Friday, March 11, 2005

HD Radio, Analog FM, mp3 and ogg Audio Samples

New Sirius Satellite Radio samples added: 10/05
New Eureka DAB Samples added: 10/05
Rough Dates added: 10/05
KEX AM 1190 added: 10/05

This page started out as a quick 'n dirty way for folks to sample real world HD Radio. It seems to be evolving as a more general comparison of the various content delivery technologies and that's a good thing. There is a lot to compare frankly and the number of choices continues to grow.

Scroll Down For the Samples

Interested in getting your samples on this page? Contact me at and I'll be happy to get that done. Please include any relevant technical information, station ID, credits, etc... with your samples so that everything can be sorted accordingly.

Call for additional samples: I am particularly interested in updated HD Radio samples. As things continue to improve in the audio processing chain, it would be great to have a record of those changes for comparison. A quality vinyl 12" and LP sample would be great to add here too.

I received a lot of material. For bandwidth reasons, I have posted a few snippets in raw wave audio format. (wav) Please be kind and download once then listen as many times as you want. Depending on how traffic goes, I'll either rotate the snippets, add new ones, or do something else.

Currently there is no real rhyme or reason to the order of samples presented. At some point in the future, I plan to reorganize the page to better reflect some of the audio tradeoffs each of the content delivery platforms represented below bring to the table. For now, each platform is colored along with the relevant samples to help tame the clutter.

All of the audio samples, save those indicated below, are presented in the form I received them in. In a couple of instances, I encoded the audio in order to allow for reduced bandwidth downloads, where I was sure the encoding process would not have a signifcant impact on the sample quality.

The various audio samples on this page are intended to help people understand where the different media delivery technologies fall on the quality scale. I was tempted to normalize the audio, but decided to just leave it as I received it. The first HD sample track from KGON was normalized, faded, etc... (EDIT: Actually the first two got this treatment...) That's all I am going to do. Anyone really needing to tweak the sound can grab their favorite audio editor/processor and tinker until happy.

And now onto the audio!

HD Radio (AM 1190 KEX Portland) 07/05
Sample 1 (raw wave audio)
Sample 2 (raw wave audio)

These represent quality improvements made over the first few months of IBOC broadcast at KEX. The originals can be found in the AM HD Radio section for reference.

HD Radio (FM) 04/05
KGON-hd-sample-01.wav (01 = Long)
KGON-hd-sample-02.wav (02 = Short)

The HD Radio samples were recorded directly from the RCA line outs on a Kenwood KTC-HR100 into a portable Marantz CD recorder. I have more material, but thought it best to start with this and go from there. ---Thanks Chris!

HD Radio (FM Secondary Streams) 07/05

The source samples were very long 320Kbps mp3 files. For length and content reasons, the samples presented here are shorter raw wav audio files, extracted untouched from the main mp3 file. Thanks go to the folks at Intercom Chicago ( Dave & A.J) for sending these my way.

Eureka DAB 10/05 [New]
[speech, 128kbit/s Joint Stereo : BBC National DAB]


[Pop Music, 128 Kbit/s Joint Stereo -- Digital 1 Network]

[Classical Music 192Kbit/s Stereo -- BBC National DAB]

Digital Radio Monidale [mp3 file]

Audio samples taken from RCA "phono" sockets of a Sony D777ES DAB tuner directly into a computer. No processing was done, other than to trim the overall sample length and save as 48Khz, 16 bit WAV audio files. The Digital Radio Monidale (DRM) sample presented with this group, came along for the ride from the same contributor. I don't have a lot of detail on this one, other than it was transmitted via Shortwave. Please consider a visit to:

Sirius Satellite Radio 10/05 [new]
Sirius 1 [channel 08]
Sirius 2 [channel 37]
Sirius 2a [channel 24]
Sirius 3 [channel 24]
Sirius 4 [channel 72]
Sirius 5 [channel 80]
Sirius 6 [channel 100]
Sirius 7 [channel 112]
Sirius 8 [channel 133]

Credit for these samples goes to some guy (you know who you are!) who preferred to remain anonymous. Several different channels, including a talk channel or two, are represented here. For more detailed information about the different channels, consult the Sirius channel guides. The samples were recorded directly from the radio as raw wave files. I have included short segments, cut from the original wav files, here for comparison purposes. No additional processing was done, other than to reduce the overall audio length.

