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HD Radio Receiver Sensitivity

These HD radios will make interesting tech toys when they are put on clearance at a fraction of their value in a few years. They will have the same advantage on AM as C-Quam AM tuners - they will have beautiful wideband response when stations switch off HD and go back to decent analog audio. On FM, they can probably be retrofitted with narrow ceramic filters to have decent reception.

When the day comes, I'll post rework instructions for the units I end up with. First on the agenda will be to get the (then useless) HD chips off the board - no doubt drinking power like they do they are needlessly stressing the power supply and heating the radio's interior.

I may even add a wide / narrow IF position to the AM for DX'ing.
 
You all seem to be for sure that HD radio will fail. How about fighting HD TV? That is STILL going on.
You people are funny.
;D
 
rbrucecarter5 said:
These HD radios will make interesting tech toys when they are put on clearance at a fraction of their value in a few years. They will have the same advantage on AM as C-Quam AM tuners - they will have beautiful wideband response when stations switch off HD and go back to decent analog audio. On FM, they can probably be retrofitted with narrow ceramic filters to have decent reception.

When the day comes, I'll post rework instructions for the units I end up with. First on the agenda will be to get the (then useless) HD chips off the board - no doubt drinking power like they do they are needlessly stressing the power supply and heating the radio's interior.

I may even add a wide / narrow IF position to the AM for DX'ing.

Well, if you get to post the rework instructions, then I get to post iBiquity's filing for Chapter 11 ! :D
 
pullitin said:
You all seem to be for sure that HD radio will fail. How about fighting HD TV? That is STILL going on.
You people are funny.
;D

There is absolutely no reason to fight HDTV. First of all, it works fine. Second, it does not interfere with its neighbors. Third, it actually gives the consumer something he couldn't get elsewhere.

With HDTV, there is some steak behind the sizzle. The improvement in picture quality is dramatic. It's hard to say that anything about "HD" radio is dramatic, unless you are talking about the interference it creates. At least, at this point, HD radio offers the consumer very little and the broadcaster even less, unless you happen to be a large broadcaster; then it gives you a legal way to interfere with your smaller neighbors.

I guess it depends on what side of the fence you happen to be sitting on. Even so, picking on HDTV has absolutely nothing to do with radio or this discussion.
 
pullitin said:
You all seem to be for sure that HD radio will fail. How about fighting HD TV? That is STILL going on.
You people are funny.
;D

"HD Unreliable at times-Need outdoor antenna"

"UH... Just a personal complaint. Today is one of them mornings where the HD wont stay locked in. I Can still listen to the Analog stations, which switch between HD and Analog, but the HD-2s arent going to be reliable enough. Does this ever happen to you? I just have to wait for better reception weather or move closer to the city."
 
"I may have found a reception solution!"

"Check this pic out. I applied a thumb tack to hold the Antenna to my Accurian, I put the end of the Antenna high, and it has solved a lot of my HD recption issues with FM! Can't promise that everybody will have the exact same results, BUT for me it did work."

[EDIT]

:D


[EDIT - Violation of TOS]
 
700WLW said:
"I may have found a reception solution!"

"Check this pic out. I applied a thumb tack to hold the Antenna to my Accurian, I put the end of the Antenna high, and it has solved a lot of my HD recption issues with FM! Can't promise that everybody will have the exact same results, BUT for me it did work."

[EDIT]


[EDIT - Violation of TOS]

:D
Apparently the object of your link was "disappeared" by the HD Radio promotions team at the other board.
The same thing happened to 2 Media Consolidation reports at the FCC, that were found by Senator Boxer.
Do you think there might be a connection?
 
SUPERCASTER said:
700WLW said:
"I may have found a reception solution!"

"Check this pic out. I applied a thumb tack to hold the Antenna to my Accurian, I put the end of the Antenna high, and it has solved a lot of my HD recption issues with FM! Can't promise that everybody will have the exact same results, BUT for me it did work."

