Are HD Radio microchips feasible ?

[700WLW]

"Bringing HD Radio to the Masses"

"This is very pioneering, very challenging work, Ma said. Our design has to be low-power, low-cost, low-noise and with enhanced sound quality... The big challenge is large-system integration because we have to address the noise problem, Chowdhury added. By its very nature, DSP is very noisy, but analog is very sensitive to noise. So we have to combine the DSP and the analog signal processing on the same chip without the DSP noise compromising the analog performance. That is where a lot of our research will be focused."

http://uanews.org/cgi-bin/WebObjects/UANews.woa/4/wa/SRStoryDetails?ArticleID=13525

I read on the other site, that the best solution for using the existing Sangean HDT-1 AM antenna, is to place the loop as far away from the unit as posible; it is reported, that the HD module creates so much noise, that it dramatically affects the reception of AM signals, and therefore requires a distance from the antenna. Any other HD radios, experiencing this problem ?

 

[Tom Wells]

"Bringing HD Radio to the Masses"

"This is very pioneering, very challenging work, Ma said. Our design has to be low-power, low-cost, low-noise and with enhanced sound quality... The big challenge is large-system integration because we have to address the noise problem, Chowdhury added. By its very nature, DSP is very noisy, but analog is very sensitive to noise. So we have to combine the DSP and the analog signal processing on the same chip without the DSP noise compromising the analog performance. That is where a lot of our research will be focused."

http://uanews.org/cgi-bin/WebObjects/UANews.woa/4/wa/SRStoryDetails?ArticleID=13525

I read on the other site, that the best solution for using the existing Sangean HDT-1 AM antenna, is to place the loop as far away from the unit as posible; it is reported, that the HD module creates so much noise, that it dramatically affects the reception of AM signals, and therefore requires a distance from the antenna. Any other HD radios, experiencing this problem ?

But of course they are! ANY radio with any digital controls (soft touch buttons) or digital displays has to fight its own clock noise.

If you want a demonstration, tune any AM radio to a weak frequency. Turn on/off a light at a wall light switch. Hear the click?
Notice that this works even though the radio may be battery powered. The noise created by discontinuous current is distributed evenly across all frequencies from DC to light. The tiny amount of energy you hear at AM xxxx is quite enough to mix with incoming signals.
Now, let's assume the display strobe clock frequency is 1 Mhz. Now turn the light switch on and off 1 million times in a second.
That hissing is a 1 Mhz noise, as real as any radio signal, and it gets in the way of desired signals.

It seems some radios, like the BA receptor have insufficient power filtering and/or shielding for the RF circuits, and byproducts of the digital signals work their way into the input. The fix was to shoot sensitivity in the foot.

A real solution would be to kill the display clock oscillator 2 or 3 seconds after tuning stops, and latch the display segments ON.

I'm not satisfied so far with ANY digitally tuned AM detection radio I've met. They all suffer from this.
Naturally, it is important to get the pickup (loop) far from the noise source as possible, but then it becomes difficult to reasonate such a loop, as the capacitance must be in the radio somewhere.

If the loop is untuned, then it's a weak effort by the manufacturer, or intentionally insensitive in order to hide digital noise.
If the loop is tuned, then the "feedline" portion must run back to the radio, again providing an opportunity for digital noise to creep in.
If it's a tuned loop, you'd have to turn a knob on a capacitor AT the loop.


If you truly value sensitivity with no degradation, you will employ passive circuits.
If digital tuning is so important, don't beef about the noise.

Now if you make a radio that has to have a full-blown computer to reconstruct the waveform, you'll likely never be able to filter or shield all the various digital noises available to mix and intermodulate the RF. Have a nice day.

 

[PhilJSmith67]

I have a new Sangean HDR-1. RFI from the receiver's internals within the AM band is absolutely no problem at all. I can even place the loop right alongside or on top of the unit and still tune in stations that my Sangean ATS-909 can hardly get at all. (I also checked for proximity noise in the AM band in close proximity to the HDR-1 using the ATS-909 and found none.)

