-
Get involved.
We want your input!
Apply for Membership and join the conversations about everything related to broadcasting.
After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
If you use a disposable or false email address, your registration will be rejected.
After your membership is approved, please take a minute to tell us a little bit about yourself.
https://www.radiodiscussions.com/forums/introduce-yourself.1088/
Thanks in advance and have fun!
RadioDiscussions Administrators
NPR Digital Radio Simulation
- Thread starter PocketRadio
- Start date
Len14043 said:
Funny, my analog listening experience is nowhere near as bad as portrayed on that site. It sounds like a sham to me. Now, I do live where it is fairly flat, but for a station around here to sound like that, either you are at the edge of its coverage area (where HD won't work either), or there is a lot of tropospheric ducting (skip) problems from co-channel stations. In either case, it is unlikely that HD will be any better or even work at all.
I will agree that under normal conditions, HD does have noticeably better signal to noise ratio than analog, and it can sound quite good. Unless you are wearing headphones, or sitting in your living room listening through very good speakers, you may not notice the increased s/n. It certainly would be hard to notice driving your car at 70 mph. The road noise masks a lot of what you may have gained.
The caveat is the audio quality (not signal to noise ratio) depends on the sampling rate used. HD can also suffer from strange digital artifacts, especially at lower bit rates. There is no free lunch; you have to get the right balance with the limited bandwidth available. The more secondary channels, the worse the primary sounds. Still, it can sound quite acceptable, assuming you have enough signal strength to overcome the systems inherent limitations.
When HD is good, it is quite good. Unfortunately, there also seem to be times where it hardly works at all due to the weakness of the HD signal.
It is very likely to be in just the wrong position and hear multipath interference similar to that on the demonstration, somewhat annoying but not enough to wipe out the signal. In a situation like that, using a decent antenna, HD is immune to the interference! The power levels used for HD are not necessarily permanent. The situation is being studied.
semoochie said:
In some place like San Fransisco, you'd be more likely to have multipath that comes close to what you hear on this demo. That is not typical. In most places, it simply would not happen. The sample on the web site is not representative of what 99% of the world normally experiences with analog FM radio. Therefore, it is simply a dishonest representation. Even the most fervent of HD supporters should be able to recognize deception when they see or hear it.
As for any potential HD power increase, that is years away at best. The FCC would do the HD radio contingent a big favor if they established a minimum power level for HD. My educated guess is anything below 100 watts digital is simply not worth doing. As it is now with the 20 db down rule, it eliminates a lot of stations from being viable in HD. I have not checked the statistics, but if I were a betting man, I'd bet that it is a minority of licensed FM stations that are over 10,000 watts.
Tom Wells said:
Correct me if I’m wrong, but the last I looked, Italy has tons of unlicensed radio and TV stations that contribute heavily to the problem. To top it off, I believe in Italy, "half-channel" multiples of 50 kHz are used rather than the usual multiples of 100 KHz. I’d love to see IBOC work under those conditions.
In the US, we use multiples of 200 KHz and insist on second adjacent protection, or in the case of LPFM stations, third adjacent protection. The Italians obviously have made more use of their available spectrum, but in doing it; they seem to have turned the place into an RF sewer. Italy makes the pirates in Miami look like a well-organized group of technically responsible broadcasters.
Chuck said:
That's what I figured, too...
PocketRadio said:
I totally agree.. Something's amiss in that simulation, as the FM's here in Savannah are very crisp and they sound just as good as the HD demo and it's analog for heavens sake!
Who are they kidding? I think we should all post a recording of our FM's for comparison to that demo and do a listening test everyone can compare.
Radiopilot
Chuck said:
I've heard a similar explanation. Some stations are licensed, but many operators just find a supposedly "open" frequency, fire up, and try to make money -- a Libertarian's dream! When I visited Rome a couple of years ago, I could copy 80 FM stations across the dial on my Walkman in a second floor hotel room -- but despite the close spacing, most sounded OK.
While traveling in Italy, I also saw a lot of vertically-polarized FM transmit antennas atop relatively short buildings. The stations typically use four or six dipoles on a short mast; there are several of these facilities across from Stazione Centrale, the main rail station in Milan. This combination of low HAAT, vertical-polarization only, and possible co-channel interference is probably responsible for the high levels of multipath in urban areas.
Concerning the WETA recording, the apparent multipath distortion might have been made worse by interference from WHYY-FM in Philadelphia, a full Class B also on 90.9 and about 120 miles away from Washington. During the summer and autumn months, VHF propagation across the Chesapeake Bay is greatly enhanced, opening a low-loss path between the two markets. Anyone who has tried to listen to 88.5, 90.1, 90.9, 99.5, 100.3, or 101.1 along the Philadelphia-Wilmington-Baltimore-DC corridor during these conditions probably knows what I mean!
