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Ideas for DTV Sub-Channels in Canada?

52K views 177 replies 59 participants last post by  bigoranget 
#1 · (Edited by Moderator)
I noticed that the CBC stations do not have any sub stations. It would be great if CBC can put Newsworld in SD format as a sub channel. Does anyone know if this has ever been discussed?

Thanks, Dave
 
#101 ·
Reply to post # 97

Yes 99.1 FM is Radio 1 here. Though, I don't think that putting radio on subchannels is a new idea? The BBC Radio 4 (equivalent programming in the UK) has been in stereo for many years and is most entertaining. I can't think that the same wouldn't work here also. As for noise on FM stereo - this has never been a problem in the UK - however transmitter powers seem to be much higher than here (main towers at 250Kw per program) and there are many filler towers. Though I hear that UK AM and FM broadcasting may become obselete in the UK in 6 years time. Their DAB system uses the jolly old Hi-band VHF which is being expanded to cover 99% of the population and all BBC channels will be in stereo as they have been for many years.

Don't think that there is any conspiracy against the West but now there is a higher population here than years ago. Better yet maybe the mobile DTV will offer more and better solutions. Radio could also be included in stereo less expensively.
 
#102 ·
The BBC Radio 4 (equivalent programming in the UK) has been in stereo for many years and is most entertaining. I can't think that the same wouldn't work here also. As for noise on FM stereo - this has never been a problem in the UK - however transmitter powers seem to be much higher than here (main towers at 250Kw per program) and there are many filler towers.
You answered your own question of why it wouldn't work here. The noise issue becomes a problem when you have a weak signal. Higher transmitter power and closer towers solve this problem. It would be prohibitively expensive for the CBC to blanket Canada with towers the way the BBC does in the UK and the population densities wouldn't justify it. Stereo might be nice when driving around within Calgary, but start heading east and before long the mono signal will still come in where the stereo one would be too noisy to listen to.
 
#103 ·
When I said that there is no reason why if wouldn't work here, I was referring to the stereo feature on Radio 1.
Agreed that a different technology would be better suited in this country due to very large distances and low population density. Maybe some kind of DAB system or Medium/Long Waveband digital system to replace the AM possibly DRM if I may suggest that? Many sound Subchannels could easily be handled and propogation is very much better than both AM and FM both day and night at lower power levels over great distances and SFNs will work to improve reception. Here is a link from the BBC with some results of their experiment.

http://www.bbc.co.uk/devon/content/articles/2009/05/11/digital_medium_wave_report_feature.shtml

What do you think?
 
#104 ·
Digital Radio to fill audio sub-channel niche

Regarding audio sub-channels of DTV, I don't see that happening since Digital Radio is on the horizon, offering the same thing.

As DAB dwindles to silence in Canada we will see HD Radio rolled out, as it has been in the U.S. already for several years. HD Radio allows FM radio stations will have a main audio channel with 1 to 3 sub-channels. You can read about HD Radio in this thread:

DAB & HD Radio Reception in Canada

That's not on topic here, so let's get back to TV sub-channels in this thread. :)
 
#105 ·
The only digital radio station that I've noticed as a sub-channel is WRUR Rochester. It's a university radio station.
 
#108 ·
I do not recall if this idea was mentioned before... or if it is even possible to do.

Using CTV as an example, would it be possible instead of them broadcasting from Toronto and from the K/W area, that they would just broadcast from Toronto. With the same strength as CBC does (a flame thrower). Most of the time CTV Toronto and K/W are showing the same program. However, when they do show specific local stuff (say at lunch time for example, or evening news) it usually for 1/2 or 1 hour. During that that, the local Toronto stuff would be on the main channel (maybe as 720P), and the local K/W stuff on a sub channel (maybe as 480p).

That way, they only need one tower to convert, yet they still provide some local content for both Toronto & KW. Global could do the same too.

Not sure if it could apply to other areas too.
 
