Not being involved directly in broadcasting, and admittingly not knowing the technical aspects, it seems most of the negative aspects with HD posted on this board, has to do with interference concerns on the AM band. If the AM HD idea was abandoned, and just FM HD were utilized, would this change any opinions? It seems if HD2 channels were to get more power & bring more diversity, it would be a plus to radio listening. I don't know what kind of ramifications if any, it would have on the current FM signals etc., but am just curious. Do FM channels suffer from a different type of adjacent channel interference when HD is utilized? John E B
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FM HD Question
- Thread starter johneb2johneb2
- Start date
R
rbrucecarter5
Guest
johneb2johneb2 said:
Let me tackle this one. FM IBOC, like AM IBOC utilizes portions of adjacent channels to encode the digital information. Like AM, the power levels on the adjacent frequencies are very much lower than those for analog. FM IBOC can and does jam adjacent frequencies. Much of the criticism of IBOC has come from DX'ers, who are used to hearing those adjacent frequencies - and therefore their choices are lost when a nearby station fires up IBOC.
As to the degree of the problem, it has come to light that properly aligned AM radios will reject more of the sideband hiss than improperly aligned ones, and those that utilize product detection (all of the former AM stereo models) should be immune to IBOC self jamming. On AM, first and second adjacent frequencies are affected. On FM, only a portion of the first adjacent frequency is affected - but if it held a previously listenable station, that station is still effectively jammed. First adjacent listening scenarios are much more common in the densly packed metro areas of the East than they are in the West. Complicating the situation even more is a brand new adaptive IF technology that allows first adjacents - even near strong local signals - to be heard without interference. Unless, of course, the local station broadcasts IBOC.
The AM system is sort of piggybacked with FM - nobody expects people will buy IBOC radios just for AM reception. The "killer application" is the HD-2 and 3 channels - but excitement may fade quickly if those become subscription based services. Subscription based technology was recently demonstrated - that if adopted by FM stations would inevitably drive people to satellite radio where they would get hundreds of channels instead of one channel. Only the most fanatical adherents to a niche format would pay for the HD-2 channels.
My objection, as a DX'er, is that it limits my listening choices to local stations. I base my objections, too, on a principle of law that states my freedom ends where my neighbor's nose begins. In other words I don't punch my neighbor in the face, I let him alone. IBOC allows big city stations, many of them monoaural news stations, to jam neighboring frequencies just so their talk will sound crisper - but ONLY on expensive HD radios. In so doing, especially at night, they are disenfranchising millions of rural listeners from their only source of free news and information. Many areas of the country are without a single local radio station, and impoverished residents depend on nighttime skywave reception. Most have no clue it will be ended on September 14th - due to corporate greed. I have absolutely no objections to a digital radio service - in fact I would welcome one that does NOT jam adjacent frequencies in any way. What a broadcaster does within their allotted channel is the broadcaster's business. But stomping on a neighboring frequency is unacceptable infringement of the rights of broadcasters on that frequency.
I better stop before I get on my soapbox.
johneb2johneb2 said:
I too will answer this. The AM system is a lot more controversial than the FM one. Despite some counter claims, even the most hard core opposition is having trouble creating issues on FM. The fact is, it basically works in a station's authorized service area. there are some people who like to listen to stations OUTSIDE of this area. This is where almost ALL of the FM complaints come from. Rbruce has stated that as a DXer, his concerns are founded to a great degree on his listening OUTSIDE of that area. That doesn't make him a bad guy. He just works a little harder to get an additional choice via distant listening on his radio. Some would contend that more "local" stations via HD could give the same result in terms of number of choices.
