Question (not trying to start anything)

[FrankB-town]

I want to know--
what good is AM HD when stations in many markets have the bandwidth on their FM IBOC stations to carry sister stations? AM HD sounds horrible on an analogue radio (which 99% of people still have, even if they have an HD radio, they probably only have 1 because of their outrageous price) and in my opinion is killing the AM band, however, the technology is not interfering with the analogue signal on FM.

 

[Radioman100]

I want to know--
what good is AM HD when stations in many markets have the bandwidth on their FM IBOC stations to carry sister stations? AM HD sounds horrible on an analogue radio (which 99% of people still have, even if they have an HD radio, they probably only have 1 because of their outrageous price) and in my opinion is killing the AM band, however, the technology is not interfering with the analogue signal on FM.

Very good question! The answer is I have no idea. I think HD on AM is worthless. Putting AMs on your FM HD2, HD3 channels is a much better solution if you have an FM. It makes AM programming listenable in steel framed buildings.

I have a nice office several floors up and a window. I can't pick up a 50kW AM I listen to from time to time, but I can pick up any and all HD2 channels.

 

[rbrucecarter5]

I want to know--
what good is AM HD when stations in many markets have the bandwidth on their FM IBOC stations to carry sister stations? AM HD sounds horrible on an analogue radio (which 99% of people still have, even if they have an HD radio, they probably only have 1 because of their outrageous price) and in my opinion is killing the AM band, however, the technology is not interfering with the analogue signal on FM.

It sounds pretty good - even with all the compromises to get it to fit into the AM bandwidth. The main problem - it takes a serious AM DX antenna to get a reliable lock. I live really close to a low band 5kW station that has a half million square mile footprint. In its C-Quam days, I could get static free stereo out to 290 miles. That was with a Sony SRF-A1 walkman and a Terk loop. Now that it is IBOC, I have trouble getting it to stay locked with an ultra-sensitive Sangean HDT-1X (I have already netted half a dozen transatlantic signals on AM with it). With a two foot AM box loop antenna, I can get lock on some - but not all - AM HD locals. It takes a lot of fiddling around to do it. One of the ones I was most interested in - KAAM - doesn't lock at all. A darn shame, because I got KAAM clear and static free - but with KKOB underneath - 290 miles to the west. The same setup easily pulls in regular AM, daytime, up to 300 miles. The average consumer just isn't going to be motivated to go to that much trouble to get AM IBOC. AM Hybrid mode - just wasn't ready for prime time and should NEVER have been approved.

The other disadvantage of AM HD, of course, is loud and vigorous sideband interference. The hybrid mode sidebands are much more robust than the analog signal. It was astonishing to me driving through the Western part of the country to hear sideband pairs on the AM band from stations up to a thousand miles away - when I could get no trace of their analog signal whatsoever! We are talking sideband pairs of Chicago stations in New Mexico and Arizona - DAYTIME!!!! Nothing more sophisticated than a normal stock car radio. That level of robustness has inspired me to be a strong supporter of the full digital mode, because it promises coverage that is only dreamed about now. I have done 1000 mile daytime analog AM DX - and it takes a huge loop antenna and sensitive receiver, in a noise free area with good ground conductivity. Not so the digital sidebands, they are easy to pull out on a very modest radio. Why the hybrid mode is so hard to make work, I don't know, given the robustness of those sidebands. I'd almost expect hundreds of miles of HD lock in hybrid mode, but I've never gotten a flicker on out of town HD stations - 50 kW blowtorches as close as 150 miles. But you can sure hear the sidebands absolutely obliterating everything under them! I NEVER hear a trace of WOR analog in Dallas. But - cancel the local 700, and there is WOR sideband hash under WLW. And WOR sideband hash under WGN. Absolutely NO other possible source of sideband hash - because no other 710 runs IBOC. Neither does anything on 690 or 720 that could be the source. It is WOR, because I throw a null towards NY listening to WGN, and the hash goes away. Amazing stuff!