I kinda figured it must be a problem with reception in the D.C. area. There are way too many stations in that corridor. At least with digital, you either get it or you don't. Kinda like digital TV. No in-betweens or static.
I found this sound file on another site. Some of you are familiar with Jeremy Andrews. He posted this mp3 file of HD stations pulled in from Kenosha, WI - roughly halfway (45-50 miles each) between Chicago and Milwaukee:
[EDIT-unauthorized promotion of commercial activities]
I found this sound file on another site. Some of you are familiar with Jeremy Andrews. He posted this mp3 file of HD stations pulled in from Kenosha, WI - roughly halfway (45-50 miles each) between Chicago and Milwaukee:
[EDIT-unauthorized promotion of commercial activities]
Much more often the FM analog signal sounds fine while the HD signals are missing. That is why all HD radios "roll back" or "fall back" to analog FM so often.
It seems the reason for posting this audio file was because it is so rare that the HD digital signal can be received while the analog is suffering such severe multipath. Of course if the antenna is adjusted a few feet, it's very likely that the analog signal will become pristine and the HD digital signal will disappear.
In spite of all the false advertising hype HD radio is not immune to multipath signal cancellation. Little or no signal is a reception problem regardless of the modulation method.
Is the demonstration unusual, contrived or bogus?
Possibly. As the title to this thread suggests, the audio is a
http://www.m-w.com/dictionary/simulation
It seems the reason for posting this audio file was because it is so rare that the HD digital signal can be received while the analog is suffering such severe multipath. Of course if the antenna is adjusted a few feet, it's very likely that the analog signal will become pristine and the HD digital signal will disappear.
In spite of all the false advertising hype HD radio is not immune to multipath signal cancellation. Little or no signal is a reception problem regardless of the modulation method.
Is the demonstration unusual, contrived or bogus?
Possibly. As the title to this thread suggests, the audio is a
Just an imitation?
http://www.m-w.com/dictionary/simulation
Chuck said:
Perhaps absolute, total silence is HD radio supporters idea of the ultimate in reception and perfect fidelity nirvana.
Some have said "silence is golden" perhaps no reception is platinum to HD supporters?
But ear plugs are much less expensive then HD radios, and often give the same result.
semoochie said:
I haven't had that problem recently. Back in the days when most FM stations were fairly low power and they weren't all on 2000' towers, it was quite common to pull up to a stoplight and the station you were listening to would turn into a fuzz of noise caused by multi-path problems. If you rolled the car ahead a few feet, it would usually clear up and sound fine. The ony time I've noticed that recently is listening to an LPFM or translator at the edge of its pattern, or maybe an out of market station. I simply have not had that problem with many full power stations recently.
Since we are talking about even lower power levels for HD, (albeit digital with nifty tricks like buffering) it seems possible that you could lose the HD signal in similar circumstances. If you are listening to an HD-2 signal, it has nothing to revert to, so you may get silence. That sounds very disconcerting to me. Since I don't have an HD radio in my car - and I'm not likely to have one for quite some time since my car is a 2007 model - I can't confirm this. Has anyone noticed this?
I can say that on a recent trip to Dallas, I checked out the JVC HD car radio at Best Buy, on Highway 183 in Irving, Texas. The store is probably about 10-12 air miles from the area where most of the FM transmitters are located. Most of the HD signals in the area come from full power stations with antennas on very tall (1500' - 1800') towers. In the store, it was difficult to keep the radio locked in the HD mode. It worked fine in analog. In this case, don't know if it was a bad radio, a poor display, or if the problem is indeed the with the system. I do have my suspicions, but the real point is it was a less than compelling presentation. The satellite radios were next to it in the display and worked quite well.
If I walked in there as a complete neophyte wanting to purchase an HD radio, it would not take very much to switch me to something else.
I have the JVC car radio and the HD works much better in the car.
While I think the extra stations are pretty cool, I would rather purchase satellite radio if I could afford it right now, especially because I live in Lubbock now and there is only 1 HD station. While I think HD is pretty cool, they need to add better formats to their other signals.
Satellite radio has formats such as "comedy". While HD only has an all 90s, or all beatles, or another commercial-free Top 40 station. All these are cool and I do enjoy listening to them, but the formats are not nearly unique as satellite radio. Now if HD started coming with cars these days, I think it might cause some people to stick with HD and not get satellite radio...but as you can see, that has only happened in a few cars.
