Renowned Cambridge SoundWorks HD Radio Designer Explains HD Radio

[KB1OKL]

Quotes from Fred Pinkerton

HD Radio broadcasts require a consistent, stronger signal than analog broadcasts. Once you receive the minimum level of signal, an HD Radio broadcast sounds perfect. Below the minimum required signal le vel, the HD Radio program switches back to the analog signal. To ensure an adequate signal level, you position small FM and AM antennas for proper reception of HD Radio program streams The SoundWorks Radio 820HD provides three FM antennas and one AM antenna. The choice of which FM antenna to use depends on where you are relative to the radio transmitters.

There is a limit to how far you can be from a transmitter and still receive an HD Radio transmission. For flat land with no obstructions, this limit could be as far away as 20-25 miles. For hilly terrain, the limit may drop to 10-15 miles.

For the strongest signal within 20 miles of a radio transmitter, the user should position the provided 30 inch dipole antenna either horizontally or vertically along a wall or window.

http://www.hdradio.com/the_buzz.php?thebuzz=87

Wow! 20-25 miles on flat terrain and you have a choice of three FM antennas, haha! I never realized HD had such a range, all the time I was thinking ummmm.... 20-25 miles, the IBOC Alliance should use that as a selling point.

 

[Radioman100]

Quotes from Fred Pinkerton

HD Radio broadcasts require a consistent, stronger signal than analog broadcasts. Once you receive the minimum level of signal, an HD Radio broadcast sounds perfect. Below the minimum required signal le vel, the HD Radio program switches back to the analog signal. To ensure an adequate signal level, you position small FM and AM antennas for proper reception of HD Radio program streams The SoundWorks Radio 820HD provides three FM antennas and one AM antenna. The choice of which FM antenna to use depends on where you are relative to the radio transmitters.

There is a limit to how far you can be from a transmitter and still receive an HD Radio transmission. For flat land with no obstructions, this limit could be as far away as 20-25 miles. For hilly terrain, the limit may drop to 10-15 miles.

For the strongest signal within 20 miles of a radio transmitter, the user should position the provided 30 inch dipole antenna either horizontally or vertically along a wall or window.

http://www.hdradio.com/the_buzz.php?thebuzz=87

Wow! 20-25 miles on flat terrain and you have a choice of three FM antennas, haha! I never realized HD had such a range, all the time I was thinking ummmm.... 20-25 miles, the IBOC Alliance should use that as a selling point.

Yet another post from a DX fanatic that is truly clueless, from an HD Radio designer that is apparently also clueless.

No mention at all of station class or power. No mention of transmit antenna height. Though Fred of Cambridge did offer this suggestion at the beginning of his comments on HD. Funny how you missed it:

Use your ability to receive analog signals as your guide. You need to receive a strong analog signal before you can count on receiving an HD Radio compliant broadcast.

In other words, if the station you're wanting to receive in HD sounds good in analog, give it a whirl. If the station you're wanting to receive sounds bad in analog, it probably won't work.

That statement puts the others in some context, but it's still a very poorly written piece.

 

[Play Freebird]

Yet another post... from an HD Radio designer that is apparently also clueless.

'Clueless' is a harsh term, but it's apparent that the FAQ was "dumbed down" to target a casual radio user, leading to a few inaccuracies. For example, Fred Pinkerton makes this statement about analog FM:

"There are a number of limitations with conventional analog FM broadcasts. Before broadcast, an analog FM transmitter must chop off deep bass sound and high treble sound to fit the allocated FM band "slot," reducing fidelity. In addition, analog processing for broadcast compresses the dynamic range of the music. An analog FM broadcast has little difference in overall level; the "quiet" passages aren't much different than the "loud" passages."

... but then, he offers these claims:

"An FM broadcast featuring digital HD Radio technology sounds better because it:

1. Has full bandwidth bass and excellent treble sound;
2. Has much better dynamic range. It better duplicates the full "soft to loud" range of an audio CD."


