Question for FraserR

I have read that some stations are managing to squeeze 2 HD channels in their allocated DTV Channel. How are they doing this? Is it because they are providing two 720p feeds? What do you think about this in terms of quality of image?

Blackburst, did you ever see this post about ATSC Subchannels:

http://www.digitalhome.ca/forum/showpost.php?p=377665&postcount=14

It answers your question to FraserR.

Funny enough stampeder

Yes I have;)

But I would like to know what somebody on the field thinks about this, and what if any advancements have been made. Are they practical or just a waste of time.

I'm not a fan of too heavy compressing. But...you never know what new codecs are out there at this point

The ATSC committee keeps everyone up to date at www.atsc.org and you can check there if any changes are being considered. At this time the situation is as you see it in that link I gave. The ATSC is discussing possible ideas for ATSC 2.0 such as different compression and other techniques, but a new version is quite a few years away. :)

Blackburst, in your post 640, you ask about 2 HD's in one channel. The following post by stampeder gives an answer that is complete, however you seem to be looking for a more subjective answer. I'm not a very technical guy, but it seems that some encoders can actively manage the inventory of available bits, so maybe a couple HD's could share the available bandwidth. If both pictures got busy, with lots of motion I suspect quality would suffer. For the most part, people find DTV to be very clean, compared to NTSC. I still live in an SD, NTSC household, and DTV looks looks pretty good to me too.

Now, to something where i can be useful. Things seem to be working here right at the moment.

I was wandering if anyone knows that after Feb 2009, Will the transmission of the NEW DTV channels remain at thier current locations or will they use the placement and existing antennas of the analogue stations?
Why I ask, is that RF Transmission is extremely dependant on Height and placement....

deepflowdude, you can check the broadcast antenna locations on both sides of the borders using the Industry Canada database:

http://www.user.dccnet.com/jonleblanc/Canada_TV_Stations/

The plan from Vermont, Mt. mansfield, is that our WCAX TV 3 will change from OTA 53 to OTA 22. All the other DTV signals from here will stay where they are for OTA channel, location and power. After that 17 Feb 09 changeover date, re-scanning will be a must, to capture our new OTA channel. Also, the changeover will require some work, which could result in varying powers, and possibly brief service interuptions, not only for our signal as well as others, not only for that date, but also for the few days before and after. It is a work in progress, which will require patience and persistence. Once all is said and done, the result will be fabulous.

The CBC who is responsible for managing the transmission site on Mount Royal have a project to replace and install new antennas next summer. Have a look at the following link (French) section 3.

http://www2.ville.montreal.qc.ca/ldvdm/jsp/ocpm/ocpm.jsp?laPage=projet29.jsp#documentation

anyone know why dtv3.1 wasn't broadcasting NCIS or Letterman in HD, this isn't the 1st time either, maybe some tech troubles?

Thanks for the link RonXYZ. One thing I find interesting is in the Description of proposed work (French) (http://www2.ville.montreal.qc.ca/ocpm/pdf/P29/3b.pdf) it states:

Aussi, TVA et CTV profiteront de l’occasion pour changer leur antenne respective pour une antenne commune qui permettra de diffuser leur service de télévision en mode analogique et, dès septembre 2011, en mode TVHD.

Now my French isn't very good, but if I translated this correctly it implies that both CTV and TVA plan on using their analog channels for DTV in September 2011 (which shouldn't come as any surprise, but is nice to hear).

Now my French isn't very good, but if I translated this correctly it implies that both CTV and TVA plan on using their analog channels for DTV in September 2011

Yes, I had confirmation recently from CTV Montreal Engineering that they plan to revert to 12 in 2011. When and if they implement their pre-transition DTV undertaking on ch 21 is up to CTV corporate.

Couple of comments on One thing I find interesting is in the Description of proposed work (French) it states:

- I can't see in the appendices where the existing CBFT-2 and CBMT-6 VHF antennas are located on the tower.
- It looks like CTV could share CBC's new UHF antenna for two years to broadcast digitally on ch. 21, at the cost of a combiner port and low power ATSC transmitter. The new digital STL would be needed eventually anyway.
- I wonder why CBC can't use the existing 1986-era 17-35-46 UHF antenna for CBFT-DT 19 and CBMT-DT 20? Perhaps it can't handle the additional power, but you'd think they could pay TQS and TQ to reduce their power by a couple of hundred kW to make up the difference in the short term. Perhaps it's an old design, and the new antenna will be more efficient?
- does the change of antenna, transmission line, and combiner for CFCF and CFTM analog stations require the issuance of a new broadcasting certificate by Industry Canada? Ditto for the FM stations that are changing. (The CBC/SRC changes are probably the implementation of the existing approvals for full dower DT operation)

Summer of 09 is a a very good news as long as the CBC holds their schedule ( I guess I am always a bit naive about this)

- I can't see in the appendices where the existing CBFT-2 and CBMT-6 VHF antennas are located on the tower.

