AM HD I have heard in the west is a 75% improvement over standard AM transmissions.
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AM STEREO
- Thread starter LasVegasRadioJunky
- Start date
WNMB in North Myrtle Beach, South Carolina, is broadcasting in AM Stereo. It is a superb technical quality and it sounds better, in my humble opinion, than AM HD. Plus, the AM Stereo gives the radio station almost all its full signal range in Stereo, unlike HD which gives you less coverage. The WNMB AM Stereo generator is a late model Delta Unit. Earlier "Platform motion" from c-quam is no longer present. If anyone would like an aircheck on mp3, just e-mail to me. You can hear the station on the web with 24 hour streaming at www.wnmb.net. As to receivers, there are lots of cars out there with AM stereo standard. We hear from people all the time who do hear us in stereo and they love it. Most of the factory cars radios in recent years have been in Fords and Chryslers. The new Thunderbird has a great AM Stereo, as do most Explorers, Expeditions and 02 through 04 Mustangs. The Audiophile Satellite radio in many Ford cars is a superb AM Stereo receiver. Another great sounding AM Stereo station is WKZY, 1580, in Albemarle, North Carolina. It is streaming, along with a sister station at 1010wspc.com
As to the history of AM Stereo, by the time the FCC finally adopted the c-quam standard, many stations had given up on Stereo. Then, after the standard was adopted, lots of radios (c-quam capable) began appearing in cars. It has seemed ridiculous to me that the all powerful do everything Federal government with its agencies like the FCC can set standards for about everything in the world, from how much water your commode can use, to whether or not you can cut down a tree in your own yard, to color tv, FM Stereo, and HDTV, but .......leave the AM band to the marketplace. There needs to be a receiver standard, including decent fidelity, and broadcasters need to get back to presenting some quality programming on the band. It works great in places like North Myrtle Beach, so there's no reason why it can't work elsewhere. Anyone can e-mail for an aircheck or with questions to : [email protected]
As to the history of AM Stereo, by the time the FCC finally adopted the c-quam standard, many stations had given up on Stereo. Then, after the standard was adopted, lots of radios (c-quam capable) began appearing in cars. It has seemed ridiculous to me that the all powerful do everything Federal government with its agencies like the FCC can set standards for about everything in the world, from how much water your commode can use, to whether or not you can cut down a tree in your own yard, to color tv, FM Stereo, and HDTV, but .......leave the AM band to the marketplace. There needs to be a receiver standard, including decent fidelity, and broadcasters need to get back to presenting some quality programming on the band. It works great in places like North Myrtle Beach, so there's no reason why it can't work elsewhere. Anyone can e-mail for an aircheck or with questions to : [email protected]
Re: AM STEREO; Some Clarifications:
I feel the need to clarify just a few minor details here.
It is true that AM stereo was developed prior to FM stereo. It is also true that the FCC halted the release of AM Stereo in the 1960's. The FCC encouraged the development of FM Stereo in order to make the fledgeling FM band more appealing. The FCC adopted the current Dolby FM stereo system. I think it's also interesting to point out that while he didn't invent FM stereo, Major Armstrong who invented FM, developed the means to multiplex on FM. Multiplexing of course paved the way for FM stereo as the "stereo information" is multiplexed onto the main carrier.
By the mid 1970's the FCC decided that FM was catching on enough and let the development of AM Stereo Commence. I'm not sure on this, but I believe the early Am Stereo contender back in the 60's was the Belar System. However by the time the FCC started testing AM Stereo in the mid/late 70's the Belar System was quickly ruled out.
Most people will say that the FCC dropped the ball by not choosing an AM Stereo standard and letting the marketplace decide. This is not entirely true. In 1980, The FCC did indeed choose the Magnavox System as the official AM Stereo System. However, Leonard Kahn was quick to file suit claiming that the FCC's test results were flawed and claimed his system was technically superior. Soon after Kahn filed suit, Motorola did the same, claiming their system was superior. That was the point where the FCC threw in the towel and decided to let the marketplace decide on the system of choice. Of course we now know that it led to 10 long years of bickering until finally the FCC adopted Motorola's C-Quam system as the standard in 1992.