Let's be honest here -- since the Serrasoid and Iron Fireman exciters were "phased out", are FM transmitters still required to 'chop off' deep bass? Excellent treble? (at a 64 k bit rate?) And is the dynamic range on HD channels that much better than the analog simulcast? Broadcasters must use similar degrees of processing -- or even a common processor, feeding both the analog and digital channels -- to minimize listener distraction when receivers blend... which helps to explain the final response to this question:

"7) How will I know when the analog to digital radio changeover occurs?

In any case, you can tell by watching the display. New text data will appear during the transition. The station call letters or adopted name will appear on the screen, additional new text data will appear, and a "signal level" icon will show "four bars" of received digital signal."


Legend has it that the "pilot light" was a major marketing factor in the early days of FM Stereo, so perhaps this is what HD Radio is really all about -- bells and whistles!

 

[Savage]

Reminds me of the days when I was blessed with programming the only AM in a three-way CHR battle in Pittsburgh against two Class B FMs. In the convenience store, I asked the clerk why she was listening to one of our FM competitors. Behind the counter was a plastic Radio Shack table radio, AM-FM mono, playing with what I would guesstimate at about 10% IMD into a single 4-inch speaker.

"It sounds better than AM," she told me.

I've always said - what we really need is a mandatory receiver standard requiring any AM radio to include a red LED tuning indicator to mimick the "stereo" light on multiband units. Presto! Instant perceived improvement by a majority of listeners!

 

[LinoNYC]

Let's be honest here -- since the Serrasoid and Iron Fireman exciters were "phased out", are FM transmitters still required to 'chop off' deep bass? Excellent treble? (at a 64 k bit rate?) And is the dynamic range on HD channels that much better than the analog simulcast? Broadcasters must use similar degrees of processing -- or even a common processor, feeding both the analog and digital channels -- to minimize listener distraction when receivers blend... which helps to explain the final response to this question:

"7) How will I know when the analog to digital radio changeover occurs?

In any case, you can tell by watching the display. New text data will appear during the transition. The station call letters or adopted name will appear on the screen, additional new text data will appear, and a "signal level" icon will show "four bars" of received digital signal."


Legend has it that the "pilot light" was a major marketing factor in the early days of FM Stereo, so perhaps this is what HD Radio is really all about -- bells and whistles!

In the spirit of the season, let's gently nudge this back to facts.

(at a 64 k bit rate?) The FM iboc sub can be as high as 96K if not subdivded.

Broadcasters must use similar degrees of processing -- or even a common processor

There is no "must" here, pop music stations do tend to use similar processing for analog/iboc, but not classical stations. The AM's show the most marked difference when they trasnsition.

How will I know when the analog to digital radio changeover occurs?

For AM: Noise is eliminated, apparent frequency response is dramatically wider and lacks the distortion often common in AM.

For FM:Noise and multipath distortion are eliminated, separation widens and frequency response is noticeably wider and cleaner. The latter two points are more a consequence of the brutal clipping used with analog to squeeze every DB out of the carrier. For a well processed Classical FM the only real difference between analog an iboc are the noise and multipath issues.

" so perhaps this is what HD Radio is really all about -- bells and whistles!

No, there are legitimate advantages to iboc. Idiot lights, not being one of them.

Lino

 

[KB1OKL]

There is a limit to how far you can be from a transmitter and still receive an HD Radio transmission. For flat land with no obstructions, this limit could be as far away as 20-25 miles. For hilly terrain, the limit may drop to 10-15 miles.

For the strongest signal within 20 miles of a radio transmitter, the user should position the provided 30 inch dipole antenna either horizontally or vertically along a wall or window.

http://www.hdradio.com/the_buzz.php?thebuzz=87

Wow! 20-25 miles on flat terrain and you have a choice of three FM antennas, haha! I never realized HD had such a range, all the time I was thinking ummmm.... 20-25 miles, the IBOC Alliance should use that as a selling point.

Yet another post from a DX fanatic that is truly clueless, from an HD Radio designer that is apparently also clueless.


[/quote]

There is only one reason I posted this: right from the horses er. mouth comes the fact that you are lucky to receive IBOC FM farther than 20-25 miles without an outside antenna. AM IBOC? Forget it it's goner, even half the advocates here know it, the other half are clueless.

