Kintronic Talks AM With FCC

Of interest here was this demonstration Tom King did for FCC staff:

"King and his staff also provided audio demonstrations of two wideband (10 kHz) CQUAM AM stereo receivers, as directly compared with a high-quality FM HD Radio tuner and a typical standard bandwidth (~2.5-kHz) AM receiver. King emphasized that the AM stereo audio quality of the older-generation and current generation wideband receivers was very similar to that of the FM HD tuner."

It's something we all knew but it may have been a surprise to the FCC.


http://www.radioworld.com/article/kintronic-talks-am-with-fccers/272707

I really like the "shape" of the audio produced by a quality C-QUAM stereo AM broadcast or even a well processed mono AM broadcast, but these people are delusional if they think that the 10 kHz bandwidth of current AM radio sounds anywhere close in fidelity to analog FM (15 kHz?) or FM HD (20 kHz). Maybe if you're one of the millions with drastic hearing loss it's the same, but for those of us who have good ears, there is no comparison. Especially if the HD broadcast has no subchannels like a few of my local Cumulus stations.

That's an excellent point Tom, and one that those who practice revisionist history as it relates to AM stereo don't mention. Besides challenges of signal to noise, stations that process their audio asymmetrically, poor transmitter interfacing, and phasing plus tuning networks that don't allow for stereo. AM stereo sounded a little better than mono, but not that much when it comes to specifications. To your point, people forget that there is a noticeable difference between 50-10kHz audio response and 20-15kHz for FM. Or that stereo separation in lab conditions for AM stereo were <30dB, where the average FM is >50dB. Add in things like received platform motion of CQUAM, losing the signal in tunnels, under bridges, etc., AM stereo simply couldn't compete with FM. By the time AM broadcasters started screwing around with stereo, all the music listeners had already migrated to FM. It was game over.

Kelly A said:

That's an excellent point Tom, and one that those who practice revisionist history as it relates to AM stereo don't mention. Besides challenges of signal to noise, stations that process their audio asymmetrically, poor transmitter interfacing, and phasing plus tuning networks that don't allow for stereo. AM stereo sounded a little better than mono, but not that much when it comes to specifications. To your point, people forget that there is a noticeable difference between 50-10kHz audio response and 20-15kHz for FM. Or that stereo separation in lab conditions for AM stereo were <30dB, where the average FM is >50dB. Add in things like received platform motion of CQUAM, losing the signal in tunnels, under bridges, etc., AM stereo simply couldn't compete with FM. By the time AM broadcasters started screwing around with stereo, all the music listeners had already migrated to FM. It was game over.

Click to expand...

Some misconceptions here.

FM is not 20 Hz to 15 kHz. It is 50 Hz to 15 kHz, unless you are in Canada where there is no bottom end roll-off. A lot of FM stations cheat and take high pass filters out of their exciters - yep, I've done it myself. I'm not sure if the 50 Hz low end is a law, a standard, or what, but it is definitely there. Listen to an artist with good bass on a Canadian station and it sounds really good! I remember hearing Jimi Hendrix on CKLW FM - quite a difference! One of the very few good things FM HD does - it gets rid of that blasted high pass filter at 50 Hz!

Platform motion was only an issue when the received AM station had an interfering signal. I've heard it myself on KAAM when I was close enough to get KKOB. But the worst case scenario was that the channels slowly reverse, and it isn't that annoying compared to something really annoying like the 10 kHz heterodyne in the received audio. Something that AMAX AM stereo radios eliminate.

You lose both AM and FM in tunnels - if anything AM penetrates further because it has a longer wavelength. If you want to talk about signal strength issues - just do drive tests on AM HD compared to AM C-Quam like I did - getting 290 miles on C-Quam as opposed to 35 on HD. And HD FM drive tests that showed a 60 mile difference in range on a station running analog only compared to the same station running HD. Just ask KHPT Houston, which is hearing from listeners all over about how well the station is coming in now that they dumped the HD. HD is a power vampire that affects range and building penetration. That won't change - it is the nature of the beast. And don't get me started on the IF image problem, which the "geniuses" at iBiquity didn't even think about when they slopped over on adjacent frequencies.

