HD Radio, Audio Signal Quality?

As good as perfect reception of an analog FM station with brighter sound, better stereo separation and no crunchy multipath.


They compress audio, not data.

Here in the DC area I notice some stations do more compression on some of their channels than others. For example the main WAMU is nearly CD-quality, but WAMU-HD3 sounds like a bad MP3.

Yeah, the main stream is pretty much CD quality, the extras are not but if they just do one extra they still sound pretty good. The greedy stations start dropping the bitrates trying to save bandwidth and money or stuff way too many streams in and they start sounding like bad MP3's.

First time I've heard someone called "greedy" while they are giving stuff away ,......assuming most stations are not running paid commercials in the HD channels. But, yes, I hope they don't try to run too many channels within the limited BW they have to work with.

I have not heard any 48 kbps HD Radio station that begins to approach CD quality.

The last 96 kbps station we had here was the only one that had significantly improved sound once the digital faded in. That was very close to CD quality. Unfortunately I don't own much classical music on CD to make direct comparisons. Now that they've dropped it down to 48 kbps, it sounds exactly like FM analog.

Are the stations here that are using their HD-2's to provide STLs for other FM stations "greedy"?

One HD-2 here has stopped displaying artists and song titles and now displays a single ad continuously:

"Ford And Hd Radio Love Portland Look For The New Taurus, New Flex And New Mustang"

I'd rather have the artist and song titles.

Well I say greedy because many start stuffing more channels in and then the sound quality sucks. And then there is the bandwidth issues and why spend a lot of extra cash for something users get for free. Luckily here my station advertises their HD streams heavily and puts the HD2 on a unused am station here as well so folks can check it out, plus they have live streams of both online.
My radios don't tell me what bitrate they are running so can't say for sure but my favorite still sounds like CD quality to me. Not sure if the Sony I have even has a option to show bitrate like some of the more expensive tuners do.

HMMM! Don't think KNRK is doing that yet but sometimes their extras just don't work or one or both streams go down for a while but hasn't happened lately as I listen to and from work then at home we tend to hit the HD2 half or the regular one depending on whats playing.
Which station is doing the add instead of artist info, maybe it helps cover the cost of the extra transmitter I guess but I like the info too and would really miss it.

I wish you had said that a few months earlier. I was just thinking about a couple of now-silent AM's in our area, who were desperate for "filler" programming while they looked for buyers. A "random sampler" of HD Radio sub-channels, and some ads might have been a good use for them.

Any takers on this in other markets are welcome to use it .

I was doing some A/B comparisons at my neighbors house who has an ONKYO system...about a 1900 dollar a/v receiver with an HD ONKYO MODULE. SO IT IS SOME QUALITY STUFF. Couple of extra channels not available on regular analog FM but there WASN'T THAT BIG OF A DIFFERENCE IN SOUND QUALITY TO ME. His receiver was definitely switching to digital......usually took couple seconds to switch from analog to digital when switching channels.

If I could find a reasonably priced home receiver I would buy in but its not worth spending a lot to me.....................

To me sound quality wasn't much better than a properly caught FM Analog station. But, trying to maintain a good connection with an analog FM station can be tough. Nothing worse than waiting for the song you like, then suddenly you drive out of range.

In my experience, while there are cases of a slightly less noisy signal being broadcast to your radio, the biggest benefit of using HD over analog FM is the better lock-in ability. I find it much easier to hold on to HD radio stations as opposed to FM stations.

It's worth it to me just to have a complete stable lock on the sound, no static and just sounds like your playing a CD whether it's truly CD quality or not. I also like all the eclectic hd2 stations we have here, even PBS has a good secondary channel with a kind of indie rock thing going on.
If you can still find one of the Sony XDR-F1HD you'll be a happy camper as it's one of the best sounding tuners out there and retailed at 100 or less. I bought mine at Frys after hearing my new Dual 6425 car HD radio that I hooked up to a power supply and jacked into my main system just to see if it worked and I liked the way it sounded. Amazon used to sell them and a few other online places but pretty sure the supply as dried up but haven't searched lately. It doesn't ave any extra bells and whistles like the more expensive tuners but it really sounds and receives nice.

Well just searched and no one has any new unless you get lucky. The typical eBay price is 200 bucks so a LOT of folks must really want these things if they like FM or FM HD Damn, for once I guess I jumped in at the right time and price but that doesn't help anyone who wants one now. I guess they were brand new in 2008 when most of us got ours and sold for a while but are now discoed

That's the tuner that damn near makes a good analog FM signal sound as good as 48 kbps HD Radio. I don't know how it does it but there is no hiss and hardly a hint of distortion. The only thing that gives it away are the highs are cut off.

You really need to compare a CD to say something is CD quality. Yes, there is no hiss or static and so on, but once you listen to something on a 48 kbps HD Radio station then immediately listen to it on CD (or even a good MP3), you'll hear how much you didn't hear on the radio. There is a lot of volume masking and other tricks that make the audio compressible to that bit rate.

From what I have read HD stations are broadcast at a much lower power than regular fm so it would make sense to lose that signal first. If it is simulcast hd/regular fm the signal would revert back to analog and if it was an hd only station you would basically just shut off. digital is all or nothing.....signal gets too low its just goes away.

Yeah this is basically what happens. Only a few stations in my area simulcast HD/FM, so most of the time if I get out of range, the station will drop out completely. But, I'd rather totaly lose the station then have it slowly degrade as I keep driving.

Both slowly degrade. With analog, first you lose the stereo subcarrier, then you have increasing hiss and distortion until you can barely hear it. Even then it can be worth listening.