Can't wait until I graduate and get a real job...then I can get satellite radio...and have even more channels.
Now the simulation...While it is true that I see a significant difference in the quality between analog and HD, that simulation is inaccurate. Analog does not have that many hisses and pops.
While I think the extra stations are pretty cool, I would rather purchase satellite radio if I could afford it right now, especially because I live in Lubbock now and there is only 1 HD station. While I think HD is pretty cool, they need to add better formats to their other signals.
Satellite radio has formats such as "comedy". While HD only has an all 90s, or all beatles, or another commercial-free Top 40 station. All these are cool and I do enjoy listening to them, but the formats are not nearly unique as satellite radio. Now if HD started coming with cars these days, I think it might cause some people to stick with HD and not get satellite radio...but as you can see, that has only happened in a few cars.
Can't wait until I graduate and get a real job...then I can get satellite radio...and have even more channels.
Now the simulation...While it is true that I see a significant difference in the quality between analog and HD, that simulation is inaccurate. Analog does not have that many hisses and pops.
EggsOverEasy87 said:
It's going to have to be in cars at little or no additional cost to the owner. I was not an early adopter for satellite radio. I'd had it in a couple of rent cars, and frankly wasn't all that impressed. Then I had to take a very tedious multi-week trip in my car. I'd done the same trip the previous year, and was depressed at the lack of radio that interested me. I spent most of it looking for a decent station, but seldom found one. In preparation for my second round of this mind numbing experience, I noticed that my local electronics super store was offering both XM and Sirius add on receivers for about $50. On an impulse I bought one. It made my extended journey a lot more enjoyable. I couldn't believe how much more pleasant the travel experience was. It reminded me of the difference when my parents bought their first car with air conditioning. It wasn't quite as dramatic, but I noticed that after 12 hours of driving, I was no where nearly as fatigued as I was when I was constantly searching for a station. It was simply one less stress factor in my trip
When I made my most recent car purchase, it came with XM on board with a free trial period. It may be possible to get the car without XM, but I think you had to sacrifice some things I really did want, like power windows and seats. It was a bundled deal. Since getting it, I don't look back. Now, as soon as I leave my home area, I switch to XM and rarely ever go back to terrestrial radio. That includes trips to radio meccas like Dallas, Austin or Houston where there are tons of stations on the dial. I suspect that lots of people do that, and the numbers are slowly increasing.
Never mind that XM and Sirius are still hemorrhaging money like there was no tomorrow, if someone is tuned in to either one of them, they are not listening to anyone's terrestrial stations. There should be a wake up call there, not only in knowing who is likely to be a competitor, but in how to market a new product.
I noticed Audiovox/Jensen is coming out with a new car unit in September. Telling by the company, this will be a lower-priced unit. I wonder what advances this will have over the JVC unit.
Incidentally, I checked out the JVC unit while I was at Wal-Mart the other day. Now, this store's car stereo selection has always been a joke, so it was no surprise that the HD signals did not come in on the JVC unit. Actually, half the local stations' analog signals were a no-show, and given that HD signals are allegedly 1/100 of their analog signals at this time, I'm not surprised. I may check out Best Buy next.
The JVC was a nice unit (as they usually are) and analog sounds pretty nice. I like the memory flash card interface on it. Now THAT's a great idea!
Incidentally, I checked out the JVC unit while I was at Wal-Mart the other day. Now, this store's car stereo selection has always been a joke, so it was no surprise that the HD signals did not come in on the JVC unit. Actually, half the local stations' analog signals were a no-show, and given that HD signals are allegedly 1/100 of their analog signals at this time, I'm not surprised. I may check out Best Buy next.
The JVC was a nice unit (as they usually are) and analog sounds pretty nice. I like the memory flash card interface on it. Now THAT's a great idea!
FightingIrish said:
I am posting a link to a page with different HD files, since the one I had posted previously had some issues.
OpenGeek collected a few recordings of stations in the Portland area, some HD, some analog, some both. It's a rather old article, but it is pretty interesting. They also include some DAB samples from the UK, as well as a clip from Digital Radio Mondiale.
The third KEX AM HD file sounds rather distorted. Lots of digital buzz.
They also include some files from both the HD1 and HD2 of WUSN in Chicago, recorded by people at the station itself. Not very good sounding. Sounds like a low bitrate on HD1, while there are some serious artifacts on HD2.
The DAB files from the UK sound really good.
Here's the link:
http://www.opengeek.org/2005/03/hd-radio-analog-fm-mp3-and-ogg-audio.html
- Status