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Author Topic: FCC adopts rulemaking for all digital AM broadcasting  (Read 8762 times)
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WB4AIO
WB4AIO
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Better fidelity means better communication.


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« Reply #25 on: December 16, 2019, 07:05:42 PM »


The good news is.................................................


There is no good news.  This will be a disaster.

Small mom and pop operators ( think under 10 kw ) won't be able to afford to abandon what analog listeners they still have to chase a handful of BMW owners with digital receivers.     

For the AM band , it's Don Meredith singing,  "Turn out the Lights, The Party is Over".  ( for you old timers )

This from a broadcast engineer who has been lovingly caring  for AMs since 1968.   End of an era.  Sad.

Don W4DNR





I have nothing against digital radio or digital audio. But IBOC, even at its best, is very BAD digital audio. What a useless turkey, vastly inferior to the analog AM it killed. It sounds bad, bad, bad. Think Real Audio files from 1996.

The (undisclosed) true design goal of IBOC was to PREVENT the adoption of a new digital broadcast band in the US. This was not wanted by the big-money boys, because it would have leveled the playing field and made all stations equally excellent in audio quality and signal to noise ratio. It would have made the Mom and Pop operations just as listenable as the big-money blowtorches. Can't have that!

IBOC is a total turkey from the word "go," and almost no one listens to it or will ever listen to it.

73,

Kevin, WB4AIO.
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« Reply #26 on: December 16, 2019, 08:09:02 PM »

The industry is all worked up now about the roll out of ATSC 3.0 that will have much better forward error correction but the fun part of that is that in order to receive ATSC 3.0 and above you are required to have a new decoder aka TV set.



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« Reply #27 on: December 18, 2019, 04:35:32 PM »

I received some new informaion on this system:

According to an acquaintance on another website:

Quote
Apparently HD Radio uses a proprietary CODEC called HDC (High Definition Coding) CODEC.

In the CBR bitrate table [from a non-HD website], the low-pass filter is set to 9640 Hz for 20 to 28 kbps, 13050 Hz for 28 to 40 kbps and 14260 Hz for 40 to 56 kbps.

Figure 5.4 [of the SY_IDD_1012S document] provides 40 kbps in 20 kHz of RF bandwidth and Figure 5.5 provides 20 kbps in 10 kHz of RF bandwidth. For a station sending the full 20 kHz of RF bandwidth, it's possible that the digital audio frequency response is 14.26 kHz. For a station sending the reduced bandwidth 10 kHz, it's possible that the digital audio frequency response is 9.64 kHz.

It was never stated in the testing that I read what the CODEC filter was set for but it appears that, depending on the bitrate used, the maximum analog audio bandpass that can be reproduced is around say 14.25 kHz for a high bitrate.

So, depending on how the CODEC was set up, about 9.5 kHz to 14.25 kHz of analog audio can be encoded.
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