The Jump may decode Cquam...I know the DIRECTED HD car radio does...so if the all digital goes bust, luckily the NX3 HAS Cquam built in
I have my NX10 on 940 in New Orleans running CQUAM...talk about sounding great..
-
Get involved.
We want your input!
Apply for Membership and join the conversations about everything related to broadcasting.
After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
If you use a disposable or false email address, your registration will be rejected.
After your membership is approved, please take a minute to tell us a little bit about yourself.
https://www.radiodiscussions.com/forums/introduce-yourself.1088/
Thanks in advance and have fun!
RadioDiscussions Administrators
AM Stereo
- Thread starter ContinuousWave
- Start date
I have my NX10 on 940 in New Orleans running CQUAM...talk about sounding great..I thought of something else.The Jump may decode Cquam...I know the DIRECTED HD car radio does...so if the all digital goes bust, luckily the NX3 HAS Cquam built in
Since Leonard Kahn died, we might be able to resurrect his system, as well.
Jeff in Sa-ra-so-ta!
Not under FCC rules...only Cquam is legal...and it's better than Kahn ever was..
That is correct about the commission...and NO WAY!
Those with a financial interest in Belar, Harris, Magnavox, Zenith, and "Rotomola" favored them but K-H stations were the only ones with stereo coverage areas equal to their monaural coverage areas, no platform motion (sort of corrected toward the end), and no weird anomalies as the signals faded out. If I can travel back a few years, "Money talks, nobody walks".
The FCC can always modify their rules to accept the ISB and the others.
Motorola's system did sound good, but, with the "platform motion" or "ping-pong" Motorola had, was a definite problem. The only way it was remedied was by increasing the pulses which allowed the radio to start decoding. It was in mono more than stereo, but the "platform motion" was gone.
I experienced a sort of "platform motion" with ISB, but at a much reduced effect.
Jeff in Sa-ra-so-ta!
It's been the standard since 1992...no one made a Kahn rcvr except Sony and it was reversed engineered. FCC will not reverse its decision after 30 yrs...
Platform motion was minimized in later updates of rcvr chip design..it was really only a bother in skywave and weak signal reception. In the 0.5mv contours, it rarely occured..Kahn had more issues than platform motion anyway..so to scratch cquam on one minor issue where Kahn had 3 major issues, I'd go with Cquam..
Oh wait, I did..on music radio 1300 KLLS, 2015 to 2020
It still lives...WYLD940 in New Orleans went Cquam in 2020. Others are coming back on...its dead? Nope, it still lives and new rcvrs are being developed
The C-QUAM system did not transmit "pulses." The system transmitted a low level 25 Hz "pilot" on the L-R (FM) carrier which caused the receivers to switch to the stereo mode.
Back in 1987, I installed C-QUAM in the WQYK-AM (Tampa Bay) transmitters. It really sounded great before we were required to install a 10kHz brick wall audio filter. At the time, the AM station was simulcasting WQYK-FM. The jocks actually liked to listen to the AM station on their headphones because it sounded "bigger." I cheated somewhat by increasing the L+R amplitude modulation so that the station could hit 125% positive modulation without causing too much C-QUAM splatter. Of course, this reduced the stereo channel separation by several dB but the station sounded great!
It could have been from my limited experience with a limited number of early stereo receivers because station engineers have differed with me on this, but I found that C-QAM stations running asymmetrical modulation became off-centered, but I can't remember whether it was to the left or to the right. In fact, I believe that one horrible sounding Jacksonville monaural station had their processor's output reversed or a severe transmitter modulation issue because it false triggered my radio and was shifted way to the other side. 🤔
I never experienced that issue with asymmetrical modulation.
Nor have I. If a person understands the concept of carrier suppression on negative peaks, it is then obvious how positive peaks, within limits, do not change anything. And carrier shift as described by the original poster sounds like the Kahn system, which played with the sidebands; Kahn was fascinated with sidebands in fact as shown with that dreadful "Powerside" device.
And, in fact, by the time that the Kahn delay ended, most music formats had already moved to FM. Nobody needed stereo for talk formats or "Music (for the remaining years) of Your Life".
Lets face it, both Kahn and Harris were superior to Motorola C-Quam. The only reason C-Quam was chosen is because Motorola had the pull and clout at the FCC to get it approved. If C-Quam had been sponsored by anyone other than Motorola, it would never have been chosen. I had three AM stereo stations and I speak from experience. C-Quam could sound very good during the day if you had a strong signal, but at night, forget it.
I had a Pioneer AM Stereo/FM Stereo car radio for a while back when AM stations were broadcasting in stereo. IF I remember correctly, WHK AM had an oldies format and it sounded way better than FM; was just amazed at just how good it sounded and the nightime signal sounded better than it did during daytime. I had talked to an engineer at the station and he said technically that AM stereo was superior to FM stereo. He was explaining the differences to me but most of it went over my head. I felt like the Neanderthals did in 2001 A Space Odyssey when they were staring at the Monolith.
Kahn sucked on DAs that were not flat across the channel..also it had no separation above 6 to 7khz where Cquam is 35db to 15/20khz...sorry Kahn was crap...Harris had higher IMD than Cquam. And Greg Buchwald, who was part of the Cquam design team and still updates Cquam stations on air, including WION which streams it Cquam via the Carver tuner, will definitely disagree with your statements...but then he is a BSEE...and I doubt you are.
Part of it includes the L-R matrix processing...when 93Q and 79Q in Houston were simulcasting in the 80s with Cquam on the AM, I preferred it over the FM...it had more presence in the audio and sounded cleaner..
Just speaking from personal experience. I dont claim to be an expert. No, I'm not a BSEE just a CPBE, DRB. Nothing close to a BSEE
I take issue with your question of "devolve into stupid AM stereo discussions".
AM Stereo was NOT a failure. The FCC was THE failure!
AM Stereo has its place and so does Digital and other transport systems.
If you had ever heard it in the real world, you would feel differently.
And the fact that "99.99%" could care less?
Well, nobody cares where their tap water comes from, either.
Or their cell phone tower is - as long as they can't see it.
You could bring out the worst in me and I am not going there, so your opinion is yours. Enjoy it.
Jeff in Sa-ra-so-ta!
Let's take this in order, shall we?
1. AM Stereo failed miserably. By the time Motorola was chosen, it was too late for any audience to care. Music listening had already migrated to FM by then. Leonard Kahn was a big reason AM stereo was delayed. He filed nuisance lawsuits in an attempt to force the Commission to delay a choice of something other than his system. If you want to place blame, one needs to look no further than Leonard. Combine all the aforementioned, with poor and inconsistent audio quality that couldn't come close to matching FM stereo and AM Stereo was doomed from the get-go.
2. AM Stereo has no place anymore, not that it had one to begin with. There are no new receivers being sold or provided in vehicles. No distribution=no interest. AM listeners are a dying breed, literally.
3. You're right about one thing: Consumers don't care where the data comes from to their cell phones. All they know is how to operate it. But, going back to what a consumer would want or not; if the an average consumer heard music on AM, even in stereo, it would be rejected because of the poor overall quality and excessive noise floor.
Regarding your comment about having heard AM Stereo, I absolutely have. I've installed (and removed) more systems over the years when AM stereo was sort of a thing for broadcasters, than you have, guaranteed. I was even involved in some of the original testing and evaluation of ISB and CQUAM. Compared with digital audio sources you can even store or stream via your phone these days? AM stereo sounds horrible.
Years ago I worked with Bob Carver on development of his rather high end AM/FM stereo tuner. As Bob put it, 'AM stereo was a complete waste of a year in R&D'. Much of that statement was because of the lack of consistency in stereo exciter interface to the various transmitter models. Differences in antenna systems. Program Directors insisting on running asymmetrical modulation.
So honestly, you can self-revise history all you want. AM stereo was/is a complete failure across the board.
Now, can we please return to the 21st Century and talk about AM digital? If you want to have a debate, let's at least debate something real and in current times.
Last edited:
- Status