Rbruce also states his concerns about people who do not have "Local radio" in very rural areas. athis is a valid concern. However these areas as a whole have no DAYTIME service either. If they DO have daytime service and their only local station is a daytimer, then they COULD be caought in a tough spot. However, over the years, the vast majority of these Daytimers in the sticks have migrated to FM. The subset of people who "Lose" their radio service because of no skywave listening is very small, IMHO. The AM band has ended the MAJORITY of skywave listening by adding more and more nighttime service on the former clear channels. Stations like 890 KVOZ Laredo does NOT run HD. Where's the outrage about their JAMMING 890 WLS in Chicago? 700 KSEV Houston does not run HD. Where the outrage over their "JAMMING" 700 WLW In Cincinatti? The list of these extends to EVERY FREQUENCY on AM I think. The "White Area Service" arguement is ring fairly hollw these days.
I also believe that the enhancement of choice on FM has NOTHING to do with the ever popular "Corporate Greed".
As for your question of whether it would change any opinions if only FM were utilized, I don't know.
Rbruce has done a fairly good job of describing AM performance. While his description is riddled with the "Jamming" silliness it is basically accurate. I have never experienced this "2nd Adajcent" interference on AM. I say experienced as in my crappy car radio circa 1993 does not get 2nd adjacent digital noise on 50KW WOAI in San Antonio once I am clear of the blanketing area, (A few hundred yards)nor have I seen it on a Spectrum Analyzer to any degree. YMMV.
You talk about additional choices and more diversity. You are correct. It IS a good thing for radio. Not so much the diversity (Since you get FORMAT diversity, not OWNERSHIP diversity) but for the choices. There is a feeding frenzy because there is a subscription capbility in HD radio. There is NOT anyone using it in the US, AFAIK.
The FM "Interference" you hear about here is almost wiithout exception on a frequency that is regarded as too weak to be reliably received, according to the FCC.
Obviously this issue has sparked a number of serious dissenters. This forum is definitly a gathering point for those Dissenters.
Somewhere, most likely in between, is the true reality. And as I have posted before, we are about to see what happens at night with HD on AM.
Those who worked on the system have demonstrated to the FCC that this will not be a big problem. Did the FCC buy a bill of goods? Who knows. According to many, the end of the world is coming next month.
We'll see. And so will you. It MAY be good or it may be very bad. Either way,. you'll be a witness.
Clouseau
johneb2johneb2 said:
FM receivers can reject the adjacent-channel noise of the digital carriers better than AM receivers, thanks to FM's "capture" effect, which causes a desired signal to overtake a weaker undesired signal, even if the ratio is only 2 to 3 dB. See:
http://en.wikipedia.org/wiki/Capture_effect
Unlike AM signals in the medium-wave band, propagation of FM signals in the 88-108 MHz VHF band generally stays consistent from day to night. Although "E-skip" sometimes is observed in the FM band during summer months, it's not an everynight problem.
The FM IBOC system also seems to be more robust and has greater ability to reject lightning crashes and powerline buzz, because less energy from these noise sources is generated in the VHF band than at MW.
Thank you
Thank you everyone for your clarifications. While I have the Radiosphy HD100 radio, and like it, for the additional programming on FM, but I must admit I would most likely abandon it if they went to subscription services. Oh well, we will see. Thanks again everyone for the input. John E B
Thank you everyone for your clarifications. While I have the Radiosphy HD100 radio, and like it, for the additional programming on FM, but I must admit I would most likely abandon it if they went to subscription services. Oh well, we will see. Thanks again everyone for the input. John E B
R
Radioman100
Guest
Re: Thank you
I really don't see much happening in the way of subscription services. I haven't heard much, but most of the conversation I've heard about it centers on blue programming that would likely get you fined on an open channel. Think Howard Stern and Opie and Anthony types without censorship.
In that scenario the subscriptions would probably be offered for free with some sort of age verification. A channel that offers the censored, broadcast version of O&A in the morning might offer an HD2 channel with replays of their uncensored XM show all day.
I can also see subscription channels being used for comedy. Much of the best stand-up material is too raunchy for radio. As far as I'm concerned, the uncensored comedy channel is the only reason to get XM.
johneb2johneb2 said:
I really don't see much happening in the way of subscription services. I haven't heard much, but most of the conversation I've heard about it centers on blue programming that would likely get you fined on an open channel. Think Howard Stern and Opie and Anthony types without censorship.
