HDTV Forum

Richard,

Thanks for the links to the articles. There is another article that seems to suggest that there may be different "flavors" of QAM:

http://www.tvtechnology.com/features/Ma ... arry.shtml

I am assuming that my Sony KDL-46XBR2 QAM tuner does not have visibility to the "flavor" QAM that Comcast is using, although my Elite does. Further, it's interesting to note that the Pioneer Elite does not see Comcast's menu screens for selecting On-Demand movie channels (as there is litttle point in viewing selection screens that can't be used without a STB), while the Sony does.

I'm left to conclude that my two-week old Sony television's QAM tuner is not capable of implenting current QAM standards, while other television manufacturers can. At this point, it doesn't speak well for Sony.

Bill

Sorry Bill but you found OLD and irrelevant news... 2001...

http://reviews.cnet.com/Sony_KDL_46XBR2 ... 01206.html

There are a number of other consumer-oriented features, such as a built-in ATSC tuner for receiving off-air HD broadcasts, but we were surprised to find that the KDS-46XBR2 lacks even single-tuner PIP (Picture-in-Picture). CableCard also goes missing, although we doubt too many buyers will complain.

Going over to the Sony site...
nothing about tuning at all on the spec page

on this page it only mentions ATSC tuner

there is nothing in the owners manual about clear QAM tuning....
http://www.sonystyle.com/intershoproot/ ... ns/xbr.pdf

Sorry I didn't look all this up earlier but it sure looks like all that display's tuner will receive is DTV OTA and NTSC.

Page 50 of that manual speaks of problems relating to digital cable channels and possible remedies. Page 52 speaks of QAM. I'm sure this TV is unencrypted QAM capable. It definitely says no Cable Card functionality.

man is this one elusive...

doing a PDF search on the manual QAM shows up twice....

page 3 states it has a QAM demodulator for unscarambled digital cable
page 52 states it has QAM on cable

Page 20 talks about running auto program for a list of all channels you can receive

No where does it mention some of the wackiness one would encounter with a QAM tuner without a channel map...

Try looking into how the Qam tuners decode the PIDs from these channels.

1) have you done a Channel scan on this unit, to see if the OTA channels being carried on your cable system show up? It sounds like the unit offers no capability to do the mapping manually, and it's unlikely your cable system will map the HD channels down into the low-numbered regions (probably reserved for SD-DTV or even analog).

2) if you do (1), you may find that Comcast has put your HD locals onto higher channel carriers, as my Charter cableco has. For example, I get all my OTA HD locals in Clear QAM, up on channels 100-x, 102-x, 104-x, and now 106-x. It's up to me to figure out that 102-3 is ABC-HD, and 100-4 is NBC-HD, etc. On the Charter STB, they've mapped them to documented 780-ABC, 782-CBS, 787-Fox, 788-NBC, etc. channels. But the QAM carriers are nowhere documented.

Hope this proves helpful.

- Tim

Bingo! Good news... I have all of the HD local channels after all!

As it turns out there are only two varieties of QAM - QAM 64 and QAM256, and reportedly any current QAM tuner that can view some of a cable system's HD channels, can with some work, see the entire channel lineup .

From what I read, all current ATSC tuners are sent a small collection of tables called a "PSIP" - the Program and System Information Protocol. The PSIP is used to define virtual channels, content ratings, as well as program guides with titles and descriptions, the station ID, as well as network IDs; typically WUSA-DT/ABC for example.

One of these PSIP tables is the VCT, or Virtual Channel Table. On a cable system, this table provides the cable operator the opportunity to change the physical location of the station's carrier frequency without affecting the user's notion of the channel number. That is to say, the user can select channel "4.1" on the remote, and the tuner knows that this represents the local NBC affiliate digital feed, which tells the tuner that it is located on the cable's channel "108.1". Thus, the cable operator can locate a channel anywhere within the service, yet keep the RF channel number that broadcasters have used for years for the analog NTSC service.

It was suggested on another forum that Comcast intentionally places errors within the the PSIP tables for certain channels so that the Sony's QAM tuner rejects these channels as it complete its Autotune (that's one-way to get you to upgrade your service). The only way to actually locate these channels from what I can see, is to physically enter the channel numbers into the remote and see if it finds the signal. As videograbber suggests above, it is not uncommon to find the digital channels in the higher 100+ ranges and so that is where I started. Below is a list of the channel locations for the local digital feeds for the Montgomery County's Comcast system:

WUSA DT (CBS) 103.1 WETA Family DT 103.3
WETA DT (PBS) 103.11 PBS Create DT 103.12
WETA World DT 103.14 CW DT 105.1
Tube DT 105.2 WTTG DT (Fox) 105.3
WRC DT (NBC) 108.1 WJLA Weather 108.2
WRC Weather 108.3 WJLA DT (ABC) 108.11
TNT TV 111.11

Thanks to everyone for the help.

Regards - Bill

Those were the wacky channel numbers I was talking about.... glad you found them!

Anyone know for sure if the TIVO series 3 HD DVR has a built-in QAM tuner and if so, can you output recordings to an external hard disk through the USB ports on the DVR?
Thanks in advance. My area has 4 HD channels on basic digital cable (ABC, NBC, CBS & FOX) and I would like to be able to record them but presently the only way I can watch them is by connecting the cable directly to my SONY SXRD 50 inch set which has no output for video signals.

John Devine
in the Palm Springs area.

if the TIVO series 3 HD DVR has a built-in QAM tuner

Yes. As for outputting to an HDD, dunno...