Time to reconsider AM stereo?

[audioguy]

I think many of us are of the opinion that HD AM is not going to make it. However, AM owners do not want to go empty-handed.

Is it time to reconsider AM stereo, in order to enable AM radio to be reasonably comparable to FM? Today, stereo transmission is the standard, so any broadcast system needs to at least provide that. Given the limited amount of AM spectrum, C-QUAM seems like an efficient way to provide improved service.

Does anybody know: How many HD radios can decode C-QUAM? How many analog AM stereo car radios are still in circulation?

Are there any tweaks that could/should be done that would improve C-QUAM if it were to be re-launched?

Could C-QUAM be successful if it got a fresh launch with some decent marketing? Starting with a more user-friendly name than C-QUAM?

C-QUAM AM stereo, while far from being perfect, does have many advantages over HD AM. In particular, it does not cause additional interference. The service area of an AM signal is almost the same in stereo as it is in mono. And if properly set up, it has decent audio quality, although not as good as analog FM (and we will not try to pretend otherwise).


http://en.wikipedia.org/wiki/C-QUAM

 

[clouseau]

You may in fact be correct. AMHD may not make it. However I believe that is a function of AM radio overall.
While AM Stereo MAY be superior to AM mono, AM overall isn't looking all that good.

With the utmost deference to our AM compadres, more and more, AM is showing up as ratings leaders less and less. I wouldn't expect that trend to change.

I suspect the future of AM radio is with FM translators and maybe with TV CH 5 & 6. Actually I suspect we will tentatively decide the 5/6 issue sometime in August, when LPTV either gets it or has it delayed.

Either way, I think you're fighting an uphill battle to get another 50 cents spent in AM radio technology for stereo in receivers.

Clouseau

 

[Play Freebird]

Either way, I think you're fighting an uphill battle to get another 50 cents spent in AM radio technology for stereo in receivers.

With today's technology, it can probably be done for less than that -- and this would certainly be less expensive than HD. Haven't Motorola's patents expired by now? If so, royalties shouldn't be a concern.

 

[KB1OKL]

I think AM stereo is great, had it in an 88 Plymouth, I can remember hearing AM stereo stations from 100's of miles at night. I have a Meduci AMX-2000 stereo tuner right now that receives C-QUAM, unfortunately there are no C-Quam stations within my listening area at all.

 

[radioman148]

I liked AM stereo, but with so much talk on AM I doubt it would help much now.

 

[pqgeorge]

I liked AM stereo, but with so much talk on AM I doubt it would help much now.

I look at it, this way. HD-AM simply doesn't work, period. What can be done right now is to reconsider switching back to C-QUAM Stereo and get rid of those horrible brick wall filters. C-QUAM will decode on many IBOC receivers, due to the chipset already in place. C-QUAM is already THE system in place for AM Stereo according to the FCC Rules and Regulations. Hey, it can't hurt and the quality on standard (mono) AM receivers would improve due to the inheritant abilities of the Motorola C-QUAM AM Stereo system. Over the years, C-QUAM has improved. The "platform motion" has been pretty much eliminated do to the better circuitry made over the years. Let get rid of HD-AM and the splatter (hiss) that comes with it, once and for all.

 

[Savage]

Amen to that. I have long been an advocate of a revision to the NRSC standard allowing 12.5 kHz bandwidth daytime, 10 kHz nighttime with the standard pre-emphasis curve MANDATORY for all USA receiver sales. Also AM stations should be encouraged to program C-QUAM fulltime.

The sound quality improvement would be well worth the slightly increased adjacent-channel splash, which would in turn be vastly less objectionable than that caused by HD sidebands. With the current US allocation standards any splatter wouldn't be troublesome to other local or nearby signals for the most part. Of course - unlike HD - the rule could also be crafted in such a way that any wideband AM causing harmful interference to an adjacent would be required to dial back to 10 kHz-U.

We could market it as "Hi-Fi AM" or some similar trade name. Actually, the way most FMs are processed these days, a 12.5 kHz-wide AM stereo signal would sound better and more realistic than many FMs.

I have always been of the opinion that C-QUAM AM stereo sounded better than FM stereo. It is truly an excellent system.

 

[rbrucecarter5]

Is it time to reconsider AM stereo, in order to enable AM radio to be reasonably comparable to FM? Today, stereo transmission is the standard, so any broadcast system needs to at least provide that. Given the limited amount of AM spectrum, C-QUAM seems like an efficient way to provide improved service.

I think one unwanted side effect of the HD-AM movement was that it killed C-Quam AM stereo completely. The few stations that still carried it for music formats quickly switched to the new technology, leaving very few C-Quam stations on the air. Those that didn't care about audio quality never had C-Quam and won't adopt HD-AM (thankfully).

The HD shills were very quick to falsely accuse C-Quam of limiting a station's range - in spite of overwhelming evidence to the contrary. I did testing in a valley 290 miles away from some Dallas stations in the daytime - and they decoded just fine in stereo. How much freakin' range do station owners want? Especially when one of those same stations would not decode HD less than ten miles away. Let's see - 290 miles vs. less than 10 miles - which stereo system would YOU pick for YOUR station?