 

[KB1OKL]

I've always said - what we really need is a mandatory receiver standard requiring any AM radio to include a red LED tuning indicator to mimick the "stereo" light on multiband units. Presto! Instant perceived improvement by a majority of listeners!

Yes!

 

[KB1OKL]

(at a 64 k bit rate?) The FM iboc sub can be as high as 96K if not subdivded.

I thought one of the wonderful selling points of FM iBOC was the fact that it has channels between channels? If these stations utilize these second channels it will cut the fidelity down, correct? Which way are you guys going to have it, decent fidelity or channels between channels?

For AM: Noise is eliminated, apparent frequency response is dramatically wider and lacks the distortion often common in AM.

I thought the frequency response of analog FM was supposed to be around 50-15K, how much better are you going to get especially with these tiny radios with their tinny speakers which are lucky to be able to reproduce anything below 100 hz? And by apparent, do you mean actual or apparent?

For FM:Noise and multipath distortion are eliminated, separation widens and frequency response is noticeably wider and cleaner. The latter two points are more a consequence of the brutal clipping used with analog to squeeze every DB out of the carrier. For a well processed Classical FM the only real difference between analog an iboc are the noise and multipath issues.

If multipath distortion is supposedly eliminated why have I recently read here that their is a lot of multipath distortion with FM IBOC?

" so perhaps this is what HD Radio is really all about -- bells and whistles!

No, there are legitimate advantages to iboc. Idiot lights, not being one of them.

Why does everyone brag about heir HD light going on all the time then even if they hear nothing?

Lino

 

[Radioman100]

There is only one reason I posted this: right from the horses er. mouth comes the fact that you are lucky to receive IBOC FM farther than 20-25 miles without an outside antenna. AM IBOC? Forget it it's goner, even half the advocates here know it, the other half are clueless.

And yet you failed to mention that the "horse" also said to basically use analog reception as your guide.

You're supposedly a knowledgable DXer, right? Do YOU believe station antenna height, power, class, etc. have NOTHING to do with your ability to receive the station?

If you truly believe that, I have a nice bridge in Brooklyn I'd love to sell you.

 

[SUPERCASTER]

There is only one reason I posted this: right from the horses er. mouth comes the fact that you are lucky to receive IBOC FM farther than 20-25 miles without an outside antenna. AM IBOC? Forget it it's goner, even half the advocates here know it, the other half are clueless.

And yet you failed to mention that the "horse" also said to basically use analog reception as your guide.

You're supposedly a knowledgable DXer, right? Do YOU believe station antenna height, power, class, etc. have NOTHING to do with your ability to receive the station?

If you truly believe that, I have a nice bridge in Brooklyn I'd love to sell you.

First you're peddling HD Radio and now the Brooklyn Bridge. Compared to HD Radio, the bridge is definitely the better buy.

 

[KB1OKL]

There is only one reason I posted this: right from the horses er. mouth comes the fact that you are lucky to receive IBOC FM farther than 20-25 miles without an outside antenna. AM IBOC? Forget it it's goner, even half the advocates here know it, the other half are clueless.

And yet you failed to mention that the "horse" also said to basically use analog reception as your guide.

He said that you could find a station in analog and then see if you can decode it and goes on to say that you need to live within 20-25 miles on flat terrain to receive IBOC correctly

You're supposedly a knowledgable DXer, right? Do YOU believe station antenna height, power, class, etc. have NOTHING to do with your ability to receive the station?

I believe that a lot of the power for the signal seems to go into the sidebands cutting the range of the signal short which seems to be the case with practically everyone that has owned one (actually almost everything I've read because I know no one who owns one of these to tell you the truth

If you truly believe that, I have a nice bridge in Brooklyn I'd love to sell you.

I believe the bridge will be around a lot longer than IBOC radio

 

[KB1OKL]

There is only one reason I posted this: right from the horses er. mouth comes the fact that you are lucky to receive IBOC FM farther than 20-25 miles without an outside antenna. AM IBOC? Forget it it's goner, even half the advocates here know it, the other half are clueless.

And yet you failed to mention that the "horse" also said to basically use analog reception as your guide.