In that scenario the subscriptions would probably be offered for free with some sort of age verification. A channel that offers the censored, broadcast version of O&A in the morning might offer an HD2 channel with replays of their uncensored XM show all day.
I can also see subscription channels being used for comedy. Much of the best stand-up material is too raunchy for radio. As far as I'm concerned, the uncensored comedy channel is the only reason to get XM.
One of the more practical applications for a subscription comes from the Public Radio arena. For members who have paid their subscription, they could be given the ability to listen to regular programming on an HD-2 channel, while the rest of the freeloaders would have to endure pledge breaks on the normal free channels.
It's a model that could be fairly popular among NPR/PRI listeners, or for those people who want special formats like Classical or Jazz that are hard to sustain through ordinary means.
It's a model that could be fairly popular among NPR/PRI listeners, or for those people who want special formats like Classical or Jazz that are hard to sustain through ordinary means.
Some people say they haven't heard or can't tell if FM inter-station noise is iBOC noise or not.
It is very easy to identify by pitch.
Sing or hum in the "standard" key..
Happy Birthday to you,
Happy Birthday to you,
Happy Biiiirrrthh.... < this drawn out and held note is the pitch of iBOC FM noise.
If the iBOC implementation were FM only I'd be somewhat annoyed, but find the FM version more in keeping
with the nature and implementation of FM broadcast with "line-of-sight" coverage.
I feel the FM is a worthwhile tradeoff, because my FM dial is cram-packed in Chicago, but others who rely on distant FMs will suffer.
It is very easy to identify by pitch.
Sing or hum in the "standard" key..
Happy Birthday to you,
Happy Birthday to you,
Happy Biiiirrrthh.... < this drawn out and held note is the pitch of iBOC FM noise.
If the iBOC implementation were FM only I'd be somewhat annoyed, but find the FM version more in keeping
with the nature and implementation of FM broadcast with "line-of-sight" coverage.
I feel the FM is a worthwhile tradeoff, because my FM dial is cram-packed in Chicago, but others who rely on distant FMs will suffer.
M
MotoMuzak
Guest
Thing about subscription services is the encryption they use *will* be cracked eventually, allowing the listener to obtain free broadcasts from an otherwise pay channel.
So, Chuck, I could be listening to the uninterrupted programming on NPR's secondary channel while all the rest of us "freeloaders" have to listen to all the pledge breaks on the main channel, and I wouldn't even be paying a penny.
See, the thing about one-way physical access points (like any radio or TV set receiving an over the air broadcast, or even cable-ready TV sets and VCRs) is they are universally insecure. Cracks, hacks, workarounds--whatever you want to call them--will be developed and unless word gets out via the Internet, issues of 2600, or wherever else, no-one will be the wiser.
Scrambled UHF TV channels over the air were tried in the 1980s for a period and ultimately failed. Reportedly we used to have one such channel--KECH-22--which would broadcast several hours of "questionable" programming late at night, scrambled. The user would deposit a coin in the box to activate it. I really have no idea if anyone developed a workaround to that system or not, but it's most likely that someone might have ;D ........
(Historic note: after KECH-22 ended in the mid-1980s it was re-branded as "KBSP TV22-In Your Interest" and was a Home Shopping Club [not Network, FYI] channel for many years before becoming a PAX and now Ion affiliate.)
Even SCA was considered by many people to be a "subscription-only" service for decades prior to the 80s. (And what's really surprising is that there are people today who think it still is! ;o) However, demodulators were made to add on to existing radios, effectively defeating its claimed purpose.
Cable TV descramblers were produced for some time, enabling the user to receive premium channels and at times, PPV movies for completely free. From what I understand some people have even done the same with analogue and digital satellite signals.
