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June 16, 2021 7:50 pm  #31


Re: HD Radio In Toronto

RadioAaron wrote:

tvguy wrote:

In a matter of weeks, look for HD on CJKX 95.9 in downtown toronto.   They have been approved for HD operation for the repeater which is on First Cdn Place and the equipment may have been installed.  Right now, the downtown repeater is analog only and nulls out the HD subcarriers from Durham region on the frequency.

That one's interesting, as I find the analog/analog transition from the Oshawa signal to the Toronto signal imperfect, specifically once you get on the DVP. Will this help?
 
 

There is no simple answer as to how effective an HD repeater will be.  There are a number of variables that can be tweaked to optimize the reception area. With synchronous repeaters, there is always some degree of interference between the two signals, creating a "mush zone". For analog signals, the conventional wisdom has been to "synchronize everything", that is to say the carrier frequencies are locked using GPS, and the modulation tracking within 0.1 dB.  The 19 kHz stereo pilot must also be locked. Then the audio modulation can be offset (by microseconds) so that the main and repeater signals arrive at the desired location at the same time.  The effective radiated power and antenna pattern of the repeater are two more variables.

For a given reception point, the difference in dB that must be achieved between the desired repeater signal and the undesired main signal will vary dramatically with the amount of error in the arrival time of the two signals. When the reception point is in line with both transmitters, the timing error can be reduced to zero, but as you move away from that straight line, the error will increase to the point where the interference becomes evident.  In the case of CJKX, the area west of First Canadian Place will likely have the best and most consistent signal quality.  Areas to the east will likely have drastic variations. 

There is very sophisticated software that allows playing with these variables to optimize the size and location of the interference-free reception zone for the repeater. Another factor which you can't really control is terrain obstruction.  Repeaters work best when the main signal has a lot of blockage. 

The hybrid digital signal requires a lower desired/undesired ratio between the two signals, and therefore the interference-free reception area of the repeated HD signal in theory should be significantly larger than that of the analog signal.

All this to say that the success of the CKJX-HD repeater will depend on whether they employ all of the available techniques, and purchase the additional equipment which will allow precision synchronization and adjustment of the aforementioned variables. 

Stay tuned.

 

Last edited by Skywave (June 19, 2021 5:43 pm)

 

June 16, 2021 11:31 pm  #32


Re: HD Radio In Toronto

markow202 wrote:

FCP was never as good as CN but yes that could be due to power.  I think that roof would also be super jammed if this occured.  CN is still the tallest over the entire city. but, good analogy I thought about this once.

Why is the CN Tower a less desirable place?

"Less desirable" only for FM's in terms of the physical location of the tower, as well as the limited space and ease to replace the Master FM systems. 

 

June 16, 2021 11:43 pm  #33


Re: HD Radio In Toronto

Juggie1 wrote:

Biggest issue with FCP is Safety Code 6! With the current load of rf stations including tv, fm, and communications companies, the rf level is at or just below the level where power reductions would start happening. Adding stations up there would further reduce the current power levels of existing stations and may even mean that the top floors may not be useable.

Also, FCP is just under 1000 feet and the CN master fm antenna is just under 1600 feet up! That height difference means much better reach at a much lower power level and a big hydro savings! Also lower maintenance costs at CN tower as only one antenna system to maintain. FCP would have to either spend lots of money for a common antenna system or each station would have to put big filters in to prevent reradiation issues!

Very interesting! I assume no FCP broadcasters are currently inhibited by these regulations? As in, are any operating at a lower power to limit overall radiation? 

I'm shocked people are allowed to work on the upper floors full-time as it stands now.... I wouldn't be surprised if the levels of radiation result in higher cancer rates among those BMO staffers. 

I guess all I'm wondering is if it would be cheaper (and easier) to move the CN FMs to FCP (and possibly include even more FMs on an Onmi-Directional Master FM system there), rather than upgrading the almost 50 year old systems at CN in their limited space and inaccessible spire. 
 

 

June 17, 2021 10:47 am  #34


Re: HD Radio In Toronto

torontostan wrote:

Juggie1 wrote:

Biggest issue with FCP is Safety Code 6! With the current load of rf stations including tv, fm, and communications companies, the rf level is at or just below the level where power reductions would start happening. Adding stations up there would further reduce the current power levels of existing stations and may even mean that the top floors may not be useable.