 

[R.F. Burns]

Please forgive me but after reading that you've been able to hear Trans Atlantics using the HDT-1X (Your quote; "I have trouble getting it to stay locked with an ultra-sensitive Sangean HDT-1X (I have already netted half a dozen transatlantic signals on AM with it"). Please tell me where you are that you can hear half a dozen Trans Atlantic stations from the US today. Oh, and also please tel me, when did the Sangean start tracking 9 Khz spaced stations? They use 9 Khz spacing outside of our region and the radio only does 10 Khz steps. That and the fact that while the HDT-1X is great a capturing weak FM signals, it is less than a great AM radio. As a matter of fact on AM they aren't that much more sensitive than my properly operating HD Receptor. Due to DSP I've heard AM stations on the Receptor that I've never heard on any other radio.

 

[Mike Walker]

A friend of mine in Florida uses gets GREAT dx from up and down the east coast on his Accurian. But he's disappointed with AM HD. Not the sound, but the reception. He has decided, however, that a longwire makes a MUCH better antenna for AM HD than the tuned loops many of us use (Terk AM Advantage, SelectATenna, etc.), because tuned loops by design are narrowband, and HD requires pretty wide bandwidth. His observations, not mine, but there's a certain logic to it, I suppose!

 

[jras20]

On HD-FM I have a very hard time of HD signals keeping locked in, I dont understand. I have a clean FM stereo sound in analog, but the HD Reception sux. On AM If I have my 300' wire hooked up I could pick up WOAI HD durring the day AM-HD, but at night its pretty spotty even on WOAI. If HD is going to work, they need to give it to go as far as the stereo signal. I dont think it has a chance on AM.

 

[Radioman100]

On HD-FM I have a very hard time of HD signals keeping locked in, I dont understand. I have a clean FM stereo sound in analog, but the HD Reception sux. On AM If I have my 300' wire hooked up I could pick up WOAI HD durring the day AM-HD, but at night its pretty spotty even on WOAI. If HD is going to work, they need to give it to go as far as the stereo signal. I dont think it has a chance on AM.

Dude, you live in the boonies. Not in the burbs, the boonies, a LOOOOOONG way from the towers.

 

[jras20]

Well guess I am SOL on HD then, well at least analog comes in good.

 

[Radioman100]

Well guess I am SOL on HD then, well at least analog comes in good.

Yes, with your ginormous tower and deep fringe antennas, analog comes in good in the boonies.

 

[grantchester]

JRAS- your inability to pull an HD signal from WOAI is a puzzle. The transmitter is on the east side of San Antonio. The ground conductivity should make it come in like a local in Lavaca County, or at your place near Austin. Your hundred meter wire should give you plenty of signal.
Likewise, KTSA should come booming in.

 

[Mike Walker]

I also live 'in the boonies". I get HD Radio just fine on my outdoor antenna (installed late last summer)...at distances to 100 miles. Now HDTV (on the same antenna) is more challenging! I can get every HD Radio station in Charlotte, for instance, but there are two DTV stations I just can't get (Channel 42 NEVER comes in, Channel 18 is spotty...sometimes solid, usually not). I get EVERY HD Radio station in the Triad (Winston Salem, Greensboro, High Point). I get the DTV signal from only two stations...WXII (the NBC outlet), and channel 26, the UNC-TV outlet (WUNE, I think are their call letters). That's it. The ABC, CBS, and Fox affiliates from Greensboro and High Point are M.I.A., despite the fact that their analog counterparts come in just fine.

So let's not bash HD Radio as if this "all or nothing" is the fault of this new medium. It's the nature of digital! It doesn't degrade gracefully, and never will. IT works, or it doesn't. You "city-slickers" who are gung-ho on satellite radio should try it in a rural, mountainous area with no repeaters. It's hardly perfect!

 

[jras20]

I also live 'in the boonies". I get HD Radio just fine on my outdoor antenna (installed late last summer)...at distances to 100 miles. Now HDTV (on the same antenna) is more challenging! I can get every HD Radio station in Charlotte, for instance, but there are two DTV stations I just can't get (Channel 42 NEVER comes in, Channel 18 is spotty...sometimes solid, usually not). I get EVERY HD Radio station in the Triad (Winston Salem, Greensboro, High Point). I get the DTV signal from only two stations...WXII (the NBC outlet), and channel 26, the UNC-TV outlet (WUNE, I think are their call letters). That's it. The ABC, CBS, and Fox affiliates from Greensboro and High Point are M.I.A., despite the fact that their analog counterparts come in just fine.