What's unfortunate about any broadcast protection (scrambling) system is for many hackers, the vulnerabilities and mathematical keys the systems use can be very trivial to exploit and spoof. The real question it seems that the people who develop these systems seem to miss is not "Will this scrambling/encrypting/encoding etc. system be cracked?" but rather "WHEN will this system be cracked?"
Needless to say, as much hatin' as I have done on IBAC in the past, I do admit I would like to be one of the first kids on my block to own and operate one of the "cracked" radios, should subscription services actually become commonplace. Over the air broadcasts pretty much have always technically been free (rightfully so) and I intend to keep it that way, even if I am but one man doing it. Think of it as a protest and/or political act of sorts.
So, Chuck, I could be listening to the uninterrupted programming on NPR's secondary channel while all the rest of us "freeloaders" have to listen to all the pledge breaks on the main channel, and I wouldn't even be paying a penny.
See, the thing about one-way physical access points (like any radio or TV set receiving an over the air broadcast, or even cable-ready TV sets and VCRs) is they are universally insecure. Cracks, hacks, workarounds--whatever you want to call them--will be developed and unless word gets out via the Internet, issues of 2600, or wherever else, no-one will be the wiser.
Scrambled UHF TV channels over the air were tried in the 1980s for a period and ultimately failed. Reportedly we used to have one such channel--KECH-22--which would broadcast several hours of "questionable" programming late at night, scrambled. The user would deposit a coin in the box to activate it. I really have no idea if anyone developed a workaround to that system or not, but it's most likely that someone might have ;D ........
(Historic note: after KECH-22 ended in the mid-1980s it was re-branded as "KBSP TV22-In Your Interest" and was a Home Shopping Club [not Network, FYI] channel for many years before becoming a PAX and now Ion affiliate.)
Even SCA was considered by many people to be a "subscription-only" service for decades prior to the 80s. (And what's really surprising is that there are people today who think it still is! ;o) However, demodulators were made to add on to existing radios, effectively defeating its claimed purpose.
Cable TV descramblers were produced for some time, enabling the user to receive premium channels and at times, PPV movies for completely free. From what I understand some people have even done the same with analogue and digital satellite signals.
What's unfortunate about any broadcast protection (scrambling) system is for many hackers, the vulnerabilities and mathematical keys the systems use can be very trivial to exploit and spoof. The real question it seems that the people who develop these systems seem to miss is not "Will this scrambling/encrypting/encoding etc. system be cracked?" but rather "WHEN will this system be cracked?"
Needless to say, as much hatin' as I have done on IBAC in the past, I do admit I would like to be one of the first kids on my block to own and operate one of the "cracked" radios, should subscription services actually become commonplace. Over the air broadcasts pretty much have always technically been free (rightfully so) and I intend to keep it that way, even if I am but one man doing it. Think of it as a protest and/or political act of sorts.
MotoMuzak said:
I suspect that your are right. I was trying to point out a possible benefit, obscure though it may be. I was leaving it up to someone else to state the obvious about encryption.
If you have me confused with an HD Cheerleader, I'm sorry. I'm not. I'm just a guy trying to figure out how to make lemonade when given a basket full of lemons. Most NPR listeners won't bother to go on the web and look for hacks. Sure, a few will, but not that many. That's what the stations on the left side of your dial are counting on. I wouldn’t rule out the possibility that they could be disappointed.
I was a subscriber to ON TV via KECH. I didn't insert any coins. I had an antenna on my roof that fed a converter box that switched channel 22 to channel 4 and it came right into my TV just like any other station. That's the way it was set up to work. I wouldn't say the concept failed. It worked very well until an area was offered real cable. As soon as that happened, it was unlikely that someone would pay $24.95 for half a day's programming on only 1 channel when the alternative was much more attractive.
I think everyone might have missed the most useful driver for "scrambled" HD2 and HD3 channels. It's the reading services for the blind that currently reside on the subcarrier channels of some stations. It has to be inaccessable to the general public for copyright reasons to protect the original source of the material. It's legal to read it to the blind, but not the general public. If someone cracks that.. oh well.. We tried to keep it scrambled so no biggie. The nice thing about using an HD channel instead of a normal subcarrier is that it doesn't take away from modulation or add additional audible noise to the main carrier. The audio quality and noise floor is much nicer for the reading service, of course.
