I find GM's decision puzzling, because there are universal chips available that cover all world-wide analog and digital standards. 
 Si4689-A10 Single-Chip, AM/FM/HD/DAB/DAB+ Radio Receiver

I think that a major stumbling block has been Ibiquity's licensing model, which requires stations to purchase a license for HD1 channels, and pay a percentage of revenue which arises from the HD2 and up channels.  They should have taken the approach used by Zenith, which patented FM stereo.  There was a simple royalty fee paid per receiver by the licensed manufacturers.

RadioActive wrote:

  
Why does it cost $2.5 million to turn something off? Only in government could not doing something cost taxpayers so much money!

Apparently there are 185 VHF transmitters, plus some low power AM and FM for a total of 230. The antennas and transmitters will have to be removed from each location, and there may be lease termination fees.  That means hiring qualified riggers to climb towers, and transporting and disposing of the material.

It averages out to about $11,000 per location. 

There is no carrier, and streaming gives an error.

The big problem with DAB in Canada was the use of the L band (1452-1492 MHz).  While it allowed for much greater bandwidth and resultant bit rates than Band III (VHF) DAB, the coverage area for each transmitter was very small compared to the analog AM or FM licensed area. The bottom line was that it was simply unaffordable to replicate the coverage.  One study indicated that it would have cost $50 million just to replicate coverage in the Windsor to Montreal corridor. 
The other big issue was the lack of receivers, especially in cars.  The only portable pocket radio, (earphones only) ran off of four AA batteries that lasted about 3 hours.  tvguy may have one and can comment.  

RadioActive wrote:

 
A long story but a really good one worth the read. 
 

Perhaps saying this is revisionist history is a little too strong, but the author totally eliminates information which is salient to understanding "the rest of the story".
Timmins, Sudbury and North Bay each had separate privately-owned CBC affiliates which were the only English language OTA services.  They also had rebroadcasters of CBOFT (CBC French - Ottawa).  In 1969, there were four competing applications to add a CTV affiliate in Sudbury only, with a population of about 150,000.  These were denied.  Instead, the CRTC came up with an innovative solution to add CTV service while maintaining marketplace equilibrium.  It licensed CFCL-TV (J. Conrad Lavigne) in Timmins to operate CBC affiliates in Sudbury and North Bay. CKSO-TV Sudbury (Bill Plaunt) was allowed to disaffiliate from CBC, become a CTV supplementary affiliate, purchase CKNY-TV North Bay, and add rebroadcast transmitters in Timmins and Kearns (Kirkland Lake/Rouyn-Noranda). So now you had two competing stations with approximately twice the market size they previously had.
The stations were linked together by a microwave network built by Lavigne and shared with Plaunt.

This more or less happy coexistence continued until 1976, when Northern Cable was licensed to bring cable service to Sudbury and Timmins.  Tne big 3 US networks, Global and TVO signals were picked up at the Maclean-Hunter cable head-end at Hornby, and carried by Bell microwave to North Bay.  There they were split off and carried via additional circuits added to the Lavigne microwave network to feed Sudbury, Timmins, and surrounding communities. 

As the article indicates, the advent of cable led to serious audience fragmentation, and the fate of the local stations became precarious.  Both owners sold out to the cable company, effectively giving them a monopoly overall all television signal delivery. The "twin-sticks" operated as MCTV.

In 1990,

Actually, no.  The nighttime protections on 1250 and 1320 are far more stringent than for 900.  900 can operate 300 watts omni at night, versus 35 to 40 watts on the other frequencies.  The 900 nighttime incoming interference is also exceptionally low, again in comparison to 1250 or 1320.  Give a listen a couple of hours after sunset.
CHIN noted in its application that in future it would hope to be able to find a site which could accommodate at least two towers, and that would allow up to 10 kW operation.

As of now, both stations are off the air. Any contemplation of omnidirectional operation from another site will result effectively in a daytime only operation, as the nighttime protections would require reducing power to a paltry 35 or 40 watts, or good enough for about three city blocks.

