have also recorded from each channel in question.

I have no guide data for any of them.

Did you mean only a lucky few get guide data or mapped?

moyekj

10-07-2006, 07:29 PM

Did you mean only a lucky few get guide data or mapped? None of them have guide data. Guide data only says "Regular Schedule". If they did have guide data then we would be able to schedule season passes, etc. but no dice. This is what several (including me) have been asking Tivo to release in a future update - proper unencrypted QAM support.

2 out of 6 HD channels were mapped to their OTA channel numbers:
99-1 = FOXHD -> mapped to 11-1 which is the Los Angeles OTAHD broadcast channel
99-3 = ABCHD -> mapped to 7-1 which is LA OTAHD broadcast channel

The others: CBSHD, NBCHD, WBHD, PBSHD did not get mapped. Haven't bothered to try and add all the digital simulcast channels in the clear since my cablecards are coming Monday anyway.

HDTiVo

10-07-2006, 07:43 PM

None of them have guide data. Guide data only says "Regular Schedule". If they did have guide data then we would be able to schedule season passes, etc. but no dice. This is what several (including me) have been asking Tivo to release in a future update - proper unencrypted QAM support.

2 out of 6 HD channels were mapped to their OTA channel numbers:
99-1 = FOXHD -> mapped to 11-1 which is the Los Angeles OTAHD broadcast channel
99-3 = ABCHD -> mapped to 7-1 which is LA OTAHD broadcast channel

The others: CBSHD, NBCHD, WBHD, PBSHD did not get mapped. Haven't bothered to try and add all the digital simulcast channels in the clear since my cablecards are coming Monday anyway.
So you don't see guide data even for the ones mapped? TiVo doesn't make the 'connection?'

So far none of the channels I have found have mapped, despite several hours recording on two of them.

Its really terrible I can't even do a manual recording on what I call 0-c (ABC-HD)

My cable cards are coming around February.

moyekj

10-07-2006, 08:16 PM

HDTiVo

10-08-2006, 07:16 AM

Yup, I have an 11-1 cbl in the guide that only says "Regular Schedule" for programming info. Right below it is 11-1 ant which has proper guide listings. I have no trouble doing manual recordings on all of the unencrypted HD cable channels however. None of these unencrypted QAM channels will get guide data no matter how long you try recording from them. Tivo has to supply the capability to manually map them to a guide channel for that to work.
I see what you are saying, but I wonder why TiVo wouldn't automatically link a remapped cable channel to the guide data (for the cable.) The channel has been identified, so why not take advantage?

I also agree the manual remap feature seems important.

HDTiVo

10-08-2006, 08:32 AM

I tried the following to get ABC-HD on 0c to record with Manual...

Unchecked 0a,b,d in the Channel List. Did Manual record of 0. That did not work...it still tuned 0a.

Cleared 0a,b,d in the Channel List. Did Manual record of 0. That worked...tuned 0c.

Because all the 0's but one were expendable, I was able to get ABC-HD to work like the HBO-SD*.

* I said earlier 85-6 was HBO digital; I now know it is HBO-SD digital.

crabbon

11-07-2006, 01:51 AM

Has anybody tried setting up a scheduled weekly recording manually for a QAM channel?

I did, and ran into a problem. See this note:

http://www.tivocommunity.com/tivo-vb/showthread.php?t=325391&highlight=duplicate+manual+recordings

Just something to consider if anybody decides to go this route.

ah30k

11-07-2006, 06:36 AM

... can you get just one and still record 2 unencrypted channels...No sorry, unfortunately this scenario (similar an S2-DT using a cable box for a premium channel and its internal tuner for an analog channel) is NOT supported. If you install only 1 CableCARD, the entire S3 reverts to single tuner mode! I think it is called asymetric tuning or something like it and is discussed in the S3 FAQ posted in the sticky. Would really be nice though!

DTap

11-08-2006, 12:09 AM

If you install only 1 CableCARD, the entire S3 reverts to single tuner mode! I think it is called asymetric tuning or something like

I should say upfront I am waiting on my S3 to arrive so I am just learning about this stuff. I agree about the FAQ and documentation on the asymetric tuning. But check out a recent post from user "zjoe". He only has 1 CC installed and is able to record an HD show while seeing the unencryped QAM HD channels with the other tuner. It sounds like he is getting the channel lineups as well.

I really don't know since I don't have my S3 yet but maybe it's a nice to have bug?

...I can't put in the URL until I have 5 posts. So check out the thread called " 1 Cablecard, 2 HD signals?!"

