Station keeping subcarrier turned off?

About a year and a half ago, I noticed that a favorite station was broadcasting in mono (KUER, SLC Utah). The stereo light on my Dynaco FM-5 showed stereo on all other local stations. Listening confirmed it was indeed mono. This went on for a week or two. I looked up the station engineer's email address and asked him what was going on. He said there was a problem relating to their HD feed that required them to broadcast standard FM in mono, and they were working on a fix. A couple of days later it switched back to stereo.

Now it's happening again. Been mono for 3 weeks or more. Anyone know what kind of problem would cause this?

John

File it under "Sh*t happens" A low budget station may suffer an equipment failure just as easy as any us of do. If you don't have back up systems in place you simply carry on as best you can. Staying on-air is paramount. No station is required to broadcast in stereo. Serving the community is the most important thing. Failure to do so can result in license loss. I worked for a college station for many years and we scrimped and saved to buy back up equipment. I can't begin to describe the trials and tribulations of a broadcast station. Yes, I can probably pin the failure item in question but it isn't that important. It's a separate item that can be bypassed and life goes on. You sleep better at nights when there is enough spare stuff that you can take a lightening hit and go on. Eventually we gathered together duplicates or substitutions for every piece of the broadcast chain. Even rented a generator once during a power outage. Owning one was out of the question, too pricey for us. In the end, our fetish for survival was our undoing. I wrote computer programs that would sustain us when any of our all volunteer staff didn't show up. Enable tardiness and you will get it. The computer generated programming and our satellite feed for overnights led to some lazy personnel. The broadcast chain is a complex one and at any point problems can be introduced. Repeaters and such make it even more complex. I've always loved radio and from my service, even more so. It's a magical medium and knowing how it's done can be a revelation.

sinewaver said:

File it under "Sh*t happens" A low budget station may suffer an equipment failure just as easy as any us of do. . . I've always loved radio and from my service, even more so. It's a magical medium and knowing how it's done can be a revelation.

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Amen. I don't want to sound preachy, but lots of us - me included - whine about the dismal state of FM radio and we gravitate to the bottom of the dial where college and NPR stations provide us with some decent music and information.

If you really dig a station, join and send them a few bucks.

The local NPR network (Vermont Public Radio www.vpr.net ) broadcasts much of its talk programming in mono. Excellent quality mono, but mono nonetheless.

... and, oh yes, we support them. Their locally-produced programming is absolutely excellent -- and they run our favorite "network" program, too www.saysyou.net
NHPR (which is, technically "our" NPR) doesn't.

Plus, mono has a larger (clean) listening range than stereo ...
But I agree with the comments on donating to your local station ...
looks like they are NPR for SLC ...

http://kuer.org/


oooh - 8PM - Midnight - the Nighttime jazz show - very cool!
Our local NPR (in DC) is talk all the time -
they drove off the regular music shows that USED to be on our station ...
or moved them to HDRadio side-channels ...

One of my favorite Hudson Valley stations, WKZE, broadcasts in mono.

http://www.engineeringradio.us/blog/2011/08/fm-stereo-vs-station-coverage/

Total plug for the station; 98.1 and 105.9; bluegrass, jazz, chamber music, folk and rock - all mixed together. Very upstate, very hippy, and very cool.

Not sure what's worse... we have a station here in Dallas, listener supported KNON-FM which has been broadcasting mono audio with the stereo pilot and subcarrier for I don't know how long, I know it's years since I noticed it and began emailing them. They don't know what stereo is apparently.

Back in the early days of FM stereo, a station in Detroit was about to play a mono record. The announcer repeated several times that it was a mono recording, getting a bit louder each time. Eventually, the engineer woke up and the stereo pilot went off.

As to broadcasting without interruption, also back in the day, Henry Ford Community College in Dearborn operated the PA system in the Student Union as if it were a radio station. The other responsibility of the organization was to produce a weekly documentary, called Spotlight, recorded on Friday night at WXYZ studios and aired late Sunday when no one was listening. At that time, WXYZ FM went off the air at midnight. There was a rack with 2 tape decks and some switching equipment. The 10:00 to midnight program was music and announcements on 4 tapes. The first tape went from 10:00 to 10:30, the second tape automatically started at that time, ran until 10:55, then the system dumped to ABC for news. At that time, the technician mounted the next 2 tapes and the process was repeated from 11:00 to 12:00. One evening, the 10:30 tape started 5 minutes early (I speculate due to high frequency content in the music that triggered the switch) and the system was going to dump to ABC at 10:50 with dead air until the 10:55 news. There was a major panic for most of that half hour as they tried to figure out how to get a studio on the air to play some music for that 5 minutes. As I recall, they were not successful and there was actually 5 minutes of dead air.

All of the above makes sense. I just did not know that there was any relationship between HD and standard FM that would cause one to affect the other. I was curious about that. Obviously I need to learn more about FM, HD, etc.

hjames said:

Plus, mono has a larger (clean) listening range than stereo ....

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That's right, and if it's just talk, why not mono?
Everybody is talking into mono mics that just get split into two unpanned channels....

WGBH 89.7 in Boston broadcasts their talk time programming in mono. The few music programs that remain are broadcast in stereo, fortunately.

