Part 15.219 AM Stereo Transmitters

why would they hide their DRM product? isn't DRM and open source standard? is their some legallities involved in selling DRM transmitters vs their other 100mW and high power CQuAM Stuff?

Hi tpreitzel: Jeff here ( Station 8 ) I have on my blog about chris chuff which had some am stereo c-quam transmitters that he was selling i don't know if he has anymore but his contact information is there. If you contact me i have a schematic in a pdf file that i can send you on building your own  am stereo transmitter and will allow you do c-quam or the kahn/ Hazeltine system.I have the asmax-1 and with that company you have to keep emailing him to get a responce from him and remember there holidays could be an issue thats what happen to me once and thats why i didn't here from him for a little bit.

I would like to see the companys make there part 15 am transmitters in stereo but give you the options if you want to send a mono or stereo signal out by throwing a switch that would be nice. 

Take it easy Jeff

Jeff,

First, I thank you for the information. I'll keep buggin' AspiSys, but I would like other options as well. Yes, I'd appreciate the schematic. I'll try to contact Chris, too.

Yep, I certainly think AM stereo should be a selectable, standard feature on ALL Part 15 transmitters.

I cant remember the last time I saw a stereo AM receiver.

I've heard allegations that the chipset used in most Hybrid Digital receivers can decode AM stereo. Furthermore, millions of AM stereo receivers have been sold over the years. Yes, the potential listener would have to either buy a new HD Radio or scour auctions for used AM stereo receivers. Although expensive, Meduci sells their new MW-2 AM stereo receiver. I bought the MW-2 recently and its performance is quite good.

Hence, there's more than enough justification to design AM transmitters including Part 15 models with AM stereo as a selectable, default standard along with monophonic. IIRC, Nautel's MW transmitters include AM stereo as a default capability, e.g. their NX-50. Since HD/AM stereo receivers are available, listeners that have the required gear shouldn't be penalized for those listeners that do not.

Jeff,

I received the schematic via e-mail just fine. I've also contacted Chris.

Thanks again

Honestly,

At this point, I don't know since I haven't been able to contact them. Except for the proprietary codec, DRM is largely an open standard with limited royalties. I apologize for the late reply as I overlooked your question initially.

Personally -- and this is just me -- I really have a hard time comprehending the need or desire to braodcast in AM stereo in the Part 15 arena. My understanding is that it doesn't hurt nor help the potential coverage area, so I'll assume it's not a coverage issue.  Now, if you're doing it because you listen to your own broadcasts and like to hear it in stereo, I get that.  I also get it if you're an experimenter type, a tinkerer who enjoys doing such things, to create the best AM sound you can.  I totally get that. Ask anyone in my household -- I do a lot of goofy things, and build a lot of stuff, simply because I can.  And if that's the driving force I wish you good luck and fine sound.

But if the goal of your station is to serve listeners wouldn't the time and effort be better spent on quality programming, raising awareness of your existance, and becoming involved in the community?  It is very hard to argue a market for AM stereo, especially in Part 15. Given your total potential audience is going to be within a mile or so radius of your station generally your max audience over the air is going to be a couple thousand people.  How many will have the potential to enjoy the benefits of AM stereo? I too cannot remember the last time I saw an AM stereo receiver. Perhaps in an auto in the 1980's.  I've never known anyone with a home AM stereo receiver.  Now, sure, if you hang with the right types of people you may well know someone who has one.  Just like computer geeks probably know someone still using a TRS-80 or a Timex Sinclair 1000.  But your typical listeners won't know or care. 

According to the FCC database there are currently 4871 AM stations in the USA. Of those 88 broadcast in AM stereo.  According to my math that's 1.84 percent.  If there was a benefit to it I would think more would be doing it. Clearly it's not cost effective for them. The only AM station I know of in these parts went AM stereo back in the day when it was a new and cool idea and their format then was country music. About 10 years or so ago they went to all news/talk format.  Lot of good stereo does them now!

Millions of AM stereo receivers may have been sold.  As were millions of Quad stereo systems. How many regular folks do you know with a Quad system in their house today? how many Quad records are being purchased?  0 are being made. There were millions of Beta video decks sold, does this mean we should start making tapes for them again? How many billions of cassette players were made? Many were built into AM stereo car radios!

So out of your potential audience of 2000 people (depending on your population density of course but it's a realistic starting figure) by the time you subtract those that won't be listening to you anyway what percentage of the remaining who will listen might have a stereo AM receiver.  Near as I can tell the answer is so statistically small that for all practical purposes it's zero.  That is unless, as I've mentioned you want to enjoy the sound in stereo and perhaps you have friends, family, and know some techie types who will enjoy it mostly for the satisfaction of being able to do so. 

But again, if you yourself enjoy doing so either for your own audio enjoyment of the technical accomplishment of doing it, more power to you. From a "radio station owner/manager" side of things it really doesn't make sense. 

But it's just me, playing devils advocate today and letting my practical side shine 🙂

Tim in Bovey

Stereophonic sound in the Part 15 world is an interesting subject on two other fronts besides AM radio...

Of course we have recently talked about the pros and cons of FM stereo at Part 15 field strengths, and the consensus is that FM mono places a noise-free clear signal to a farther distance than is possible with stereo FM.

Then there's internet streaming. Is it a good idea to stream in stereo? Does it even matter? I'm still not sure.