On another topic, someone asked if it would be possible to run AM Stereo and HD Radio at the same time on the same station. The answer is yes and no. The actual answer is NO. C-Quam AM Stereo and AM HD-Radio can not co-exist at the same time on the same signal. The reason is because Ibiquity's am HD-Radio system injects part of its digital signal in quadrature much the same way that C-Quam injects the analog stereo information in quadrature to the main carrier. That is why its so easy for the HD-Radio chipsets to decode analog C-Quam AM Stereo. It can be found in the same place as part of the HD signal. Of course HD uses more bandwidth, so it also uses the upper and lower sideband of the main carrier signal as well.
Back when AM-HD was only allowed during the day, I had heard of some engineers rigging up the transmitters to operate HD during the day and C-Quam at night. If the antenna system is wideband enough to pass HD, then it's sure wide enough to pass C-Quam.
Finally, People comment on how the stereo separation seems superior on AM Stereo than it seems to on FM Stereo. I have a few comments on that...
First of all, the kind of audio processing employed in AM Stereo Broadcasting will tend to maximize the stereo image. With AM Loudness means more coverage. With FM this is not really the case, for in FM loudness is simply loudness. I'm not going to get into a technical dissertation on how processing for AM and FM differs, so just trust me on this point.
Secondly, due to the design of the FM stereo system, the further we get from an FM station, the noisier the FM stereo signal gets. If your FM radio has a stereo/mono switch, you will observe that a station with a mediocre signal will sound much cleaner in the mono position than it will in the stereo position. The reason is because the "Stereo Information" which is piggybacked on the main FM carrier (multiplexed) is effectively an AM signal. Once again, I'm not going to get overly technical on how it works, but trust me on this. Modern radios tend to have circuitry built in to compensate for noise in the distant stereo multiplex signal. It is often called FM blend or stereo blend. As the signal gets weaker, the radio will automatically reduce the gain of the stereo information to prevent the noise from entering the audio. The result is similar to flipping the mono/stereo switch, except its a bit more gradual.
Thirdly, I think that the music we hear on AM stereo stations is mostly older music which was produced much more stereo than the contemporary music which dominates the FM band today. Not to say there aren't Oldies on FM, but I think you may find that even the Oldies stations on FM may display better stereo separation than the contemporary stations do.
I don't think any of these factors alone make AM stereo have a wider stereo image, but working in tandem, I think my crackpot theory holds water.
Peace out!
I feel the need to clarify just a few minor details here.
It is true that AM stereo was developed prior to FM stereo. It is also true that the FCC halted the release of AM Stereo in the 1960's. The FCC encouraged the development of FM Stereo in order to make the fledgeling FM band more appealing. The FCC adopted the current Dolby FM stereo system. I think it's also interesting to point out that while he didn't invent FM stereo, Major Armstrong who invented FM, developed the means to multiplex on FM. Multiplexing of course paved the way for FM stereo as the "stereo information" is multiplexed onto the main carrier.
By the mid 1970's the FCC decided that FM was catching on enough and let the development of AM Stereo Commence. I'm not sure on this, but I believe the early Am Stereo contender back in the 60's was the Belar System. However by the time the FCC started testing AM Stereo in the mid/late 70's the Belar System was quickly ruled out.
Most people will say that the FCC dropped the ball by not choosing an AM Stereo standard and letting the marketplace decide. This is not entirely true. In 1980, The FCC did indeed choose the Magnavox System as the official AM Stereo System. However, Leonard Kahn was quick to file suit claiming that the FCC's test results were flawed and claimed his system was technically superior. Soon after Kahn filed suit, Motorola did the same, claiming their system was superior. That was the point where the FCC threw in the towel and decided to let the marketplace decide on the system of choice. Of course we now know that it led to 10 long years of bickering until finally the FCC adopted Motorola's C-Quam system as the standard in 1992.
On another topic, someone asked if it would be possible to run AM Stereo and HD Radio at the same time on the same station. The answer is yes and no. The actual answer is NO. C-Quam AM Stereo and AM HD-Radio can not co-exist at the same time on the same signal. The reason is because Ibiquity's am HD-Radio system injects part of its digital signal in quadrature much the same way that C-Quam injects the analog stereo information in quadrature to the main carrier. That is why its so easy for the HD-Radio chipsets to decode analog C-Quam AM Stereo. It can be found in the same place as part of the HD signal. Of course HD uses more bandwidth, so it also uses the upper and lower sideband of the main carrier signal as well.
