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CBS/Infinity and IBOC-AM?
Perhaps the Kiwa is too narrow band to allow the IBOC sidebands to come
through. Byung Myung Sying wrote: I actually have IBOC capability on my home receiver (the Yamaha RX-V4600). The "mutlicasting" on FM is actually pretty nice since it allows commercially-untenable formats to be broadcast. Here in Detroit, we have 9 stations broadcasting "second IBOC" channels. One (94.7) uses its second IBOC channel to broadcast "deep album rock" from the 1960's and 70's. Another (105.1) broadcasts classical "pops" on its second IBOC channel. Another broadcasts "live rock concerts" on it's second IBOC channel. The audio quality on the FM IBOC channels is about as good as a 256K MP3. An analogue FM transmission is capable of MUCH better sound quality (although only a few stations such as WFMT in Chicago or WQXR in New York actually broadcast uncompressed FM analogue sound). The big problem, reception-quality-wise, is that FM IBOC is unreceivable unless you are in a strong, local reception condition. For example, there's an NPR station that broadcasts classical music in Lansing, MI (about 80 miles from me) and I can't pick up their IBOC signal, even with a yagi directional FM antenna. Their analogue signal comes in just fine, and my receiver reverts to analogue since the digital IBOC signal is unreceivable. As far as AM IBOC goes, Detroit's 950 AM and 910 AM broadcast an IBOC signal. 950's audio quality was HORRIBLE when it first started up, with echoey, swishy, digital artifact sound. Now, Ibiquity seems to have fixed something and 950's signal sounds okay with nice high frequency reproduction. It sounds about as good as a 64K MP3. 910's IBOC signal still sounds awful (although it's in stereo). AM IBOC though does NOT in any way, shape, or form have "FM quality sound" as Ibiquity's advertising trumpets. There is an AM stereo station locally (CFCO in Chatham, ON) which indeed DOES have "audio quality approaching FM" when listened to on a good AM stereo receiver (I have an AM stereo tuner in my Ford Escape Hybrid which has the best sound that I've ever heard out of an AM radio). As far as "IBOC vs DRM" for "high fidelity AM" broadcasts, since IBOC "shares" the allotted bandwidth with an analogue signal, it requires an extremely strong local signal in order to receive it. There is an AM NPR station in Lansing, MI which is UNRECEIVABLE in IBOC mode from 70 miles away, even using a Kiwa Air Core Loop which brings in the analogue AM signal 20 dB over S9. In contrast, since DRM does not share it's bandwidth with an analogue signal, the ability to "DX DRM" is much greater. I can receive DRM test transmissions with perfect decoding from stations that are inaudible in analogue mode (Deutsche Welle and Radio Nederland quite often "switch over" from analogue to DRM in the midst of a broadcast). As far as "Eureka DAB" goes, it's deader than a doornail in Canada. The foppish bureaucrats who were trying to "act European and declare their independence from the U.S." by implementing DAB in Canada failed miserably and wasted millions of Canadian tax dollars in the process. Since most Canadian stations (except the CBC) are dependent on U.S. advertising, absolutely NONE of them were about to replace AM and FM with DAB and lose all of the U.S. advertising dollars. I spoke with an engineer at the local CBC station in Windsor, ON and he didn't even KNOW that there was still a DAB transmitter operating in Windsor. The Canadians quietly abandoned their ill-conceived DAB pork-barrel and have allowed XM and Sirius to begin service in Canada. The above comments are based on empiricle results from my own listening and DX'ing experiences using analogue AM Stereo, IBOC, and DRM receivers. Fred E. - N8UC Detroit, MI |
The Whore House Years (was: CBS/Infinity and IBOC-AM?)
Carter, K8VT wrote:
Well, buried back in Appendix C was an *actual quote* by an FCC Commissioner back in the 1950s who said "Yeah, we called those the 'Whorehouse years' because everything, including us, was for sale". Now this from an actual FCC Commissioner back in the days of "Ozzie and Harriet" and "Leave it to Beaver". If it happened back in those "innocent" days, do you think it could happen today???? There's zero question it happens. A high position in the FCC is nothing more than a holding position from which one can trade favors for the right job offer. -- If John McCain gets the 2008 Republican Presidential nomination, my vote for President will be a write-in for Jiang Zemin. |
CBS/Infinity and IBOC-AM?
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CBS/Infinity and IBOC-AM?
Doug Smith W9WI wrote:
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. " And from FCC Private Notice DontTellNoOneYHear: "To bring about further notice, deposit $10,000,000 in account number 604472849 at Banc Suissishe in Geneva. Alternately, to obtain an exclusive one-year advance on competitors, deposit $100,000,000 plus an amount equal to your eight-digit secret ID so that we can identify our benefactor." -- If John McCain gets the 2008 Republican Presidential nomination, my vote for President will be a write-in for Jiang Zemin. |
CBS/Infinity and IBOC-AM?
The feds are going to provide ATSC to NTSC converters free (cough
cough) of cost to the poor. Cable and dish are a big part of the market. It isn't clear to me if the feds are going to mandate that HD be delivered over those services. Even if they feds do mandate HD to subscribers, there is cash flow to recover the cost of new set top boxes. My preference would have been for a new broadcast band for terrestrial digital audio services, rather than a retrofit that causes interference to conventional users. I don't get too bent out of shape over FM IBOC, since the capture ratio of the analog receiver will give the fringe listener a fighting chance at decent reception. However, AM BCB is another story. You can't reject the IBOC hash in AM. clifto wrote: wrote: 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. Funny, there are more television sets than people in the USA, yet they are being abandoned virtually overnight. Or at least the chuckleheads in the FCC think so. The cable and dish providers, and the public, know better. -- If John McCain gets the 2008 Republican Presidential nomination, my vote for President will be a write-in for Jiang Zemin. |
CBS/Infinity and IBOC-AM?
