Without HD - Improving FM (Stereo)

[kfbkfb]

Is there evidence of a demand for good quality
(noise as low as FM Mono) FM Stereo
(primarily for mobile/portable users)?

If so, why is FMeXtra/VuCast not more popular?

Kirk Bayne

 

[audioguy]

I think background noise is less of a problem than many people make it out to be (especially HD proponents). How many people listen to radio sitting in a quiet living room like they did in the 1980s? A lot of radio listening is done in the car, in the kitchen, and on the go in environments that have relatively high background noise levels. Even in my Camry, which is a relatively quiet car, I rarely notice the background noise and only while listening to very quiet passages of classical music.

 

[rbrucecarter5]

I think diversity antenna systems would reduce a lot of the noise in cars. The down side would be convincing automakers to install two antennas instead of one in cars.

 

[spunker88]

Stereo systems like the Sony XDR-F1HD have already improved FM stereo. The typical increased static that weak stereo signals have on most radios isn't there with the Sony, and the system is able to provide stereo for signals much weaker than most units. I think modern DSP chips are the answer to these problems as they are able to provide cleaner audio, automatic RF gain to prevent overloads, etc.

 

[tomservo]

DSP has to be a better solution than the typical 'blend to mono' most radios employ. More than anything, that tells me that people don't even notice the difference in stereo and mono content for the most part.

 

[DaveBayArea]

I think diversity antenna systems would reduce a lot of the noise in cars. The down side would be convincing automakers to install two antennas instead of one in cars.

There's more of those than you think, mostly done with tricks involving wires in windows. When I saw the subject for this thread I thought it was discussing the "ssb fm stereo" idea, which concentrates the L-R information in only the lower sideband.

But on the subject of DSP receivers, I just bought one of these:

http://www.broadcastwarehouse.com/bw-broadcast/rbrx1-fm-re-broadcast-receiver-/1393/product

for a translator site. Easily the most expensive FM radio I've ever seen. But I have to say I am duly impressed with what is possible with analog FM.

Dave B.

 

[Chuck]

But on the subject of DSP receivers, I just bought one of these:

http://www.broadcastwarehouse.com/bw-broadcast/rbrx1-fm-re-broadcast-receiver-/1393/product

for a translator site. Easily the most expensive FM radio I've ever seen. But I have to say I am duly impressed with what is possible with analog FM.

Dave B.

I have one too. It is easily the best (and most expensive) FM radio I've ever owned. I believe that it owes its sensitivity and selectivity to the Sony chip set that was used in the Sony HD radios. They guys at BW Broadcast figured out how to make it do many things that make it amazing receiver for translator duty. Even though it is expensive, in my application, it is worth every penny.

The Sony XRFHD-1 sold for under $100 and used similar DSP technology. From that, we can conclude that there are inexpensive ways to improve modestly priced radios. It could solve many of the problems HD is supposed to address, and do it at a very low cost. The technology is certainly there. It works. If demand for the parts ever became high enough, you can bet the cost of doing it would go down as the quantities go up.

Of course, just adding DPS does not address the issue of multi-casting, but that too could be addressed much more simply and cheaply. FM-Extra comes to mind...

 

[kfbkfb]

Some background:
I live in the Kansas City area and most often drive
a 2004 Honda Civic with a factory installed AM/FM
radio with the antenna in the back window.
Most of the FM stations are at or near the maximum
power.

While driving around in the suburbs, I notice the FM
radio quite often blends to mono, my original comment
should probably have stated that FMeXtra/VuCast
would likely have allowed stereo reception until the FM
signal was too weak to demodulate, unlike the current
all analog (Zenith/GE) FM Stereo system, which needs
a fairly strong signal to work properly.

Kirk Bayne

 

[Chuck]

A few years ago I had the opportunity to get a demo of FMeXtra on a 74 watt LPFM station. The digital signal hung in there well past the point that anyone would put up with the analog signal. Audio quality was excellent, and of course, it did not blend to mono as we drove farther away.

 

[JohnnyElectron]

For a knockout (expensive) analog tuner, I suggest the Fanfare FTA-100P. The NPR station was better than digital anything with a concert on FM. The AM was spectacular with stereo CQUAM audio from over 100km away - noise blanking, 7.5KHz audio response. Noise floor on FM was amazing. Selectivity was great. About $1800, but nice, nice hardware.

 

[dumber than a box of hair]

Is there evidence of a demand for good quality
(noise as low as FM Mono) FM Stereo
(primarily for mobile/portable users)?

When the medium of the moment is bit-rate-reduced, digitally compressed 64kbps MP3's, loaded with artifacts and listened to through ear buds?

No.