Also, FCP is just under 1000 feet and the CN master fm antenna is just under 1600 feet up! That height difference means much better reach at a much lower power level and a big hydro savings! Also lower maintenance costs at CN tower as only one antenna system to maintain. FCP would have to either spend lots of money for a common antenna system or each station would have to put big filters in to prevent reradiation issues!

Very interesting! I assume no FCP broadcasters are currently inhibited by these regulations? As in, are any operating at a lower power to limit overall radiation? 

I'm shocked people are allowed to work on the upper floors full-time as it stands now.... I wouldn't be surprised if the levels of radiation result in higher cancer rates among those BMO staffers. 

I guess all I'm wondering is if it would be cheaper (and easier) to move the CN FMs to FCP (and possibly include even more FMs on an Onmi-Directional Master FM system there), rather than upgrading the almost 50 year old systems at CN in their limited space and inaccessible spire. 
 

Oh I get you now, in terms of the accessability in the tower.  Well, I still find it strange how when it was built, the white radome on the antenna was installed first, then the antennas were put into place.  So im guessing a reverse order could be in process.  Who knows.  Incredible its working full time for that long with literally no issues.

 

 

June 17, 2021 3:28 pm  #35


Re: HD Radio In Toronto

A bit of firsthand knowledge.  A couple of things about FCP vs Master FM..  First, the Master FM at CN Tower was (originally) designed for omni-directional stations. Most of the stations in the early 70's were relatively grandfathered, in terms of their coverage - case in point CKFM, CHFI and CHUM FM.   CKFM, if memory serves me correctly was over 210 kw at the old CIBC building - and omni directional.  It's last "home" was on the "new" CIBC building at a relatively high power and omni-directional.   CHFI was at an even higher power from the CFTO tower in Agincourt.  So when they moved to CN Tower the Class "C" grandfathered stations were around 40 KW on Master FM.  CHIN FM was at a lower power because it is "B" class.  The Department of Transport (later ISED) wanted all Toronto area TV and FM stations to be clustered at one point.  When CKO came on the air, - which required a directional antenna at 99.1, it operated from FCP and various other stations followed. Many were licesned after the CN Tower master FM was built.    My recollection was that the CN Tower went into operation in 76, but the Master FM antenna was designed months or a couple of years before it was installed up there.  Antenna installation(s) took place in '75.

One other odd recollection.  I remember going up to the roof level of the "new" CIBC building when I worked at CKFM.  (before the windows were installed within the building) I took a portable TV up there and did some TV DXing.  This was when the CKFM antenna was being installed and the building was under construction.  That's a long time ago, a number of years before the CN tower went into operation.

 Most of the stations at FCP have highly directional antennas to protect U.S. and other Canadian stations on the same or adjacent frequencies.  Several were "drop in" frequencies - like 88,9 CIRV which originally operated at 88.7 (WBFO's frequency) and the arboriginal radio station on 106.5 (WYRK Buffalo).  (Classical) 96.3 "relocated" from an office tower in Mississauga and is directional to protect 96.1 Buffalo (formerly WJYE).   Other stations have literally been shoe-horned into the site, with specially designed antennas - i.e. 96.7 CFZM-FM-1. There have already been major changes to several FM antennas at FCP due to Safety Code 6 problems.  The problems included high levels of radiation over cooling towers on the roof. Several stations were required to re-design their antennas, to throw less RF onto the rooftop.  This antenna work occurred in May 2009 and included CFMZ, CBLA-FM and CJBC-FM.  There were some other Safety Code 6 issues when the outside (granite) cladding started falling from the face of the building.  There was a multi-year project whereby sidecars of workers (in side cars) were slung over the side of the building.  RF levels had to be reduced for some stations (that over and above the antenna design changes).  I believe that RF levels were reduced on "working" nights to accommodate the crews on the rooftop.  Every addition of an HD signal notches up RF levels a few hundred (or thousand) watts.  My recollection is that some prospective tenants proposed adding height to one or more of the towers, so that rooftop level RF could be reduced, or at least the stations requiring power increases, would not add to the RF at rooftop level.  Bottom line, FCP is basically "maxed out".  The remaining TV transmitters, which I believe are standby/auxiliary to the CN Tower (main) UHF transmitters, have not added to the SC6 problems.  This has been an FM issue, primarily.  I think that had Evanov been granted changes for Proud FM or CIDC at FCP, there would have been some significant power reductions that would have been required of incumbent stations.  The evanov applications were turned down on multiple occasions.  Skywave a big yellow board contributor may have additional first-hand knowledge.  FCP is also a very expensive place to do business. It is to my knowledge the only antenna site in the world, where the landlord charges an excess fee to stations for each HD subchannel that they use, after the main HD channel.   That surcharge works out to be around 10% of the cost to transmit from the building.   So, for example if the site rental fees were $160K per year for the main signal, the HD-2 would cost an additional $16K , plus some additional nickel-and-dime fees, including additional costs for the hockey-puck sized GPS antenna which is needed for HD operation.  To my knowledge there aren't similar HD2, HD3 etc costs anywhere in North America - by other landlords.  An FM station with 3 HD signals will be pushing $200K per annum, plus additional fees for standby generator, and other sundry costs imposed by Brookfield.   Clearly if you're operating an omni-directional station, CN Tower is a better location, particularly the "business" environment.  The building management at FCP has if I can use a phrase "take no prisoners" negotiating tactics.  And of course they have a number of tenants who couldn't relocate at any cost that would make business sense vs. the annual increases in costs charged by Brookfield.

