Posted by TriSec, due to technical issues....but written for us today by Trojan Rabbit!

Note: I was afraid I'd get too technical with this and I probably did. But I feel this is important because most of the progressive stations are smaller AM stations and it looks like they could be squeezed out by the large corporate stations if HD become more prevalent. This little bloggie post is just scratching the surface.

We all know the state of the print media world, as many long established newspapers are unable to deal with shrinking ad revenues and a shrinking reader base as people get their information elsewhere in more immediate forms.

Another form of media, around since the turn of the last century, is heading towards the same cliff towards oblivion. Many of its problems are of its own doing, aided and abetted by a government agency more interested in creating revenue streams and bowing to lobbying pressure than insisting upon technical feasibility.

AM radio used to be king, of course it was also the only broadcast entertainment available. During the day, the small local stations could keep you abreast of what was going on in your home town. At night, when the sun went down, your favorite network shows could be easily heard from the stations in the big cities, hundreds of miles away. All it took was a bit of imagination on the part of the listener to transport you anywhere the shows writers wanted to take you. And while reception was more or less dependable, the listener would have to deal with static from thunderstorms on many nights or the occasional passing motorist with bad spark plug wires.

Along came [WIKI=Edwin_Armstrong]Edwin Armstrong[/WIKI] (the inventor of the [WIKI=Superheterodyne_receiver]superheterodyne[/WIKI] system which is the basis of just about every receiver made) with his new invention - [WIKI=FM_broadcasting]FM[/WIKI], promising near noise free reception and greater fidelity. The AM radio industry (most notably RCA), and AT&T, who saw FM as a threat to their voice transmission line business fought fiercely against it, lobbying the FCC to delay its widespread acceptance as long as possible, even going as far as to have the original FM band moved, instantly making useless thousands of radios.

It took many years for FM to become the predominant medium for music, thanks to pioneering (read - desparate for listeners and willing to try anything) stations like [WIKI=WBCN_%28FM%29]WBCN[/WIKI] where progressive and album rock became a staple. And AM became mostly a medium for news, sports and talk radio.



Now TV (both cable/satellite and over-the-air), satellite radio and, most importantly, the ability to carry your entire music collection in your pocket, have further eroded radio's audience. Radio stations responded by cutting costs wherever they could by cutting staff (who needs people to cover news when it's available from a satellite) and increasing the amount of advertising aired. In many cases stations either shut down or sold out to conglomerates who, thanks to the Telecommunications Act of 1992, were able to buy many more stations than they previously had. As any corporation with many "outlets" will do, they carried the cost cutting even further, technology made it possible to make a far away DJ sound like he's right at the studio and that DJ would handle more than one station. Same with the technical staff, one engineer may have to handle multiple stations, though to be fair the transmitters of today are much smaller and much more reliable than the early ones.

There were feeble attempts to make AM more listenable. [WIKI=AM_stereo]AM Stereo[/WIKI] was tried starting in 1980 when the FCC selected a system designed by Magnavox, though they soon tired of all the lawsuits flying around from the 3 incompatible systems that were not selected and decided to "let the marketplace decide". That meant that you had to know what system your favorite station used and switch your radio accordingly. Not surprisingly, AM Stereo never really caught on, even though the improvement in sound quality was very noticeable. A very small number of stations still broadcast with this format.

This boondoggle, unfortunately, is dwarfed by the latest disaster unleashed upon AM, IBOC or HD-Radio. It's fine in concept, a digital stream is transmitted along with the normal audio which will allow greater fidelity, close to FM quality. But it appears the FCC bowed to lobbying pressure from the radio industry to approve a system that the industry itself had a stake in, and the FCC had no idea what they were approving.

In many parts of the country, the AM band is completely full. The very property that was very useful in the early days of radio, long distance communications at night, now becomes an engineering nightmare. During the day, a layer in the ionosphere, the D-layer, absorbs radio waves at the frequencies used by AM. When the sun goes down, the D-layer disappears and the radio waves will be reflected back to earth, hundreds of miles away from the transmitter. The FCC dealt with this by requiring some stations to either shut down, significantly reduce power, or change the "antenna pattern" after sunset. In the early days, certain stations were given "clear channel" status, meaning no other stations were allowed on those frequencies at night. But, for the most part now, what you hear at night is a cacophony of stations on top of each other. You can find out just about anything you need to know about your friendly "local" AM station at the FCC website. Here you can see how each station has to direct its signal or reduce power to avoid interfering with stations on the same frequency.

HD-Radio throws a big monkey wrench into all of this planning.

An AM-HD signal takes more spectrum space than an analog AM signal does. If you know of a station that transmits in HD, you use your radio and hear noise from that station interfering with other stations not even on the same frequency. Actually, a station transmitting a signal taking that much space would have been against FCC rules before HD came to be. And when stations began transmitting in HD a few years ago, interference complaints started to come in to the FCC. Some companies responded by not transmitting HD at night, mostly because there was interference among their own stations.

But there's another hidden issue. Designing a transmitting antenna (using two or more towers) to direct all its power in a certain direction is not an easy task. And suffice to say that that transmitting antenna was designed years back without HD in mind. While there were federal grants available for stations to upgrade their facilities, in some cases a suitable antenna just cannot be designed to handle the wider bandwidth HD signal.

Which brings up the title of the article. No matter what is done, as Scotty would say from time to time, "You canna change the laws of Physics". We're progressing towards carrying one device on our person to do everything from make our phone calls to hold our music collection to access the internet. That device MIGHT have an FM receiver in it, but it definitely WON'T have an AM receiver. As the frequency of the station goes down, the antenna used to receive and/or transmit that frequency must get longer. It's easy to hide an efficient antenna for the cellphone or mobile internet frequencies, for FM it's relatively easy to make the headphone cord serve double duty as an antenna. Early AM radios had coils of wire on the back of the (very large) cabinet, the first transistor sets had many turns of wire on a ferrite bar usually located on the top of the radio. Even something of that size is way too big to be used in your typical slender iPod/iPhone/mp3 player. Worse yet, unlike the early transistor sets, the circuitry in today's devices generate lots of electrical noise that a receiver can pick up. Just try bringing an AM radio next to your PC. And just about every piece of modern electronics, from your TV, those fancy CFL/LED energy saving lamps, most AC adapters (or wall-warts) even your new front-loading washing machine generates enough electrical noise to make AM reception dodgy at best.

Well, it would be dodgy if you had a receiver designed for high performance. AM seems to be an afterthought in receiver design. Manufacturers handle the problem of stations too close to each other by reducing the sound quality, almost to telephone-quality. Much cheaper than adding circuitry to reject the interference. Hey, it's talk radio or sports, who cares?

IMO we lost a great opportunity to create a new service when the analog TV stations went off the air. In the same time period that the digital TV stations were brought on line, arrangements could have been made to move some of the crowded AM stations to the TV channels freed and convert them to FM (supposedly channels 2-6). Up to 30 FM stations could fit in the space that just one TV channel took. And it would be relatively simple to get new receivers on sale quickly since Japan already uses those frequencies for their FM service and a frequency change like this could be done by reprogramming the radio's microprocessor. They would no longer have to worry about shutting down or reducing power at night. In a few years, what AM stations survive may well have more of their listeners "tune in" through internet radios. At that time, it might just be time to "pull the switch" on the transmitters and another era will end.