 

[Chuck]

For a knockout (expensive) analog tuner, I suggest the Fanfare FTA-100P. The NPR station was better than digital anything with a concert on FM. The AM was spectacular with stereo CQUAM audio from over 100km away - noise blanking, 7.5KHz audio response. Noise floor on FM was amazing. Selectivity was great. About $1800, but nice, nice hardware.

The Fanfare is an awesome analog tuner. I have several of them. Still the BW Broadcast RBRX-1 beats it in terms of sensitivity and selectivity. It also can do some things that no other tuner can, including including adjustable audio and IF bandwidths, adjustable de-emphasis and blending for stereo. A built in multiplex generator makes it ideal for translator duty. They also make a "consumer" version which doesn't have the MPX generator, which is much less expensive, although still pretty pricey. If you have a real reception problem, it is worth every penny.

 

[iyiyi]

For a knockout (expensive) analog tuner, I suggest the Fanfare FTA-100P. The NPR station was better than digital anything with a concert on FM. The AM was spectacular with stereo CQUAM audio from over 100km away - noise blanking, 7.5KHz audio response. Noise floor on FM was amazing. Selectivity was great. About $1800, but nice, nice hardware.

The Fanfare is an awesome analog tuner. I have several of them. Still the BW Broadcast RBRX-1 beats it in terms of sensitivity and selectivity. It also can do some things that no other tuner can, including including adjustable audio and IF bandwidths, adjustable de-emphasis and blending for stereo. A built in multiplex generator makes it ideal for translator duty. They also make a "consumer" version which doesn't have the MPX generator, which is much less expensive, although still pretty pricey. If you have a real reception problem, it is worth every penny.

Yeah... But...

Every method used to "improve analog FM" results in a trade off for audio quality. Blending to mono, narrowing bandwidth, pre distorting the audio (equalizing), fooling with de-emphasis adjustments, trying to hang digital subcarriers on (and in lieu of) the SCA portion the signal... Every 'improvement' - including analog DSP - compromises the audio in some manner.

Try as one may, there ain't no way to turn a Ru Paul into a Miss Universe!

-

 

[rbrucecarter5]

Yeah... But...

Every method used to "improve analog FM" results in a trade off for audio quality. Blending to mono, narrowing bandwidth, pre distorting the audio (equalizing), fooling with de-emphasis adjustments, trying to hang digital subcarriers on (and in lieu of) the SCA portion the signal... Every 'improvement' - including analog DSP - compromises the audio in some manner.

But - at least there is audio present. On HD-2, when the audio drops, the radio goes silent, which is FAR more annoying than blending to mono, etc. At least something is there. All those problems are in the fringes or downtown with tall building and severe multipath. Everywhere else, analog FM works pretty well.

 

[iyiyi]

Yeah... But...

Every method used to "improve analog FM" results in a trade off for audio quality. Blending to mono, narrowing bandwidth, pre distorting the audio (equalizing), fooling with de-emphasis adjustments, trying to hang digital subcarriers on (and in lieu of) the SCA portion the signal... Every 'improvement' - including analog DSP - compromises the audio in some manner.

But - at least there is audio present. On HD-2, when the audio drops, the radio goes silent, which is FAR more annoying than blending to mono, etc. At least something is there. All those problems are in the fringes or downtown with tall building and severe multipath. Everywhere else, analog FM works pretty well.

Yeah, but...

Everyone will agree the FM HD power boost from -20 to -14 dBc has made a phenomenal improvement in HD's digital coverage and performance! One might extrapolate the improvements reasonable HD power increases to -10 dBc or even higher could possibly provide for HD coverage! I'm basically saying that HD's current signal problems can be fixed with realistic HD power increases.

Peeps with CODEC and bit rate type issues can take a hike. One paragraph they say that background noise in automobiles renders HD's noise floor advantage moot. Next paragraph HD's "digital artifacts" are fingernails screeching across the blackboard to them. Reality is that if a guy said 'digital artifact' in front of an average man's wife, he'd probably be in danger of receiving a punch in the nose from her husband.

The quiet dropouts at the outskirts of an HD's coverage area are not disturbing. When they first appear I always figure maybe a commercial did not go. When they start occurring to the point of distraction, it is time to change the station anyway. The static and picket fencing make the analog signal an equally lousy listen.

-

 

[Tom Wells]

I will only agree that the higher level of digital sidebands have increased the flutter and and multipath noise outbursts into
much louder events, much more often.

"They" won't be satified until FM works as poorly as the AM.
Don't ask who "they" is..it's us, collectively.

 

[rbrucecarter5]

Everyone will agree the FM HD power boost from -20 to -14 dBc has made a phenomenal improvement in HD's digital coverage and performance! One might extrapolate the improvements reasonable HD power increases to -10 dBc or even higher could possibly provide for HD coverage! I'm basically saying that HD's current signal problems can be fixed with realistic HD power increases.