Higher frequencies, including the FM band, is different story. Internal RFI is strong enough within two feet of the unit to artifically reduce the HDR-1's range using the stock whip. I easily solved the problem with mini-rabbit ears on three feet of coax, but that might not be something every consumer would try. Think about it -- How many people under 40 these days have a pair of rabbit-ears or an FM dipole laying around in a closet?

With the stock AM loop and my "rabbit ear extension" for FM, the HDR-1 really works well. The sensitivity is good and selectivity is great on AM and FM, for analog or HD Radio stations. If Sangean figures out how to better shield the RFI-generating circuits in their upcoming HDR-2, it could be a nice performer right out of the box. If new laptops can be made that generate very little inteference, I'm sure it could be done for a couple chips with noisy clocks. This isn't really an HD Radio / iBiquity phenomenon, either -- I imagine that receivers with DRM chips could generate RFI unless they're properly shielded.

 

[w9wi]

I read on the other site, that the best solution for using the existing Sangean HDT-1 AM antenna, is to place the loop as far away from the unit as posible; it is reported, that the HD module creates so much noise, that it dramatically affects the reception of AM signals, and therefore requires a distance from the antenna. Any other HD radios, experiencing this problem ?

It's certainly an issue with the Boston Acoustics Recepter HD.

When used with an indoor antenna I get a strange "blocking" effect on many frequencies and wide swaths of the dial. It works MUCH, MUCH better with an outdoor antenna connected. I believe this interference would probably affect HD reception as well as analog, though it's hard to tell since its effect would be to prevent reception altogether rather than to create strange noises.

BA seems to have taken two post-production measures to combat this interference:
- They provided a separate loop antenna, similar to those provided with stereo receivers, but with a few feet of extra coaxial cable spliced in, so it can be placed at a distance from the radio.
- They spliced a RF noise filter, in a small plastic box, into the power cord.

I don't see this as inherent in HD - hams have been using receivers with CPUs and digital signal processing for two decades, and we listen to signals far weaker than anything anyone would listen to in the AM broadcast band. And self-interference from our equipment is rare indeed.

 

[Mike Walker]

ALL HD Radios generate noise, so antennas should be placed at a distance. "Ah-Ha" I hear 700 say. But here's the rub. As Tom pointed out, ALL DIGITAL RADIOS produce noise, and antennas should be placed at a distance. ALL computers produce noise, and antennas for Media Center PCs and others with tuner cards should be placed at a distance. Ditto audio devices. It's an issue for me in my studio...get a mixer too close to a PC, and there's noise. It's one of the reasons why I use condenser rather than dynamic microphones. Ever used a dynamic mic within a couple of feet of a crt? BZZZZZZZ!

I thought you were a computer guy, 700. CPUs, like all digital devices, produce noise. But electrical shielding can stop the noise at it's shource. YAWN!

 

[700WLW]

ALL HD Radios generate noise, so antennas should be placed at a distance. "Ah-Ha" I hear 700 say. But here's the rub. As Tom pointed out, ALL DIGITAL RADIOS produce noise, and antennas should be placed at a distance. ALL computers produce noise, and antennas for Media Center PCs and others with tuner cards should be placed at a distance. Ditto audio devices. It's an issue for me in my studio...get a mixer too close to a PC, and there's noise. It's one of the reasons why I use condenser rather than dynamic microphones. Ever used a dynamic mic within a couple of feet of a crt? BZZZZZZZ!

I thought you were a computer guy, 700. CPUs, like all digital devices, produce noise. But electrical shielding can stop the noise at it's shource. YAWN!

Why are you attacking me ? I never stated, that I didn't realize that digital devices make noise - I knew that, when I bought my RS PLL digital radios, so that is one reason, why I went with the analog-tuned Sony. That is the main reason, that I started this thread, because SiPort claims that they will have a IBOC micro-chip by this Fall, but TI states that it is going to be very challenging, because of the DSP noise. Then I read on the other site, about how the DSP for the Sangean HDR-1 causes interference to AM, so the loop-antenna needs to be moved far away, as possible. Then I was wondering, about reception in portable HD radios, and came across this excellent link about DAB in the UK:

"A Look at DAB"

To quote:

Extra radio channels are always a good thing, so there's no real downside. There are only two areas that are holding back the mass takeup of digital radio at the moment, and they're set to change soon:

Cost. Fortunately, prices are now beginning to fall, and you can get a DAB radio from Currys for under £30. Until prices start to tumble, many think that it's too expensive to replace home, portable and car radios with DAB radios.