Of course you would stream in stereo. Assuming you have modern world bandwidth. Your largest percentage of stream listeners are listening in stereo. Smart phones with headsets/earbuds. People like me who plug their iPhones into their car systems and listen in loud, clear stereo sound.  Virtually every computer has stereo speakers, even if they're crappy and 18 inches apart the clarity and seperation can be easily heard. Millionos of streamers using their home entertainment systems to listen, etc.  This, of course assumes your source material is in stereo.  I  listen to the Walburg Radio Network (a part 15er in Texas) and WREN (a stream only station in Topeka) all the time in the car streaming in loud, wonderful clear stereo. 

We must be careful lest we hijack this thread!

Tim in Bovey

You all can have your thread back in a minute, I just want to say that Tim's influence in advising stereo streaming will have me doing the math and running stereo trials.

My main programming is talk which is why I've been set for mono, but then again I do have quite a bit of great concert music and it's unfair to send that in mono.

Here's your thread back.

this guy does carrier current cquam...

http://www.krocksradioone.com/

by the way carl have you heard anything from RFB? i haven't heard from him really since he started his new job.

i tried emailing him but got no reply.

First, about RFB and KROCKS... it's been over a month now but back then I learned that his new job as contract engineer for a whole batch of AM FM stations all over Wyoming is keeping him busier than he can be. At one point he did attach a batch of pictures from his stations, but all my e-mail went missing so I'll have to ask him to send them again so I can share them.

And yes, KROCKS is all about stereo AM and there's plenty going on at that website including a Part 15 forum!

NOW, to the present moment, I just spent a half-hour looking for stereo AM radios at the two biggest radio sites, Universal Radio and C.Crane Company. It looks like only portable AM radios exist from them, always with FM and frequently with SW and Weather Band. Gone are those radios that tune to VHF TV band, since there no longer is a VHF TV band since digital came along. In fact, even rack-size radio tuners no longer seem to exist.

AHA, but I found something very interesting and I'll let you read it for yourself:

http://meduci.com/

"But if the goal of your station is to serve listeners wouldn't the time and effort be better spent on quality programming, raising awareness of your existance, and becoming involved in the community?"

Since I've already covered most of the objections raised here, I'll confine my additional remarks to some specific concerns.

A good broadcaster should do all of the aforementioned items. Broadcasting AM stereo can help raise awareness of both the station and the potential of AM stereo.

"It is very hard to argue a market for AM stereo, especially in Part 15. Given your total potential audience is going to be within a mile or so radius of your station generally your max audience over the air is going to be a couple thousand people.  How many will have the potential to enjoy the benefits of AM stereo?"

Initially, not many people will have the capability of decoding AM stereo within the potential listening audience. I'm convinced that the quality of AM stereo can sell itself in time. True, on Part 15, the sale will be more difficult due to the lack of field strength with distance, but I still see little reason for not including AM stereo in all MW transmitters. FM experienced a long, LONG period of trial before its adoption by the masses as well.

"I too cannot remember the last time I saw an AM stereo receiver."

This issue has already been addressed with the availability of HD Radios

"But your typical listeners won't know or care."

This issue has already been addressed as well. True, the average listener probably won't care, but the lack of discretion on the part of the average listener is no reason to penalize those listeners with the necessary hardware to decode AM stereo.

"According to the FCC database there are currently 4871 AM stations in the USA. Of those 88 broadcast in AM stereo.  According to my math that's 1.84 percent.  If there was a benefit to it I would think more would be doing it. Clearly it's not cost effective for them."

I'm not so sure. The broadcasters clearly PERCEIVE that adopting AM stereo is not cost effective for them. Perceptions can be wrong.

"The only AM station I know of in these parts went AM stereo back in the day when it was a new and cool idea and their format then was country music. About 10 years or so ago they went to all news/talk format.  Lot of good stereo does them now!"

I've heard good talk radio in dual channel and it does sound better than monophonic in some cases, e.g. sports where the ambience of the background adds to the drama of the broadcast. Furthermore, many talk radio stations broadcast music during the weekends.

"Millions of AM stereo receivers may have been sold.  As were millions of Quad stereo systems. How many regular folks do you know with a Quad system in their house today? how many Quad records are being purchased?  0 are being made. There were millions of Beta video decks sold, does this mean we should start making tapes for them again? How many billions of cassette players were made? Many were built into AM stereo car radios!"

You're assuming that AM stereo isn't viable as a platform any longer. Why? Has IP streaming replaced it? Have radio listeners abandoned AM for FM? You're assuming that the current lack of dedicated AM stereo receivers is an indication of a failed platform. I don't agree. The current lack of dedicated AM stereo receivers is symptomatic of more choices in the marketplace. Back in the 1980s, I was vaguely aware of AM stereo. However, like MANY folks in the 1980s, I was moving from broadcasting to networking for my information, e.g. CompuServe. Over the past 30 years or so, the world has slowly begun to see the problems with global networking since it fosters global spying. More and more servers are banning proxies as well. If given the chance, would listeners rather listen to content where the broadcaster assumes the risk or the listener? If given the chance, would listeners rather listen to quality broadcasts without the buffering of streams commonly found on networks?

Unfortunately for AM stereo, the problem wasn't with the platform, the problem was its timing.