A paltry 6 to 10 dB of power increase??? You have to be kidding! Signal strengths of FM can vary by decades in a few feet. Especially if you are on the approach path of a nearby airport. Every place HD drops out on its own, the remaining analog is also weak. 6 to 10 dB is NOTHING compared to those fluctuations of several decades of received strength. And no amount of HD power increase can help the problem of jamming from nearby radios tuned 10.4 to 11.0 MHz below the HD station. I get dropouts from nearby cars when I can literally see the Houston towers less than 20 miles away - full class C, 100 kW on 2000 foot towers over flat terrain. 6 to 10 dB more power may seem like a lot, but the signal strength from the local oscillator in the car next to me is a lot closer. No - not everybody agrees that HD power increases will help. Not by a long shot.

With the degradations in analog FM, you can judge very well if the signal is likely to return in a few seconds. When HD drops, you don't know the reason, it is 100% there or 100% gone.

If you really want to help HD FM - and give it a fighting chance of working, move the sidebands back into the channel. Give up on RDS, SCA, and blind reading - after all it was easy to obsolete C-Quam on AM, and all of those auxilary services on upper sidebands of FM channels can be done better in HD anyway. What you would gain is the very real increase in received signal strength that comes from reducing bandwidth - the physics of the gain / bandwidth ratio would give HD FM a tremendous boost - much more than upping transmit power on the sidebands. You immediately solve the local oscillator problem, and HD will no longer drop out because of skip from adjacent FM stations. It is a win-win situation for HD FM, transparent to users, who will only notice that HD FM is now working when it didn't before. I don't think it would even take a firmware upgrade, the radio would just detect the sidebands at their new location. Subsidizing the few blind service people with new HD radios would cost a tiny fraction of the cost of increased electricity going along with the more powerful sidebands, not to mention the good will and publicity it would generate.

 

[local oscillator]

Let's face it, those who find any value whatsoever in HD Radio are akin to those who look at a canvass at which a chimpanzee has splashed some paint and call it art. Most of us know it's crap; but a few pay big money for it and want to put it in a museum. The differences between iBiquity and the chimp? Unlike iBiquity, the chimp has no idea that it's creating junk art and perpetuating a scam that is damaging the industry that it purportedly claims to help.

 

[tomservo]

I will only agree that the higher level of digital sidebands have increased the flutter and and multipath noise outbursts into
much louder events, much more often.

All I know is the two stations nearest me that run maximum HD power are both dropout-free (when listening to the HD2s where it's most noticeable) pretty much everywhere inside the 60 dBu+ areas. The ones that run lower power are a dropout-prone mess and unusable for any length of time if moving. For the public radio station, that's only about 30 miles out from the transmitter. Not far enough to reach where I live. But the big country station? I get it reasonably dropout free reception for at least 50 miles in all directions I've been, and have gotten it to decode while standing still up to about 75 miles. Well outside their intended target area.

Since the HD signals do come and go occasionally, I can say with a little certainty that the presence/lack of HD does not affect any of our local stations' coverage within the main metros (Mobile & Pensacola) with additional noise or interference. At least not on any of my radios. Maybe it trims distance on the fringes, but that's not where the advertising is sold so who cares? A station that's depending on its fringe coverage to reach a metro area or rural fan base shouldn't run HD, but for everyone else it's not such a bad deal when done right.

NONE of the local stations' HD drops out due to airplanes (I'm near three busy local airports, two regional airports and five or six naval air training fields/stations so air traffic from banner planes to the Blue Angels to hot air balloons are a daily occurrence.) NONE of them drop out due to IF interference. I've listened for both issues time and time again in HD and never have been able to replicate what rbrucecarter5 claims. I hear the flutter on analog signals, but only weak ones. For whatever reason, it just doesn't seem to affect HD where I live.

 

[DaveBayArea]

Yeah... But...

Every method used to "improve analog FM" results in a trade off for audio quality. Blending to mono, narrowing bandwidth, pre distorting the audio (equalizing), fooling with de-emphasis adjustments, trying to hang digital subcarriers on (and in lieu of) the SCA portion the signal... Every 'improvement' - including analog DSP - compromises the audio in some manner.

I used to think that, and even had some negative things to say about the analog performance of the venerable Sony XDRF1-HD (somewhat revered by FM enthusiasts these days). But we bought one of those BW Broadcast receivers to use at a translator site that is receiving severe HD interference from an adjacent-channel station. All I can say is you should take a listen for yourself. You'll be a believer. Doing an A/B comparison between over-the-air HD and over-the-air analog with the RBRX1 we chose the analog receiver for the translator input. In either case the preamps and/or source material in the studio were the limiting factor in the S/N ratio, and the analog signal didn't have the digital artifacts.

There may be some compromise of the analog audio, but it's not as bad as HD encoding/decoding.

Dave B.