Re: [IRCA] More IBOC discovery
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Re: [IRCA] More IBOC discovery



The noise floor on AM BCB here in the Denver area is also noticably increased due to IBOC. 560 seems to be the worst, spewing various degrees of hash on everything from 530 to 590. Stating the obvious: the AM band is not laid out to accept IBOC - the bandwidth needed is too great for the current channel definition (10kHz). Hence, there will be interference, reduced coverage ranges, and now we know there's an increased noise floor. It's legalized jamming blessed by the FCC political haxors who knew this would be the case from the beginning. Thus endeth my rant. lol. 73.

Chris Knight
Fort Lupton, Colorado


From: "Neil Kazaross" <neilkaz@xxxxxxxxxxxxx>
Reply-To: Neil Kazaross <neilkaz@xxxxxxxxxxxxx>, Mailing list for the International Radio Club of America<irca@xxxxxxxxxxxxxxxx> To: "Mailing list for the International Radio Club of America"<irca@xxxxxxxxxxxxxxxx>
Subject: Re: [IRCA] More IBOC discovery
Date: Sun, 10 Aug 2008 19:21:42 -0500

One wonders what lies station management believed in order to justify spending all this money on installation and consulting !

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 that
were 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 is
visible 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 the
band.

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 be
made compatible. Night pattern in this place was too narrowband. The IBOC
carriers were there and as noisy as ever.  The distortion caused by the
narrowband antenna system prevented the receiver from decoding them even in
the transmitter building (!).  Neither of my radios would decode it even a
few miles away. It just flat out wouldn't work. The consultant spent a lot
of 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 of
all this is that a significant fraction of AM stations may never be able to
implement IBOC.  Therefore, either all those stations eventually fail or
IBOC in general fails. Mutually exclusive. I should also mention that the
labor 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 radios
are factory equipped in cars, not because the buyer wanted it? And how many
are bought by the industry itself?  And how many are bought and returned
because they "don't work"? None of this is factored in to the sales numbers
posted 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 been
less than a handful of calls complaining about audio quality. These radios
don't sell because the average listener doesn't give a flying fig.

This whole system is badly designed, shoved down our throats by overfinanced
and 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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