How's your FM hiss these days?

[Tom Wells]

A few days ago I was on the way home from work, and while I don't find much on FM I like, I decided to listen to FM.
My car radio is mono, and I have often heard FMs from across Lake Michigan, so no sensitivity problems..
The level of hiss in FMs now for me, locally, 7 miles and line of sight, is about what it used to be when I lived 45 miles out in the 1970s.

It's on all the HD FMs, and in Chicago it's now everywhere. I went up and down the band, and if the audio had the raspiness on it,
the sidebands were there to account for it. The one signal with clean audio was WLUP, oddly, with no sidebands. I was shocked, but then
when I checked again upon arriving home the sidebands and fuzz were back

The saddest change of all is on WFMT, where the zizz of the sidebands jump in to make a spitty noise in tiny spots of signal loss, where
formerly, "quiet" white noise wold creep in. So now, though I'm local, I experience a "fringe" sort of detriment.

Then, even in a parked car, other revelations are apparent. We'll never hear a woodwind instrument properly again!
The zizz "rides" on all audio and if the audio is anything but brash or strident, there's no escaping it.

At one point on the drive home I was about 500 ft from WFMT's studios, 500 feet from home, line of sight to the stick, and
I could not listen to WFMT without hearing hiss.

Perhaps newer radios with narrower IF sections do not suffer this?
Those with golden ears please relate your FM self-noise obsevations.

 

[audioguy]

Tom,

The problem I find with WFMT is that ever since they installed their new HD transmitter, the audio has sounded horrible on sibilants (listening to FM). It "spits", especially on voices that have a lot of high frequency energy, including Lisa Flynn and George Preston. I've contacted their chief engineer about this, and he claims it has nothing to do with HD transmission. At the time I first mentioned it to him, he said that he was still adjusting the audio processing. But that was about 6 months ago, and to me it still sounds bad.

I believe what is happening is that high frequency audio signals are mixing with the IBOC sidebands and causing the transient distortion. I have now proven to myself that this happens on multiple different FM receivers; some new and some older models. A recent note to the station did not elicit a response.

If you are hearing this too, I invite you to get in touch with the station and let them know that it's degrading their signal. The only way we will get any action is if they hear from multiple listeners with valid complaints. If you're not hearing this, I'd be interested to hear about that as well. I think the problem happens at the receiver end, but that's not acceptable if most reasonably good quality FM receivers do it.

How about any of the rest of you reading this board that are Chicago area listeners? Take a listen to WFMT sometime and tell us what you hear. George is on during afternoon drive. Lisa is on at various other times. I don't really hear the problem with music, although some selections that have a lot of bells or other "zingy" high frequency sounds can cause it to happen.

 

[scanman1]

IBOC must die!! Chicago FM is definitely "hissier" now than it's ever been! Several stations I could formerly receive with extremely low noise floors now have the "hash" using the same tuners and it's virtually impossible to achieve full quieting. The biggest offenders include Q101 and Jack-FM, both of which are noisy no matter what I do (in the case of Jack-FM they have bad audio modulation to further compound the problem). One station with IBOC I listen regularly is WLS-FM and it's one of a few stations I can, surprisingly, still receive with full quieting.

 

[Link]

I thought WFMT was not going HD? Did this change? Thanks

 

[Len14043]

While traveling through Chicago enroute to Milwaukee, WFMT was a pleasure to listen to and the classical format was great. The digital signal was solid from Gary, IN to Waukegan, IL and was hiss free - until the digital faded to analog. I found the other Chicago digital stations to be hiss free. Three stations had HD-3s. A power increase will make a good situation great.

 

[audioguy]

While traveling through Chicago enroute to Milwaukee, WFMT was a pleasure to listen to and the classical format was great. The digital signal was solid from Gary, IN to Waukegan, IL and was hiss free - until the digital faded to analog. I found the other Chicago digital stations to be hiss free. Three stations had HD-3s. A power increase will make a good situation great.

Not for those of us who cough up $400-500K every 3 months ostensibly to keep the station on the air, and who prefer to listen in ANALOG withOUT the crap in the background from the digital hiss maker.

 

[BRNout]

I thought WFMT was not going HD? Did this change? Thanks

They've been in HD for quite a while now and, from where I live N of Chicago, their sidebands are stronger than that of any other station. I haven't really noticed the same level of analog signal degradation (for the analog version of the HD station) as I do on AM. The analog signals of AM stations such as WBBM and WSCR sound just awful when compared with non-IBOC WLS. Have not noticed the same phenomenon on the FM side. That said, I don't tend to listen with high-end equipment so subtle differences may not be noticeable on my systems.