So let's not bash HD Radio as if this "all or nothing" is the fault of this new medium. It's the nature of digital! It doesn't degrade gracefully, and never will. IT works, or it doesn't. You "city-slickers" who are gung-ho on satellite radio should try it in a rural, mountainous area with no repeaters. It's hardly perfect!

Your right, I had XM for a 2 months and dumped it, the only way I could get a good signal is for the antenna to be outside, I wasnt going to do that for that radio. It had a poor reception anywere. I had one place where I could get 1-2bars of power and that was right by the window if I moved it it went out!

 

[Mike Walker]

Now I'm NOT saying I've got poor reception of XM here "in the boonies". Don't read it that way. I'm saying it either works, or it doesn't (like any other digital transmission system), and without repeaters, there are places (where mountains and trees block line-of-sight to any satellite) where it just doesn't work. Having said that, I'm sometimes amazed at where it (XM) DOES work! A winding mountain pass, on the "backroads" between West Jefferson and Boone, NC. There are several stretches where YOU CAN'T SEE THE SKY (because of mountains on both sides, and tall trees), but XM MOSTLY works (sometimes you'll lose it for just a few seconds). Impressive, really!

 

[rbrucecarter5]

Please forgive me but after reading that you've been able to hear Trans Atlantics using the HDT-1X (Your quote; "I have trouble getting it to stay locked with an ultra-sensitive Sangean HDT-1X (I have already netted half a dozen transatlantic signals on AM with it"). Please tell me where you are that you can hear half a dozen Trans Atlantic stations from the US today. Oh, and also please tel me, when did the Sangean start tracking 9 Khz spaced stations? They use 9 Khz spacing outside of our region and the radio only does 10 Khz steps. That and the fact that while the HDT-1X is great a capturing weak FM signals, it is less than a great AM radio. As a matter of fact on AM they aren't that much more sensitive than my properly operating HD Receptor. Due to DSP I've heard AM stations on the Receptor that I've never heard on any other radio.

I should have clarified - I've gotten the usual hets, indicating TA's are there. I've only heard TA analog on 531, a few days ago there was a terrific inversion and just about every radio in the house could hear Algeria over Cuba and T&C. That hasn't repeated. It was amazing while it lasted, though.

The fact I had to add a two foot loop just to decode local HD might have something to do with the amazing DX. With the supplied loop, it is OK, but nothing to brag about.

 

[rbrucecarter5]

A friend of mine in Florida uses gets GREAT dx from up and down the east coast on his Accurian. But he's disappointed with AM HD. Not the sound, but the reception. He has decided, however, that a longwire makes a MUCH better antenna for AM HD than the tuned loops many of us use (Terk AM Advantage, SelectATenna, etc.), because tuned loops by design are narrowband, and HD requires pretty wide bandwidth. His observations, not mine, but there's a certain logic to it, I suppose!

A box loop has to be made out of litz wire or something pretty hefty in guage to have that high of a Q. If it is a problem, put a 100k pot in parallel with the loop to adjust the Q at the expense of gain.

 

[rbrucecarter5]

I also live 'in the boonies". I get HD Radio just fine on my outdoor antenna (installed late last summer)...at distances to 100 miles. Now HDTV (on the same antenna) is more challenging! I can get every HD

I'll try to stretch that to 120 or more - there are a couple of nearby cities like Tyler and Waco that might have HD stations.

You are right about the all or nothing nature of the signal. I want to see how it handles routine fades that kick in at these distances, given its buffer of a few seconds of audio. It might just have some robustness.

What is troublesome is the lack of HD reception with normal, built in antennas or dipoles you find in the suburbs. FM stereo works fine out there with almost no antennas. But HD is not good at 35 plus miles with receivers installed the way most people install and use them. And they are not prone to fiddling much with antennas. Unfortunately, affluent suburbs where desirable listener demographics are located are many more than 35 miles away in a large number of metro areas. I don't think more sideband power is going to help unless it is an exponential increase, and there are documented self jamming scenarios at the present power levels. This many, indeed, be an inner city - or at least near the tower - solution. That, or DX.

 

[jras20]

XM I know did catch a better signal than HD is now, but the SQ was horrible on XM.