iyiyi said:
. Please remember that the analog stereo noise level increases 200 times the level of mono. This rapidly makes itself apparent the farther from the transmitter you go. Please try to be objective here because NO man made device can ever approach the quality of live!
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For a starter, FM Stereo degrades the signal by about 10 db, which is a factor of 10, not 200. Secondly, most modern car radios deal with this by blending to mono as the strength degrades. In other words, about the time a HD channel starts to cut in and out, the analog channel reverts to is mono on most people's radios. So, when the HD signal falls back on the analog channel, the comparison is drastic, since at the very least, you have gone from stereo to mono. That's probably why some people think HD sounds so much better. In fact, most people with analog radios are probably listening to mono in their car, and don't even notice. It beats silence, which is what you get when a HD-2 or HD-3 channel craps out. I think that is a reasonable trade off.
To further compensate for analog FM's shortcomings, a lot of radios actually lower the volume as the signal strength decreases. That is done so you won't notice the noise and multipath problems. It seems to work, except if you are switching from HD to analog. The analog signal is likely to be 6 db lower in level than the HD signal. Maybe more. Since “louder is better” a lot of people would think the HD signal is better, even though, in many instances, critical listening will reveal otherwise. The folks who bring us Sirius-XM play this trick with car radios. On every one I've ever heard, the XM feed is louder than any analog signal. The old “louder is better” trick is at work once again. It is an effective sales pitch.
You asked “What am I missing?” Do you own or engineer for a radio station that is not a part of a large corporate group? I do. I own a FM station that is co-channeled with a HD station about 135 miles due west of me. Under some atmospheric conditions, if you approach (but not cross over) our 60 dbu “Protected Contour,” the co-channeled HD-FM will capture the radio and start playing their programming, rather than mine. I feel that is a problem. Wouldn't you?
Further the HD signal noticeably degrades the primary analog signal of the station. If everyone had a digital radio, that would not be a problem, but 99.98% of all listening is still analog, so it is a problem. It's kind of like shooting yourself in the foot.
I have several acquaintances in the noncommercial radio business (yes, it is a business, even if it is done with the best of philanthropic intentions). The noncommercial band is much more crowded due to short spacing, than the commercial band. Several of them report that adjacent channel HD stations have seriously cut their coverage areas, and by FCC rules, there is nothing they can do about it. The problem of decreased coverage translates to decreased pledges, thus lower income. Most of these stations run on a very tight budget to begin with. With today's economy, things are bad enough. Having their listener base reduced due to HD interference is making things very difficult for them.
As a business owner (Who happens to be in the FM Broadcasting biz), the ultimate problem I see is little or no return on investment. At least not in my lifetime. The only justification I can come up with for converting to HD is so I can jam the signal of the offending co-channel station that is causing me problems. That's hardly a win-win proposition. Don't misunderstand, I'm actually enthusiastic about the idea of Digital Radio. It is our future. My problem is with the current system. We deserve better and certainly could have done better.