One thing I DID notice was that, when WLS-FM's HD was down for a couple of days, I had a much easier time pulling in distant stations on 94.5 and 94.9. Yes, I usually get WLWK on 94.5 - but it was clearer without WLS-FM's hash. Then again, I know that nobody worries about such 'trivial' things. :

 

[JohnnyElectron]

For some odd reason, after reading this post, I can 'picture' a satire song sung by Mr. Eddy Arnold entitled "Make the Hiss Go Away" for those of you old enough to remember "Make the World go Away". I could start writing the lyrics right now, but the Strubble Police would probably arrest me.

"Make the hiss go away, and bring back my station, my old radio worked great, turn off the hiss, and go away...bum,de,bum,bum. My old analog worked just great......and make the hiss, go, a-waaaaayyyy"

From the upcoming remastered and updated 1973 RCA vinyl LP & new CD album entitled "The World of Eddy Arnold"

 

[tomservo]

Maybe they've discovered they can run the encoded HD audio (decoded to analog) through the analog portion of the transmitter so the analog and digital sound equally bad.

The artifacts you describe sound like the problems the digital codec introduces into the music I've heard on my HD radio. I tried listening to A Prairie Home Companion tonight on the HD-2 subchannel of my local public outlet and it sounded absolutely terrible. Every time a singer would belt out a tune, it sounded like someone had a 'digital kazoo' playing along with her, only off key.

Of course, it was better than the 50% volume level on the HD-1. Blend to digital and it'd become nearly inaudible, blend to analog and it'd blast the speakers out.

It's bad enough they use a crappy codec on FM, but the other technical quibbles (bad levels, bad processing, bad sync) are just sad.

 

[Len14043]

While traveling through Chicago enroute to Milwaukee, WFMT was a pleasure to listen to and the classical format was great. The digital signal was solid from Gary, IN to Waukegan, IL and was hiss free - until the digital faded to analog. I found the other Chicago digital stations to be hiss free. Three stations had HD-3s. A power increase will make a good situation great.

Not for those of us who cough up $400-500K every 3 months ostensibly to keep the station on the air, and who prefer to listen in ANALOG withOUT the crap in the background from the digital hiss maker.

Audioguy, you solicited input from Chicago area listeners on WFMT as stated in a previous post:

"How about any of the rest of you reading this board that are Chicago area listeners? Take a listen to WFMT sometime and tell us what you hear. George is on during afternoon drive. Lisa is on at various other times. I don't really hear the problem with music, although some selections that have a lot of bells or other "zingy" high frequency sounds can cause it to happen."

I responded honestly on my listening experience with WFMT. Perhaps my response wasn't what you wanted to hear and didn't comply with the party line expressed on this board.

 

[radioskeptic]

I’m shocked that WFMT has installed this garbage technology. I think I read some time ago that they wouldn’t use SCA’s because they didn’t want to risk even the slightest degradation of their main channel audio.

And now they’re giving in to industry pressure to do this. What happened? Did all the sane people at WFMT retire?

And to think that just last August, Steve Robinson, who was identified as an executive VP at ’FMT, was quoted in the St. Louis Post-Dispatch as saying, “The HD stuff is a flop” and that it was “dead on arrival.”

(That article appeared on August 16, 2009, and I’m afraid stories from the print edition disappear from the paper’s web site after seven days. But you can get it here: http://www.allbusiness.com/government/government-bodies-offices/12665340-1.html -- that quote is on the second page. And if that doesn’t link work for you, go to a large public or college library with licensed databases like Newsbank, limit your search to the Post-Dispatch, limit it to that date, and use “KFUO” as your search term.)

 

[audioguy]

While traveling through Chicago enroute to Milwaukee, WFMT was a pleasure to listen to and the classical format was great. The digital signal was solid from Gary, IN to Waukegan, IL and was hiss free - until the digital faded to analog. I found the other Chicago digital stations to be hiss free. Three stations had HD-3s. A power increase will make a good situation great.

I responded honestly on my listening experience with WFMT. Perhaps my response wasn't what you wanted to hear and didn't comply with the party line expressed on this board.

Len,

Your response indicated that you were listening primarily to the digital signal. My concern is with the transient distortion that is appearing on high frequency sibilants when listening to the analog signal. As far as I can tell from the information you posted, you did not have a comment on that issue. Others have commented on the increased hiss level that is now present in the background when listening to the analog signal. You did not comment on that, either.