HD Radio 03/05 (AM)
1190 KEX HD 1 (wav)
1190 KEX HD 2
1190 KEX HD 3
1190 KEX HD 1 (mp3)
1190 KEX HD 2
1190 KEX HD 3

Credit for the AM HD Samples goes to Dylan. He recorded these for me, using Larry's HD radio @ KBPS, and fiddled with the antenna to simulate rough signal conditions and allow comparisons between the analog AM and HD AM audio reproduction on an HD radio.

I went ahead and made quality mp3 encodes that don't appear to change the overall quality of the audio much. If you are on a slow connection or just want to save bandwidth, feel free to download those. The content is the same.

UPDATE: The folks at KEX 1190 have been doing some serious work on their HD AM audio processing chain. Look for samples here soon that represent their latest work as of Aug, 05.

Analog FM 03/05
Another FM Analog Sample.wav

Analog FM Samples were recorded from an older MCS Series tuner, directly into the computer sound card. Honestly, my gear is not the best though it probably represents the median of FM radios out there. My location also suffers from multi-path, which can be heard in these samples. If you have a better FM sample or two, you are willing to get to me, let me know.

CD Audio 03/05
CD Sample 1
CD Sample 2

These samples represent some very good dynamic CD audio. Given the huge variation in CD quality, these samples are really more about representing what CD audio is capable of, not what we mostly see today...

Compressed Audio 03/05
Analog FM Compressed to Mp3 (.mp3)
Analog FM Compressed to Ogg Vorbis (.ogg)
CD Audio 1 Compressed to Mp3 128Kbps
CD Audio 1 Compressed to Mp3 192Kbps
CD Audio 2 Compressed to Mp3 128Kpbs
CD Audio 2 Compressed to Mp3 192Kbps

LAME was used for the mp3 endode, and the standard Ogg Vorbis tools were used for the ogg encode. You might need a plug in to play the Ogg encoded audio. Mp3 is capable of a notch better than you hear on this page, but the encode time is probably 3-5X that required for the file I posted here. Better to just use ogg.

Update: I decided to post some CD audio and mp3 compressions for another data point for those looking for simple metrics. ie: How much better does CD sound than FM? If there is demand, I'll add ogg files later on.

Other HD AM/FM Samples 05/05
WOR HD AM samples
WOSU HD AM and FM Samples

Sadly, these appear to have been re-encoded as mp3 files with what sounds like the Fraunhoffer codec, thus limiting their accuracy. You may find the quality of the real signal better than what you hear on this page.

Ibiquity HD Radio Sampler 06/05
A quick disclaimer is in order. I'm posting these with permission. (Thanks David!) Before sending me a happy fun C&D letter, please contact me and I will provide my contact information just to clarify things. Thanks and now onto a sample of the sampler:
01 - Intro
02 - FM Cont. Rock
04 - FM Jazz Inst.
07 - FM Urban
09 - FM Contemp
10 - FM Country
11 - AM Jazz
12 - AM Talk
14 - AM Oldies

Each of the tracks is roughly a minute of audio comparisons between analog broadcasts and digital ones, produced by Ibiquity. I've not had the time to check these to see if they are the same ones on the Ibiquity page or not but I suspect they are. The ones there are re-encoded as mp3 and have quality issues. These appear much better in that regard.

That's it for the samples page! Check back from time to time as new samples will be added as technologies appear, change and grow. Thanks for reading OpenGeek.


Blogger Unknown said...

Thanks for the work Doug,

I haven't looked at an actual unit yet but I'm thinking of getting the JVC car head unit.

Do you know what the actul compression format is for the digital stream? Is it something I could save to my Ipod or other device?

I'm driving cross country and it'd be fun to make an auto-audio-collage!


Neil Kerr

August 20, 2007 11:40 PM  

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