What killed C-Quam was Leonard Kahn - who delayed its adoption long enough that talk radio was starting to gain a foothold, and FM had begun to make inroads into top-40 music - because there was no stereo on AM and kids were hearing stereo on 45's and albums and wanted it on the radio, so they switched to FM to get stereo.

rbrucecarter5 said:

Some misconceptions here.

FM is not 20 Hz to 15 kHz. It is 50 Hz to 15 kHz, unless you are in Canada where there is no bottom end roll-off.

Platform motion was only an issue when the received AM station had an interfering signal. I've heard it myself on KAAM when I was close enough to get KKOB. But the worst case scenario was that the channels slowly reverse, and it isn't that annoying compared to something really annoying like the 10 kHz heterodyne in the received audio. Something that AMAX AM stereo radios eliminate.

What killed C-Quam was Leonard Kahn - who delayed its adoption long enough that talk radio was starting to gain a foothold, and FM had begun to make inroads into top-40 music - because there was no stereo on AM and kids were hearing stereo on 45's and albums and wanted it on the radio, so they switched to FM to get stereo.

Click to expand...

As Frankberry pointed out, FM does have response down to 20hz. It may not be flat to 20, but on several of my stations running a proof, I frequently measured audio down that low. Some old legacy exciters had issues with low frequencies (Collins comes to mind), but not all.

AMAX was a joke. Even in their demo at NAB, there was a high frequency whistle in the audio. That and the high frequency response was even worse than non-AMAX options. As I recall, AMAX would only pass up to 8Khz (except for the HF whistle). Even back in the early 80's I argued in Radio World that if you can't hear the difference between 10kHz and 15kHz in high frequency response, you need your hearing checked.

I'll grant you that Leonard suing everything that moved didn't help the whole adoption of AM stereo, but that was hardly the sole reason. The lack of consumer interest, inferior quality to FM, inferior installations and adoption by most stations running AM stereo, were only some of the other numerous reasons. AM stations during that time were still in loudness wars and AM stereo didn't work well when modulating above 100% with positive asymmetry. And (as I said earlier), and the majority of music radio listeners had already made the jump to FM.

It's time to let the fractured memory of AM stereo Rest In Peace.

tomservo said:

I really like the "shape" of the audio produced by a quality C-QUAM stereo AM broadcast or even a well processed mono AM broadcast, but these people are delusional if they think that the 10 kHz bandwidth of current AM radio sounds anywhere close in fidelity to analog FM (15 kHz?) or FM HD (20 kHz). Maybe if you're one of the millions with drastic hearing loss it's the same, but for those of us who have good ears, there is no comparison. Especially if the HD broadcast has no subchannels like a few of my local Cumulus stations.

Click to expand...

There is only about a half an octave of musical notes from 10,000 hz to 15,000 hz. A good wideband AM tuner sounds great, I defy anyone here to tell the difference between a good AM wideband tuner with a wideband signal and analog FM, there is virtually no difference, especially in a car. Wideband stereo AM has at least one advantages over FM, much longer range. And since IBOC hisses over a 30 khz range that means theoretically a station could transmit 15 khz audio in the AM band which would be LESS objectionable to adjacent stations than IBOC is. Again digital radio is a fix looking for a problem. I can remember listening to stereo AM stations from all over the East while driving through Vermont late at night years ago. Every fix that comes along is detrimental to AM radio and is a step backwards in ease and listenability for the consumer. Turn on your C-Quam AM stereo radio at night and you're in business, you get stations from all the country, which equates choice.
If the industry had put the time and money into C-Quam receivers and transmitters that they put into FM, we would all be listening to AM stereo right now.
I have very good hearing by the way and have been a musician for over 40 years.