Last edited by tvguy (June 17, 2021 3:44 pm)

 

June 17, 2021 4:38 pm  #36


Re: HD Radio In Toronto

tvguy wrote:

I remember going up to the roof level of the "new" CIBC building when I worked at CKFM.  (before the windows were installed within the building) I took a portable TV up there and did some TV DXing.  This was when the CKFM antenna was being installed and the building was under construction.  That's a long time ago, a number of years before the CN tower went into operation.

All great info, as always tvguy, but inquiring minds want to know: how did your TV DXing go? Any out of towners worth mentioning? 

 

June 17, 2021 4:49 pm  #37


Re: HD Radio In Toronto

It was a hot and muggy day. I remember because there was very little visibility.  No great tropo that day.  I was using something minimal like a 4-bay bowtie.   The Erie PA stations were certainly very strong at that elevation.  My recollection is that the flamethrower on Ch. 26  from Jamestown NY which was an indie that carried CFTO's programming a great deal of the time - was rock solid.   Only had a few minutes to try things out and the TV was a very heavy "transportable" - clunky - because it was of late 1960's vintage.  Commerce Court West was completed in '72, so I would have been up there in the summer of '71.  Not that many local (Canadian) TV stations on the air at the time.  My visit preceded Global, Citytv, Omni(s), and many other stations.  So there wasn't much on the air on UHF at that time in this area.  DXing would have been great - had there been an opening.  OECA (TVontario) would have been transmitting either from Canada Square or perhaps the old CBC tower on Jarvis St.

Last edited by tvguy (June 17, 2021 4:52 pm)

 

June 17, 2021 5:25 pm  #38


Re: HD Radio In Toronto

Wow. One of a kind opportunity. Glad you were able to take advantage of it. 

 

June 18, 2021 11:55 am  #39


Re: HD Radio In Toronto

Wow great indepth info as always Tvguy!  Have you been or worked on CN yourself?

 

June 18, 2021 1:12 pm  #40


Re: HD Radio In Toronto

Tim Brown 2016 wrote:

tvguy wrote:

CHUM FM will not be running HD any time soon, from what I hear. 
The balance of stations which broadcast from the CN Tower, will need to have an upgrade to the "Master FM" antenna

Thanks for this tvguy... To be precise, is it not the CN Tower FM combiner that needs replacement to accommodate HD Radio? Why would the actual antenna need to be replaced? From what I recall (40 years ago), that's a broadband antenna up there. Is it a polorization issue?

The antenna itself probably does not need any changes as it is broadband.  The main issue is the FM combiner.
 
A multi-station combiner is really a set of filters interconnected such that all signals "combine" to feed a common antenna all the while preventing each stations signal from getting back into each other’s transmitter.
 
Due to FM band frequencies, each “filter” is physically large (about the size of a big hot tub), and there are multiple filters per station.
 
The filters are finely tuned to pass only a single FM station, within a specific frequency & bandwidth.  Adding HD signals expands the bandwidth such that the existing filters will chop off some of the HD signal.  Each stations series of filters would need to be retuned and/or replaced to permit HD transmission.  That’s a big job and would involve coordinating with all other players using the combiner.
 