"Use your ability to receive analog signals as your guide. You need to receive a strong analog signal before you can count on receiving an HD Radio compliant broadcast"., A direct quote from the text of the horse. Yes a strong signal like about 20-25 miles out, that means only very local strong signals will be decoded as has been reported over and over again by critics everywhere except for here of course where 5000 mile IBOC reception is the norm on 48.00 sangean radios that never break or if they do the thread is mysteriously deleted

You're supposedly a knowledgable DXer, right? Do YOU believe station antenna height, power, class, etc. have NOTHING to do with your ability to receive the station?

Of course I do but explain to me the lousy reception of all these radios then? Why do AM stations that boom in to certain areas only light up the gimmick HD lights on these doodads and are not heard or are heard in telephone quality sound? Why do FM stations that boom in to areas do the same thing? How much of the total power is going into the sidebands creating the lovely jamming noise that ruins adjacent channels night after night against the current insipid clueless FCC's rules of harmful interference?

If you truly believe that, I have a nice bridge in Brooklyn I'd love to sell you

I'll buy the bridge, at least it will still exist in 10 years unlike IBOC which will be in the scap pile along with 8 track machines and AM stereo receivers.

 

[Mike Walker]

Next time you're in NC, I'd LOVE to show you my consistent, 24/7/365 reception of HD from 100 miles (WMIT Black Mountain NC), 90 miles (take your pick from Greenville/Spartanburg SC), 60 miles (Winston Salem and Greensboro...multiple stations), or 40 miles (Hickory NC). I have posted recordings demonstrating as much. http://www.theproductionroom.net/hd.wma is a very old one, made with an INDOOR antenna about a year ago at my home in the foothills of northwest NC. I now get FAR BETTER reception with my outdoor antenna/rotor/preamp.

 

[GundamRadioOne]

I don't get it all the fuss about HD Radio. I have a Radiosophy "MultiStream" receiver that I borrowed from a friend of mine. I checked out the local HD Radio "content" here in Indy and I found it lacking, at least for my tastes. My favorite radio stations here in Indy are WTTS 92.3 and a high school radio station WBDG "The Giant" 90.9. Both stations are doing a fine job broadcasting in analog, but again that is just my opinion. ;D

Getting back to the Radiosophy receiver, the audio quality between the analog signal and the digital one wasn't anything to get excited about. I even connected the receiver to my stereo using the optical SPDIF output
and it still didn't make a significant improvement in sound quality. Don't get me started on the lackluster reception of this particular HD receiver. I am sure there are better HD radios out there (Sangean?), but again there isn't anything currently being broadcast here in Indy to justify buying a better HD receiver for myself. I will continue to listen to my XM, Roku and my iPod.

 

[R.F. Burns]

If you can listen to XM and be satisfied it's obvious that you don't care about audio quality. XM's best bit rate is 64 Kbps using a less accurate codec then what is being used by HD stations. Also, the fact that you have claimed that a high school radio station was one of your two favorites shows that your tastes are far outside the mainstream. I am not judging you on your choices but lets be honest here. The vast majority of listeners in the US would disagree with you about what is and what isn't quality. The FM HD audio even at 64 Kbps is far superior to the audio quality of any of the XM channels. HD doesn't require a monthly fee, is mobile which your internet radio is not yet and is more than an I-Pod. I have a 80 G I-Pod for music but there is no live element for things liike news and sports on my I-Pod.

 

[Radioman100]

If you can listen to XM and be satisfied it's obvious that you don't care about audio quality. XM's best bit rate is 64 Kbps using a less accurate codec then what is being used by HD stations. Also, the fact that you have claimed that a high school radio station was one of your two favorites shows that your tastes are far outside the mainstream. I am not judging you on your choices but lets be honest here. The vast majority of listeners in the US would disagree with you about what is and what isn't quality. The FM HD audio even at 64 Kbps is far superior to the audio quality of any of the XM channels. HD doesn't require a monthly fee, is mobile which your internet radio is not yet and is more than an I-Pod. I have a 80 G I-Pod for music but there is no live element for things liike news and sports on my I-Pod.