OKCRadioGuy said:I think everyone might have missed the most useful driver for "scrambled" HD2 and HD3 channels. It's the reading services for the blind that currently reside on the subcarrier channels of some stations. It has to be inaccessable to the general public for copyright reasons to protect the original source of the material. It's legal to read it to the blind, but not the general public. If someone cracks that.. oh well.. We tried to keep it scrambled so no biggie. The nice thing about using an HD channel instead of a normal subcarrier is that it doesn't take away from modulation or add additional audible noise to the main carrier. The audio quality and noise floor is much nicer for the reading service, of course.
Why not just keep the reading services on SCA just make them digital, even add open (public) digital streams and ditch HD radio entirely?
Use FMeXtra:
http://www.dreinc.com/company/pr/conditional.html
http://www.dreinc.com/company/pr/3_1-05.html
M
MotoMuzak
Guest
Oooooh-kaaayy....*laughs*......thanks for the commercial, Supercaster.................
I wouldn't *entirely* go as far to say radio reading service are intended to be "hidden", tho. Some broadcast via the SAP channels of TV stations and are readily listenable to pretty much anyone with a TV set and BTSC tuner. (And who DOESN'T have one of those sets nowdays I want to know ;D ) Oregon Public Broadcasting's "Golden Hours" RRS (in fact, my personal favourite) is one of them. They are available on SAP, and also on the Net (for free, even, at least late time I listened online) IBAC and to some extent, sporadically on one of OPB's digital TV channels' audio sub-channels. It advertises itself as being quote "specifically for the use of the disabled, blind and senior citizens throughout the state of Oregon" but just the amount of delivery it seems to have, to me, indicates otherwise. It seems to counterdict its spot announcements simply by the amount of delivery it has; as it is targeting itself at the general public's consumption.
To my knowledge the GHRRS on OPB's IBAC channel (currently over H.D. 3) is completely unscrambled and is free for anyone to listen to.
I don't deny, however, that the RRS' on SCA are in fact hidden, and that some of the services' personnel and volunteers may have some reservations of the public deliberately listening.
(However, this could go another way as well--several months ago I had to send a talking book tape deck back to Washington Talking Book & Braille Library; with it being my boss' mother's tape deck, and her mother being elderly, my boss wanted me to send it back because her mother couldn't figure out how to use it, and as such didn't want it any longer. Ergo, I got on the phone to WTBBL and gave me instructions on how to send it back. I also mentioned how I listen to their reading service when I am travelling in eastern Oregon/Washington via KPBX in Spokane, WA and asked how I could send them a financial donation. [ERRS, like NPR stations, is completely publically-funded.] Nevertheless, when I mentioned I listen they seemed very thrilled--almost ecstatic it seemed--and were pleased with the fact that I was enjoying the programming. I could almost imagine how even more thrilled they mighta been when they saw a $500 money order arrive a month later!!)
Semoochie, thank you for the clarification. A neighbour of mine years ago used to have a KECH-22 box and for some reason when I wrote my post I had envisioned it as having a coin I/O of sorts. Of course, it's been about 17 years since I last saw the thing!! ;o)
"I wouldn't say the concept failed. It worked very well until an area was offered real cable. As soon as that happened, it was unlikely that someone would pay $24.95 for half a day's programming on only 1 channel when the alternative was much more attractive."
Actually, that was the failure I was alluding to. When cable really caught on it practically choked the OTA system (like 22 had) to death. That's why, with likely the exception of satellite, you rarely (if even at all) see scrambled TV channels over the air today!
