I've long wondered...

How good (and what characteristics) do the following (and other common) audio transmission methods have:

AM radio (mono & stereo)
FM radio (mono & stereo)
Satellite radio
over-air broadcast tv (NTSC & PAL)
cable tv (NTSC & PAL)
cable digital tv (NTSC & PAL)
music/radio channels on digital tv
Satellite tv

And any other common things you might think of.

Basically, what is the frequency range. How much noise. What kind of artifacts. Already compressed (satellite radio?) if so, how.

How would it compare (very roughly & subjectively) to a LAME mp3? 32k, 64k, 128k?

And so on.

I've tended to feel that a good radio signal is about the same level of quality as what many shared mp3's are, but I have nothing to back it up, so I figured I'd ask about the quality of the audio broadcasts.

I recently learned about this. Basically, anything >15KHz is noise, and at 19 or 19.5KHz there's a solid pilot tone....a picture is included in this thread

AM radio has even less range, I think it's like 8KHz or something like that.

Thread about FM sound quality : http://www.hydrogenaudio.org/forums/index.php?showtopic=8109

I have done tests with recording a strong AM station with my fancy schmancy Twin Coil Ferrite AM antenna... the highest frequency I've been able to get is about 9.5 KHz. I've seen claims that the limit of AM is 10 KHz, which I guess is pretty accurate.

You can look at hard data of what's possible, but many radio stations are not concerned about a flat response or staying true to the audio as it was recorded. It's not uncommon for stations to boost the bass in order to sound louder. They are in business to catch the attention of listeners and sell ads. Reproducing audio accurately becomes a less important matter.

On a side note....state of the art digital transmission over radio is supposedly being spearheaded by these guys...

http://www.ibiquity.com/index.htm

The technology is just now starting to roll out. They supposedly have a new compression codec that beats everything. Imagine being able to get 4 stations where you currently only see one being broadcast. That may be possible in the future.

That doesn't answer your question.

Mti

Oh ! They must have achieved "compact-disc-like quality" (as they say) at 48 kbps, I guess...

Sat. TV music channels (DirectTV):

Certainly compressed. I don't notice any of the classic low bitrate artifacts, but overall the quality seems less engaging than good FM... as if it's mastered to be background music rather than something you sit and listen to.

The levels on these channels is something like 10 - 20dB lower than it would be from CD. There is also a bit of compression here (it is MPEG 2 encoded), but it still sounds reasonably good unlike XM & Sirius.

I have heard Ibiquity at CES both on AM and FM. The AM was simply horrible, and the FM was only slightly better than say XM or Sirius (50% more bandwidth). It was a tossup between analogue and digital FM for me. I guess it would depend on reception conditions and the specific encoder. IIRC the bandwidth for FM is 96kbps (can be split up between audio and data). If a station only broadcasts digitally 128kbps can be reached. One of the interesting things is that you would be able to time shift radio programs al la Tivo, or pause a station if needed.

I believe that European DAB uses 128kbps as standard with some broadcasting at up to 192kbps.