I don't think XM is using anything near 64k on most channels. All the channels I used to listen to when I had it sounded absolutely horrible. The only exceptions were the ones that Clear Channel owns. I'd guess their deal with XM specifies some minimum bitrate, and it's higher than most of the XM offerings.

 

[Tom Wells]

I agree most of XM's channels are less than 64 Kbps. Any one of the channels I've ever tried to listen to for content had me grating my teeth after 5 to 10 minutes. And I've listened to streaming audio at 64k that wasn't nearly as grating.
If XM wants to run such a low rate, they really ought to start rolling off their highs at 3khz so the transmission method is adequate for the information. Brickwalled 5khz AM sounds better than highly distorted artifacting from low bitrates on high-frequency info.

 

[GundamRadioOne]

I would agree that both HD radio and satrad can't even come close to "CD audio" quality. I will let others worry or obsesses over the difference in bit rates and perceived sound quality. Hey, I know what like and there is a reason that I pay $$ for XM and that would be the diversity and selection of programming. I haven't "given up" on OTA radio but I don't spend the same amount of time listening to it as once did. Being an XM subscriber is a choice that I made and stand by it. I don't knock anyone's choice in what they chose to listen to or what "electronic conveyance" they choose to listen to it with. Isn't there plenty of room in the "media sandbox" for all? ;D

//Later

Tim Wootton
Indianapolis IN USA

 

[chrish]

I have two of the Cambridge Soundworks 820HD radios and I just don't get it.
One is in my office 7 miles line of site of the majority of FM station transmitter
sites ( can look at the skyline and with the rod antenna I get 4 of the class B's
on Prudential Tower), nothing from the Newton antenna farm 12 miles away and I
am talking analog! With major effort I can get a couple in HD.
In my office I have a GE portable bought at Walgreens (something you would take to the beach with a rod antenna) On this radio I get everything from Boston and the suburbs plus several stations from Providence and Southern NH.

At Home in Southern NH I get nothing from Boston (38mile), just WCRB-FM 99.5 in Andover Ma and and very poor reception from 2 class B stations in Manchester NH,
In both cases there was a bit of improvement using the "T" antenna.

Talking to several engineers at CSW brought nothing but "RAGTIME" telling me that
this radio was not built to be as good as the $20.00 throw away GE.

Is it me ....who the hell is going to pay $300.00 (the public) for a radio that picks
up only three or four stations when their junk radio picks up 40-50

I don't see the average listener embracing this technology, this is not the 50's early days of FM where a console sat in the living room connected to a roof antenna.
The public is used to crap like walkmans and cheap radios that perform reasonably
well with no "T" or outside antenna

Look what happened when FM car radios filtered down into the cars of the average
American idiot in the 70's, there was so much whining about a little static as
the drove into the fringes that Delco, Ford and every other manufacturer came
up with the "hi blend" circuit that not only monos the audio but also takes highs and lows out of the audio that if you are more than 10 miles from the transmitter you are not hearing much stereo. AN ABSOLUTE ABOMINATION. in the 70's and 80's Delcos a call to Kokomo, Indiana would get you easy instructions on how to
defeat the circuit.
Todays radios are so sophisticated, defeating the feature is impossible.

The 8020HD if you don't count the FM section has great features and the AM is not bad at all.

My corporate people keep asking do you want to go HD on our three FM's, the studios are about to be upgraded tho digital in the next few months and most
everything else is in place. With such low HD power and such poor radios being
sold in the field I find it hard to say.. lets do it

 

[scanman1]

I agree most of XM's channels are less than 64 Kbps. Any one of the channels I've ever tried to listen to for content had me grating my teeth after 5 to 10 minutes. And I've listened to streaming audio at 64k that wasn't nearly as grating.
If XM wants to run such a low rate, they really ought to start rolling off their highs at 3khz so the transmission method is adequate for the information. Brickwalled 5khz AM sounds better than highly distorted artifacting from low bitrates on high-frequency info.

As a long time XM subscriber, I can vouch for the reduced quality in audio. Back when I first subbed (Jan. 2002), the audio was a lot better and remained so until about 2005, when all the extra channels added reduced bitrate to the existing ones (currently, Fine Tuning actually represents well what XM used to sound like in its early days).