[opendtv] Re: Fw: Re: FCC Opens TV Spectrum for Broadband Use
- From: Cliff Benham <flyback1@xxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Sun, 05 Dec 2010 01:33:10 -0500
On 12/5/2010 12:22 AM, Albert Manfredi wrote:
Cliff Benham wrote:
I think one of the major reasons digital radio came about
is because broadcasters realized they can now 'prevent'
listeners from receiving programs from outside the local DMA.
How cynical!!
Absolutely. I am cynical! I am the chief curmudgeon.
And I'm also right!
True for the AM band, since HD radio uses 30 KHz of spectrum in that band when
it is used in hybrid mode (10 or 20 KHz if used in all digital mode). But I've
noticed that the stations that initially went to HD radio, during the day, at
least in this area, seem to have quit that. Maybe I should check again. Never
listen to that band much anymore.
BTW, the same would also happen if AM stations tried to transmit dedent quality
audio in AM, spreading out to 30 KHz. Some did just that, years ago. In AM,
your audio bandwidth translates directly to RF bandwidth, on both sides of the
carrier. So, 15 KHz audio AM takes up 30 KHz.
I like HD radio, though. Should be used more effectively.
Bert
When WLW, Cincinnati was broadcasting 'CLEAR CHANNEL" at 50KW after WWII
they were transmitting with the 50KW driver stage for the 500KW final
that was not in use after the FCC limited AM power to 50KW.
With the 500KW final on air, WLW could be received from coast to coast
and was then known as 'The Nation's Station'. This was the period from
1934 to 1939.
http://en.wikipedia.org/wiki/WLW
This driver and antenna had a pass band of 30KHz and WLW billed itself
as the 'High Fidelity Voice' of AM radio. While the sidebands do contain
energy out to 15 KHz each side of the carrier, the energy diminishes
greatly and is far less apparent the further from the carrier one measures.
However it does not cause anything like the kind of interference to
reception of other AM stations that HD radio causes.
HD causes a wide band blanketing effect [white noise] which extends at
the same high level out to + - 15KHz either side of the carrier and
blanks out reception of distant AM stations for hundreds of miles.
This effectively prevents DX reception of other clear channel AM stations.
Tell me what I posted above is not so.
Cliff
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:
- Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.
Other related posts:
