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FM HD Quality
- Thread starter trusty
- Start date
> Pardon me for an elementary question here, but just HOW does
> HD (IBOC?) IMPROVE the quality of an FM station?
>
>
> Or, are stations just trying to get more signals (read $$$)
> on their frequency?
You just answered your own question here.
> Thanx for the input.
You are indeed welcome!
Powell
<P ID="signature">______________
NNNN</P>
> HD (IBOC?) IMPROVE the quality of an FM station?
>
>
> Or, are stations just trying to get more signals (read $$$)
> on their frequency?
You just answered your own question here.
> Thanx for the input.
You are indeed welcome!
Powell
<P ID="signature">______________
NNNN</P>
K
k9ez
Guest
> Pardon me for an elementary question here, but just HOW does
> HD (IBOC?) IMPROVE the quality of an FM station?
>
The digital CODECS allow for great dynamic range (lower noise floor), but more importantly, higher frequency range. In analog, you need to roll off before the 19kHz pilot to protect it. When you hear HD Radio, you can hear a difference. When you go back to analog, it is like someone threw a towel over the speakers. Also there is no more picket fencing when traveling around buildings.
>
> Or, are stations just trying to get more signals (read $$$)
> on their frequency?
>
Well of course. Why not? If you could get more bang for your buick, wouldnt you?
> Thanx for the input.
>
> HD (IBOC?) IMPROVE the quality of an FM station?
>
The digital CODECS allow for great dynamic range (lower noise floor), but more importantly, higher frequency range. In analog, you need to roll off before the 19kHz pilot to protect it. When you hear HD Radio, you can hear a difference. When you go back to analog, it is like someone threw a towel over the speakers. Also there is no more picket fencing when traveling around buildings.
>
> Or, are stations just trying to get more signals (read $$$)
> on their frequency?
>
Well of course. Why not? If you could get more bang for your buick, wouldnt you?
> Thanx for the input.
>
R
rbrucecarter
Guest
> The digital CODECS allow for great dynamic range (lower
> noise floor), but more importantly, higher frequency range.
> In analog, you need to roll off before the 19kHz pilot to
> protect it. When you hear HD Radio, you can hear a
> difference. When you go back to analog, it is like someone
> threw a towel over the speakers. Also there is no more
> picket fencing when traveling around buildings.
Now that there is the potential for this quality, I see that surround and multi-casting are being touted as the real killer apps that will persuade people to buy HD radios. But - you sacrifice bit rate for extra audio channels, so the quality of the main program material will suffer to accomodate the extra channels. Fascinating study in RW engineering extra.
As for picket fencing around buildings, it is seldom an issue for the 99% of the population that doesn't live in major metro downtown areas. And in the fringes it is more a function of the moire pattern of coverage introduced by multiple antenna bays than it is anything else - I doubt HD will do anything to help that scenario, because the signal levels will have long since degraded to the point that HD reception is no longer possible. The only possible strategy to help in that scenario only works for lower power stations - crank the transmitter power and electric bill and use a single bay. I've heard a station that did that - the signal didn't picket fence at all in the fringes.
> noise floor), but more importantly, higher frequency range.
> In analog, you need to roll off before the 19kHz pilot to
> protect it. When you hear HD Radio, you can hear a
> difference. When you go back to analog, it is like someone
> threw a towel over the speakers. Also there is no more
> picket fencing when traveling around buildings.
Now that there is the potential for this quality, I see that surround and multi-casting are being touted as the real killer apps that will persuade people to buy HD radios. But - you sacrifice bit rate for extra audio channels, so the quality of the main program material will suffer to accomodate the extra channels. Fascinating study in RW engineering extra.
As for picket fencing around buildings, it is seldom an issue for the 99% of the population that doesn't live in major metro downtown areas. And in the fringes it is more a function of the moire pattern of coverage introduced by multiple antenna bays than it is anything else - I doubt HD will do anything to help that scenario, because the signal levels will have long since degraded to the point that HD reception is no longer possible. The only possible strategy to help in that scenario only works for lower power stations - crank the transmitter power and electric bill and use a single bay. I've heard a station that did that - the signal didn't picket fence at all in the fringes.
K
k9ez
Guest
> > The digital CODECS allow for great dynamic range (lower
> > noise floor), but more importantly, higher frequency
> range.
> > In analog, you need to roll off before the 19kHz pilot to
> > protect it. When you hear HD Radio, you can hear a
> > difference. When you go back to analog, it is like
> someone
> > threw a towel over the speakers. Also there is no more
> > picket fencing when traveling around buildings.
>
> Now that there is the potential for this quality, I see that
> surround and multi-casting are being touted as the real
> killer apps that will persuade people to buy HD radios. But
> - you sacrifice bit rate for extra audio channels, so the
> quality of the main program material will suffer to
> accomodate the extra channels. Fascinating study in RW
> engineering extra.
>
> As for picket fencing around buildings, it is seldom an
> issue for the 99% of the population that doesn't live in
> major metro downtown areas. And in the fringes it is more a
> function of the moire pattern of coverage introduced by
> multiple antenna bays than it is anything else - I doubt HD
> will do anything to help that scenario, because the signal
> levels will have long since degraded to the point that HD
> reception is no longer possible. The only possible strategy
> to help in that scenario only works for lower power stations
> - crank the transmitter power and electric bill and use a
> single bay. I've heard a station that did that - the signal
> didn't picket fence at all in the fringes.
>
It is correct that you do lower the bit rate when adding channels. I have listened to an HD-1 signal while the station was running all three channels. It sounds a tad more compressed but surprising good. The nice thing is that the high end is still there. I took another engineer with me to listen to the HD-1 signal and he was surprised as well.
Your normal listener will really not notice the compression, it is still quite pleasing to the ear.
You are correct about the picket fencing. One hting I noticed though, is the total lack of noise on an HD signal. You dont realize how much noise is on an analog signal until you listen to an HD signal.
All this coming from a guy that really didnt support IBOC. I am just trying to give you an honest opinion.
> > noise floor), but more importantly, higher frequency
> range.
> > In analog, you need to roll off before the 19kHz pilot to
> > protect it. When you hear HD Radio, you can hear a
> > difference. When you go back to analog, it is like
> someone
> > threw a towel over the speakers. Also there is no more
> > picket fencing when traveling around buildings.
>
> Now that there is the potential for this quality, I see that
> surround and multi-casting are being touted as the real
> killer apps that will persuade people to buy HD radios. But
> - you sacrifice bit rate for extra audio channels, so the
> quality of the main program material will suffer to
> accomodate the extra channels. Fascinating study in RW
> engineering extra.
>
> As for picket fencing around buildings, it is seldom an
> issue for the 99% of the population that doesn't live in
> major metro downtown areas. And in the fringes it is more a
> function of the moire pattern of coverage introduced by
> multiple antenna bays than it is anything else - I doubt HD
> will do anything to help that scenario, because the signal
> levels will have long since degraded to the point that HD
> reception is no longer possible. The only possible strategy
> to help in that scenario only works for lower power stations
> - crank the transmitter power and electric bill and use a
> single bay. I've heard a station that did that - the signal
> didn't picket fence at all in the fringes.
>
It is correct that you do lower the bit rate when adding channels. I have listened to an HD-1 signal while the station was running all three channels. It sounds a tad more compressed but surprising good. The nice thing is that the high end is still there. I took another engineer with me to listen to the HD-1 signal and he was surprised as well.
Your normal listener will really not notice the compression, it is still quite pleasing to the ear.
You are correct about the picket fencing. One hting I noticed though, is the total lack of noise on an HD signal. You dont realize how much noise is on an analog signal until you listen to an HD signal.
All this coming from a guy that really didnt support IBOC. I am just trying to give you an honest opinion.
>
> As for picket fencing around buildings, it is seldom an
> issue for the 99% of the population that doesn't live in
> major metro downtown areas.
Bruce,
In cities near mountain ranges I have visited such as Salt Lake City, Denver, Gatlinburg TN, and Huntinton WV, multipart distortion and picket fencing are major annoyances on the FM band. I cities with no nearby mountain ranges, if you travel slightly beyond the line of sight, the signal will be weak but still fairly clean. However, in cities adjacient to mountains, as soon as you leave the line of sight, the distortion and picketing are horrible - although the signal may still be strong. This is especially true while driving. For instance, in Salt Lake City, most of the FM antennas are located in the Oquirre (not sure of the spelling)Mountains southwest of the city. But if you can't see the mountains, the signal will be distorted but still easily receivable on any radio.
> As for picket fencing around buildings, it is seldom an
> issue for the 99% of the population that doesn't live in
> major metro downtown areas.
Bruce,
In cities near mountain ranges I have visited such as Salt Lake City, Denver, Gatlinburg TN, and Huntinton WV, multipart distortion and picket fencing are major annoyances on the FM band. I cities with no nearby mountain ranges, if you travel slightly beyond the line of sight, the signal will be weak but still fairly clean. However, in cities adjacient to mountains, as soon as you leave the line of sight, the distortion and picketing are horrible - although the signal may still be strong. This is especially true while driving. For instance, in Salt Lake City, most of the FM antennas are located in the Oquirre (not sure of the spelling)Mountains southwest of the city. But if you can't see the mountains, the signal will be distorted but still easily receivable on any radio.
R
rbrucecarter
Guest
Perhaps you can forgive my ignorance - living, as I do, in wide open flat spaces.
The last time I was near mountains, it was Denver on vacation. I went into the Rocky Mountain National Park, and pretty much everything was line of sight. Go around a corner, the signal drops completely from one station, another comes in. Not too much distortion. At the top of the peaks, the whole band was alive with 300, 400 mile type of DX common. Next time I go to Colorado, I'll drive up Pike's Peak and spend some time DX'ing 2000 feet higher than the Rockies. I've heard stories of 600, 700 mile stuff up there.
But -- no distortion that I can tell except as the signal drops to nothing. But HD wouldn't help that. The signal just drops completely.
The last time I was near mountains, it was Denver on vacation. I went into the Rocky Mountain National Park, and pretty much everything was line of sight. Go around a corner, the signal drops completely from one station, another comes in. Not too much distortion. At the top of the peaks, the whole band was alive with 300, 400 mile type of DX common. Next time I go to Colorado, I'll drive up Pike's Peak and spend some time DX'ing 2000 feet higher than the Rockies. I've heard stories of 600, 700 mile stuff up there.
But -- no distortion that I can tell except as the signal drops to nothing. But HD wouldn't help that. The signal just drops completely.
> Perhaps you can forgive my ignorance - living, as I do, in
> wide open flat spaces.
>
> The last time I was near mountains, it was Denver on
> vacation. I went into the Rocky Mountain National Park, and
> pretty much everything was line of sight. Go around a
> corner, the signal drops completely from one station,
> another comes in. Not too much distortion.
When I lived in Utah, I had a difficult time receiving a clean FM signal if not within the line of sight of the transmitter. Most of the SLC stations are on a mountain peak overlooking most of the Salt Lake valley and you are usually within line of sight, i.e. you can see the mountain. However, if you travel east and go on the other side of the Wasatch Mountain range and out of the line of sight of the transmitters, the signal is still strong because it is reflected off the adjacient mountains with typically full needle deflection on the meter. But it is difficult getting a clean signal under those circumstances. This is also true when traveling through most of the canyons along the Wasatch front east of the city.
At the top of
> the peaks, the whole band was alive with 300, 400 mile type
> of DX common. Next time I go to Colorado, I'll drive up
> Pike's Peak and spend some time DX'ing 2000 feet higher than
> the Rockies. I've heard stories of 600, 700 mile stuff up
> there.
You are correct. When on a peak, you can get clean signals from hundreds of miles away. When traveling west from SLC on I-80, the SLC stations can easily be received in Wendover Nevada - some 150 miles away! This is because Wendover NV is within line of site of the mountains near SLC.
I am not an expert Bruce, but I do know that a FM signal can be of a city grade strenght but also extremely distorted. I wonder if IBOC will help in cleaning up those signals.
> wide open flat spaces.
>
> The last time I was near mountains, it was Denver on
> vacation. I went into the Rocky Mountain National Park, and
> pretty much everything was line of sight. Go around a
> corner, the signal drops completely from one station,
> another comes in. Not too much distortion.
When I lived in Utah, I had a difficult time receiving a clean FM signal if not within the line of sight of the transmitter. Most of the SLC stations are on a mountain peak overlooking most of the Salt Lake valley and you are usually within line of sight, i.e. you can see the mountain. However, if you travel east and go on the other side of the Wasatch Mountain range and out of the line of sight of the transmitters, the signal is still strong because it is reflected off the adjacient mountains with typically full needle deflection on the meter. But it is difficult getting a clean signal under those circumstances. This is also true when traveling through most of the canyons along the Wasatch front east of the city.
At the top of
> the peaks, the whole band was alive with 300, 400 mile type
> of DX common. Next time I go to Colorado, I'll drive up
> Pike's Peak and spend some time DX'ing 2000 feet higher than
> the Rockies. I've heard stories of 600, 700 mile stuff up
> there.
You are correct. When on a peak, you can get clean signals from hundreds of miles away. When traveling west from SLC on I-80, the SLC stations can easily be received in Wendover Nevada - some 150 miles away! This is because Wendover NV is within line of site of the mountains near SLC.
