So I was thinking… Let’s get back to Kelly’s original question.
First, on the issue of programming, I’ll quote dbdigital (Reply No. 20):
“I have a young co-worker who listens to her favorite music on her cell phone. We aren't raising a nation of audiophiles here. Convenience and "something new" seems to be what motivates them. On the other hand, a few of her friends drive Ford Falcons and Rambler Americans. What was once old is now new again. So a new generation of listeners might discover AM if it's programmed right, they find it on their own and think it's 'cool'.
“In this regard, I think AM needs to be where FM was in it's early days before the corporate greed weasels got hold of it...a place to go to hear music and other 'stuff' mainstream radio, AM at the time, wasn't playing. FM was the place to be if you wanted to hear album cuts, world music, hardcore jazz and left-wing talk.”
I couldn’t agree more. And FM ignores the older demographics too. (See Phyllis Stark’s column, “Why Dad Hates the Radio, And Other Stories, ”posted this week at
http://www.radio-info.com/content/column.php?rcID=19.)
But to make music formats work, we’ll have to make AM audio as good as possible -- for the analog listener -- because, as Tom Wells has pointed out in other threads on this board, the medium wave band is inherently ill-suited to digital transmissions. So the first step would be turning off the IBOC!
As for analog AM stereo, it would be better to abandon C-Quam, with its platform wobble and vulnerablitiy to multipath and phase problems, and use Leonard Kahn’s independent sideband system instead, since C-Quam receivers could still get Kahn stereo broadcasts in mono. And forget the AM mask for daytime broadcasting, too. There’s no reason to limit audio bandwidth during the day.
The stereo difference AM (actually double sideband suppressed carrier) signal on analog stereo FM has response to 15 kHz, and the (suppressed) subcarrier frequency is only 38 kHz. So it’s clearly no problem to generate that kind of audio bandwidth in the AM band. The problem is with some antenna systems.
In Reply No. 24, hipporadio said, “I remember a very old and talented "AM guy" telling me once —‘It's 50-percent in the antenna’...”
That’s so true. Antennas, like any other components with reactance, have a “quality factor,” or “Q.” And this is a much more significant factor in AM than in FM. An FM station at the bottom of the band, broadcasting only an analog signal, has sideband components no more than 0.115 percent above and below the carrier frequency. With IBOC, all the energy in the antenna is no more than 0.171 percent off the carrier. BUT AN AM STATION WITH A CARRIER FREQUENCY OF 1500 KHZ AND 15-KHZ MONO ANALOG AUDIO HAS SIDEBAND COMPONENTS UP TO 1 PERCENT ABOVE AND BELOW ITS CARRIER, AND ONE OPERATING AT 600 KHZ HAS COMPONENTS UP TO 2.5 PERCENT OFF ITS CARRIER FREQUENCY.
And that’s a big difference. Obviously, if the Q is the same, an AM antenna designed for a low frequency will have less audio bandwidth than an equivalent antenna for a higher frequency. But with good design, it’s still possible to get good bandwidth at the low end of the band. After all, if they can transmit I-BUZZ -- with its 50-kHz of noise and distortion -- at all, 15-kHz audio should be a snap.
The only real problem is with directional patterns, which can complicate things even more, especially at the low end. But even in the worst cases, fairly flat response to 6 or 7 kHz (within the directional pattern) should be possible.
At night, however, it would be wise to restrict audio to 5 kHz or even little less, with a steep roll-off beyond that point in order to minimize adjacent channel “monkey chatter.” AM has no protected contour, but the “principal community contour” for AM’s 74 dBu (while it’s only 70 dBu for FM’s), and distant adjacents’ skywaves can be a problem beyond the 74 dBu! . A 7 kHz component from a first adjacent is only 3 kHz from your carrier, and creates a 3-kHz noise! Let’s eliminate those noises by restricting nighttime, and only nitgttime, bandwidth.
But these changes in broadcast standards would be useless without the availability of high quality receivers with two, or perhaps three, bandwidth positions for AM.
And all of that would be for naught unless the FCC amends Part 15 to cover devices that cause easily preventable interference to AM.
Case in point: An engineer friend found that AM on his new car radio practically useless when the car’s engine was running, but it worked very well with the engine off. The noise was coming through the electrical system from microprocessors under the hood. With some effort, he was able to locate the culprits and, through shielding and bypassing them, eliminate the noise with compromising their function. BUT WHY WASN’T THAT DONE AT THE FACTORY? And why doesn’t the FCC require that? Just more proof that AM gets no respect!
With better, more varied programming, aimed at currently underserved audiences, and with the above technical improvements – and with a promotional campaign costing perhaps one-tenth of what the industry is now spending to promote a medium-wave digital system that sounds worse than the primitive internet audio of a decade or more ago – AM could have a bright future.
But without those things, it’s probably doomed.