Unfortunately, I don’t have a personal photo of the CNT FM combiner but a simple search reveals a picture taken by Mr. Fybush during one of his site visits.  Perhaps he has more images to share.

https://www.fybush.com/wp-content/uploads/2015/05/cn-combiner.jpg
 

 

 

June 18, 2021 2:12 pm  #41


Re: HD Radio In Toronto

I was able to find a few photos in my library that might be of interest:

photo 1 - looking down, from the very top of the CN Tower mast, at a single panel of the original CITY-TV antenna.  It is located in the top aperture on the CN Tower (the red section).  The outer radome can be seen on the left and right side of the photo.  It is very tight up there (only 5 foot diameter).  There are some fine lines in the image due to RF radiation (from other TV transmitters).  This antenna is now out of service due to the repack.

photo 2 - a view (from 1979) looking down, from the CITY-TV aperture, into what was designated as "future antenna space".

photo 3 - an internal view, looking down, into the FM antenna section of the mast.  You will note there is a fair amount of space in this section.  I have highlighted a fellow climber in yellow, standing on a rest transition section, for reference.  A number of transmission lines can be seen along with a "spider" splitter to feed one of the tiers of the FM antenna.

photo 4 - a view of the top of one of the FM antenna dipoles.  The wire mesh, in the lower section of the photo, and behind the antenna acts as a reflector.  The inside, and curvature of the radome can be seen here.

https://i.ibb.co/ChhQdxq/Photo-1.jpg
https://i.ibb.co/qWSJwxz/Photo-2.jpg
https://i.ibb.co/bPB8jHd/Photo-3.jpg
https://i.ibb.co/JdJffTg/Photo-4.jpg

 

 

June 18, 2021 2:26 pm  #42


Re: HD Radio In Toronto

My understanding is that the new Master FM antenna will occupy the aperture formerly used by CBLT Channel 5.  This will raise the centre of radiation by about 34 metres.  The Class C stations operating at 40 kW max ERP (for Class C equivalence) can reduce ERP to 32.5 kW.  This relocation has several benefits:
1) increases the distance to the Skypod, thereby reducing Safety Code 6 radiation.
2) lower transmitter output powers.  
3)increased headroom for the combiner and the antenna harness and radiators.

The CN tower master antenna is rated at a maximum of 150 kW per half..  The combiner is certainly at its limit, and in any event my understanding is that the bandpass curves were less than ideal for passing HD sidebands. A very important consideration with hybrid digital is the peak breakdown voltage which occurs when the digital carriers all add up.  For hybrid digital operation, the limiting factor for transmission lines and antenna harnesses is not so much the average power rating but rather the peak breakdown voltage.  This is a function of both the number of transmitters AND the power output of each transmitter.

Further to another question, CFTO-DT uses part of the original Channel 9 antenna, with the dipoles rotated from horizontal to add a vertical component, resulting in elliptical polarization.

 

June 18, 2021 3:13 pm  #43


Re: HD Radio In Toronto

Fascinating stuff, although I have to confess some of it is a bit above me (kinda like the CN Tower itself!) I really love the photos. They remind me of a great news serial City TV's Kevin Frankish once did. It was called "Hidden Toronto" and took viewers into places no member of the public could go so they could see what is normally off limits. (Backstage at a Mirvish play while it was in performance, for instance or at the City's water filtration plant to discover what goes on behind closed doors. That kind of thing.)  One of them was City's room (or whatever it was) on the CN Tower. 

I still remember how it ended. Frankish started poking around in the place and pretended to pull out a wire, asking, "I wonder what this does?", which sent the screen to static and snow for about 5 secs. He then put it back, saying something like, "I guess we know now!" 

It was a great 5-day series and I wish it was still around online. Really interesting look at places we were never meant to see. Years later, there would be an annual tour called Doors Open Toronto with a similar theme, but this was long before that. (And I think one of the Doors Open places they toured was the new City TV HQ at Yonge & Dundas. Talk about completing the circle!) 