Back when AM-HD was only allowed during the day, I had heard of some engineers rigging up the transmitters to operate HD during the day and C-Quam at night. If the antenna system is wideband enough to pass HD, then it's sure wide enough to pass C-Quam.
Finally, People comment on how the stereo separation seems superior on AM Stereo than it seems to on FM Stereo. I have a few comments on that...
First of all, the kind of audio processing employed in AM Stereo Broadcasting will tend to maximize the stereo image. With AM Loudness means more coverage. With FM this is not really the case, for in FM loudness is simply loudness. I'm not going to get into a technical dissertation on how processing for AM and FM differs, so just trust me on this point.
Secondly, due to the design of the FM stereo system, the further we get from an FM station, the noisier the FM stereo signal gets. If your FM radio has a stereo/mono switch, you will observe that a station with a mediocre signal will sound much cleaner in the mono position than it will in the stereo position. The reason is because the "Stereo Information" which is piggybacked on the main FM carrier (multiplexed) is effectively an AM signal. Once again, I'm not going to get overly technical on how it works, but trust me on this. Modern radios tend to have circuitry built in to compensate for noise in the distant stereo multiplex signal. It is often called FM blend or stereo blend. As the signal gets weaker, the radio will automatically reduce the gain of the stereo information to prevent the noise from entering the audio. The result is similar to flipping the mono/stereo switch, except its a bit more gradual.
Thirdly, I think that the music we hear on AM stereo stations is mostly older music which was produced much more stereo than the contemporary music which dominates the FM band today. Not to say there aren't Oldies on FM, but I think you may find that even the Oldies stations on FM may display better stereo separation than the contemporary stations do.
I don't think any of these factors alone make AM stereo have a wider stereo image, but working in tandem, I think my crackpot theory holds water.
Peace out!
Re: AM STEREO; Some Clarifications:
The FM stereo L-R subcarrier is generated as a double-sideband, 38 kHz suppressed carrier AM waveform, but that waveform is then transmitted by the FM station by frequency modulation of its main carrier. So the stereo subcarrier benefits from the usual advantages of FM transmission compared to AM transmission.
The reduction in noise noticed when switching an FM stereo receiver to mono mode is related to the smaller r-f bandwidth required, and the distribution of r-f noise within that bandwidth.
//
Ted Russell said:
The FM stereo L-R subcarrier is generated as a double-sideband, 38 kHz suppressed carrier AM waveform, but that waveform is then transmitted by the FM station by frequency modulation of its main carrier. So the stereo subcarrier benefits from the usual advantages of FM transmission compared to AM transmission.
The reduction in noise noticed when switching an FM stereo receiver to mono mode is related to the smaller r-f bandwidth required, and the distribution of r-f noise within that bandwidth.
//
S
strangelove
Guest
While we're sort of on the topic, what became of Quad on FM?
One of the only good things about IBOC - their radios decode Motorola CQAM Stereo. Unfortunately, the only stations left broadcasting in Stereo in St. Louis are Crawford Broadcasting's religious stations KJSL & KSTL. I have to say that I think they sound better broadcasting in AM Stereo than the IBOC stations. KSTL broadcasts a Black Gospel format in Stereo; Clear Channel's KATZ does the same format, but has IBOC. On KSTL, you can notice highs and lows in the music, and it sounds darn near as good as FM, versus KATZ sounds like a bad web stream.
I have a Chrysler vehicle with the AM stereo radio, but unfortunately I don't know of any AM stereo stations. WSM doesn't seem to be broadcasting stereo any more. CE Watt Hairston still makes it sound good though.
Frank Provasek said:
I always had WLS at night in Indiana for music but after WOWO added the Harris stereo and later made the mod to the Motorola stereo encoding it sounded great.
If you had the right tuner and help me the Sparkomatic car radio was the best I ever heard AM sounded great. Friend had this in his car and always had a cassette covering the name plate. Narrow and Wide band modes allowed you to get rid of some trash.
N
Neal
Guest
Well Guys there is still one AM Stereo Station that I know Of IN New Jersey. and thats WHWH 1350
Radio T.E.D. running in full C-Quam. sounds great on my Carver Receiver.
Neal-CE....