Signal. Although the DAB signals are less prone to interference, they're currently weaker than FM signals, which can cause problems if you're in a fringe area. If you're looking for a hi-fi option - you may want to consider something with an external aerial socket, especially if you're not in a strong signal area . Also note that handheld personal DAB radios are likely to have less effective aerials than tabletop and Hi-fi DAB radios.

http://www.radioandtelly.co.uk/dab.html

So, if portable HD becomes a reality, there are still going to be issues of cost and reception (it seems that if IBOC makes it into iPod-type devices, reception is going to be more of an issue, with the lack of substantial external antennas). Just some thoughts, from an ignorant software engineer...

 

[Mike Walker]

In metro areas where most listening is done, the headphone cord will do just fine for an antenna, just like it does for FM (fm stereo pops in and out on Walkman portables, and nobody's screaming about that. Ditto the occasional blend to analog). The antenna issue just ain't that big a deal. Again, HD uses the same types of antennas that have been used for fm forever.

Note the shape of a headphone wire coming out of a portable, going to left and right ears. Looks like a dipole to me!

As for why I'm "attacking" you...for fun and profit. Except the profit part. Seriously, people who put a negative spin on EVERYTHING posted here annoy me. It ain't personal, but this IS a forum for discussing HD Radio. Your insistance on attacking every piece of positive news, putting a negative spin on everything, and quoting things out of context (take the "Dead on Arrival" thread) annoy not just me, but lots of us! Take a more civil, tolerant tone, and I'm sure others will oblige.

 

[700WLW]

In metro areas where most listening is done...

So, just like with iBiquity's mentality, to heck with everyone else - yea, that will fly !

...the headphone cord will do just fine for an antenna, just like it does for FM (fm stereo pops in and out on Walkman portables, and nobody's screaming about that. Ditto the occasional blend to analog). The antenna issue just ain't that big a deal. Again, HD uses the same types of antennas that have been used for fm forever.

Note the shape of a headphone wire coming out of a portable, going to left and right ears. Looks like a dipole to me!

As for why I'm "attacking" you...for fun and profit. Except the profit part. Seriously, people who put a negative spin on EVERYTHING posted here annoy me. It ain't personal, but this IS a forum for discussing HD Radio. Your insistance on attacking every piece of positive news, putting a negative spin on everything, and quoting things out of context (take the "Dead on Arrival" thread) annoy not just me, but lots of us! Take a more civil, tolerant tone, and I'm sure others will oblige.

It is well-known, that HD radios require AM-loop and externally-mounted dipole antennas, so it is highly-doubtful, that IBOC chips would work properly in iPod-type devices and portable HD radios, plus, I am highly-suspicious that DSP noise would not be an issue. So, are portable HD radios going to have AM-loop antennas - remember, the antennas can't be too close to the DSP ! Actually, all of this hostility makes for spirited-debate !

 

[Mike Walker]

"It is well known" that they "require" these types of antenna, is it? I just hooked up a longwire (completely different type of am antenna), and 6" piece of straight wire from the back of my HD radio. 60 miles from the nearest HD station I still got several HD stations just fine, and my AM reception didn't noticably change (I don't have ANY AM HD stations near me...check the map).

For fun I hooked up a ferrite loopstick to my AM antenna terminals...the same type of antenna used in portable AM radios forever. It brough in all the locals as well. Were there any HD stations in my immediate area, OF COURSE THEY WOULD COME IN!

The fact that car HD radios use either a monopole or a wire in the windshield, and some new models use a whip antenna, disproves the "well known requirement". Loops are the most efficient small passive AM antennas, and dipoles the most efficient small passive FM antenna. They certainly aren't the ONLY ones which work. Geez!