I agree that C-Quam would be vastly superior to HD-AM, but iBiquity backing off of it to promote C-Quam? Even re-branded? I don't think so. Those folks have proven to be vindictive and under handed, using high pressure tactics and outright lies to scare off all criticism of their faulty system. Their colossal egos refuse to admit that they are wrong, so they will cling to the sinking boat until they drown at the bottom of the ocean rather than take a life preserver like C-Quam.

 

[w9wi]

I think many of us are of the opinion that HD AM is not going to make it. However, AM owners do not want to go empty-handed.

Is it time to reconsider AM stereo, in order to enable AM radio to be reasonably comparable to FM? Today, stereo transmission is the standard, so any broadcast system needs to at least provide that. Given the limited amount of AM spectrum, C-QUAM seems like an efficient way to provide improved service.

Does anybody know: How many HD radios can decode C-QUAM? How many analog AM stereo car radios are still in circulation?

Are there any tweaks that could/should be done that would improve C-QUAM if it were to be re-launched?

Could C-QUAM be successful if it got a fresh launch with some decent marketing? Starting with a more user-friendly name than C-QUAM?

C-QUAM AM stereo, while far from being perfect, does have many advantages over HD AM. In particular, it does not cause additional interference. The service area of an AM signal is almost the same in stereo as it is in mono. And if properly set up, it has decent audio quality, although not as good as analog FM (and we will not try to pretend otherwise).


http://en.wikipedia.org/wiki/C-QUAM

IMHO AM stereo addresses the same problem as IBOC: poor audio quality. (perceived or real)

Thing is, poor audio quality is not what's fundamentally wrong with AM.

The fundamental problem with AM is poor and unpredictable (by the average listener) coverage, especially at night.

At least AM stereo, unlike IBOC, doesn't make that problem worse!

I would suggest there has been one positive development that's come out of IBOC: the development of inexpensive receivers with digital signal processing. Most listeners are finding that HD receivers have exceptional performance when tuned to analog stations. AM operators should push for the inclusion of that technology in as many receivers as possible. And yes, there's no reason they shouldn't be able to include C-Quam capability in the DSP firmware.

 

[ajc_trw]

I worked (DJ overnights) for an AM stereo station back in 1995 (KAZM 780 Sedona AZ) and the sound was quite good, for AM radio. C-QUAM's big problem was platform motion, but that was only a problem with a weak signal.

AM Stereo can sound quite good. When I first went into the air studio they were playing music and as I heard the monitors I didn't know if they were monitoring the board or off-air. I couldn't hear audio above 9kHz so I thought it was off-air but the dynamic range was too wide for broadcast (as I was used to it) so I thought it was from the board. KAZM definitely did C-QUAM right!

As far as crosstalk, there is little to none. We had a cassette recorder on the board where we could record our air-check tapes. Unfortunately they only wired one channel from the off-air stereo monitor. Just listening to California Dreaming (male vocals on one side female on the other) testifies how little crosstalk there is in C-QUAM.

My recommendation: Widen the bandwidth to 12.5kHz, kill asymmetric processing and lighten up on the Optimod. All IMHO, YMMV.

 

[wnmb]

At WNMB in North Myrtle Beach, SC, we broadcast in AM Stereo. It has made a big difference for us in several ways including the fact that there are a lot of AM Stereo radios in cars on the road today. Many Ford Explorers and Expeditions (all Eddie Bauer editions) through 2005 have AM stereo. Every new Thunderbird came with AM Stereo. They are also in many Escapes (Limited) and other vehicles.
As to platform motion, the newer generation AM stereo exciters pretty much eliminate the problem. We use a Delta exciter made in 2006.
As to signal coverage, we get about 90% of our pattern that decodes to Stereo. Only the fringe areas remain mono. This is much better coverage than AM HD.
There are three things needed for the AM band to be viable. 1. The broadcasters themselves must do their part and put quality programming on the air. They must serve their communities and they must sound good, both programming wise and technically. 2. The FCC needs to adopt a standard for AM receivers. If you have a VW Beetle that cuts off AM freq. response at 2.5 hz, then no matter the radio station does, the listener thinks AM is bad. The radio station gets the blame for some manufacturer's two bit receiver. Adopting a standard, such as was tried with AMAX is no big deal. After all, The Federal government does everything else in the world. They might as well have a minimum standard for a receiver. 3. The radio stations must invest in the technology. Putting AM Stereo on the air is a lot less costly than HD AM. Then, the stations have to promote it.
Finally, will analog even have a chance in today's digital age? The answer is yes as long as we remember the listener cares most of all about the programming. There are still some characteristics of AM which have a big advantage including more coverage for less power.
Oh yes.....in addition to the Stereo......stream your signal and marry it to your website.

 

[kenglish]

The only advantage I see for AM HD Radio over AM Stereo/NRSC is that HD Radio kills the annoying hum/buzz that makes analog impossible to listen to.