I am not an expert Bruce, but I do know that a FM signal can be of a city grade strenght but also extremely distorted. I wonder if IBOC will help in cleaning up those signals.
Mountain DX in Missouri
I've never been out west, but I'm betting the FM dial is much cleaner to get strong signals on mountain peaks. In the Ozarks outside of St. Louis, I can receive signals from Missouri, Illinois, and Arkansas competing with each other, fading in and out so another station can dominate every couple minutes. It's good for DX'ing, but when I actually want to aircheck something, it's normally a lost cause unless I have a local signal.
> > Perhaps you can forgive my ignorance - living, as I do, in
>
> > wide open flat spaces.
> >
> > The last time I was near mountains, it was Denver on
> > vacation. I went into the Rocky Mountain National Park,
> and
> > pretty much everything was line of sight. Go around a
> > corner, the signal drops completely from one station,
> > another comes in. Not too much distortion.
> When I lived in Utah, I had a difficult time receiving a
> clean FM signal if not within the line of sight of the
> transmitter. Most of the SLC stations are on a mountain peak
> overlooking most of the Salt Lake valley and you are usually
> within line of sight, i.e. you can see the mountain.
> However, if you travel east and go on the other side of the
> Wasatch Mountain range and out of the line of sight of the
> transmitters, the signal is still strong because it is
> reflected off the adjacient mountains with typically full
> needle deflection on the meter. But it is difficult getting
> a clean signal under those circumstances. This is also true
> when traveling through most of the canyons along the Wasatch
> front east of the city.
>
> At the top of
> > the peaks, the whole band was alive with 300, 400 mile
> type
> > of DX common. Next time I go to Colorado, I'll drive up
> > Pike's Peak and spend some time DX'ing 2000 feet higher
> than
> > the Rockies. I've heard stories of 600, 700 mile stuff up
>
> > there.
> You are correct. When on a peak, you can get clean signals
> from hundreds of miles away. When traveling west from SLC on
> I-80, the SLC stations can easily be received in Wendover
> Nevada - some 150 miles away! This is because Wendover NV is
> within line of site of the mountains near SLC.
>
> I am not an expert Bruce, but I do know that a FM signal can
> be of a city grade strenght but also extremely distorted. I
> wonder if IBOC will help in cleaning up those signals.
>
I've never been out west, but I'm betting the FM dial is much cleaner to get strong signals on mountain peaks. In the Ozarks outside of St. Louis, I can receive signals from Missouri, Illinois, and Arkansas competing with each other, fading in and out so another station can dominate every couple minutes. It's good for DX'ing, but when I actually want to aircheck something, it's normally a lost cause unless I have a local signal.
> > Perhaps you can forgive my ignorance - living, as I do, in
>
> > wide open flat spaces.
> >
> > The last time I was near mountains, it was Denver on
> > vacation. I went into the Rocky Mountain National Park,
> and
> > pretty much everything was line of sight. Go around a
> > corner, the signal drops completely from one station,
> > another comes in. Not too much distortion.
> When I lived in Utah, I had a difficult time receiving a
> clean FM signal if not within the line of sight of the
> transmitter. Most of the SLC stations are on a mountain peak
> overlooking most of the Salt Lake valley and you are usually
> within line of sight, i.e. you can see the mountain.
> However, if you travel east and go on the other side of the
> Wasatch Mountain range and out of the line of sight of the
> transmitters, the signal is still strong because it is
> reflected off the adjacient mountains with typically full
> needle deflection on the meter. But it is difficult getting
> a clean signal under those circumstances. This is also true
> when traveling through most of the canyons along the Wasatch
> front east of the city.
>
> At the top of
> > the peaks, the whole band was alive with 300, 400 mile
> type
> > of DX common. Next time I go to Colorado, I'll drive up
> > Pike's Peak and spend some time DX'ing 2000 feet higher
> than
> > the Rockies. I've heard stories of 600, 700 mile stuff up
>
> > there.
> You are correct. When on a peak, you can get clean signals
> from hundreds of miles away. When traveling west from SLC on
> I-80, the SLC stations can easily be received in Wendover
> Nevada - some 150 miles away! This is because Wendover NV is
> within line of site of the mountains near SLC.
>
> I am not an expert Bruce, but I do know that a FM signal can
> be of a city grade strenght but also extremely distorted. I
> wonder if IBOC will help in cleaning up those signals.
>
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