"Well known" that they "require"??? HOOK UP ANOTHER KIND OF ANTENNA TO ONE AND SEE IF HEY "require" it...especially in a metro area, WHERE MOST LISTENING IS DONE! Yes they "require" an antenna, but aren't noticably more picky about which one than FM stereo! This is just a rumor, dude!

 

[700WLW]

"It is well known" that they "require" these types of antenna, is it? I just hooked up a longwire (completely different type of am antenna), and 6" piece of straight wire from the back of my HD radio. 60 miles from the nearest HD station I still got several HD stations just fine, and my AM reception didn't noticably change (I don't have ANY AM HD stations near me...check the map).

For fun I hooked up a ferrite loopstick to my AM antenna terminals...the same type of antenna used in portable AM radios forever. It brough in all the locals as well. Were there any HD stations in my immediate area, OF COURSE THEY WOULD COME IN!

The fact that car HD radios use either a monopole or a wire in the windshield, and some new models use a whip antenna, disproves the "well known requirement". Loops are the most efficient small passive AM antennas, and dipoles the most efficient small passive FM antenna. They certainly aren't the ONLY ones which work. Geez!

"Well known" that they "require"??? HOOK UP ANOTHER KIND OF ANTENNA TO ONE AND SEE IF HEY "require" it...especially in a metro area, WHERE MOST LISTENING IS DONE! Yes they "require" an antenna, but aren't noticably more picky about which one than FM stereo! This is just a rumor, dude!

"HD Radio Receiver Sensitivity"

http://www.radio-info.com/smf/index.php/topic,51315.0.html

God, this is exhausting - maybe, I should get that punching bag, after all, that a therapist recommended getting years ago !

 

[SUPERCASTER]

At 1/100th the broadcast power, HD radio signals are already much weaker to start with, and problematic.
Yes, HD signals have very serious problems in metro areas, especially penetrating buildings and obstructions, the same as any low powered signal. Changing the method of modulation does not change propagation.

 

[700WLW]

For fun I hooked up a ferrite loopstick to my AM antenna terminals...the same type of antenna used in portable AM radios forever.

The only standard AM antenna, that I am aware of for portable analog AM/FM radios, is the internal ferrite-bar antenna - I've never had to, "hook up a ferrite loopstick to my AM antenna terminals". Portable HD-AM is not going to work, with just internal ferrite-bar antennas.

 

[Mike Walker]

Dude, you're ocmparing apples (portable radios, which are self-contained) with component and high quality table radios, which almost never include internal antennas. There are no portable HD units yet. Whent here are, they'll use internal antennas. At least one table radio, the Cambridge Soundworks, already uses a built-in whip antenna.

I connected a loopstick antenna to the terminals to see what reception would be like on a small portable. It pulled in all the local AM stations just fine, which was my point. I also tried the wire antenna to simulate the headphone cord which is used for FM on a Walkman. IT ALSO WORKED FINE! This is a non-issue. HD is no more difficult to receive (in my experience) than clean FM Stereo.

 

[700WLW]

I connected a loopstick antenna to the terminals to see what reception would be like on a small portable...

AM loopstick antennas, are not standard equipment with Walkman-type portable analog AM/FM radios - good luck portable HD Radio !

 

[Mike Walker]

700 you seem to be unaware that it's not the TYPE of antenna (loop or longwire for AM, dipole whip or yagi for fm) that's the issue. It's whether it's AMPLIFIED, and whether the amplifier produces noise which obscures the digital information which is at a much lower level than analog. For the fifteen thousandth time, HD works with the same types of antennas as analog, EXCEPT for the amplified variety. And when lower noise amplifiers are developed, those will work too.

 

[700WLW]

700 you seem to be unaware that it's not the TYPE of antenna (loop or longwire for AM, dipole whip or yagi for fm) that's the issue. It's whether it's AMPLIFIED, and whether the amplifier produces noise which obscures the digital information which is at a much lower level than analog. For the fifteen thousandth time, HD works with the same types of antennas as analog, EXCEPT for the amplified variety. And when lower noise amplifiers are developed, those will work too.

