C-QUAM AM Stereo

You guys did great !

I tryed AM Stereo using 0-30 MHz KIWISDR, KH6ILT, Elida OH USA SW Version 1.441 to WIOE 1450 Fort Wayne, Indiana United States.

I could hear Stereo using Bluetooth headphones on my HP Laptop.... Works good..... Thanks....

When can we get HD AM Stereo ?



  • does the SAM Carrier Offset still apply to C-QUAM? It is displayed

  • jksjks
    edited March 2021

    Yes. The carrier PLL operates in all the modes SAM/SAL/SAU/SAS/QAM. While monitoring an AMBC station, offset the frequency 100 Hz by clicking the smallest "circle-plus/minus" icon and the PLL should follow.

  • edited March 2021

    I'm loving the AM stereo, but ever since the change all of my synchronous modes create a "popcorn" like clicking at random intervals from 100ms to about 3 seconds. I believe I can see it on the waterfall as well. I observed this on the Edinburgh kiwisdr (WZZB) as well as my own 2 kiwis. It is obvious when tuning in a silent carrier. Regular AM mode works fine.

    Is it just me?

  • I can't confirm that (using Firefox).

    Just a thought: Did you make sure the SQ slider is in the leftmost position while testing?

  • Try tuning in a carrier in CW or CWN mode. I hear "clicks' in the tone.

    3 different kiwis and 2 different computers. Both using chrome browser. v1.442

    I also keep having sessions lock up and have to refresh the page.

  • Wish it had a Am Stereo Led light..... That would be cool....

  • @ShaneBrook AFAIK, the only way to do that is to detect the 25 Hz pilot tone.

  • Here's 1390 WBBZ, Seymour, IN, USA, which does transmit C-QUAM, showing the 25 Hz pilot tones. You don't see this on any non C-QUAM station.

    The Kiwi waterfall at zoom level 14 has about 1.8 Hz resolution per bin. Everyone forgets the Kiwi can do this. Useful for a lot of stuff like determining the sweep rate of OTHRs. The audio path FFT, used for the main passband filtering, only has about 12 Hz resolution (20 Hz for 3-channel mode). So no good for this task. Another pilot-specific detection filter would be needed.

  • I love the C-QUAM AM-stereo function! Thanks for implementing it. That makes the Kiwi one of the few receivers currently produced that can decode AM-stereo broadcasts. I listen to Album Rock 540 WXYG in AM-stereo on my Kiwi fairly often. There's also a few other Kiwis throughout the world that receive AM-stereo stations that I like to listen to from time to time.

    Only one thing I noticed is the stereo channels are reversed. It's not a big problem and I wouldn't mess with correcting it if its a bunch of work or could open up the possibility of inducing other problems. I have a collection of older AM-stereo radios that decode WXYG with the proper channeling. Interestingly, some of the early HD radios that could decode C-QUAM also output with the channels reversed.

    A stereo indicator like maybe the QAM button turning from green to red when an AM stereo station is received would be "fun" if a way to do it could be found, but as mentioned, you can zoom in on the waterfall/spectrum and see the pilot tones.

    It would be interesting to see all-digital MA3 IBOC decoded one day, but Xperi would probably not be thrilled about it. I thought I read on another forum some time back about someone who was trying to decode WWFD by using a recording of the IQ output from a local area Kiwi.

  • The C-QUAM idea is all due to contributed code from Github user MaPePeR. So we have them to thank. I'll see if I can reverse the channels.

  • I think the L/R channels are swapped in v1.517 Please let me know if you think it worked or not.

  • Very cool!

    I'll let you know tomorrow when WXYG is on day power.

    Thank you.

  • It sounds good, correct stereo channeling. Here's a clip of WXYG from my Kiwi and their online stream. I'm about ~70 miles away from the 850 watt station and ground wave conditions on the low end of the band are deteriorating as the weather warms up, so that clip is a bit noisy, but you can hear the stereo separation.

    Thanks for the fix.

  • Okay, here it goes. I need to apologize. The stereo channeling was correct the way it was before.

    I should’ve double checked a few other Kiwis receiving AM-stereo stations and my old AM-stereo tuners before mentioning anything about reversed channels. It turns out the reversed channel issue was only with WXYG (which was just corrected at the station yesterday, believe it or not, without any mentioning of this topic). WXYG must’ve been “reversed” since at least about the time the QAM function was implemented in the Kiwi. I have a number of recordings over the past few years of WXYG off older tuners that exhibit correct channeling, so I was basing a lot off those. Aside from WXYG, the idea of the channels being reversed on the Kiwi was also reinforced in my mind when I recall having to flip the channels of recordings made of KRGE (Spanish Christian station) on a Brownsville, TX KiwiSDR when comparing the music recorded with that on YouTube to confirm whether the separation was legitimate stereo or the effect of pseudo-stereo. That was for a discussion on a Facebook group where a member or two firmly disagreed that the station was claimed to be broadcasting in stereo and wanted the station removed from a list of known AM-stereo stations.

    Anyway, while listening to WXYG on my Kiwi (v1.518) early yesterday and discovering the channels were reversed once again, I spent some time closely analyzing my own hardware based AM-stereo tuners, and a number of KiwiSDRs receiving other stations broadcasting in AM-stereo (such as the Elida, OH Kiwi v1.518 receiving 1450 WIOE). The stereo channeling was correct the way it originally was. So if you would kindly reverse the channels back once again, that would be great. Hopefully it’s not a lot of work.

    WXYG was having feed issues, cutting in and out all day the day I recorded the clip I shared above. The stereo channels must’ve been corrected when that feed issue was solved. …LOL, if only I had waited a couple more days before mentioning anything (something I had planned to mention for quite a time).

    Once again, sorry for the unnecessary hassle.

  • No worries. It makes more sense that it wasn't wrong to begin with. I'll undo the change.

  • Thanks again.

  • jksjks
    edited May 2022

    From Twitter just now. Accuracy uncertain. But in combination with map.kiwisdr.com might make searching for active stations slightly easier. https://twitter.com/radiomatt1/status/1525233360431419394

  • I actually made that map and posted it on the AM-Stereo C-QUAM Facebook group https://www.facebook.com/groups/385327984878627 and the I Love AM Radio Facebook group https://www.facebook.com/groups/iloveamradio. Where many members added input on whether stations were still stereo or not. Some of the members being the engineers or owners of the stations listed. Based on a list on Wikipedia, it started out looking like this:

    It got picked away at until I ended up with that map last updated in November of last year. I need to make a few updates to it for 2022. I don't believe CHQR is in stereo anymore, in addition to a few other edits that I need to track down and make.

    That map is a 2021 recreation of a C-QUAM coverage map from 1988:

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