[EDIT]


[EDIT - Violation of TOS]

Apparently the object of your link was "disappeared" by the HD Radio promotions team at the other board.
The same thing happened to 2 Media Consolidation reports at the FCC, that were found by Senator Boxer.
Do you think there might be a connection?

700WLW said:
Let's see, how long this one lasts:
[EDIT]

[EDIT - Violation of TOS]

Well... Your latest “working” link posted at 11:55AM was no longer on the server by 12:15PM the same day. 'Gone in 20 minutes!

This is really sad... And so is that “board” which I’ve never established an account at—and very rarely read. I guess the frustrated I-Buzzers have lost their sense of humor.

Have a great day all! 'Now back to reading my new holiday Hammacher-Schlemmer catalog—with dozens of upscale (and not-so-upscale) consumer electronics items... But NO HD Radio!
 
"Sorry, but I'm underwhelmed"

"Well, I've been listening to HD radio every morning this week. I finally got around to getting a splitter so I can hook up my regular FM tuner and compare it to the Sangean. Fortunately, according to the VU meters, the levels were darned close, I know it's difficult to compare levels between the two due to different analog processing, but if anything, the analog tuner has lower output. The differences were startling to me. HD sounds absolutely dead and lifeless. Granted, all the Bay Area offers is 48 Kb stuff, so it's probably not entirely fair, but I can really tell. The highs seem to be missing, even with these 56 year old ears. I am monitoring using a pair of Sennheiser HD-600 phones, a lot of people think these are pretty good. The sibilants sound artificial, like they're inserted after the fact. Kind of reminds me of poorly processed Dolby, where you hear no highs in the breath sounds until a strong sibilant comes along and opens up the high pass filter on the receiver. This was also true on the local Rock station I like here, KFOX. The music just seemed dead. I'm not one driven to these botique descriptions I hear when people are comparing audio components. I've never heard differences between competently designed power amplifiers, for instance. I also can't explain why I haven't yet detected a difference between Mike's audio files either, I'll be spending more time on them soon. Maybe I just need something that plays a little longer or more material. I also noticed on the vectorscope of my Marantz receiver that there is something going on with the phase relationship between channels. When a lone instrument is played on the classical station, you see the display go from a 90 degree phase shift, through all the phases to in phase and through the cycle again. I think it's due to the random phases a pair of microphones pick up during a classical concert. This doesn't happen as much on HD. It seems like the same music has mostly in phase information. I don't see how this is possible, you need phase information for imaging, I just notice there is a real difference. Maybe the HDT-1 has a high freqency problem. I am going to compare analog stations between the two and see. This doesn't prove much, since the digital and analog signals go through a different analog chain before they are presented to the output terminals. Too bad you can't measure the frequency response of the digital channel, and they didn't show that spec in the Sangean spec. sheet. I'm going to keep comparing stations, but so far, HD loses big time to me. I'm going to put up a bigger antenna to get the noise down on my FM analog channels."
 
Hey, someone mentioned HDTV a while back on this thread~

I bought a Fortec HD/Digital TV convertor box for my VCR and regular NTSC set just over a year ago, and I must say living in an area where decent analogue reception of anything above channel 10 is a distinct challenge, digital over the air TV is truly a GODSEND. Now while it is correct to say I am not seeing it in "true" high-definition resolution (I don't plan on getting an HDTV set for a very, very long time yet...tight budget, you know.....) at least even on an NTSC set through the yellow-cable composite video socket (and even the S-Video, which I feel is better by far) it is a TREMENDOUS improvement over our analogue TV channels.

That, and my VCR isn't getting out-moded. I can still tape off the box through the line-out, switching the VCR to one of its input channels.

It's a shame, then, that Ibiquity couldn't follow this same example for radio!! At least in most cases analogue FM (and even AM) come in perfectly fine around here.
 
"It's a shame, then, that Ibiquity couldn't follow this same example for radio!! At least in most cases analogue FM (and even AM) come in perfectly fine around here."

