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2026 C-QUAM AM Stereo Coverage Map

N

nitroengine

I figured some here may enjoy this. This is a 2026 remake of a map Motorola put out in 1988.

Let me know if there are any stations missing or any of those shown are known to no longer be broadcasting in AM stereo. The map will need to be updated again at the end of April as 630 CFCO (Chatham, ON) is set to go off the air.

There's a few stations that are running a 25Hz C-QUAM pilot but are known to have a mono feed. Those are marked with an asterisk. Also, while not marked as such on the map, 1310 WOKR (Canandaigua, NY) and 900 WKDA (Lebanon, TN) are currently known to be running with a severe channel imbalance.

c-quam13.jpg


1988:
c-quam10.jpg

I added a PDF of the map in case that's easier to download and zoom in on. The small text is intentional, to resemble that used on the 1988 map.
 

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Todd Mitchell said:
KBMR hasn't been stereo for well over 20 years.
Click to expand...
In early July 2025, they were heard and seen with a 25Hz pilot on the Valley City, ND KiwiSDR. That KiwiSDR hasn't been online for a couple of months now. 1130 KBMR often shows up at sunset here under my local, KTLK. I'll have to watch and see if the 25Hz pilot is still visible on the spectrum when they are in.
 
radiofan2023 said:
Where did you get the information to make your new map, @nitroengine?
Click to expand...

Jeff Deck's list AM Stereo Stations, the AM stereo list on Wikipedia: List of AM stereo radio stations - Wikipedia, as well as input from the AM Stereo "C-QUAM" Facebook Group: Facebook

I tossed one of these maps together in 2021 and posted it on the Facebook groups. At that time, it had a lot more stations on it. Comments and discussions weeded out a lot of outdated data and even added a few new ones that were previously unknown.
 
Wikipedia is (or was, in 2021) a starting point. Discussions like these on here is what helps refine the data.

A good number of these can be confirmed yourself by checking out online KiwiSDRs. If you zoom all the way in on the waterfall spectrum, you can visibly see the 25Hz pilot tone, and they have a C-QUAM decoder mode built in. Wideband shortwave radio receiver map
 
nitroengine said:
In early July 2025, they were heard and seen with a 25Hz pilot on the Valley City, ND KiwiSDR. That KiwiSDR hasn't been online for a couple of months now. 1130 KBMR often shows up at sunset here under my local, KTLK. I'll have to watch and see if the 25Hz pilot is still visible on the spectrum when they are in.
Click to expand...
Well, that would be interesting, given the stereo chain has been gone for a few decades now.
 
nitroengine said:
In early July 2025, they were heard and seen with a 25Hz pilot on the Valley City, ND KiwiSDR. That KiwiSDR hasn't been online for a couple of months now. 1130 KBMR often shows up at sunset here under my local, KTLK. I'll have to watch and see if the 25Hz pilot is still visible on the spectrum when they are in.
Click to expand...

Ummm.... @Todd Mitchell wou;ld be THE ONE to know........ if he says its gone at KBMR, it's GONE
 
I'll get the map updated.

@Todd Mitchell Is the stereo card/C-QUAM exciter still installed that could be generating a 25Hz pilot?
 

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Even taking the map at face value, the percentage of Americans covered by AM stereo is quite small. Only 5 of the top 25 markets appear to have an AM stereo station in 2025: Chicago, Boston, Philly, Portland and Detroit (if you count a rimshot from Canada)
 
Co-channels a little off frequency especially around 25 Hz apart will trigger the C-QUAM decoder & pilot.
Just tuning to a "graveyard" channel (1230 1240 etc) would trigger C-QUAM the Motorola in the Ford Explorer.
 
PTBoardOp93 said:
Even taking the map at face value, the percentage of Americans covered by AM stereo is quite small. Only 5 of the top 25 markets appear to have an AM stereo station in 2025: Chicago, Boston, Philly, Portland and Detroit (if you count a rimshot from Canada)
Click to expand...
From what I understand, someone GAVE KBPS a C-QUAM exciter, so they put it on the air!
 
boiseengineer said:
Co-channels a little off frequency especially around 25 Hz apart will trigger the C-QUAM decoder & pilot.
Just tuning to a "graveyard" channel (1230 1240 etc) would trigger C-QUAM the Motorola in the Ford Explorer.
Click to expand...
False decoding was common at night, especially with the earlier decoder chips. For a number of years, an off-freq carrier along with my local on 1440 used to do that on my AM stereo tuners at night. Even causing a pseudo-stereo effect.

The forced-stereo decoder in the Sony AM stereo portables was fun to DX with at night, particularly the independent sideband Kahn-Hazeltine mode. It really brought out stations that were normally buried on crowded frequencies like the graveyard channels. Today, "SAS" mode on the KiwiSDR is just like that.
 


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