#109 ·
They are limited by the total power that the CN Tower transmitter can output across all the channels broadcast from it at once. The Industry Canada database shows CFTO-DT at 17.4kW on UHF channel 40, but the post-transitional plan is to have CFTO go back to VHF channel 9 at a grand total 2.4kW ERP! :mad:
 
#111 ·
In Houston here, I see that there is a good mix of subchannel usage e.g. KPRC broadcasting in HD 1080i on 2.1 (35 RF), "this" on 2.2 480i and yes Spanish on 2.3 480i LATV. Just excellent usage of the bandwidth. Then on (RF 24) 14.1 KETH-D1 480i, KETH D2 480i, KETH D3 480i, KETH D4 480i, KETH D5 480i.

This allows for broadcasters who don't have the funds for HD to provide more programming at lower investment levels for increased revenue/bandwidth.

For the larger Canadian cities wouldn't this be more economical for the financially strapped broadcasters e.g Alberta Access?

In Calgary CFCN-DT could be 4.1 and Access CIAN-DT 4.2. (Instant savings)! :)
 
#112 ·
Isn't CFCN the CTV affiliate? Why would they want to do this and reduce the bandwidth (and therefore the quality) on their main CTV channel unless the CRTC gave them some credit for this? Doesn't every sub-channel reduce the bandwidth available for the main channel?
 
#113 ·
ACCESS is owned by CTVgm, so they would benefit from the the savings. Having said that, the CRTC has said that all stations in major markets must have their own transmitter, so this couldn't me done in Calgary. This could be done in smaller markets however. Right now step one is to get all the stations in large markets broadcasting digitally. Once that is done, the stations will figure out what they are doing with the smaller market transmitters (with pressure from the CRTC of course ;)) since they have recently been granted an exemption from the analog shutdown as long as they aren't outside of the new (reduced) UHF band.
 
#114 ·
Yes - CFCN is part of CTVglobemedia and so is CIAN (Access). My point exactly, from what I can see here in Houston, KPRC is broadcasting high quality HD 1080i on 2.1 and two other channels on 2.2 and 2.3 at 480i SD. OK the bandwidth must be shared but I don't detect any difference in quality of the HD 2.1 as a result. It seems that the definition 1080i is the same but there are 2 more SD channels. Maybe the data throughput will degrade to that of HD satelite or HD cable but it's hard to notice it! I guess that's why the cable companies can get away with using such drastic compression techniques without affecting their bottom line???? interesting! :)
 
#116 ·
Having two HD broadcasts share one channel will result in picture degradation. How much you notice this depends on a variety of factors including the type of programming being broadcast, the TV you are watching on and how critical an eye you have.

The CRTC are afraid that if this was allowed, the broadcasters will push the envelope and broadcast a picture that is vastly inferior to the OTA viewers under the guise of saving money, while giving a top notch picture to the BDUs.
 
#117 ·
That's interesting because I don't know that here that this is a problem! Ofcourse as I mentionned in my earlier post, there is a DTV channel with 5 SD subchannels and all seem to reveal clear images here! Maybe a little more experience/research is needed by the CRTC as from what I understand CICT-DT is using 19Mbits/sec while the cable and satelite companies are using much less and they manage to sell their product as such!

Ofcourse, I respect any decision by the CRTC to uphold OTA broadcast quality! But my old boss always used to say "you have to make the suit according to the quality or "cut" of the cloth". ;)
 
#120 ·
from what I understand CICT-DT is using 19Mbits/sec while the cable and satelite
I don't know about Shaw, but Roger's uses 19Mbits/sec for the locals, yet people still say they get a better picture OTA. As for DTH, their PQ has always been much worse because of the additional compression, but they have/are switching to MPEG4 to allow additional compression without sacrificing PQ.
 
