No surprise that it doesn't work well, if at all at night due to array patterns. However, I bet said station will leave it on at night anyhow and will, like many other stations leave IBOC on for several years more.
If I understand correctly, don't stations pay Ibequity a monthly license fee ? How long is the contract minumum ? ie..lets say a station has been using IBOC full time since last September ...and now they realize it's a waste of money.. when can they stop paying Ibequity if they turn it off.
Re: increased noise floor. This was quite apparent Friday when I was giving an area DXer a daytime demo of my Phased BOG System in Grafton WI. Pre-IBOC I could do lots better daytimes..ie basically copy at least half of the audio from WABC and WOR, although phasing is a big help, it only helps when the IBOC QRM is from a different direction than the DX. During the demo, there was background hiss in lots of places, and as IBOC stations continue to come on the air (morons) hiss on channels that I couldn't even explain where it was from.
At night, skip signals are strong, and fewer stations use IBOC and some fringe area stns have lower power or directional patterns not aimed at me, but there still was hiss and in strange unexpected places on the band. IBOC has put a damper on TA DX here and also my efforts to chase TP's (when I can manage to wake up). Here's an example of what I had to do to get decent audio from Croatia 1134 (often the strongest TA) Friday night. 1134 is where KMOX has a big IBOC hiss spike, so I have to phase KMOX (somewhat off the back end of 65 degree BOGs) and luckily local WISN 1130 (also IBOC) is from the same direction and reduced. The 1138 IBOC from WISN is far enough from 1134 to not overpower it using a 4 KHz filter. Additional tweaking of the phaser was usually needed to further reduce the crud/hiss on 1134 to make it decently audible.
Pity the poor DXer in the mid-west without a superb antenna setup as IBOC QRM comes from nearly all directions. I phoned the area DXer who lives 7 miles south and almost as close to Lake Michigan as I, and he thinks he may have just been able to get audio traces on 1134 with a loop, while easily hearing what I had, played over the phone.
I remain shocked that IBOC was ever allowed on AM as it is an extremely flawed and destructive technology and doesn't, unlike FM, even allow for additional channels (sub channels or what ever they are called). Hiss can be heard behind analog audios here, and back in IL where I live about 18 miles from WSCR 670, it was very very touchy to tune the ULR to not have a sideband hissing when listening to WSCR as an example.
73 KAZ expecting even worse hiss for several years until stations or lawsuits or the FCC wakes up and turns off AM IBOC for good. ----- Original Message ----- From: "Craig Healy" <bubba@xxxxxxxxxxxxxxxxxxxx> To: "Mailing list for the International Radio Club of America" <irca@xxxxxxxxxxxxxxxx>
Sent: Sunday, August 10, 2008 8:10 AM Subject: [IRCA] More IBOC discovery
Well, I try to limit comments on IBOC to once a month or so. Here's a current bit.. Recently I helped install IBOC at a local AM station (Infidel! Infidel!). It was a rather interesting and informative job. We all know about the adjacent channel trash that is put out by design.What is not publicized are the undesired sidebands caused by mixing products beyond that first adjacent. This job had sidebands at around +/-25KHz thatwere about 65db down though perfectly legal in the mask that the FCC mandates. This makes hearing a third adjacent station in that area of the transmitter site quite unpleasant. It does carry a fair distance and isvisible on my home SDR-14. There were also wider sidebands further out than that of consequence. All this IBOC noise is additive and destructive to theband. Since a third adjacent can be geographically close, it may be more of an issue than we realize. It can raise the overall noise floor. I have to wonder if my local 1320 station has damage from local 1290 IBOC which is 24/7. Another thing that came out of this is that not all antenna systems can bemade compatible. Night pattern in this place was too narrowband. The IBOCcarriers were there and as noisy as ever. The distortion caused by thenarrowband antenna system prevented the receiver from decoding them even inthe transmitter building (!). Neither of my radios would decode it even afew miles away. It just flat out wouldn't work. The consultant spent a lotof time on that system and got it as good as it can be. I'm not convinced that even all digital mode would work on this system. The bottom line ofall this is that a significant fraction of AM stations may never be able toimplement IBOC. Therefore, either all those stations eventually fail orIBOC in general fails. Mutually exclusive. I should also mention that thelabor costs for all this is far greater than many stations can handle. Sales of IBOC receivers isn't exactly as they present. Let's face it, how many DXers have bought the Sony XDR-F1HD because it's a stellar analog receiver and not because they want HD capability? And how many HD radiosare factory equipped in cars, not because the buyer wanted it? And how manyare bought by the industry itself? And how many are bought and returnedbecause they "don't work"? None of this is factored in to the sales numbersposted by the proponents of IBOC. I've been in radio a long time. There has not been even one complaint to any of my clients that they don't have IBOC. In fact, in the nearly 40 years I've been in radio, there have beenless than a handful of calls complaining about audio quality. These radiosdon't sell because the average listener doesn't give a flying fig.This whole system is badly designed, shoved down our throats by overfinancedand blinder-equipped companies, and flawed in excecution. The public is apathetic toward it. It's dead, Jim... Craig Healy Providence, RI
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