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Classic stereo, wideband FM broadcast also sounds great when you have a good signal and good production. In theory, the newer HD Radio scheme can provide equiv

Classic stereo, wideband FM broadcast also sounds great when you have a good signal and good production. In theory, the newer HD Radio scheme can provide equivalent or better quality even with marginal signals, but most broadcasters choose to continue regular FM simulcast and subdivide the remaining digital bandwidth across multiple virtual channels. This results in audible compression artifacts on most stations.

Aloha 9y ago
Wideband FM does sound lovely - FM Stereo however, less so - much.. uhh, crappier signal to noise radio, and relatively low channel separation depending on conditions. All told, I generally prefer analog FM to FM HD Radio - though I also listen to AM extensively - and I like how it sounds on a receiver with more than communications grade bandwidth - AM can push upwards of 10 khz - before 1982, it was not uncommon to find stations who ran closer to 15khz though - I've heard test recordings that just sound fantastic.
- Infernal 9y ago
  Out of curiosity, where does one find test recordings of things like this? And what happened in 1982?
  - akira2501 9y ago
    In 1982 the FCC allowed stations to apply for C-QUAM [1] operation. Don't let the OP fool you, it uses a nearly identical technique to FM stereo and thus has nearly the same limitations and impact on quality of the station. Or he's thinking about 1989 when the FCC actually limited AM bandwidth to 20kHz (10kHz audio). [1]: https://en.wikipedia.org/wiki/C-QUAM https://en.wikipedia.org/wiki/C-QUAM
  - fzzzy 9y ago
    https://archive.org/details/schweizerairchecks https://archive.org/details/schweizerairchecks
akira2501 9y ago
> but most broadcasters choose to continue regular FM simulcast and subdivide the remaining digital bandwidth across multiple virtual channels. The FCC has not approved all-digital modes yet. Further, we cannot control the bitrate of the "main" digital simulcast. We _can_ control the sub-channels, but it doesn't matter how much bandwidth you throw at it, the HDC codec (which is a bastardized form of HE-AAC) always sounds like garbage. This is partially owing to the codec, but also to the fact that we only have 96kbit/s in total to allocate to all sub-channels.
GeorgeTirebiter 9y ago
Looks like IBOC DAB like HD Radio has, at best, an audio codec rate of 96 kb/s. A CD has 2 x 16 bits x 44,100 samples per second = 1,411,200 b/s of audio data (doesn't include FEC). Seems to me that even with the best codec there's going to be loss going from 1,411 kb/s to 96 kb/s. So, HD Radio cannot achieve CD quality. The analog "Accuphase" T-101 FM tuner gives 70 dB SNR, guaranteed. http://www.accuphase.com/cat/e-202en.pdf http://www.accuphase.com/cat/e-202en.pdf That's equivalent to about 12 bits dynamic range, so already we see that analog FM is not as good as CD. If we take also the fact that the highest frequency is 15 kHz on analog FM, let's set the sample rate at (wave hands) 32 k sample/sec; so the 'equivalent' best-case uncompressed digital rate that's equivalent to the best analog FM is 2 x 32000 x 12 bit/sample = 768 kb/s. Given that when you add in that stereo pilot at 19 kHz and then do the L-R and L+R de-muxing thing in analog, you lose more dBs in SNR, wave hands and say the 'true' non-compressed equivalent of analog FM is around 500 kb/s. AAC gets 50% +/- 10% compression, so we're down to 250 kb/s. So, it's hard to see how HD Radio can claim it is 'as good as' old-fashioned analog FM.
- FireBeyond 9y ago
  Well, this is the big con with HD Radio. Everything around it is "High Def", "now broadcasting in High Def..." HD Radio isn't High Definition radio, it's Hybrid Digital Radio, effectively simulcasting a digital and an analog signal.

Aloha 9y ago

Wideband FM does sound lovely - FM Stereo however, less so - much.. uhh, crappier signal to noise radio, and relatively low channel separation depending on conditions. All told, I generally prefer analog FM to FM HD Radio - though I also listen to AM extensively - and I like how it sounds on a receiver with more than communications grade bandwidth - AM can push upwards of 10 khz - before 1982, it was not uncommon to find stations who ran closer to 15khz though - I've heard test recordings that just sound fantastic.

Infernal 9y ago
Out of curiosity, where does one find test recordings of things like this? And what happened in 1982?
- akira2501 9y ago
  In 1982 the FCC allowed stations to apply for C-QUAM [1] operation. Don't let the OP fool you, it uses a nearly identical technique to FM stereo and thus has nearly the same limitations and impact on quality of the station. Or he's thinking about 1989 when the FCC actually limited AM bandwidth to 20kHz (10kHz audio). [1]: https://en.wikipedia.org/wiki/C-QUAM https://en.wikipedia.org/wiki/C-QUAM
- fzzzy 9y ago
  https://archive.org/details/schweizerairchecks https://archive.org/details/schweizerairchecks

akira2501 9y ago

> but most broadcasters choose to continue regular FM simulcast and subdivide the remaining digital bandwidth across multiple virtual channels. The FCC has not approved all-digital modes yet. Further, we cannot control the bitrate of the "main" digital simulcast. We _can_ control the sub-channels, but it doesn't matter how much bandwidth you throw at it, the HDC codec (which is a bastardized form of HE-AAC) always sounds like garbage. This is partially owing to the codec, but also to the fact that we only have 96kbit/s in total to allocate to all sub-channels.

GeorgeTirebiter 9y ago

Looks like IBOC DAB like HD Radio has, at best, an audio codec rate of 96 kb/s. A CD has 2 x 16 bits x 44,100 samples per second = 1,411,200 b/s of audio data (doesn't include FEC). Seems to me that even with the best codec there's going to be loss going from 1,411 kb/s to 96 kb/s. So, HD Radio cannot achieve CD quality. The analog "Accuphase" T-101 FM tuner gives 70 dB SNR, guaranteed. http://www.accuphase.com/cat/e-202en.pdf http://www.accuphase.com/cat/e-202en.pdf That's equivalent to about 12 bits dynamic range, so already we see that analog FM is not as good as CD. If we take also the fact that the highest frequency is 15 kHz on analog FM, let's set the sample rate at (wave hands) 32 k sample/sec; so the 'equivalent' best-case uncompressed digital rate that's equivalent to the best analog FM is 2 x 32000 x 12 bit/sample = 768 kb/s. Given that when you add in that stereo pilot at 19 kHz and then do the L-R and L+R de-muxing thing in analog, you lose more dBs in SNR, wave hands and say the 'true' non-compressed equivalent of analog FM is around 500 kb/s. AAC gets 50% +/- 10% compression, so we're down to 250 kb/s. So, it's hard to see how HD Radio can claim it is 'as good as' old-fashioned analog FM.

FireBeyond 9y ago
Well, this is the big con with HD Radio. Everything around it is "High Def", "now broadcasting in High Def..." HD Radio isn't High Definition radio, it's Hybrid Digital Radio, effectively simulcasting a digital and an analog signal.