I was wondering the same thing. Looking at the Listings Of OTA Television Stations In Canada (http://www.user.dccnet.com/jonleblanc/Canada_TV_Stations/QC.html) it says the HAAT of CBFT and CBMT are 276 and 259 m respectively where as CFCF-TV and CFTM-TV are 295.7 and 296.3 m respectively, so it looks like they are on a lower part of the tower somewhere.

- It looks like CTV could share CBC's new UHF antenna for two years to broadcast digitally on ch. 21, at the cost of a combiner port and low power ATSC transmitter. The new digital STL would be needed eventually anyway.

Yes, other broadcasters could certainly share this antenna. CBC has left an opening for this when they said (assuming my translation is correct):

Le projet propose aussi l’installation d’une nouvelle antenne UHF
pour permettre la diffusion en mode numérique des stations de Radio-
Canada et, potentiellement de d’autres services de télévision
numérique.

- I wonder why CBC can't use the existing 1986-era 17-35-46 UHF antenna for CBFT-DT 19 and CBMT-DT 20? Perhaps it can't handle the additional power, but you'd think they could pay TQS and TQ to reduce their power by a couple of hundred kW to make up the difference in the short term. Perhaps it's an old design, and the new antenna will be more efficient?

Not sure why, but one thing I did notice is that there actually are two antennas since CIVM-17 and CKMI-46 have an HAAT of 300 m and CFJP-35 has an HAAT of 302 m. Regardless, there must be some sort of technical limitation that prevents them from being used for DTV.

Originally Posted by tvlurker
I can't see in the appendices where the existing CBFT-2 and CBMT-6 VHF antennas are located on the tower.

In section 3.2 page 22 shows the antennas as they are now and page 26 shows them after the project is completed.

In section 3.2 page 22 shows the antennas as they are now and page 26 shows them after the project is completed.

I know, those were the figures I was looking at. I still don't see CBFT and CBMT's analog antennas identified. Page 26 shows CBFT-DT and CBMT-DT, but not their analog counterparts. PAge 22 (the present situation) doesn't show CBC at all.

For that matter, the CBC and SRC FM antenna(s) are not shown either.
It's probably just an incomplete diagram, but I'd be curious to know what the plans would be for those two VHF-TV antennas in 2011.

Roger1818's explanation seems more likely. Perhaps the VHF low antennas are immediately below their VHF high counterparts. After all, they were installed first.

Yes, kool 105 (post 648) there are some problems with the WCAX HD sound, which has been hard to sort out. In the meantime, we are feeding the HD signal with the SD feed, until the problems are corrected.

More,,,,the sound problem started monday night, with normal background sound, but no (or low) voice sound. At some point that evening the studio started feeding the HD path with the SD program stream, which resulted in a proper left and a right stereo, with voices (instead of the 5.1 sound). The SD feed is small (3x4) format, with black sides. Troubleshooting continued into the evening, and also tuesday. At this point I do not have word on if it is fixed, but I have seen some feedback loop anomallies and some material (both commercials and news stuff) where the sound was distorted or not there at all. My guess is that they are still working to fix the original problem, and the rest is the result of the confusion that occurs when fix-it people are rubbing elbows with the show producing people.

They seem to send wide screen when they can, but if the sound is bad, they go to the back up SD feed, which is what you are seeing with the black sides.

I know, those were the figures I was looking at. I still don't see CBFT and CBMT's analog antennas identified. Page 26 shows CBFT-DT and CBMT-DT, but not their analog counterparts. PAge 22 (the present situation) doesn't show CBC at all.



never mind - I found the location of the antennas. They're below the level of the candelabra platform. You can see it in the original application for the Montreal DTV stations on the CRTC website at: http://www.crtc.gc.ca/public/broad/applications/2004/2004-0251-1.zip and http://www.crtc.gc.ca/public/broad/applications/2004/2004-0252-9%20.zip

thanks for the confirmation, FraserR. i did notice on Monday the hd was really having troubles, thought something was wrong on my end. had to watch analog channel 3. Hope it all gets resolved. thanks for keeping us informed.

I have extremely weak signal on WFFF 44.1 / 44.2 today- anyone esle?