WBUR 90.9 also broadcasts their talk in mono, and maybe everything else (if they carry any other programming).

JRhoBurton said:

All of the above makes sense. I just did not know that there was any relationship between HD and standard FM that would cause one to affect the other. I was curious about that. Obviously I need to learn more about FM, HD, etc.

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HD is just a data channel at it's simplest, because of the radiated power limitations of the station licenses, that data channel is effectively taking power away from the audio content. This makes for a weaker signal overall, so if you are on the fringes of the FM Stereo portion of the signal (to recieve it cleanly) A station switching to HD may lose that region entirely in the fringe area, or the stereo signal drops out and all you get is mono in that fringe area. If you are local to the transmitted within 30 miles, you will not note any difference in most cases with the larger transmitters.

Our sports talk FM station broadcasts in mono. No point in the added expense for the multiplex equipment if it's just guys chattering. That said, I think the local "news" talk station (think Limbaugh) broadcasts in stereo. I'd have to check. I can't imagine why they would bother...it's still just people chattering. No need for a soundstage there.

There's ways of getting around HD signal limitations on low power stations ...



The FM1 stick is omni, and the FM6 yagi is pointed directly at my favorite low watt college station. They're just ganged together at the top with one feed line coming down. Couple hundred bucks for the antennas, but crystal clear and excellent stereo without drops at around 25 air miles, so the investment was worth it. Signal runs through a Magnum Sleuth FM amplifier.



PS ... the radio head was $100 and is hooked up to an LED monitor 12v power brick. Not much draw as I just use the line outs into my classic receiver.

Trio said:

HD is just a data channel at it's simplest, because of the radiated power limitations of the station licenses, that data channel is effectively taking power away from the audio content. This makes for a weaker signal overall, so if you are on the fringes of the FM Stereo portion of the signal (to recieve it cleanly) A station switching to HD may lose that region entirely in the fringe area, or the stereo signal drops out and all you get is mono in that fringe area. If you are local to the transmitted within 30 miles, you will not note any difference in most cases with the larger transmitters.

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Completely incorrect. The HD carriers are in addition to the analog. Does not in anyway take anything away from the analog side.

EV3

Yup ... your basic FM mono only uses about 15% of the licensed spectrum for a station - even with multiplex broadcasts, that leaves plenty of room for piggybacking signals such as HD Radio, data, and muzak ...

What's surprising is the quality of digital music that can be broadcast - up to 300kbps depending on their equipment and how the signal is allocated.

evsentry3 said:

Completely incorrect. The HD carriers are in addition to the analog. Does not in anyway take anything away from the analog side.

EV3

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Nope- you are not understanding what I have written.

In order to have power available to transmit that data signal, they have to reduce the power to the other content in order to stay within the power limits set forth in their license, unless they file to get a higher power license.

In other words, as an example: if your transmitter license is for 10,000 watts- that is it- 10,000 watts- so if you are adding a data signal, you have to lower your transmitter power for your other content accordingly because the FCC license considers the aggregate for your commercial station, this was why so many people on the fringes of broadcasts lost their signal when some stations added the HD data stream. If you are close to the transmitter, you hear no difference- if you are on the fringes, you will hear or not hear it.

Now, if all we have is just your sayso evsentry3, with no FCC rules, regulations, or documentation to the contraradict what I have posted- as this topic has come up in other threads- you just qualify as a keyboard comando troll who just wants to disrupt things and worth no further attention.

I understand perfectly what you wrote and it's still wrong. Don't know where it came from originally, but it was wrong then too.

And there is no logic at all to any fringe listener anywhere loosing a signal because of the HD carriers being added. Because nothing is taken away from analog to add the digital. Not RF power or modulation.

Thanks for being judge and jury on me, btw. That's ok though, I won't hold it against you. I'm just stating the simple facts and you can use the information or not. It's ok with me either way.

EV3

sKiZo said:

What's surprising is the quality of digital music that can be broadcast - up to 300kbps depending on their equipment and how the signal is allocated.

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My understanding was that ibquity's content was limited to 64kB or 128kB for audio streaming. I may be wrong...

Code of Federal Regulations part 73.404.

"FM stations are permitted to operate with hybrid digital effective radiated power equal to one percent (−20 decibels below carrier (dBc)) of authorized analog effective radiated power and may operate with up to ten percent (−10 dBc) of authorized analog effective radiated power in accordance with the procedures set forth...."

http://www.ecfr.gov/cgi-bin/text-idx?rgn=div6&node=47:4.0.1.1.2.3#se47.4.73_1404

Note the "...of authorized analog...". It's not changing the analog, only adding the digital.

I believe what you are incorrectly referring to is digital reception issues. Originally conducted tests were aimed at matching the digital reception to the analog. The very carefully controlled and documented tests conducted in many different areas of terrain came up with a match between analog and digital at a carrier level of -20. In the real world with real world radios, instead of lab test equipment, this later proved to be a deficent digital carrier strength to match the analog. So later it was changed to allow -14 for all FM's and if spacing allows, -10 for the digital carrier below analog signal strength.

So that's the story from the CFR, complete with english interpretation from a comando (sp) troll.

EV3