11-08-2006, 04:12 AM

This is the thread:

http://www.tivocommunity.com/tivo-vb/showthread.php?t=325542

Rocko62580

11-08-2006, 09:32 PM

Are we still waiting for Tivo to update the QAM channels? I would buy the new S3 if they got this going! Any updates?

cbordman

11-09-2006, 10:35 AM

Does any cable company publish the list of clear QAM channels that they carry ?

vstone

11-09-2006, 10:44 AM

Does any cable company publish the list of clear QAM channels that they carry ?Some publish a list of HD channels that are free or free with a digital box rental. Sometimes these channels can be inferred from cable lineup listings.

However, as has been discussed elsewhere, you're still subject to the vagaries of your tuner, it's software, and proper population of the digital signal stream by the cable company.

Check out this thread:

http://www.avsforum.com/avs-vb/showthread.php?t=725598&highlight=clear+qam

Saxion

11-09-2006, 06:13 PM

Does any cable company publish the list of clear QAM channels that they carry ?Cable companies do not publish their QAM frequencies, or at least I've never seen one do so. However, QAM assignments are very easy to find as enthusiasts post them in public forums all over the place. Contrary to some people's belief, the Big 6 (ABC, CBS, NBC, Fox, CW, PBS) do not tend to get their frequencies reassigned often, although it is always possible for the cable company to move them at will. If they do, these public forums tend to get updated within hours.

Rocko62580

11-12-2006, 06:20 PM

Sot it would not be possible to use the S3 to record a season pass of Nascar on a QAM channel?

11-12-2006, 06:26 PM

No. No guide data for QAM channels without CableCards.

Rocko62580

11-12-2006, 06:35 PM

No. No guide data for QAM channels without CableCards.
Where do you get a cable card?

11-12-2006, 07:29 PM

Where do you get a cable card?

Your cable company.

Saxion

11-13-2006, 01:53 AM

Keep in mind that your cost for a pair of CableCards (beyond the cost for Limited Basic or Standard Cable service) can be substantial. For Cox San Diego, you would have to add Digital Gateway service ($6/mo), HDTV Service ($9/mo), and a pair of CableCards ($4/mo) for a total of $19/month, at least until they raise prices again.

On the other hand, you can receive the local HD rebroadcasts (ABC, CBS, NBC, Fox, CW, PBS) just fine with a $12.50/month Basic Cable package. TiVo just needs to provide a mechanism for users to map those QAM frequencies into the Program Guide, just like every other HD DVR ever made can do.

I remain hopeful that TiVo will correct this situation soon and add this sorely needed feature. I still very much want to buy an S3, but am now leaning toward an HTPC solution for this very reason. And TiVo needs every single subscriber they can get at this point...

Rocko62580

11-15-2006, 11:11 PM

Waiting for S3 TivoToGo and proper unencrypted QAM support

I am waiting too! Do you think it will happen?

Saxion

11-16-2006, 12:02 AM

You (and I) are not alone. If TiVo comes to realize there is a sizeable number of sales to be made if they added this feature, I believe it will happen. There aren't that many missing features on the S3 that are both fixable and which could actually be showstoppers for some people...TTG, MRV and manual QAM mapping are the only ones that come to mind. If I were TiVo, I'd make first priority anything that is causing me lost sales.

Word from TiVo is they are "considering it".

JimPa

11-16-2006, 03:58 AM

A question about QAM.

Originally, I had a problem tuning in 201,211 and 216 which are local affiliates of nationals networks (36093). You could up/down channel these, but couldn't go to them directly by entering their channel number, if you were already on any of the three. Somewhere along the way and I don't know if Tivo fixed it from a similar post I made a couple of weeks ago or if it was the cable company, 211 and 216 straightened up. 201 is still a problem.
The channel that 201 shares its frequency with (206) tunes in just fine.

My guess is that there is some code somewhere that is wrong/missing that keeps 201 from tuning in properly.

Could anyone with a better understanding of how QAM works comment on if this sounds like a QAM problem with channel designations. Like I said, two of the three channels I had the problem with are now working fine, so I believe that its reasonable to assume that its not a TIVO hardware problem. I'm wondering if there is some coding through Tribune's program guide that affects this as the two channels corrected between 8:00pm and 2:00am. My S3 phones home at around 1:30a.m. I know that software is sometimes updated during the nightly call, but I don't know if Tivo would actually do that for this type of problem.

Any thoughts?

drosoph

11-16-2006, 12:14 PM

I too am dying for in-bound TTG functionality, and QAM mapping!!!

Here's a question for you ... there is a TV Listing in my area that ONLY lists QAM channels, but does not list the standard channels ... Its as if I have TWO cable providers blended together ... Can TiVo do something like that ?

Leo_N

11-16-2006, 01:50 PM