All this talk about Power Stations, made see if the url still
worked, fortunately it did, have been listening so little, that
generally they switch servers, or even service providers, everytime I
want to tune in. For instance it took me over four months to find out
Little Jimmy had finally passed away shorty after his 94th birthday.
Eventhough most of Europe has done away with Medium Wave (the
mighty 747 that flew across most of Europe, was disctinued years ago
and the more local 1008, was taken out of service last year). I doubt
even one of those 50 Kilo Collins Tube monsters could pick up the
Aircastle of The South these days, airwaves being polluted like they
are, and and earth's surface being cluttered. In the early days they
reached all the way to the Caraibean on a few thousand Watts.
Long Wave are we also talking spread-spectrum? Traditional Long
Wave requires giant generator halls, the prime example being Radio
Kootwijk, recently restaured, concrete temple of progress, or Sphinx,
rising up from the shifting sands wastelands. Long replaced by
undersea lines, or even shortwave.
http://www.hierradiokootwijk.nl/p/home-radio-kootwijk[1]
Donald
Quoting Cliff Benham <flyback1@xxxxxxxxxxx>:
Bert, your point of view is 180 degrees from mine. You are writing
about making HD radio better
and deleting standard AM broadcasting all together.
I am writing about getting rid of HD radio all together and preserving
the AM radio service that has served the entire country since the 1920s.
AM radio will cover the country with news, information and music much
more easily and much more cheaply than HD will.
HD will never have the nationwide footprint that AM radio has had in the past.
Just as 8VSB was supposed to be a major improvement in television
broadcasting [AND ISN'T]
HD radio was supposed to improve reception so I could listen to
Atlanta, Baltimore or Cincinnati
in my car and at home BUT IT DOESN'T.
Why not put HD radio into the new long wave band the FCC is making.
This might aid HD since
long wave radio has a much larger ground wave than AM radio does.
Cliff Benham
On 10/26/2015 9:47 PM, Manfredi, Albert E wrote:
Cliff Benham wrote:
Bert, I completely disagree with all you say below.
Now you sound like Craig. :)
http://www.hd-radio.com/i/pdfs/Waveforms_AM.pdf[2]
The above link is the Ibiquity white paper that describes IBOC (aka HD Radio) as applies to the AM band. It provides the power level restrictions and channel width, in hybrid and digital-only modes. I'll refer to it below.
HD radio is 24 hours a day.
I checked. You're right, although some AM stations do shut AM-band HD off at night.
http://www.radioworld.com/article/am-hd-radio-has-stalled-now-what/3774[3]
"Citadel Broadcasting turned off the nighttime digital on its 10 AMs in the fall of 2007. At the time, Director of Corporate Engineering Martin Stabbert cited complaints from listeners and stations on adjacent channels, including both Citadel stations and others, in and outside the affected markets."
"Journal Broadcast Group has two out of six AMs airing IBOC signals full-time; it has not turned any off."
HD radio is limited to 17% of the radiated power of standard AM.
Take a look at the white paper, Table 1. In hybrid mode, the "primary upper and lower" digital sidebands, which are the strongest ones and stretch way out to +/- 15 KHz from the AM carrier, use 64-QAM and must be 30 dB down in power compared with the AM carrier. Closer in digital sidebands are 16-QAM, and must be 37 or 43 dB down. So overall, that's way down. 30 dB down is 0.1% of the analog carrier level, and that's only the strongest digital sidebands. That's how compromised the strongest HD Radio digital signal is, in hybrid mode. Pathetic.
If the station goes all digital, Table 2, those primary sidebands are now adjacent to the center frequency, and 15 dB down (3% of the center carrier). That's already 30 times as much digital power as they can transmit now. And it's also likely that the FCC would rethink its power limits, in all digital mode, as they did for the VHF DTV stations. You haven't even seen what AM-band HD could do, especially if all other analog AM were off the air.
HD requires a 20 KHz channel bandwidth which encroches into the
two adjacent AM channels making their reception practically
impossible because of the digital noise that interferes with them.
Take a look at Figure 2. In hybrid mode, indeed, the HD Radio digital sidebands extend to +/- 15 KHz (slightly less actually) from the center frequency. But at quite reduced power, which makes hybrid mode very compromised. Yes, that's a wide channel, and intrudes on adjacent AM stations, no doubt, but it's also allowed, in daytime, for analog AM (in case anyone has a receiver that can actually benefit from it!).
But now look at Figure 3. In all-digital mode, Cliff, the strong primary sidebands extend only +/- 4.9 KHz of channel center, and the low power secondary and tertiary sidebands go to +/- 10 KHz, but 30 dB down in power. This beats the existing AM spectral emissions mask, Cliff, which calls for 25 dB down from 10 to 20 KHz of center. Table 3.
And potentially, if the FCC bans use of those secondary and tertiary digital sidebands at night, you'd still be left with a very useful digital signal, taking up the existing 10 KHz channel width only. (In daytime, even today, analog AM stations can go out to +/- 15 KHz, right?)
You cannot pick up an AM HD signal much farther than the local
footprint, certainly not from a state or half the couotnry away.
You mean, when the signal is at best 30 dB down from the analog carrier, and there are tons of other high-powered AM stations crowding the AM band? Not surprising, right? Even that Radio World article suggests this improvement would occur, in digital-only.
Bert THESE ARE NOT MINOR TWEEKS!
I meant, minor tweaks to AM band use, compared to eliminating analog altogether. "Minor tweaks" in the sense that they make the AM band even less useful than it already is, under the guise of helping revitalize AM.
Yes, the HD signals are intended only to be received within
the markets they are located, hence the lower power allotted
to the HD signals.
We went through this with DTV. The digital power is always down compared with analog, not just because digital reception is less impaired by analog artifacts, but also because digital power is continuous, as opposed to peak power usually quoted for analog. In the FM band, the hybrid mode digital is 23 dB down from analog, but in all-digital mode, only 10 dB down. And again, I wouldn't be surprised if the FCC increased that all-digital limit some.
You have to be careful with Wikipedia articles, Cliff. It does not tell the whole story. Their description of FM, for example, is amazingly misleading. They apply AM ideas to explain FM bandwidth. Ibiquity also wrote an FM-band HD Radio white paper, separately.
Bert
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