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CBS/Infinity and IBOC-AM?
Fred E - N8UC wrote:
"The audio quality on the FM IBOC channels is about as good as a 256K MP3. An analogue FM transmission is capable of MUCH better sound quality (although only a few stations such as WFMT in Chicago or WQXR in New York actually broadcast uncompressed FM analogue sound)." Here we have to be careful about the term 'compression', especially in tems of audio quality and digital audio through-put. 'Compression' in the analog audio sense defines the process of 'squashing' an audio signal - reducing its dynamic range - in an effort to make it of a more consistent level. This is felt to be important by most radio broadcasters for competitive reasons; the 'louder' stations are felt to have more 'dial presence' and therefore are more able to capture listeners scanning the dial. It is true that some high-powered classical music stations employ very little compression, and yet analog FM is always hampered by the 75 us audio pre-emphasis and the 10% injection of the stereo sub-channel (which requires a hefty received signal to get anywhere near a 60db S/N ratio - a pretty poor showing). 'Compression' as it relates to digital radio refers to the ammount of (audio) data that is 'thrown away' due to the need to fit the signal into the available bandwidth. The ubiquitous "MP3" at 128 kbps has "thrown away" about 90% (ninety percent) of the material that was found on the origianl (uncompressed) Compact Disc. The 'computer' programs that perform this task are running a 'compression algorithim', and much work is and has been done in this field. It is the basis of *ALL* of the current crop of consumer / portable / personal music devices (Ipod / cell-phone audio / Internet Radio etc). To illustrate: Fred E quantifies his IBOC FM experience as beig similar to a 256 kbps MP3. In reality, FM IBOC stations are limited to a total data through-put of 98 kbps, 2 kbps of which are reserved for overhead and data. Hence, Fred E was listening to a 96 kbps signal. Quite remarkable, really especially in a direct A-B comparisson between most (uncompressed) source material and the recovered IBOC signal. AM IBOC is limited to a bit rate of only 32 kbps (!) - about 95% of the original data has been tossed overboard, and yet... Fred E and I will have to disagree on the aural result, which has a lot to do with the care the radio station has taken in their audio and RF infrastructure (IBOC *mandates* a very flat antenna system, something most AM stations have not historically had to consider. Hence, ones aural experiences, especially in these young days of AM IBOC may vary). I too am a vetran of C-Quam AM stereo, and IMHO IBOC has a much lower noise floor and much better stereo separation. Lastly, the "specifications" page of Fred E's Yamaha receiver (nice unit!) : http://www.yamaha.com/yec/products/r...4600_specs.htm completely ignores the AM section. Hummm... could this be the trouble with your AM IBOC reception...? Mike Worrall Los Angeles |
CBS/Infinity and IBOC-AM?
wrote in message oups.com... The feds are going to provide ATSC to NTSC converters free (cough cough) of cost to the poor. Cable and dish are a big part of the market. It isn't clear to me if the feds are going to mandate that HD be delivered over those services. Even if they feds do mandate HD to subscribers, there is cash flow to recover the cost of new set top boxes. The feds are not even mandating HD on OTA stations. As far as I can see, most programming on DTV stations is in low res format (720i?) And I'm not impressed in the least, analog looks much better (we're stuck with digital satellite feed for our US/English content, and it looks like total garbage). |
CBS/Infinity and IBOC-AM?
Mike,
Thanks for your comments. When I spoke of "compression" being responsible for the horrid sound of many of today's analogue FM stations, I was speaking of compression in the analogue sense, in other words, dynamic compression where there are no soft passages and no loud passages, everything is the same loud obnoxious level. As far as your comments on FM IBOC being 96K, I was well aware of that fact. The issue is that the digital compression algorithm that they use is much better than "a 96K MP3" and appears to me to have the audio quality of a 256K MP3 (some harshness due to the "Simpson's Rule" effect, but good enough for automobile listening and background music). All of my statements were based on empirical listening tests comparing the sound of IBOC in AM and FM mode to AM stereo and analogue FM on a Marantz 10B tuner etc. As far as your comments on the AM section of the Yamaha RX-V4600, I think that it's a fair to midland AM DX tuner. If you read my statement carefully about the Lansing MI station, I said that the analogue signal comes in with excellent signal (20 to 40 dB over S9 in ham radio terms), but the IBOC "subcarrier" is not detected. Your comments on the audio quality of AM IBOC disagree with my empirical listening tests though, I still think that the Canadian AM Stereo station CFCO is far superior to any of the 3 IBOC stations that I've heard locally. In conclusion, I think that AM IBOC is not going to go anywhere and is indeed really pesky in terms of the QRN that it spews out, but that FM IBOC has the promise of success due to the "narrowcasting" that's possible using the alternate channels. Luckily, we here in Detroit are seeing the advantages of FM IBOC with very interesting and appealing "second HD channel" broadcasting by 9 local stations. Fred E. |
CBS/Infinity and IBOC-AM?
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