Last edited by RadioActive (June 18, 2021 3:17 pm)

 

June 18, 2021 3:53 pm  #44


Re: HD Radio In Toronto

In Phase wrote:

I was able to find a few photos in my library that might be of interest:

photo 1 - looking down, from the very top of the CN Tower mast, at a single panel of the original CITY-TV antenna.  It is located in the top aperture on the CN Tower (the red section).  The outer radome can be seen on the left and right side of the photo.  It is very tight up there (only 5 foot diameter).  There are some fine lines in the image due to RF radiation (from other TV transmitters).  This antenna is now out of service due to the repack.

photo 2 - a view (from 1979) looking down, from the CITY-TV aperture, into what was designated as "future antenna space".

photo 3 - an internal view, looking down, into the FM antenna section of the mast.  You will note there is a fair amount of space in this section.  I have highlighted a fellow climber in yellow, standing on a rest transition section, for reference.  A number of transmission lines can be seen along with a "spider" splitter to feed one of the tiers of the FM antenna.

photo 4 - a view of the top of one of the FM antenna dipoles.  The wire mesh, in the lower section of the photo, and behind the antenna acts as a reflector.  The inside, and curvature of the radome can be seen here.

https://i.ibb.co/ChhQdxq/Photo-1.jpg
https://i.ibb.co/qWSJwxz/Photo-2.jpg
https://i.ibb.co/bPB8jHd/Photo-3.jpg
https://i.ibb.co/JdJffTg/Photo-4.jpg

 

Wow thanks so much for sharing these and the info.  Post more stuff if you have the time   Im always facinated in the enginerring of the CN tower behind the scenes. 

Last edited by markow202 (June 18, 2021 3:57 pm)

 

June 18, 2021 3:54 pm  #45


Re: HD Radio In Toronto

Skywave wrote:

My understanding is that the new Master FM antenna will occupy the aperture formerly used by CBLT Channel 5.  This will raise the centre of radiation by about 34 metres.  The Class C stations operating at 40 kW max ERP (for Class C equivalence) can reduce ERP to 32.5 kW.  This relocation has several benefits:
1) increases the distance to the Skypod, thereby reducing Safety Code 6 radiation.
2) lower transmitter output powers.  
3)increased headroom for the combiner and the antenna harness and radiators.

The CN tower master antenna is rated at a maximum of 150 kW per half..  The combiner is certainly at its limit, and in any event my understanding is that the bandpass curves were less than ideal for passing HD sidebands. A very important consideration with hybrid digital is the peak breakdown voltage which occurs when the digital carriers all add up.  For hybrid digital operation, the limiting factor for transmission lines and antenna harnesses is not so much the average power rating but rather the peak breakdown voltage.  This is a function of both the number of transmitters AND the power output of each transmitter.

Further to another question, CFTO-DT uses part of the original Channel 9 antenna, with the dipoles rotated from horizontal to add a vertical component, resulting in elliptical polarization.

Will this be the actual plan?  It does make perfect sense. Coverage might be even better!  Also, where did Bell stick their new HD radio antenna which im told is what caused that smoldering mess in 2017?

 

June 18, 2021 3:59 pm  #46


Re: HD Radio In Toronto

markow202 wrote:

Also, where did Bell stick their new HD radio antenna which im told is what caused that smoldering mess in 2017?

I have the same question! I assumed Bell was in that old CBC space now.....

 

June 18, 2021 4:30 pm  #47


Re: HD Radio In Toronto

RadioActive wrote:

One of them was City's room (or whatever it was) on the CN Tower.  I still remember how it ended. Frankish started poking around in the place and pretended to pull out a wire, asking, "I wonder what this does?", which sent the screen to static and snow for about 5 secs. He then put it back, saying something like, "I guess we know now!"

one more photo - the original CITY-TV transmitter at the CN Tower

https://i.ibb.co/nPpkgzR/Original-CITY-TV-transmitter.jpg

 

June 18, 2021 4:37 pm  #48


Re: HD Radio In Toronto

In Phase wrote:

RadioActive wrote:

One of them was City's room (or whatever it was) on the CN Tower.  I still remember how it ended. Frankish started poking around in the place and pretended to pull out a wire, asking, "I wonder what this does?", which sent the screen to static and snow for about 5 secs. He then put it back, saying something like, "I guess we know now!"

one more photo - the original CITY-TV transmitter at the CN Tower

https://i.ibb.co/nPpkgzR/Original-CITY-TV-transmitter.jpg

lots of great movies and epic shows came out of that!  Unlike now...

 

June 18, 2021 6:19 pm  #49


Re: HD Radio In Toronto

Skywave wrote:

RadioAaron wrote:

tvguy wrote:

In a matter of weeks, look for HD on CJKX 95.9 in downtown toronto.   They have been approved for HD operation for the repeater which is on First Cdn Place and the equipment may have been installed.  Right now, the downtown repeater is analog only and nulls out the HD subcarriers from Durham region on the frequency.