Radio T.E.D. running in full C-Quam. sounds great on my Carver Receiver.
Neal-CE....
Japan still very much embraces AM Stereo. I just went to Tokyo in February and would've brought back airchecks had it not been for the fact that my Hi-MD recorder generated a nasty amount of RF and I couldn't tape anything.
In Tokyo alone there are 3 AMs currently broadcasting it (not counting the many AM Stereo stations in areas outside of Tokyo), and Sony Japan makes no less than 3 current model radios (in fact, you can get them here in the US at www.audiocubes.com).
In Tokyo alone there are 3 AMs currently broadcasting it (not counting the many AM Stereo stations in areas outside of Tokyo), and Sony Japan makes no less than 3 current model radios (in fact, you can get them here in the US at www.audiocubes.com).
So why not bring AM stereo back? It sounds great and is less filling.
It appears that the transition to HD for AM stations has stalled. And I'm assuming that this has more to do with the harsh economic realities facing the industry (and particularly AM) as anything else.
But AM stereo is relatively cheap to install, indeed many stations already have the equipment in their racks and there's no license or royalty fee to pay. Plus the station can transmit a no compromise, full bandwidth, full power high fidelity signal.
There is already a large installed base of AM stereo radios in use, and if HD receivers can decode it, so much the better.
I just don't understand this phobia on the part of station management against broadcasting in AMS. Seems like a no brainer to me, especially if there are no immediate plans to convert to HD.
C5
It appears that the transition to HD for AM stations has stalled. And I'm assuming that this has more to do with the harsh economic realities facing the industry (and particularly AM) as anything else.
But AM stereo is relatively cheap to install, indeed many stations already have the equipment in their racks and there's no license or royalty fee to pay. Plus the station can transmit a no compromise, full bandwidth, full power high fidelity signal.
There is already a large installed base of AM stereo radios in use, and if HD receivers can decode it, so much the better.
I just don't understand this phobia on the part of station management against broadcasting in AMS. Seems like a no brainer to me, especially if there are no immediate plans to convert to HD.
C5
John Holcomb II said:
It is... he works for KEVA 1240- Evanston, Wyoming.. 880 Watts full time.
The Part 15 he was referring to is at his house.
Add WZZB 1390 Seymour,IN "Classic 1390" to the list of Stereo music AM's still active today. No IBOC plans here...Carmine5 said:
The weirdest thing I ever did was quite a few years ago WSM Nashville was still broadcasting in stereo and they simulcast the CMA awards in stereo. Since my local TV station was in mono, I listened to the audio simulcast of the show on my little AM stereo Walkman with the TV audio turned off. Even though WSM is over 500 miles away and would occasionally fade, it still sounded better than the mono audio from the TV station. I bet I was the only person that actually did that.
One thing I'd like to see as a possible 'rebirth' of AM Stereo is in this new crop of FM translators that are rebroadcasting AMs. Aren't they supposed to relay the AM off air?? Wouldn't AM Stereo then be one of the ideal ways to provide for a Hi-Fi means of audio for the FM translator?
radiosanchez said:
No, the FM translators relaying AM stations don't have to be fed by the over the air AM signal. They have to be fed by the AM stations STL.
I used to hear the Grand Ole Opry on WSM Nashville and also Bill Mack playing country music overnights on WBAP Fort Worth.
I had the Chrysler radio from the late 80's and the GM Delco (square) radio in my 92 Silverado. I got WSM on the Chrysler & WBAP on the Chevy radio. I think the Chevy had a Kahn decoder & the Chrysler was C-QUAM. Both radios sounded great on AM. I think both stations have gone back to mono unfortunately. Was a lot of fun when it was around. Signal would fade in and out sometimes, but once it locked onto stereo the sound was amazing.
Dump IBOC & bring back C-QUAM.
I had the Chrysler radio from the late 80's and the GM Delco (square) radio in my 92 Silverado. I got WSM on the Chrysler & WBAP on the Chevy radio. I think the Chevy had a Kahn decoder & the Chrysler was C-QUAM. Both radios sounded great on AM. I think both stations have gone back to mono unfortunately. Was a lot of fun when it was around. Signal would fade in and out sometimes, but once it locked onto stereo the sound was amazing.
Dump IBOC & bring back C-QUAM.
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