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DXing in HD mode

B

Boulder Engineer

I've had a lot of fun doing this lately.
Locking my Kenwood in HD-only rx mode and skimming the AM band these quiet autumn nights.

The radio locks on at least a dozen HD stations, but makes audio on only a few.

KFAB in Omaha, 1110, a thousand miles from here, KOA in Denver, WHO in Des Moines.

The effect of a weak digital signal is pretty cool. You only hear "blips" to a few seconds of audio on the weakest. The middle-signal stations have continuous stereo, hi-fi audio, but with a 1960s 'flangy' effect on fades.

It's kind of neat stuff, actually. The IBOC receivers recognize the presence of digital sidebands, but the codecs won't play audio until it's beem verified twice, from what I've heard.

I want to meet a hacker than can get me a DXers decoder chip!

An open note to Ibquity:

Release your decoder code and let the crackers and hackers have at it.
Guaranteed that they'll come up with some very cool stuff that you will never
even think of. For cheap.

Of course, you will only allow manufacturers to use your 'lcensed' decoder chips, so what real revenue are you going to lose?

Let the geeks get involved and have fun with it.

Seriously!


------------------------------------
I hate Nevada

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I was hoping to be able to DX HD-AM, but the best I can do is the PAD info for 3 or 4 stations and never a lock besides the two AM-HD in my city of license.

iBiquity letting the hobbyists have a go at HD-AM would be great - that's how many fans of C-Quam AM Stereo came about - Motorola gave you a chip for free and a schematic and you could plug-n-play on your own. It is a pipe dream for iBquity to give us enough rope to try out our own schemes - you might end up with a Kahn CAM-D or RDM version of HD-AM that would work even better!

I'd like to see them use a variation of the XM SatRad codec with a DRM mix to get the ultimate MediumWave digital system that is more skywave fade resistant.
 
I had high hopes of AM HD DX, but I confess I've all but given up. Life is short!
 
JohnnyElectron said:
I was hoping to be able to DX HD-AM, but the best I can do is the PAD info for 3 or 4 stations and never a lock besides the two AM-HD in my city of license.

iBiquity letting the hobbyists have a go at HD-AM would be great - that's how many fans of C-Quam AM Stereo came about - Motorola gave you a chip for free and a schematic and you could plug-n-play on your own. It is a pipe dream for iBquity to give us enough rope to try out our own schemes - you might end up with a Kahn CAM-D or RDM version of HD-AM that would work even better!

I'd like to see them use a variation of the XM SatRad codec with a DRM mix to get the ultimate MediumWave digital system that is more skywave fade resistant.
Click to expand...


Another cool project would be to somehow get the HD chipset (like buy it) on a piece of perfboard and hang it after the IF amps in different receivers. You could use a good communications receiver and play with bandwidths and tuning. I'd like to see a schematic of an HD receiver to see how they detect the digital sidebands. Are they simply added together? Would it be better to have the ability to manually select the upper, lower or both digital sidebands? Maybe use one decoder on the upper and a different one on the lower?
Maybe an HD-modified Superradio would work well?
Lots of questions.
 
Unfortunately, the GE SuperRadio III won't work very well with the HD radio, in much the same way that it doesn't make that good of an analog AM stereo deoder. The SRIII has some sloppy phase modulation with the varactor tuning, and therefore doesn't decode the Phasemodulated info (L-R analog) (digital PM).

The best customers for HD AM are stations that have/had a great CQuam or Kahn AM Stereo signal, as they've done the housecleaning to get a tuning network prepped for the wide bandwidth; that being said, WJR is a sad lump of it's formerly robust self.
Listen to what WJR used to sound like (even using a small loop antenna) with a 7.5KHz AM filter here:
http://www.fanfarefm.com/soundbites.html
 
Speaking of communications receivers, I'd love to see some manufacturer (Sangean?) take the HD chip, and use it to create a budget DX powerhouse of a communications receiver, allowing HD to be switched out (or in) the circuit, so that DSP power could be used for ANALOG reception...allowing MANUAL access to all those freakin' bandwidths and modes that dsp uses to make automatic adjustments. It would seem to be possible to produce a budget communications receiver with continuously variable if bandwidth from, say, 2khz to 20khz, with just a few components (and some firmware) to allow those dsp functions to be addressed BY THE USER, rather than do all that automatically.

Even IBOC-bashers would have to admit that this would be using the technology for good, not evil! Hey, HD Radio chipsets have made affordable the DSP power of what were VERY expensive receivers used only by hobbyists! Why not produce a receiver for radio geeks that takes advantage of this?
 
Mike Walker said:
Speaking of communications receivers, I'd love to see some manufacturer (Sangean?) take the HD chip, and use it to create a budget DX powerhouse of a communications receiver, allowing HD to be switched out (or in) the circuit, so that DSP power could be used for ANALOG reception...allowing MANUAL access to all those freakin' bandwidths and modes that dsp uses to make automatic adjustments. It would seem to be possible to produce a budget communications receiver with continuously variable if bandwidth from, say, 2khz to 20khz, with just a few components (and some firmware) to allow those dsp functions to be addressed BY THE USER, rather than do all that automatically.

Even IBOC-bashers would have to admit that this would be using the technology for good, not evil! Hey, HD Radio chipsets have made affordable the DSP power of what were VERY expensive receivers used only by hobbyists! Why not produce a receiver for radio geeks that takes advantage of this?
Click to expand...

LOVE......LOVE......LOVE the idea! Sounds like a perfect project for C. Crane and Sangean.

Are you listening, Master Theseus?
 
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