That one's interesting, as I find the analog/analog transition from the Oshawa signal to the Toronto signal imperfect, specifically once you get on the DVP. Will this help?
 
 

There is no simple answer as to how effective an HD repeater will be.  There are a number of variables that can be tweaked to optimize the reception area. With synchronous repeaters, there is always some degree of interference between the two signals, creating a "mush zone". For analog signals, the conventional wisdom has been to "synchronize everything", that is to say the carrier frequencies are locked using GPS, and the modulation tracking within 0.1 dB.  The 19 kHz stereo pilot must also be locked. Then the audio modulation can be offset (by microseconds) so that the main and repeater signals arrive at the desired location at the same time.  The effective radiated power and antenna pattern of the repeater are two more variables.

For a given reception point, the difference in dB that much be achieved between the desired repeater signal and the undesired main signal will vary dramatically with the amount of error in the arrival time of the two signals. When the reception point is in line with both transmitters, the timing error can be reduced to zero, but as you move away from that straight line, the error will increase to the point where the interference becomes evident.  In the case of CJKX, the area west of First Canadian Place will likely have the best and most consistent signal quality.  Areas to the east will likely have drastic variations. 

There is very sophisticated software that allows playing with these variables to optimize the size and location of the interference-free reception zone for the repeater. Another factor which you can't really control is terrain obstruction.  Repeaters work best when the main signal has a lot of blockage. 

The hybrid digital signal requires a lower desired/undesired ratio between the two signals, and therefore the interference-free reception area of the repeated HD signal in theory should be significantly larger than that of the analog signal.

All this to say that the success of the CKJX-HD repeater will depend on whether they employ all of the available techniques, and purchase the additional equipment which will allow precision synchronization and adjustment of the aforementioned variables. 

Stay tuned.

 

Thanks for this! I even understood a good portion of it. So the answer to my question basically amounts to 'maybe, if they do it right.'

All the talk above about the "how" in terms of getting other big signals to HD is really interesting too, but like with anything, you sometimes have to slow the technically-inclined with the question "why?"


 
 

June 18, 2021 8:38 pm  #50


Re: HD Radio In Toronto

In Phase wrote:

Tim Brown 2016 wrote:

tvguy wrote:

CHUM FM will not be running HD any time soon, from what I hear. 
The balance of stations which broadcast from the CN Tower, will need to have an upgrade to the "Master FM" antenna

Thanks for this tvguy... To be precise, is it not the CN Tower FM combiner that needs replacement to accommodate HD Radio? Why would the actual antenna need to be replaced? From what I recall (40 years ago), that's a broadband antenna up there. Is it a polorization issue?

The antenna itself probably does not need any changes as it is broadband.  The main issue is the FM combiner.
 
A multi-station combiner is really a set of filters interconnected such that all signals "combine" to feed a common antenna all the while preventing each stations signal from getting back into each other’s transmitter.
 
Due to FM band frequencies, each “filter” is physically large (about the size of a big hot tub), and there are multiple filters per station.
 
The filters are finely tuned to pass only a single FM station, within a specific frequency & bandwidth.  Adding HD signals expands the bandwidth such that the existing filters will chop off some of the HD signal.  Each stations series of filters would need to be retuned and/or replaced to permit HD transmission.  That’s a big job and would involve coordinating with all other players using the combiner.
 
Unfortunately, I don’t have a personal photo of the CNT FM combiner but a simple search reveals a picture taken by Mr. Fybush during one of his site visits.  Perhaps he has more images to share.

https://www.fybush.com/wp-content/uploads/2015/05/cn-combiner.jpg
 

 

Unfortunately the antenna cannot handle the peak voltage when all of the stations go HD!   Splitters and câbles will also need to be replaced.   

Plus when the HD is added into the safety code 6 calculations, the Space Deck becomes unusable!   Too much radiation.   So the best plan is to replace both antenna and combiner, from what understand and stick it in the aperture above, which is the old CBC channel 5 antenna space. 
 

 

June 18, 2021 8:45 pm  #51


Re: HD Radio In Toronto

Juggie1 wrote:

Unfortunately the antenna cannot handle the peak voltage when all of the stations go HD! Splitters and câbles will also need to be replaced.