It's easy to make it appear that the digital signal sounds far superior to the analog signal when the digital signal, by its nature, has seriously degraded the quality of analog reception. This is a little trick that the pro-IBOC group has used more than once. Another example that I can think of was the way that they requested all of their AM stations to cut down the analog audio bandwidth to telephone quality so that the sound quality would be awful in analog mode (it was).

Let's be honest about the interference caused by IBOC to the host analog signal and not try to sweep this issue under the rug. Most listeners, including the ones that are paying the bills for WFMT (and a lot of others) and keeping them on the air are listening, and wish to listen, to the analog signal. Probably less than 1 in a thousand people listen to the digital signal. Why should the other 999 have to suffer with impaired reception?

I'm all for digital radio as long as it does not interfere with the host station and its neighbors. IBOC interferes with both.

There is no party line on this board, but technical honesty is something that we all expect.

You are entitled to your opinion about the quality of the digital transmission, and I don't dispute it. But you did not address the issue that I raised.

 

[briankay]

I have not heard the hiss you speak about.

I've emailed WFMT to increase their IBOC power and as they have a Nautel HD radio transmitter which I believe was installed when they first switched on the HD last year, so I think they have the headroom to switch up to -10dBc if they wish. Gordon Carter has been very helpful and detailed in his replies.

Anyway I listen to them in my car with their HD radio signal, because given the choice in a mobile environment between analog FM stereo with all the noise, swishing and fading in and out of mono or IBOC with a noise free signal with audio quality that is almost indistinguishable from uncompressed digital, the IBOC wins hands down in WFMT's case, especially during those low audio levels that are part and parcel of WFMT's audio. They use the full 96 kbps bandwidth of HDC codec which does not use SBR or PS at the 96 kbps rate. So if I was home listening to high end speakers would I then hear the deficiencies of the digital codec? Well barely, but my conclusion is that for mobile reception, HD wins in almost every way unless I'm within 10 miles of their stick, which I rarely am. Also when at home I listen to their online stream which has excellent sound quality. I live 40 miles from Chicago so their FM stereo is too noisy at that distance and the HD lock is 90% of the time. So I will be a happier camper if they turn up their HD power.

I suggested to Mr. Carter to increase their HD power during commute hours in the morning and afternoon drivetime when the biggest listenership is mobile and keep it at standard power level at other times and at the weekend.

We'll see.

 

[Chuck]

I suggested to Mr. Carter to increase their HD power during commute hours in the morning and afternoon drivetime when the biggest listenership is mobile and keep it at standard power level at other times and at the weekend.

We'll see.

I doubt he'd be very wild about that idea. In fact, I don’t think the FCC would allow them to do it, at least without getting a Special Temporary Authorization (STA) for the experiment. For a variety of reasons, changing your power several times a day isn't a particularly good idea, unless you just have to do it, as is the case with many AM stations. If you are going to increase HD power, you'd be better off doing it full time.

The reason WFMT-HD sounds decent is (as you mentioned) they are using the full 96 kbs for just one stream. That can sound pretty good. The problem is when you add those pesky HD-2, HD3 and even HD-4 signals. Those extra signals are the main reason broadcasters in this country are interested in digital broadcasting. Improving the fidelity of your listening experience is not very high on their list. When these sub channels are added, the quality goes down. The digital pie is only so big, and every secondary channel degrades the primary.

I think you will find that WFMT and a few other pubcasters are the exceptions in broadcasting. They are a station that really cares about fidelity, so they view HD as a potential improvement. They run HD at the expense of adding additional programming streams. Even among public broadcasters that is a minority point of view. Most are primarily interested in using HD to bring more programming to their facility. Since NPR has flipped to mostly talk, the sub channels give them a way to placate their classical and jazz listeners. When you run three streams, things can get ugly.

For the few stations like WFMT, HD may be a good thing. For the rest of us, the current system is a compromise at best.

 

[Play Freebird]

I should also point out that WFMT's HD performance as reported by Brian is completely in accordance with what the developers of IBOC originally intended. At 40 miles from Chicago, he is right at the edge of the predicted F(50,50) 54 dBu service contour of a maximum Class B facility, which means that a field strength of 0.5 mV/m is exceeded 50 percent of the time at 50 percent of the locations. IBOC was designed from the start as the "solution" to Eureka-147 DAB -- it would allow a form of digital modulation while "maintaining the status quo" in terms of coverage, but not give any broadcaster a signal advantage, nor allow for additional audio channels. Surprisingly, the developers thought people would adopt this technology even though it was intentionally crippled.