The CKTB site was built in 1959/60, so what you have is perhaps one of the most ancient set of towers, transmission lines and phasing equipment extant. This will be an ongoing agony of technical "whack-a-mole".

RadioActive wrote:

I thought the same thing, although they already air a fair bit of it overnight and in the early mornings. If I'm not mistaken, their licence only allows them to play so much foreign language programming. 

CINA has already pushed the regulatory envelope with CHAM 820.  A rather curious (and in my view ridiculous) wrinkle in the definition of ethnic broadcasting is that it's the spoken word which defines the "ethnicity" of the programming.  So they can play all Punjabi music for the other 85% of the time as long as the spoken word and commercials are English or French.

The root of their problem was getting into the real estate business by purchasing the Alberta Hotel, the rebuilding of which was unfinished, and taking out a $6 million dollar loan to finish off the project.  Then the main tenant went bankrupt.
Whatever possessed them to have such delusions of grandeur that they would go this route instead of leasing?  The  gory details are here:
Address-To-The-Community-CKUA-April-2024-FAQ.pdf
The telling lines are "We can't afford to sell. We can't afford to stay".
Gross mismanagement, and most of the government gift will go towards paying off the ill-advised mortgage. They had no business getting into the real estate business.

 

gch wrote:

 I have seen no news about CHOK so maybe they are happy with 103.9 and 1070 continuing together...I have no idea how old the 1070 tower(s) would be.   Several big city stations in the states are continuing with AM and FM  (for example WFAN in New York and WBBM in Chicago.

CHOK increased power to 10 kilowatts day and night in 1968 in response to the arrival of CKJD 1250. The towers are 57 years old.

Actually WKBW moved to 1520 in 1941. CKOT didn't start until 1955, so they weren't actually protected, but did take advantage of the reduced signal in their direction.
It's not unusual for stations sharing clear channels to use the same pattern day and night. The market for WKBW was clearly Buffalo/Niagara and east. Shooting extra signal out over Lake Erie with an omni signal daytime would have been a waste, as well as reducing the signal strength in Buffalo. Being at the high end of the dial, the groundwave signal deterioirates rapidly.
 

RadioActive wrote:

  
As for that station in Monroe, Michigan, what, exactly, is the point of even bothering to stay on at 14 watts at night? You might be able to get them in the parking lot or a block away. Other than that, why bother?

The same might be asked of CIRF 1350 Brampton, which is supposed to be 1000 watts day and (ahem) 40 watts night. 
Funny, I don't seem to notice in change in their signal at night.
 

CFRB's plan was to transmit Channel 13 from a 500 foot tower near Hornby. They would pay for CKCO Kitchener and WOKR Rochester to switch from Channel 13 to Channel 6.  The low band VHF channel had a larger Grade B contour, and that would be the motivation for Kitchener and Rochester to accept the proposed change.
The CRTC instead licensed Channel 6 to Global at Paris (Ayr), and for a rebroad of CJ.OH Ottawa at Deseronto.
If CFRB had been willing to go to UHF Channel 25, they would probably have won the license hands down.

Some trivia. The CFRB site was sold to Maclean-Hunter cable who used it for their major head-end for the GTA. It also served as the starting point for the CUC cable network feeding North Bay, Sudbury, and Timmins.  When Rogers took over Maclean-Hunter, the site was decomissioned, and ultimately expropriated for the 407 ETR.
 

For AM, the occupied bandwidth is a function of the maximum modulating frequency, not the channel spacing. If you were to truncate the audio bandwidth sharply to 5 kHz, the sidebands would extend +/- 5 kHz, and the sidebands of 1st adjacent AM stations would not overlap.  But you would also need to limit the intermediate frequency bandwidth of the receiver to achieve any real benefit.
Back in the early days of AM broadcasting, a common telco broadcast "twisted pair" connecting the studio to the transmitter was equalized to 5 kHz, so you had a virtual inadvertent limitation of transmitted bandwidth.