Indeed - there is no point to digital radio.
 
I finally found a Radio Shack with an Accurian set up for testing in the store.
This was last week in Houston, I'm just now getting around to posting this.

Accurian- The waiting is the hardest part.
In AM, the delay between pressing the frequency + or - button and hearing output is maddening!
If this were the only problem, it would be enough to keep me from buying. It would take 3-4 minutes to scan the band just to see if there were something I was interested in listening to. It might not be annoying for someone who sets presets or only listens to one station, but for me, it's frustrating not to be able tune this as a radio. There is also no ability to offset from the fixed 10kc steps, very sad.

In this case, there was no AM reception at all, and the empty jacks on the back made me wonder...
A built-in loop would have picked up all the "ambient" noise in the store, but there was almost none.
Do these radios have no built-in loop or ferrite bar antenna?
It may be that such an antenna IN the radio would pick up all the clock noise from the CPU osc or display.
The radio itself might make enough noise to self-interfere on AM, necessitating an external AM antenna.....
But then how could just any loop attached to these connections be very effective unless it were of a specific inductance, so
as to be reasonant with the capacitance of the tuning?
Or is the loop just broadbanded and loose coupled? At any rate, I would not ever expect much for AM sensitivity.

But finally, I got to hear FM HD. I did not have time to log stations and frequencies, but there were 3 or 4 signals that did decode in HD, and 2 or 3 had HD-2 channels that did work. The step-tune delay is not quite as bad as on the AM, but still annoying.

The HD mode did not stay solid on any of the signals, despite much rearranging of the antenna, and even when I thought I had it just right, the HD came and went for no apparent reason. The analog signals did not exhibit noise from the store environment.

700WLW said:
The differences were startling to me. HD sounds absolutely dead and lifeless.
The highs seem to be missing.... The sibilants sound artificial, like they're inserted after the fact. Kind of reminds me of poorly processed Dolby, where you hear no highs in the breath sounds until a strong sibilant comes along and opens up the high pass filter on the receiver.
And this does not occur smoothly, but digitally, as in "all or nothing"
I did not have enough time to truly compare whether the stations with 2nd feeds suffered more from the shared bandwidth, but I expect this would be noticable, as with all other zero-sum equations.

One of the stations was a classical music outlet, and the overtones on violins sound harsh and screechy, as if the difference was changing the local oscillator in the radio from sine-wave to square wave. It definitely is ADDING unnatural coloration.

It actually made this type of music sound like there was MORE hiss, as the analog did not exhibit this, and this effect in the digital mode does not sound more like live music.

I hear the same digital zizzlies in this as in all digital deliveries.
If I wished to distort music in this fashion, I would devise a motor to rapidly waver the azimuth of a tape player head, but why would I want that?

The data rate is clearly better than that used for the AM version, but still calls too much attention to itself.
The result is not as good as a sine-wave mixer-detected analog FM.
And the lack of "air" in recordings makes me wonder if the encoding has a threshold for low levels that ignores such whisper-level signals,
converting everything under 2% modulation to zero.

If the mode is incapable of delivering a clean sine wave at 15 khz, why not roll off the highs before encoding, so the result
only contains data which the mode can reasonably reproduce?
This is no different from digital photography with low resolution, where diagonal lines cannot reproduce as anything other than "stairsteps".

There is also some audio "stunting", where processing of the analog and digital do not match, so the HD kicks in as "louder",
but unfortunately, all the "louder" parts accentuate the inadequacies of the encoding (in the high freq phase innaccuracy).
This might sound good if the audio were upper-end limited to 10 or 12 khz, below the maximum resolution of the sampling.

Back in the 1920s and 30's, some early superhets and autodynes used IF frequencies just above audio, and the mixer byproducts were
every bit as annoying as this. This is ONE of the resons why AM radio standardized on higher IFs, in order to provide higher resolution.

Mr Fourier, call your office. There are some questions from your students in the remedial classes.
 
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