If the HD locks up 90 percent of the time at his distance, it's already working better than it should.

 

[OKCRadioGuy]

"The problem I find with WFMT is that ever since they installed their new HD transmitter, the audio has sounded horrible on sibilants (listening to FM). It "spits", especially on voices that have a lot of high frequency energy, including Lisa Flynn and George Preston. I've contacted their chief engineer about this, and he claims it has nothing to do with HD transmission. At the time I first mentioned it to him, he said that he was still adjusting the audio processing. But that was about 6 months ago, and to me it still sounds bad."

There's a way of turning on pre-emphasis with the exporter, and usually also a way within the exciter. If it's turned on in both boxes, it will sound spitty as hell. Been there... seen that on a checkout at a station (not mine) one time.

Also, another thing that can reach up and bite someone is the limiter built into the Harris digital exciters when going in digitally. If you exceed the preset limit without making some changes to it's setting, you start clipping off peaks. That has a very unplesant sound to those of us that can hear.

Does WMFT use a seperate antenna (or the seperate port like a reject port) for their HD carriers? If they do, you are likely hearing the HD exceeding the analog signal in certain areas. We have some FMs here in OKC that have that issue. I can litterly take my spectrum analyzer and move it's whip around, watching the analog and HD signals NOT track with each other. If the HD crap becomes too strong compared to the analog host, you'll get EXACTLY what you're discribing.

On a side note, if anyone wants to bother with the elevated HD sidband thing, they better figure out how to get it into the same piece of coax and antenna, even if it costs more to do so. Anything else will create long-term signal issues IMHO.

 

[Tom Wells]

I just plugged in my Sony headphones to the Sangean 803 ATS, and compared two stations whose studios are only a
hundred or two hundred feet apart. WFMT and WZRD. WFMT is high power on high elevation downtown, while WZRD 88.3 is 100 watts
at 100 feet on Northeastern Illinois Universtiy. Both are about a half mile from my home.
The hiss on WFMT, even in mono reminds me of the level of hiss heard in old normal-bias cassettes used without dolby or other hiss reduction. I'm not hearing the artifacts I earlier described "riding on" crisp audio.
I will be doing some more listening to see if the hiss is from the particular original source recording.
OK, there's a break...the hiss is continuous in nature.
Betcha the kitchen radio can't pick up WFMT anymore, it was always in a "funny" spot.

WZRD, on the other hand, with no iboc, is hiss free in either mono or stereo.

If everyone listened to FM on headphones, the FM version would be under attack.

 

[satech]

I have to wonder if modern car radios treat the FM HD sidebands as if they were adjacent channel interference, and respond by narrowing the IF bandwidth and blending the audio to mono. On the factory radio in my 2008 Mazda, I don't hear a lick of stereo from FM "HD" stations unless I'm practically parked right underneath their tower, while I can hear stereo from non-IBOC stations at least 20-30 miles away. This radio offers neither HD nor RDS, although its tuner circuitry may be using DSP, considering how steep of a 4.5 kHz "brickwall" lowpass filter it uses on AM.

 

[OKCRadioGuy]

Honestly, it doesn't bother my DSP-based GM radio in my truck. I've got stereo with no problems. Portable and cheap radios are the more likely problem childs of the iBuz self-jamming issue.

 

[audioguy]

WFMT is a grandfathered station, so they are allowed to make more hiss than the others (one would think). For the several people out there listening to WFMT's HD-1, hope you enjoy it! Partly because of the IBOC issue and partly for other reasons, I reduced my contribution to WFMT this year and gave more to two fine university stations that I enjoy; WNIU and WAUS. Since they both now have online signals, a "radio" is no longer necessary. Some people don't like it when we refer to the Internet signals as "radio", so let's just call it "digital broadcasting".

Concerning the idea of using different digital power levels at different times, I doubt that this would fly. However, AM, stations turn their digital signals on and off entirely, apparently whenever they feel like it. At the moment, WSCR has theirs off, and it has been off for several days. I have never heard anyone announce that they would be turning off their digital signal, nor how long it would be off. Apparently they don't think it's very important to tell their listeners about this, or to restore it promptly.

We've had HD radio for how long now? And it still just goes on and off the air for no apparent reason. Does this sound like a successful, mature technology?