USMC0407 said:
Where do you get your information?
I have an HD radio and the sound is much better in digital, no multipath at all, no static, and it causes no interference at all to adjacent channels, it is , however alot more complicated to install at a site.
I get my information from technical papers published by Ibiquity, tech sessions at the Texas Association of Broadcaster’s meetings, various trade publications like Radio World, Radio Guide, etc, as well as various engineering news boards. I’d also include engineers who are personal friends who have had to deal with the technology, as well as my personal listening experience. Many of these opinions have originated from people whose opinions I respect. They are reliable sources, and they are having problems with the technology. It is especially so in the Public Radio sector, where they are beginning to suspect that they have been sold a bill of goods.
Sure, with AM, HD does sound a lot better than analog AM. No argument there, but it is at a price. The problem is it does it at the expense of its analog listeners. 99.999+% of all AM radio listening is still done on analog radios. It will be that way for a very long time.
You can hear the interference caused by IBOC quite clearly on any analog AM radio. If you are within a few hundred miles of Dallas, tune in KRLD, 1080. Now tune in 1070. and then 1090. You will notice a loud hissing noise. That is digital hash generated by the IBOC exciter. That is not good, and it is no way to treat your neighbor. There is nothing "In Band, On Channel" about this technology. If you are not near Dallas, try it on any HD AM station in your area. They take up at least three channels, and frequently five. How big a problem that is has a lot to do with the bandwidth of your radio. Wide band radios will have big issues with this.
For FM, the interference issue is not as great in commercial channel allocations, but in the much more crowded "Reserved (noncom) Band" it has been a problem for many Pubcasters who are finding that HD has reduced their effective audience, and thus their donor base. Check out the archives of Pubtech Digest if you have any questions. Further, any short spaced FM stations do exist in some parts of the country. This technology is not good news for them, unless you like the notion of rendering all small stations as “local.” Seeing ones market area shrink does not go down well with many broadcasters.
Any radio station that I know of that is running HD uses exactly the same processing for FM analog as it does for their HD broadcast. Why? So it will sound the same when the HD drops out and the radio reverts to analog. It would be silly to do otherwise. It is true that HD does provide for audio up to 20 KHz, rather than FM's 15 KHz top end, but if you do that, the blend mode will not be seamless. I guess it is your station's decision to extend frequency response on your HD feed if you like, but it makes little sense to do that at this point. It is jarring when it switches to analog for the half dozen listeners who have the appropriate car radios.
The real problem is we're trying to come up with a hybrid solution to transition to digital. I have no problem with the idea of Digital Radio. In fact, I'm quite in favor of it. I just don't think we have chosen the best way to go about doing this. It's NTSC all over again.