Re: [IRCA] IBOC Revisited

[Bill Harms <philcobill@xxxxxxxxxxx>]

Hi Renee:
	
	I have just a couple of observations.

	1. Your tuning techniques work and I have done the same thing myself 
especially when just one station is causing the hiss. However, 710 was 
completely unDXable and I could not use any technique to get rid of the 
hiss because it was getting the channel from both sides - WLW 700 and 
WGN 720. It was difficult to hear even Cuba on that channel no matter 
what I tried, and Cuba is not even great DX. If the DX signal is 
substantially weaker than say Cuba on 710, then it would be nearly 
impossible to hear it. The band is not full yet and there are only a few 
places where a channel is getting hit from both sides. If there were 
more stations using IBOC, this would be more problematic.

	2. Things get a little dicey when DXing splits. Sometimes things work 
and sometimes they don't work. That is because the hiss is not confined 
to 10 kHz spacing.

	3. My gut feeling is that while we might be able to pick distant 
stations using IBOC on occasion, we will not be able to hear large 
numbers, especially the weaker stations. Virtually all of the distant 
stations that certain DXers have been able to hear in digital have been 
the stronger, more regular stations, and then decoding them has been 
dicey. As more stations come on the air with IBOC, I bet things will be 
even more difficult.

	These comments represent my own thoughts and are just points of discussion.

Bill

R. F. Tetro wrote:
> Now that we have experienced several nights of IBOC operation throughout
> the country, and most of us have had a chance to do some initial Dxing
> under these new conditions, I am interested in your responses to the
> following question:  Has the sky indeed fallen as many of us predicted?
> 
> Here is what I have found over the past few evenings.  As we all know,
> nighttime IBOC does indeed create the same hash as we have become
> accustomed to during the day, particularly on the first channel
> adjacents, but to a lesser extent to the second  adjacents, as well.
> It must be remembered that the IBOC information is carried on sidebands
> from 8kz-15khz removed from the carrier.  So that if IBOC is being
> transmitted on 1210 WPHT, its digital artifacts will not just effect
> stations on 1200 and 1220, but - to a lesser extent - 1190 and 1230.
> This is because the IBOC information has encroached about the second
> adjacent's analog sideband by at least 5khz.  To make this more clear a
> station on 1230 will receive digital IBOC hash from 1210 on its lower
> sideband from 1220-1225 Khz.
> 
> I have experimented with several techniques to alleviate this situation,
> most of which are available to anyone with a general coverage receiver.
> 
> 
> The first technique, and one of the most effective, is to use the USB
> and LSB modes on you receiver.  If, for instance, you are receiving IBOC
> has from 710 on 690, switch operation to lower sideband so that the hash
> on 695-700 becomes diminished or altogether invisible.
> 
> Another technique is to use extremely narrow bandwidth filters (such as
> 2.4 and 1.8 khz), either when monitoring on AM, or when using sideband
> techniques.  The narrow bandwidths, coupled with good notch filtering
> practices, may render the IBOC hash almost invisible.
> 
> So, has the sky fallen?  Are we up against the demon forces of HD radio
> to the extent that many of us suspected?  Or, has the IBOC revolution
> merely opened up a new chapter in the history of our hobby.?  I tend to
> believe the latter.  For instance, in the past two nights I have been
> able to log several stations in the digital mode...some stronger than
> others, some solid and others with their HD signals fading in and out
> and tough to pull in.  
> 
> I think this whole IBOC thing may, contrary to what many of us (myself
> included) may in the end be a boon to Dxing.  It may force us to develop
> new techniques, but it also will afford us the opportunity to pull in
> digital signals from hundreds of miles away.  For me, the bottom line is
> that it is - for the time being - a mixed blessing, but one which we
> Dxers can take advantage of.
> 
> Looking forward to a great DX seasons, and glad to be back on the NRC
> and IRCA lists after a break during the summer.
> 
> 73,
> Rene'
> 
> Rene F. Tetro
> Lansdale, PA, USA
> W2FIL, WPXG816, WPXU288
> Coordinates:  40D12'41"N  75D18'22"W
> Grid:  FN20IF
> Email:  rtetro@xxxxxxxxx
> Websites:  www.westpointcommunityradio.org; www.veronicafm.org;
> www.exalt1700.org; www.breezy1630.org; www.dxhub.com  
> NOTE:  Opinions expressed are my own and do not necessarily represent
> those of my employer, family, friends, co-workers, God himself, or any
> others.
> 
> 
> 

-- 
Bill Harms
Elkridge, Maryland

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