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  #201   Report Post  
Posted to rec.audio.tech,rec.audio.car,rec.radio.shortwave,ba.broadcast
Chronic Philharmonic Chronic Philharmonic is offline
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Posts: 90
Default HD RADIO is no worse than DAB or DRM radio



"Earl Kiosterud" wrote in message
newst%Yi.403$CI1.60@trnddc03...


"Robert Orban" wrote in message
...
In article ,
says...



"SFTV_troy" blabbed:
... this new receiving technique would not improve the sound
(it would still be limited from 100-6000 hertz), but would only reduce
interference.

At least in the States, AM & FM broadcasting is limited to 50 Hz to
15KHz.


There is no low frequency limit for either AM or FM; 50 Hz was the
minimum
performance standard that would meet the now long-deleted FCC Proof of
Performance measurements.

The effective HF limit on FM is about 18.5 kHz; this leaves a +/- 500 Hz
guard
band for the stereo pilot tone. Again, 15 kHz was the minimum spec that
would
pass a Proof of Performance, not a limit on bandwidth.

Currently, the legal FCC-mandated HF limit on AM in the US is a hair less
than
10 kHz, which almost completely protects second-adjacent stations from
interference. This was changed around 1990 as a result of work done by
the
National Radio Systems Committee (NRSC). More recent work by the NRSC has
indicated that 7 kHz is probably the optimum compromise between causing
interference and loss of audio quality on typical AM radios (which are
down 3
dB at about 2.6 kHz). However, limiting bandwidth to 7 kHz is voluntary.


Robert,

Was AM radio ever allowed audio to 15 KHz? I read many years ago that it
was, perhaps before the NRSC recommendation was adopted by the FCC. I
presumed that the stations either were allowed to overlap 5 KHz
(doubtful), or that stations in a given area were separated by at least 30
KHz.
--
Regards from Virginia Beach,

Earl Kiosterud
www.smokeylake.com


I was a broadcast engineer in the late 1970s to the late 1980s. At that time
(before NRSC) AM was required to transmit a minimum 5KHz bandwidth, but the
maximum modulated bandwidth was not really defined. There were limits on
"spurious" emissions, caused by audio distortion products and carrier
harmonics. I don't recall the exact mask, but 15KHz was legal at that time.
Our studio transmitter link was a Mosely PCL-505, which was flat to 15KHz,
and we employed no artificial band limiting, so the station was flat to at
least 12KHz. Our tower was the limiting factor for bandwidth. It sounded
just like monophonic FM on the modulation monitor.

During the day there was no overlap, because stations were allocated on
second alternate channels in most markets. Local stations that did overlap
usually worked out a solution amongst themselves if the interference was
objectionable. At night it got quite a bit noisier as distant stations would
skip into the area, but it wasn't generally sidebands that caused the
problem, it was the carriers themselves, each whining away at 10KHz. That is
still a problem, even today.

The real problem was that in the late 1980s, AM stations began adding
proprietary "pre-emphasis" -- high frequency boost to make their station
sound brighter on typical pathetically band-limited AM receivers. This can
and did cause severe interference in some congested markets. Partially to
address this, and to standardize the pre-emphasis, NRSC limited AM sidebands
to 10KHz in the early 1990s. Since most AM radios do not even come close to
being flat to 5KHz, 10 KHz is still two or three times more bandwidth than
most listeners can use.



  #202   Report Post  
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Steven Steven is offline
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Posts: 138
Default HD RADIO is NO!, and your mother will back me up so don't bother asking

On Sep 30, 3:48 pm, "Soundhaspriority" wrote:
"Steven" wrote in message

ups.com...



On Sep 30, 3:09 pm, "David Eduardo" wrote:
"SoCal Tom" wrote in message


...


"SFTV_troy" blabbed:
... this new receiving technique would not improve the sound
(it would still be limited from 100-6000 hertz), but would only reduce
interference.


At least in the States, AM & FM broadcasting is limited to 50 Hz to
15KHz.


AM is restricted by the NRSC standard to a 10 kHz brick wall.


Digital broadcasting is limited to under 20 Hz to over 20KHz, or
basically, the extent of the normal human hearing range.


If you're listening to 100 to 6,000 Hz, you're listening to a poor
telephone connection.


Bob Orban, on the NRSC committee, found that consumer radios almost
without
exception, rolled off by at least 10 db by 4.2 kHz, and passed
practically
nothing over 5 kHz.


Bob Orban is the alien from the late Weekly World News.


god darn it, we've had EVERY TROLL in the group except the K-Man, the
Scott Lifshine/Wereo entity, and the RRAP brigade in this thread!


Morein/McCarty/66.6% of the world's asshole postings has chimed in
even.


Steven ?,
I haven't seen McCarty in this thread yet, though I'm sure he's reading
it. I sign my post with my phone number, and you can really reach me at it,
so please don't put me down with the anonymous asshole brigade.

Bob Morein
(310) 237-6511- Hide quoted text -

- Show quoted text -


Thought you could hide, asshole, but you're just an average asshole
and not very good.

  #204   Report Post  
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Doug McDonald Doug McDonald is offline
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Posts: 37
Default HD RADIO is no worse than DAB or DRM radio

Jason wrote:


A ham buddy of mine who was a transmitter engineer at WLWO, the VOA
station that shared the Mason site with WLW, built a high-tech crystal
set (multiple tuned RF stages) to see how good AM could sound. It was
remarkable.


I once tried a simple single-tuned crystal AM radio connected directly
to a guy wire of a 5 kW AM station, feeding a KEF 105 speaker. It sounded
wonderful.

Doug McDonald
  #205   Report Post  
Posted to rec.audio.tech, rec.audio.car, rec.radio.shortwave, ba.broadcast
Steven Steven is offline
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Posts: 138
Default HD RADIO is no worse than DAB or DRM radio

On Nov 21, 11:40 am, Doug McDonald
wrote:
Jason wrote:

A ham buddy of mine who was a transmitter engineer at WLWO, the VOA
station that shared the Mason site with WLW, built a high-tech crystal
set (multiple tuned RF stages) to see how good AM could sound. It was
remarkable.


I once tried a simple single-tuned crystal AM radio connected directly
to a guy wire of a 5 kW AM station, feeding a KEF 105 speaker. It sounded
wonderful.

Doug McDonald


I'm only half a mile away from the towers and I don't need a single
tuned crystal nor does my TV or computer bug it.

I'm not sure why IBOC means much to RRS but then again the IBOC
whiners' cabal/snake reproductive schemers that post these retarded
flaming marshmallows minus chocolate and graham crackers and their
hairdressers do.


  #206   Report Post  
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Billy Burpelson Billy Burpelson is offline
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Posts: 2
Default HD RADIO is no worse than DAB or DRM radio

Doug McDonald wrote:
Jason wrote:


A ham buddy of mine who was a transmitter engineer at WLWO, the VOA
station that shared the Mason site with WLW, built a high-tech crystal
set (multiple tuned RF stages) to see how good AM could sound. It was
remarkable.


I once tried a simple single-tuned crystal AM radio connected directly
to a guy wire of a 5 kW AM station, feeding a KEF 105 speaker. It sounded
wonderful.

Doug McDonald


When I was restoring a ca. 1915 loose-coupler crystal set, I was
actually startled by how good it sounded. No pesky IF or AF stages to
add distortion or pass band limiting!
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