KB1OKL said:

There is only about a half an octave of musical notes from 10,000 hz to 15,000 hz. A good wideband AM tuner sounds great, I defy anyone here to tell the difference between a good AM wideband tuner with a wideband signal and analog FM, there is virtually no difference, especially in a car. Wideband stereo AM has at least one advantages over FM, much longer range.

Click to expand...

Now back to reality: There are no "wideband" AM tuners available to consumers, so your what-if statement isn't based on reality of today. Second, broadcasters don't care about listeners hearing their station outside their market. Maybe that was true back in the 40's through 60's, but those days are long gone. David G. was correct when he stated that the majority of the major market AM stations don't even cover the entire market, let alone caring about skywave listeners or the few DX'ers in the world.

Finally, it could be your hearing may be affected by your love for the "good ol' days".

Kelly A said:

As Frankberry pointed out, FM does have response down to 20hz. It may not be flat to 20, but on several of my stations running a proof, I frequently measured audio down that low. Some old legacy exciters had issues with low frequencies (Collins comes to mind), but not all.

AMAX was a joke. Even in their demo at NAB, there was a high frequency whistle in the audio. That and the high frequency response was even worse than non-AMAX options. As I recall, AMAX would only pass up to 8Khz (except for the HF whistle). Even back in the early 80's I argued in Radio World that if you can't hear the difference between 10kHz and 15kHz in high frequency response, you need your hearing checked.

I'll grant you that Leonard suing everything that moved didn't help the whole adoption of AM stereo, but that was hardly the sole reason. The lack of consumer interest, inferior quality to FM, inferior installations and adoption by most stations running AM stereo, were only some of the other numerous reasons. AM stations during that time were still in loudness wars and AM stereo didn't work well when modulating above 100% with positive asymmetry. And (as I said earlier), and the majority of music radio listeners had already made the jump to FM.

It's time to let the fractured memory of AM stereo Rest In Peace.

Click to expand...

I have a Sony XRA-33 FM/AM Stereo rcvr (with the two chip circuit that allows reception of all 4 modes)...790 and 93Q (KKBQ AM and FM) Houston were simulcast and the AM (originally ran Kahn but went to CQUAM) sounded better to be than the FM did...

890 WLS transmits in CQUAM and listening to its audio with music (from the 07 and 08 BIG89 Rewinds) taken directly from its AM stereo monitor at the studio has no audio about 10kHz but playing songs like Dancing Queen, etc and comparing it to the same song off a FM has little difference (WLS(A) has less bass than a FM)....

AM stereo could be done better with current DSP technology to offer variable audio bandwidth to eliminate the whistle and also auto/manual switching of IF filters would also help....

AM stereo is not dead yet...

Kelly A said:

Now back to reality: There are no "wideband" AM tuners available to consumers, so your what-if statement isn't based on reality of today. Second, broadcasters don't care about listeners hearing their station outside their market. Maybe that was true back in the 40's through 60's, but those days are long gone. David G. was correct when he stated that the majority of the major market AM stations don't even cover the entire market, let alone caring about skywave listeners or the few DX'ers in the world.

Finally, it could be your hearing may be affected by your love for the "good ol' days".

Click to expand...

The reality of today is that the AM band is neglected and scorned by people like you who have no idea how good it can sound because you probably weren't around before the FCC started "fixing" it. This whole thread is about Kintronics demonstrating tuners that are wideband and stereo to boot. So they are available and if Kintronics has their way they will be widely available again if the FCC actually does something to help the band instead of ruin as it has. AM radio can sound very good. I have some very good AM radios and regularly listen to CFZM AM 740 out of Toronto, Canada. I don't know how wide their signal is but they sound very good. They brag about the fact that they are widely heard as do several other stations such as WSM, Nashville. People don't listen for long distance AM radio anymore because the dial is so congested now it is a waste of time unless you are a DXer and don't care about noise. We don't need digital radio, we need less congestion on the AM band and the ability to widen the signal so that these stations can sound good again and yes DSP technology could help a lot.

True, and maybe if we brought back horse drawn buggies, there would be less highway congestion. Somehow I see neither scenario happening.