If the FCC could do some real enforcement of Part 15 rules, and stop the incessant buzzing and arcing of nearly every electrical and electronic device currently made (and NOT maintained properly), I'd be thrilled. But, listening to AM radio anywhere but out in the country (waaaaaaaay out in the country) is getting impossible.

And, yes....I do have an HD Radio tuner, an "NAB Supertuner", several portable radios (including some with Kiwa mods), and a Ten-Tec, plus an assortment of loops and other antennas. But, I doubt that many "city dwellers" go to nearly that extent to listen to AM Radio .

 

[rbrucecarter5]

The only advantage I see for AM HD Radio over AM Stereo/NRSC is that HD Radio kills the annoying hum/buzz that makes analog impossible to listen to.

It is precisely that interference that keeps AM HD from locking - it is very sensitive to interference. In my view - AM HD was doomed from the start by its own sensitivity to interference.

 

[w9wi]

The only advantage I see for AM HD Radio over AM Stereo/NRSC is that HD Radio kills the annoying hum/buzz that makes analog impossible to listen to.

At least in my experience, if there's enough hum/buzz to be annoying, HD won't work at all.

I do concur wholeheartedly with your comments about enforcement of Part 15. But it's way too late to fix that now.

Besides the inclusion of DSP in consumer receivers, maybe the other big benefit of IBOC for AM stations has been the simulcasts of some such stations on the HD2/HD3 channels of co-owned FM stations. In the unlikely event I want to listen to WLAC, it's a whole lot easier to receive on WNRQ-HD3 than on AM 1510. (and even if it does come in in HD on AM 1510, the HD3 of the FM sounds better...)

 

[Savage]

Which raises the obvious point: what's the point of HD-AM in any case, if the best way to hear those stations is via an HD-FM sub simulcast?

It's obvious that HD-AM is NOT going to make it. Why not just turn them all off and simply rely on the FM subs?

 

[K6JHU]

I believe that along with the move to FM translators and getting an HD-1 FM signal (e.g. KCBS-AM), the future of AM may be on HD-2 and HD-3. In Los Angeles KNX, KABC, KFWB, KGIL (that I am aware of) are all on HD-2 and HD-3. They definitely sound better since it seems that the AM processing is off on the HD. KNX sounds particularly good.

 

[rbrucecarter5]

I believe that along with the move to FM translators and getting an HD-1 FM signal (e.g. KCBS-AM), the future of AM may be on HD-2 and HD-3. In Los Angeles KNX, KABC, KFWB, KGIL (that I am aware of) are all on HD-2 and HD-3. They definitely sound better since it seems that the AM processing is off on the HD. KNX sounds particularly good.

Again - I have to ask the question - what is the point of wideband stereo for talk and sports? A bandwidth of 5 kHz is plenty for those formats. Unless it is for musical beds and commercials, there is no point wasting spectrum for talk and / or sports. Let 'em stay on AM, and reserve wide bandwidth stereo channels for music only.

 

[K6JHU]

At the risk of getting dumpted on....

I have read a whole lot of complaints about how AM bandwidth was narrowed so as to support AM-HD and how the old analog 12.5 KHz or 10 KHz was so much better sounding on AM. So I post that an AM signal sounds so much better on an FM-HD and what is the comment.... what is the point of wideband stereo for talk and sports?

Maybe one of the mistakes of the IBOC implementation was to only allow two HD subs. We could probably stick several 5KHz AM signals on HD subs if the receiver could decode it

 

[rbrucecarter5]

So I post that an AM signal sounds so much better on an FM-HD and what is the comment.... what is the point of wideband stereo for talk and sports?

Maybe one of the mistakes of the IBOC implementation was to only allow two HD subs. We could probably stick several 5KHz AM signals on HD subs if the receiver could decode it

Not trying to dump, but --- the stations you listed were a whole bunch of talk stuff. UGH! Who freakin' cares? Once in a while for traffic, but don't clutter my FM dial with 'em, leave them were they are and put music on FM, even if it is HD-2 and 3. I don't care for right wing, left wing, religious preaching, or anybody else's drivel.

 

[stacker]

I believe that along with the move to FM translators...

The FCC Order authorizing AM use of FM translators is very restrictive. The 60 dbu contour of the translator can't extend beyond 25 miles from the transmitter site or beyond the AM's 2 mV contour, whichever is less. Plus, only presently licensed translators are eligible. Assuming you can find an existing translator, that's a tough standard to meet. Especially for stations with a directional signal.

It's not uncommon for an AM station to have a deep null over an unpopulated area in order to maximize signal over the population; however, that null comes into play when determining whether you can use a translator since it sucks in the 2mV contour. Also, many AM's are located outside of the population center for real estate reasons, and that brings the 25 mile rule into play.

Some might say my post belongs on another discussion area. But I believe the translator order was offered, in part, as a result of the noise being introduced into the AM band due to IBOC. Frankly, the new translator rules just provide lip service to AM broadcasters.

I wonder if the stations that have been using translators under STA's will be required to adhere to the coverage/distance rules?