Basically what it all boils down to is this: I don't mind, really, if stations like IBAC's decide to scramble their signals. It gives tinkerers and children of engineers (like myself) who practically have hacking in their blood, something to do!! ;o)
In the real world I'm kinda curious as to how much money is usually spent developing and deploying these systems (i.e. Macrovision, Digicipher, CSS, Nagravision etc etc...) per year, industry-wide, only to have them rendered as ineffective not too long after deployment because cracks are developed. 'Twould truly put it in perspective............
Hopefully the industry has their eyes open. I would doubt that tho, because with recent developments in scrambling tech, it appears the industry continually turns blind eyes and deaf ears to the fact their previous attempts at encryption have but all been foiled. And yet new encryption systems keep being developed keeping fellow hacker brothers on our toes. Noblesse oblige.
I wouldn't *entirely* go as far to say radio reading service are intended to be "hidden", tho. Some broadcast via the SAP channels of TV stations and are readily listenable to pretty much anyone with a TV set and BTSC tuner. (And who DOESN'T have one of those sets nowdays I want to know ;D ) Oregon Public Broadcasting's "Golden Hours" RRS (in fact, my personal favourite) is one of them. They are available on SAP, and also on the Net (for free, even, at least late time I listened online) IBAC and to some extent, sporadically on one of OPB's digital TV channels' audio sub-channels. It advertises itself as being quote "specifically for the use of the disabled, blind and senior citizens throughout the state of Oregon" but just the amount of delivery it seems to have, to me, indicates otherwise. It seems to counterdict its spot announcements simply by the amount of delivery it has; as it is targeting itself at the general public's consumption.
To my knowledge the GHRRS on OPB's IBAC channel (currently over H.D. 3) is completely unscrambled and is free for anyone to listen to.
I don't deny, however, that the RRS' on SCA are in fact hidden, and that some of the services' personnel and volunteers may have some reservations of the public deliberately listening.
(However, this could go another way as well--several months ago I had to send a talking book tape deck back to Washington Talking Book & Braille Library; with it being my boss' mother's tape deck, and her mother being elderly, my boss wanted me to send it back because her mother couldn't figure out how to use it, and as such didn't want it any longer. Ergo, I got on the phone to WTBBL and gave me instructions on how to send it back. I also mentioned how I listen to their reading service when I am travelling in eastern Oregon/Washington via KPBX in Spokane, WA and asked how I could send them a financial donation. [ERRS, like NPR stations, is completely publically-funded.] Nevertheless, when I mentioned I listen they seemed very thrilled--almost ecstatic it seemed--and were pleased with the fact that I was enjoying the programming. I could almost imagine how even more thrilled they mighta been when they saw a $500 money order arrive a month later!!)
Semoochie, thank you for the clarification. A neighbour of mine years ago used to have a KECH-22 box and for some reason when I wrote my post I had envisioned it as having a coin I/O of sorts. Of course, it's been about 17 years since I last saw the thing!! ;o)
"I wouldn't say the concept failed. It worked very well until an area was offered real cable. As soon as that happened, it was unlikely that someone would pay $24.95 for half a day's programming on only 1 channel when the alternative was much more attractive."
Actually, that was the failure I was alluding to. When cable really caught on it practically choked the OTA system (like 22 had) to death. That's why, with likely the exception of satellite, you rarely (if even at all) see scrambled TV channels over the air today!
Basically what it all boils down to is this: I don't mind, really, if stations like IBAC's decide to scramble their signals. It gives tinkerers and children of engineers (like myself) who practically have hacking in their blood, something to do!! ;o)
In the real world I'm kinda curious as to how much money is usually spent developing and deploying these systems (i.e. Macrovision, Digicipher, CSS, Nagravision etc etc...) per year, industry-wide, only to have them rendered as ineffective not too long after deployment because cracks are developed. 'Twould truly put it in perspective............
Hopefully the industry has their eyes open. I would doubt that tho, because with recent developments in scrambling tech, it appears the industry continually turns blind eyes and deaf ears to the fact their previous attempts at encryption have but all been foiled. And yet new encryption systems keep being developed keeping fellow hacker brothers on our toes. Noblesse oblige.
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