#119 ·
Just because you can have subchannels doesn't mean you should.
Even with just one HD channel occupying all available bandwidth, there's sometimes evidence of macro-blocking, especially with fast-moving subjects.
(Such was the case during the Olympics and NFL football on CFCN Calgary.)
I can't imagine how weird it would look if only about half that bandwidth was available.
The only sub-channels I would support (in urban markets anyway) would be audio services.
For example, CBC could use its TV stations to carry Radio One, Two and Three. All together, assuming 192 kbit/sec for each stereo audio stream, they would take up about 0.6 Mbit/sec of the 19 Mbit/sec available.
 
#122 ·
The only sub-channels I would support (in urban markets anyway) would be audio services.
Yes, that would be nice. How about low frame rate SD video? An example of this would be a traffic cam refreshed at say 2 frames per second. This should be good enough to serve its purpose (seeing if cars are moving) yet it shouldn't use up very much bandwidth. I know the ATSC standard doesn't technically support this frame rate, but it could be faked by providing a new image every time there is a frame redraw (I think it is twice a second), and saying there are no changes to the image between them.
 
#123 ·
Thank you for your responses on the above topic! I didn't personally experience any macro blocking when watching the Olympics over CFCN-DT but then I receive a good signal from the CFCN tower (76 - 82%).

I also understand that people are saying that the OTA quality is better than the equivalent cable or sateilite and that macro blocking is an issue here in North America. The UK is using DVB which uses an MPEG format which seems to give good clear moving pictures OTA at least to my eye.

I suppose that underlying question is what is visually perceptible on the HD channel versus the bandwidth required and associated costs for secondary programming?
 
#126 ·
Reminder on some facts

The ATSC digital OTA broadcast system, using 6MHz channels, allows broadcasters to slice-and-dice each channel in a variety of ways between television programming and data. Post #15 in the OTA FAQ gives a detailed explanation of sub-channels and bandwidth issues.

If you didn't know that, now you do. :)

As for whether to do it or not, roger1818 reminds that Canadian policy is for major market DTV stations to use their maximum bandwidth for a single channel.

The CRTC has opened the door to co-located rural DTV transmitters, in which a group of broadcasters may share tower and channel space. Whether that means discrete full bandwidth HD channels, discrete bandwidth-reduced HD channels with SD sub-channels, or one SD channel with SD sub-channels remains to be seen in policy and practice.

Now, speaking purely as a consumer, I applaud that major city DTV broadcasters must use their full bandwidth for their single channel. The visual benefits to the viewer are not arguable. It is not necessary for DTV broadcasters to slice up their bandwidth allotments with info that can easily be found elsewhere.
 
#127 ·
Whether that means discrete full bandwidth HD channels,
This is already being done in urban areas (IC is encouraging shared towers and antennas where ever possible) so I doubt if the CRTC means this for rural areas as approving it is a given. They specifically say multicast services, which to me means more than one broadcast per 6MHz channel. This could be two bandwidth reduced HD broadcasts or any of the other combination of HD and SD broadcasts you mention on one (or possibly more) channel. Who knows, they may even experiment with using MPEG4, though that would mean consumers having to buy new tuners.
 
#128 ·
roger1818 reminds that Canadian policy is for major market DTV stations to use their maximum bandwidth for a single channel.
Where is this policy written?

Personally I also prefer the best picture definition possible and so have no argument against this however the rule is rigid in that it doesn't give marginal stations in major markets any chance of lowering their operating costs by means of channel sharing. The US as far as I can now see benefits greatly in their major markets by doing exactly that - e.g. different languages and a greater variety of programming. The UK also does the same thing in it's major market areas via DVB-T multiplexers neatly organized in the UHF band. They are also assigning a dedicated multiplexer for HD channels only using (DVB-T2). :)
 
#131 ·
Where is this policy written?
Post #6 in this thread has a link to the policy. Since then the CRTC has encouraged multicast services outside of the core markets as a way of making the transition to DTV more affordable for the broadcasters, but i expect this original policy still stands in the core markets.
 
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