Plus when the HD is added into the safety code 6 calculations, the Space Deck becomes unusable! Too much radiation. So the best plan is to replace both antenna and combiner, from what understand and stick it in the aperture above, which is the old CBC channel 5 antenna space.
 

Another reason why EVERYONE. IS. NOT. GOING. HD.

There's zero ROI.

The smaller players will still experiment; that's it.
 


 
 

June 19, 2021 3:34 am  #52


Re: HD Radio In Toronto

In regards to the safety 6 regulation codes, is the now called “sky pod” formely spacedeck, actually safe this whole time with master fm literally above their heads?

 

June 19, 2021 8:15 am  #53


Re: HD Radio In Toronto

Rest assured that the CN Tower diligently monitors the Safety Code 6 limits in the publicly accessible spaces as well as those accessed by occupational workers. They have a registered professional engineer on retainer and any changes in configurations are verified for compliance.

 

June 19, 2021 11:08 am  #54


Re: HD Radio In Toronto

With a new master FM antenna/combiner system in the CN Tower's future, is allowance being made for a potential move of the omnidirectional stations on FCP over to the CN Tower? I'm referring to the additional RF power, along with the actual connectivity to the new combiner.

CJBC-FM was originally on the CN Tower and CIUT is omnidirectional. I think CBLA has only a very minor null to the southeast - something that could be addressed with a modest power reduction. The only other consideration I can think of for CBLA is whether 98.7 (CKFG) needs to be collocated with CBLA because of it being a weak second adjacent to CBLA.

Skywave, tvguy, any thoughts?  BTW, Thank you very much for all this information.

Last edited by Tim Brown 2016 (June 19, 2021 4:36 pm)

 

June 19, 2021 5:58 pm  #55


Re: HD Radio In Toronto

CBLA-FM is limited to the equivalent of 50 kW at 150 metres effective height above terrain (Class B) to protect a 1st adjacent station in Rochester NY. As it is operating at 98 kW max at an EHAAT of 303 metres, it has a fairly deep null in the direction of Rochester.  CJBC-FM shares the same antenna and as a consequence is directional, although it could operate with full Class B omnidirectional parameters.

I wouldn't be surprised to see CBLA-FM move to the CN Tower with a directional antenna in the present Master FM aperture, which will become vacant.  CIUT and CJBC could be added into the new omni antenna operating with an equivalent ERP of about 4.5 kW. But I have no actual knowledge of any plans.

All the other stations on FCP are operating with directional antennas customized to maximize signal while maintaining all the requisite co-channel and adjacent channel protections to other stations.. It is possible to create different patterns for different frequencies using common panels, but that typically requires a combiner feeding each panel face  with different power ratios for each frequency.  The auxiliary antenna for CFMZ-FM is a variation on that.  It shares two panels of the CFZM-FM antenna and has a power split to feed a third panel pointing westward.

 

June 19, 2021 10:12 pm  #56


Re: HD Radio In Toronto

Juggie1 wrote:

Unfortunately the antenna cannot handle the peak voltage when all of the stations go HD! Splitters and câbles will also need to be replaced.

Plus when the HD is added into the safety code 6 calculations, the Space Deck becomes unusable! Too much radiation. So the best plan is to replace both antenna and combiner, from what understand and stick it in the aperture above, which is the old CBC channel 5 antenna space.
 

I did not know the antenna system was that close to max capacity.  Its been a while since I was close to it.

Nonetheless, installing a new antenna system just to add a few digital signals per station is a lot of effort, risk and cost, especially when the future is not on such a platform (my opinion).

Some stations may not want, or need, to implement HD and therefore have no benefit in a new antenna system.  An interesting situation given the Master FM consortium.

CBC may have some coverage & financial benefit in moving stations off FCP and over the CNT however.

Possibly the plan is to add an antenna system just for the HD carriers and leave the analog platform as is?
 