During the late 70's and early 80's I remember the last gasp of a few stations trying to make AM stations compete with FM for playing music. The station I worked at was even testing the Kahn Hazeltine ISB AM stereo system, so I do remember what the comparison sounded like. Could AM sound better than it does now? Sure! Could AM sound as good as FM did, or even does now? Nope.

There can be only one reason Kintronic is proposing C-Quam - it decodes on some, perhaps most, HD radios and is a more robust system than HD AM is. I wonder, though, what the business model is with the decline in AM music programming, ever increasing interference levels on the AM band, and lack of interest in AM on the part of consumers.

Now, you take a major 50 kW outlet like WLS that has some musical content - there may be a reason for a stereo system for AM.

I must, once again, dispel the notion that AM radios are narrowband. Narrowband AM radios haven't been manufactured in 30 years. Everything now is cheap one ceramic filter: http://earmark.net/gesr/Current_Radio_Design.htm They are inherently broadband. If they have limited frequency response, the only reason is an audio low pass filter. That is a different issue than broadband vs. narrowband IF. ALL as in ALL AM radios manufactured in the last 30 years are broadband. Because it is CHEAP and easier for the consumer to tune the radio. No other reason.

Should AM go all digital, what I would like to see are "jailbroken" or digitally agnostic radios. We know the current DSP chips used in HD Radios will decode most if not all the digital standards. Why not mandate a radio that receives all the standards and let broadcasters choose which encoding platform they want to use? Being forced to use only iBiquity's technology seems legally dubious, in my opinion.

As much as some of us would love to see the return of CQuam,there would be a
problem.
The Sony SRF-A1 and 42 were designed for the AM band circa 1985-1994...they
have a problem with today's overcrowded band at night;
you will hear the lower or upper sideband of some adjacent station.
It's a real "rock and a hard place" thing,
narrow the bandwidth and lose the reason for doing it.

If you can find an Aiwa portable receiver with "AM Wide",get it.
Aiwa took the easy (cheap) way out and just put in a wider
Murita filter.
They are not up to AMAX (no stereo,either) but a happy accident is the
bandwidth just about matches today's 10,200 cycle limit.
The few music stations (WSM etc.) sound fine on them.

rtc said:

As much as some of us would love to see the return of CQuam,there would be a
problem.
The Sony SRF-A1 and 42 were designed for the AM band circa 1985-1994...they
have a problem with today's overcrowded band at night;
you will hear the lower or upper sideband of some adjacent station.

Click to expand...

I was using the SRF-A1 until a year ago when I got an SRF-59. It didn't have any problem with adjacent channels at night. Still a darn good little radio - just a little bigger and heavier on trips so I wanted something smaller. Both the SRF-A1 and SRF-59 are fantastic little DX radios with excellent sensitivity and selectivity.

Kelly A said:

The station I worked at was even testing the Kahn Hazeltine ISB AM stereo system, so I do remember what the comparison sounded like. Could AM sound better than it does now? Sure! Could AM sound as good as FM did, or even does now? Nope.

Click to expand...

Kahn had several issues...it had no stereo separation above 7kHz, the antenna (or array) reactance curve had to be symmetrical for both channels to have the same frequency response, etc. No, if you only listened to Kahn, you have no idea what CQUAM can sound like (especially if it was allowed full bandwidth). Can AM sound as good as FM? Yes.....with same bandwidth and a receiver matching the transmitted signal, yes it does....Stereo AM sounds richer to me than FM does when done right...The problem with AM is NOT the mode.....(AM on VHF would sound as good as FM...remember, the stereo component of FM is AM!!! rather DSB-Suppressed Carrier)..its the crappy receivers

rbrucecarter5 said:

I must, once again, dispel the notion that AM radios are narrowband. Narrowband AM radios haven't been manufactured in 30 years. Everything now is cheap one ceramic filter: http://earmark.net/gesr/Current_Radio_Design.htm They are inherently broadband. If they have limited frequency response, the only reason is an audio low pass filter. That is a different issue than broadband vs. narrowband IF. ALL as in ALL AM radios manufactured in the last 30 years are broadband. Because it is CHEAP and easier for the consumer to tune the radio. No other reason.