"SONY ICF-S10MK2 Pocket AM/FM Radio"

"The Sony ICF-S10MK2 with a Radio Shack Loop was compared against a modified ICOM R75 with a Quantum QX Loop. This testing was, in essence, a shootout between a $31 portable setup and a $780 tabletop setup! The R75 provides ~1.77 µV AM sensitivity [PREAMP "1" ON] and the Quantum adds another +40 dB of RF gain."

http://www.radiointel.com/review-sonys10mk2.htm

Care to explain, why an unamplified Radio Shack AM loop-antenna was used for the test ? HD Radios require externally-mounted dipole and AM loop antennas, to have any chance of picking up the HD channels.

 

[PhilJSmith67]

I wouldn't assume that HD Radio chips cannot work in portable devices. I have a new Uniden BR330T scanner that is chock full of processing power. It has more memory and has the fastest microcontroller clock speed of any scanning receiver I own. It is also the smallest scanning receiver I own. Amazingly, as for RFI, it is by far the quietest I own. I usually use the stock antenna. From 0.54 to 1300 MHz (no gaps, less cellular) I have found under a dozen "birdies," none of which are strong. That's phenomenal compared to scanners from the 80s and 90s.

The most recent PC-based ATSC tuner I bought is the smallest. It is also the quietest. The last two I owned were not only bulky, they were so noisy that reception of VHF channels 2 - 6 was very difficult, even with an outdoor antenna. The new one works well using an indoor antenna, even if it is placed in close proximity to the tuner.

New laptops are typically less noisy than older ones, even though they are significantly more powerful.

Miniaturization produces internal components that require less power and produce less RFI. Board designs improve over time to reduce RFI, too. Given the assumption that HD Radio sticks around (there are plenty of other reasons to contrary), the internal electronics will improve to reduce the RFI, and battery life will improve.

 

[700WLW]

I wouldn't assume that HD Radio chips cannot work in portable devices. I have a new Uniden BR330T scanner that is chock full of processing power. It has more memory and has the fastest microcontroller clock speed of any scanning receiver I own. It is also the smallest scanning receiver I own. Amazingly, as for RFI, it is by far the quietest I own. I usually use the stock antenna. From 0.54 to 1300 MHz (no gaps, less cellular) I have found under a dozen "birdies," none of which are strong. That's phenomenal compared to scanners from the 80s and 90s.

The most recent PC-based ATSC tuner I bought is the smallest. It is also the quietest. The last two I owned were not only bulky, they were so noisy that reception of VHF channels 2 - 6 was very difficult, even with an outdoor antenna. The new one works well using an indoor antenna, even if it is placed in close proximity to the tuner.

New laptops are typically less noisy than older ones, even though they are significantly more powerful.

Miniaturization produces internal components that require less power and produce less RFI. Board designs improve over time to reduce RFI, too. Given the assumption that HD Radio sticks around (there are plenty of other reasons to contrary), the internal electronics will improve to reduce the RFI, and battery life will improve.

"Bringing HD Radio to the Masses"

"This is very pioneering, very challenging work, Ma said. Our design has to be low-power, low-cost, low-noise and with enhanced sound quality... The big challenge is large-system integration because we have to address the noise problem, Chowdhury added. By its very nature, DSP is very noisy, but analog is very sensitive to noise. So we have to combine the DSP and the analog signal processing on the same chip without the DSP noise compromising the analog performance. That is where a lot of our research will be focused."

http://uanews.org/cgi-bin/WebObjects/UANews.woa/4/wa/SRStoryDetails?ArticleID=13525

I never stated that HD Radio chips cannot work in portable devices - from my original post that started this thread, I was questioning SiPort's claims about their HD/IBOC chip, when TI had the above comments.

 

[PhilJSmith67]

10-4. I understand your original point.

 

[700WLW]

10-4. I understand your original point.

Could have been my bad...