 

June 20, 2021 8:31 am  #57


Re: HD Radio In Toronto

The plan is to use the new antenna for both the analog and digital signals.  Early implementations of IBOC sometimes used separate antennas for the digital component, but this does not work very well.  IBOC digital signals actually cause interference to the host analog FM signal, even when using the same antenna..  This interference is tolerable at injection ratios of up to -13 dBc per sideband (-10 dB overall).  But if a separate antenna is used this ratio will vary considerably because the centre of radiation and the vertical patterns don't match.  When CKFM and CHUM first tested HD, the HD component only was fed into the single bay antenna at the bottom of the Channel 9 aperture.  The analog signal was transmitted by the 5 bay FM antenna below.  It was predicted beforehand that concentric donuts of interference would exist in the downtown core, and the actual tests determined that these zones of interference were unacceptable.  So CKFM is transmitting both signals from the single bay antenna at reduced ERP on an interim basis (shown as TO "temporary operation" in the ISED database),

 

June 20, 2021 12:42 pm  #58


Re: HD Radio In Toronto

Skywave wrote:

The plan is to use the new antenna for both the analog and digital signals.  Early implementations of IBOC sometimes used separate antennas for the digital component, but this does not work very well.  IBOC digital signals actually cause interference to the host analog FM signal, even when using the same antenna..  This interference is tolerable at injection ratios of up to -13 dBc per sideband (-10 dB overall).  But if a separate antenna is used this ratio will vary considerably because the centre of radiation and the vertical patterns don't match.  When CKFM and CHUM first tested HD, the HD component only was fed into the single bay antenna at the bottom of the Channel 9 aperture.  The analog signal was transmitted by the 5 bay FM antenna below.  It was predicted beforehand that concentric donuts of interference would exist in the downtown core, and the actual tests determined that these zones of interference were unacceptable.  So CKFM is transmitting both signals from the single bay antenna at reduced ERP on an interim basis (shown as TO "temporary operation" in the ISED database),

Great info and knowledge again.  I’m guessing feeding two stations like that into a single bay definately caused it to melt back in 2017.  That engineer missed the boat somewhere.

 

June 20, 2021 1:42 pm  #59


Re: HD Radio In Toronto

In Phase wrote:

RadioActive wrote:

One of them was City's room (or whatever it was) on the CN Tower.  I still remember how it ended. Frankish started poking around in the place and pretended to pull out a wire, asking, "I wonder what this does?", which sent the screen to static and snow for about 5 secs. He then put it back, saying something like, "I guess we know now!"

one more photo - the original CITY-TV transmitter at the CN Tower

https://i.ibb.co/nPpkgzR/Original-CITY-TV-transmitter.jpg

Are those a pair of British Pye TVT transmitters?, or like Monty Python says... Am I very much mistaken ? 

Are they working as main and back-up or are they running in parallel operation?

 

June 20, 2021 2:02 pm  #60


Re: HD Radio In Toronto

tvguy wrote:

It was a hot and muggy day. I remember because there was very little visibility.  No great tropo that day.  I was using something minimal like a 4-bay bowtie.   The Erie PA stations were certainly very strong at that elevation.  My recollection is that the flamethrower on Ch. 26  from Jamestown NY which was an indie that carried CFTO's programming a great deal of the time - was rock solid.   Only had a few minutes to try things out and the TV was a very heavy "transportable" - clunky - because it was of late 1960's vintage.  Commerce Court West was completed in '72, so I would have been up there in the summer of '71.  Not that many local (Canadian) TV stations on the air at the time.  My visit preceded Global, Citytv, Omni(s), and many other stations.  So there wasn't much on the air on UHF at that time in this area.  DXing would have been great - had there been an opening.  OECA (TVontario) would have been transmitting either from Canada Square or perhaps the old CBC tower on Jarvis St.

I knew that City TV had the original transmitter atop Canada Square at 2180 Yonge St. Power was around 20Kw  ???  Power and antenna gain increased when City moved to CN Tower in May 76...  I thought City stayed at Canada Square until they moved to CN Tower.

I never heard of TVO/OECA also transmitting from Canada Square, I thought it was only City TV.

I was under the belief that TVO/OECA was transmitting Channel 19 from the CBC tower at Jarvis St. until they moved facilities to the CN Tower.   TVO had a clear shot to the CN Tower, so they employed a microwave as the STL.

TVOntario later leased the former City Transmitter space at 2180 Yonge St. in the mid 80s and set-up the Ku band uplink for delivery of the TVO, La Chaine (later TFO) and the Ontario Legislative Assembly tv service (OLA).

(unrelated but, TVO always had difficulty with C Band TVRO reception at 2180 Yonge St. due to interference from Bell's 4Ghz microwave path between the Bell towers at Ronald Ave. and Pharmacy Ave.)