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CBS/Infinity and IBOC-AM?
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As has been discussed, HD Radio is not currently authorized on AM stations at night, ("night is *not* defined as 6 AM to 6 PM, but rather varies with a station's geographic location and the time of year) though a serious lobbying effort is on to change this. Hence, at this point it does not seriously impact DX opportunities, since most long-range reception is a nighttime phenomenon (when the IBOC signals are off). From FCC Public Notice DA-03-831: (http://www.fcc.gov/fcc-bin/audio/DA-03-831A1.pdf) "Until further notice, AM stations must restrict IBOC operation to daytime hours. An AM station with authority to operate between 6 a.m. and local sunrise (pre-sunrise hours) and between local sunset and 6 p.m. (post-sunset hours) may operate its hybrid IBOC system during those periods. " As I read that, AM stations that are authorized to operate in analog between the hours of 6am and 6pm are also authorized to operate IBOC during those hours. Admittedly those two sentences could have been worded a lot better! That is indeed a different definition of "night" than the one the FCC uses for determining whether a station should be on nighttime power and/or antenna pattern. Mike's KDIS is required to reduce power from 50kw to 20kw at night, and that change is required to take place at 4:45pm. (for the next two days; it slips to 5pm on the 1st of January) But as I read it, they can leave the IBOC on - on the lower power and night directional pattern - until 6:00. Again, my sense is that broadcasters are thinking that the analog technology that served us well in the 20th Century has run its course, and that to remain a viable medium a transition to digital *must* take place. The trouble is that there are (probably) a half-billion analog receivers in the USA alone capable of receiving analog AM / FM, and these can't be abandoned overnight. The Station's around the country are now in the first phase of implementing digital radio, in the form of IBOC / HD Radio. And my bet is that it's *not* going to go away. We are finding in TV just how slowly old receivers are being dropped. In TV we have the advantage of cable and satellite operators doing the downconversion for us in 85% of households - and the fact that a given household has a relatively small number of TV receivers. Also, by using an "in-band separate channel" conversion scheme, the new digital TV signals result in little or no interference to existing analog service. Even so it appears the transition will take more than ten years. Radio doesn't have most of those advantages. Nobody will be downconverting HD to analog for old receivers. Most households have handfuls of radios - far more than they have TVs. For the millions of us in outer suburbs (and the millions in lightly-populated and rural areas), the interference will not be negligible. Especially on AM. FM IBOC is certainly an upgrade for those who listen to mainstream stations *and* live (and commute) in the core of the market. It is likely to be a major unpleasant surprise for those who live in outer suburbs and outlying towns. -- Doug Smith W9WI Pleasant View (Nashville), TN EM66 http://www.w9wi.com |
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