When you start losing digital, you hear it, then you don't. Then you hear it again. Then you don't. Then you hear, oh wait gone again. Then you think about switching to another station, then it comes back. Damn, it's gone again!

Repeat until you finally never hear it again. But wait it's back! Wait, never mind, gone again...

I drive too fast to have this problem..

But seriously, my receiver will move to the next available station as soon as the HD signal is lost. No chance for it to leave and return the way you are saying it will. I just assumed this was a feature with all car HD receivers.

Ack! That's a terrible feature! To get back to your original station, you have to tune it back and wait. It would drive me nuts.

They ruined RDS in the same way. Stupid Star94 used to always display: Atlanta's #1 hits radio station... Star94

It was so annoying. If I'm seeing that then I'm listening. Just show me the artist/song title.

I'd say that overall RDS was completely screwed up. When it worked, it was great, there were a number of different fields and radio stations didn't seem to use them wisely.

There was one 6-character field that they'd just cycle stuff through (like the message above) or song/title but then they'd leave the other fields like RDS+ fields (I forget all of the details) blank when they could have put in station, artist, song, etc.

You'd think that they'd get that this is all part of the experience of listening to their station but, to them, the experience is: Put an ad up so that people know that the station they're listening to, ours, is the best!

HD Radio allows the broadcaster to alternate between different text messages. The problem with this station is that they're only showing the ad, nothing else. If they want to alternate between the artist/song title and something that generates revenue then I would have no problem with that.

The worst station for HD radio from what I've heard is 97.9 in Baltimore. The station's main signal is horrid, the hd2, hd3, and I believe even hd4 are just unlistenable. The best HD sound I've heard is either 103.7 The River in Richmond, VA (no subchannels) and WTQR here in NC. I am on the edge of the WTQR HD signal and you can REALLY tell when it drops out and comes back.

i am, for the most part, impressed with my boston acoustics receptor HD radio, except for the analog AM quality, whose AM tuner seems to be an afterthought, and is barely intelligible with voices, much less music. the reception is not especially robust, with much night-time fading and whistling. the FM analog tuner, OTOH, is excellent, with great sensitivity and low noise, great for DXing with just a rudimentary antenna- living in shelton, WA, i can receive [using just a crude window-mounted dipole facing in the wrong direction] stations all the way from the pacific coast of washington, and in the correct antenna heading, i can receive stations well up in vancouver island BC. the FM HD signal quality is more variable, and the reception of distant stations is limited to roughly 70 miles as the crow flies. the only remotely "CD-quality" station i've heard is KING-FM, a seattle classical music station. the rest of 'em are probably "48khz" stations with roughly the audio quality of a good close FM station. the AM HD signal sensitivity is extremely weak, with only one AM HD station within 10 miles receivable. the sound quality of that one AM HD station was akin to a well-done 96kb/s MP3 file. their spectral substitution algorithm would be a nice thing for me to try on my own audio restorations of old 78 rpm acoustic recordings. i wonder how they do it? anyways, i'd love to be able to hear more of the AM HD, out of curiosity as to how well it can sound on a real music station [the one i heard was just a sports/news station]. thanx all for bothering to read me.

From what I can tell, the industry seems to be giving up on AM-HDRadio.

Here in Atlanta it was never widely adopted but, over time, those that did adopt it have turned it off and are back to the analog signals.

If you were to compare the AM radio list on HDRadio.com from years ago to now I think you'd see much the same thing.

If it's like FM HDRadio then I don't really know how it'd work. I'd think that the signal would be even less stable than FM as power lines and over passes do a pretty good job of knocking out AM, and, for home use, it's really hard to get AM into the home.

What's weird is that I remember when I was a kid we regularly listened to AM in the home and, yes, sometimes it helped to turn your radio a little bit, for the most part it worked quite well. You don't get that now. I don't know if it's because of more electrical devices and interference, crappier AM radios, or a combination of them both.

AM HD Radio has much more aggressive error correction and temporal redundancy than FM HD Radio. That's why it takes longer to switch to digital when you tune it in.

Unfortunately the stereo stream (like the stereo subcarrier in analog FM) has less error correction so it dies more often than the mono stream. That makes stereo reception more difficult. I've never been able to get our Disney AM station in stereo at work for more than a few seconds, but it's perfectly reliable in mono.

Resurrecting this thread.

I recently compared several songs on 48 kbps HD radio stations to the same songs played through Pandora and Slacker over 3G, which use 40 or 48 kbps HE-AAC. (I used the same DAC, amp, and speakers, only difference in playback equipment was the HD radio module to listen to the HD radio tracks vs iPhone 4 to listen to Pandora/Slacker tracks). In my opinion, the HD Radio tracks sounded edgier and more digital than the HE-AAC tracks. To my ears, the HE-AAC at the same bitrate gave a much more natural sound. Has anyone else made similar comparisons, and if so, what's your opinion? Also, is anyone aware of a more technical comparison of iBiquity HD Radio Codec (HDC) to HE-AAC? If so, please share a link!

It's gonna vary by stations. Which radio stations did you sample and which songs?

I listened to 98.1 KISQ-HD and 103.7 KOSF-HD, both in the SF Bay Area. Tracks were Michael Jackson "Don't Stop til you Get Enough" and Marvin Gaye "Gotta Give It Up" from 98.1, and Eric Clapton "White Room" and Jimi Hendrix "Purple Haze" on 103.7.

Interestingly, I just realized that both stations are owned by Clear Channel, so if the HD radio sound quality varies by station, maybe both of these stations are using similar/identical equipment or encoders.

By the way, in no way do I think my very limited comparison represents a scientific experiment. I'm really interested in what others think about HD Radio vs 3G-based services.