Click to expand...

The radio you linked to is a cheap portable/table top design..it does NOT equate to the digitally tuned home or car rcvrs which have a narrow ceramic filter in the IF...No, not ALL AMs are broadband....since the auto radios are the majority sold, the reverse is the case.

ContinuousWave said:

The radio you linked to is a cheap portable/table top design..it does NOT equate to the digitally tuned home or car rcvrs which have a narrow ceramic filter in the IF...No, not ALL AMs are broadband....since the auto radios are the majority sold, the reverse is the case.

Click to expand...

Digitally tuned home radios are the same exact thing - but with an additional chip to generate tuning voltage to varactor diodes. I own at least 3 such radios, including a $900 AV receiver that has - wait for it - one ceramic filter on AM and is broadband as heck. Funny thing is - the tuning voltage steps are not exact. If you put a narrow ceramic filter IF in digitally tuned home radios, they won't hit every frequency. That is how bad the tuning voltage steps are. I know because I tried - I had to roll back the narrow ceramic filter modification just so I could tune all of the AM frequencies.

Car radios are definitely better, but with shark fin antennas they are deaf on AM. Sure you can hear Rush or the home game on strong local stations, but any advantage you would have from narrow IF is lost because those shark fins are anything but adequate. Another reason HD radio is doomed, because you need better antennas - NOT WORSE - to make it work on AM or FM. HD's introduction coincided with the elimination of whip antennas on cars. Talk about bad timing!!!

rtc said:

As much as some of us would love to see the return of CQuam,there would be a
problem.
The Sony SRF-A1 and 42 were designed for the AM band circa 1985-1994...they
have a problem with today's overcrowded band at night;
you will hear the lower or upper sideband of some adjacent station.
It's a real "rock and a hard place" thing,
narrow the bandwidth and lose the reason for doing it.

If you can find an Aiwa portable receiver with "AM Wide",get it.
Aiwa took the easy (cheap) way out and just put in a wider
Murita filter.
They are not up to AMAX (no stereo,either) but a happy accident is the
bandwidth just about matches today's 10,200 cycle limit.
The few music stations (WSM etc.) sound fine on them.

Click to expand...

I have a few wideband radios circa 1937 (RCA 816K and RCA 13K) these have adjustable bandwidth controls as do most of my communications receivers. I usually have no problem with adjacent sidebands unless of course they're running IBOC and even if I do the sidebands are not continuous noise like IBOC is. I'm listening to WFAT out of Athol Ma right now on my 816K, it sounds wonderful, not sure how wide they are but this would make a believer out of anyone and radios that sound like this could be made again and probably much cheaper than an 816K, maybe a little smaller too!

KB1OKL said:

I have a few wideband radios circa 1937 (RCA 816K and RCA 13K) these have adjustable bandwidth controls as do most of my communications receivers. I usually have no problem with adjacent sidebands unless of course they're running IBOC and even if I do the sidebands are not continuous noise like IBOC is. I'm listening to WFAT out of Athol Ma right now on my 816K, it sounds wonderful, not sure how wide they are but this would make a believer out of anyone and radios that sound like this could be made again and probably much cheaper than an 816K, maybe a little smaller too!

Click to expand...

All it would take - and all it takes - is to pull out an RC low pass filter to open up the high end, and usually change the value of a DC blocking capacitor to a larger value to open up the low end. Problem is, these cheap one ceramic filter radios have really bad 10 kHz whine, and my ears haven't gotten bad enough to reject it yet.

As for IBOC stations - unless you are tuned EXACTLY on frequency, the phase modulated side bands from 5 to 10 kHz turn into amplitude modulated and rush like an invasion of locusts in your ear. Given the imprecise tuning steps of digitally tuned AM radios, that is pretty much a guarantee.