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Weird problem-skippy audio

R

Randy Lahey

On my station there is one song that sounds like it skips when it's on the air. It's tough to explain so here is a link to a youtube video that shows what I'm talking about. The audio is ripped from our logger.

http://youtu.be/3uLb8Vqaukk

The song starts off normal, and than it starts sounding crazy, and this lasts for about 25 secs. The song then goes back to normal for most of the song, and then there is about 10 more seconds of skipping near the end.

This skipping is not part of the track. It sounds fine in Media Player, TLC, Adobe Audition etc. It only does this when it's on the air. The board's program feed sounds fine too.

We've done some weird tests, but they just make us more confused. It doesn't happen on every radio. Today I was in my office, and somebody else was in their office and we were listening to see if it would do it. I thought the problem was fixed as it sounded perfect in my office, but on her radio it was still skipping. They are both regular radios getting the signal over the air (FM). On at least 3 radios I've tested this skpping happens. And another 3 it sounds perfectly fine.

I re-downoaded and replaced the song and it still did it. I than downloaded the mp3 (I used a WAV before) and it still does it.

It doesn't make sense that different radio's are picking up different things. Any idea what is going on?

...and it's only with this song...Bruno Mars-It will rain.
 
Randy, I don't know; but I've recently witnessed some audio via a stream the confuses me, too.... ???
 
That's passin' fair strange. What's the chain? If the file is good, someting in the air chain doesn't like it. As we do digital, we find more hiccups caused by the new tech. Remember the Crystal Gayle Syndrome?
 
Is your station HD? (and are the radios that skip also HD?)

I wonder if you've found a "magic record" that causes the HD encoder to do something not really supported by the iBiquity standards?
 
Thanks for the responses guys. No, it's not an HD station. It's just a regular FM...actually it's simulcast on AM as well. I'm not sure if this problem is affecting the AM too. The crappy thing is I can't really do any tests without playing it on the air.

My chain is as follows: Scott SS32 (playing an uncompressed WAV and not MP2) > Ward Beck R2k Radio series board > Arrianne Sequel Processor > Omnia 6 processor > 950 STL. It probably doesn't matter, but I want to give you all of the info I can, It's also running through a 25-seven delay, but the delay has been on "bypass" everytime this has happened.

I'm going to downlad it from Itunes and take it to work on Moday and see if I still have problems. The weirdest thing is how it affects some radios, but not others. It makes no sense.
 
Listen to the audio at different locations in the air chain and watch the input / output metering on each piece of gear and see if it can be isolated to one location. Another thing... are you running RDS? If so, try disabling or bypassing it.

RFB
 
Lessee... reboot the Omnia.
Monitor the output of the SS32 and be sure the breakup isn't there
Is the STL composite or discrete?
Does the delay hardwire the inoput to the output when it's bypassed? If not, jumper past ot with hard wire. The 'catchup' algorithms in some of them can do strange things.
 
It goes away on the first bass drum... The entire portion of skipping is where the song is singing and instrumental... Sounds like it is being gated out on the AGC.
 
This may be the "Axel F"* phenomena. AFC problem in the STL caused by a large amount of low frequency audio energy on that particular cut (may even be subsonic and sub-audible).

Recently moved a studio when we bought a station, had mysterious noise getting into air chain, would take the transmitter off-air. Never figured out the source, seems to be something in the vicinity of the new studio site generating noise that would show up on FM receivers and get into the STL (an Armstrong). I added an outboard Corcom line filter and ferrites in and out of the Corcom which tamped it down considerably from the STL transmitter. May have been something around 10 MHZ?

Anyway, what was taking the transmitter off-air when this noise hit was the AFC circuit in the exciter,--an Energy-Onix SST-30. When the noise hit, the exciter lost lock, dumped, and the transmitter went away. We replaced it with a Continental 802A which simply passed the noise through. What may be happening in your case is something similar--perhaps the AFC circuit in the STL transmitter is seeing this low-frequency energy and dumping the STL momentarily--causing the audio to sound like it is "skipping." Same thing could happen with the STL receiver.

*The "Axel F Phenomena" was noticed back in the early 80's; this was the theme from Beverly Hills Cop--started out with a synthesizer "doot-doot-de-doot Dummmm" which was good in triggering the 25 hz. decoders on tape decks and did a number on a lot of older exciters. Harris MS-15's, for one.
 
rfburns said:
Listen to the audio at different locations in the air chain and watch the input / output metering on each piece of gear and see if it can be isolated to one location. Another thing... are you running RDS? If so, try disabling or bypassing it.

RFB
Click to expand...

I'll try monitoring different steps in the chain.

...and no, we are not running RDS.
 
littlejohn said:
Lessee... reboot the Omnia.
Monitor the output of the SS32 and be sure the breakup isn't there
Is the STL composite or discrete?
Does the delay hardwire the inoput to the output when it's bypassed? If not, jumper past ot with hard wire. The 'catchup' algorithms in some of them can do strange things.
Click to expand...

Coming out of the SS32 seems fine. As I mentioned, monitoring the boards program feed is fine. The problem seems to come further down the chain.

I'm not sure exactly how the delay is set up. I'll look into it.
 
TomT said:
This may be the "Axel F"* phenomena. AFC problem in the STL caused by a large amount of low frequency audio energy on that particular cut (may even be subsonic and sub-audible).

Recently moved a studio when we bought a station, had mysterious noise getting into air chain, would take the transmitter off-air. Never figured out the source, seems to be something in the vicinity of the new studio site generating noise that would show up on FM receivers and get into the STL (an Armstrong). I added an outboard Corcom line filter and ferrites in and out of the Corcom which tamped it down considerably from the STL transmitter. May have been something around 10 MHZ?

Anyway, what was taking the transmitter off-air when this noise hit was the AFC circuit in the exciter,--an Energy-Onix SST-30. When the noise hit, the exciter lost lock, dumped, and the transmitter went away. We replaced it with a Continental 802A which simply passed the noise through. What may be happening in your case is something similar--perhaps the AFC circuit in the STL transmitter is seeing this low-frequency energy and dumping the STL momentarily--causing the audio to sound like it is "skipping." Same thing could happen with the STL receiver.

*The "Axel F Phenomena" was noticed back in the early 80's; this was the theme from Beverly Hills Cop--started out with a synthesizer "doot-doot-de-doot Dummmm" which was good in triggering the 25 hz. decoders on tape decks and did a number on a lot of older exciters. Harris MS-15's, for one.
Click to expand...

I just took a look at the song in spectral view in adobe audition. Just by looking at that, it is such a difference that I can tell exactly where it will skip. It's definitely an issue with frequencies.
 
This phenomenon started appearing on exciters with single speed AFC's it was the reason for the Harris MX-15 replacing the MS-15 which had a real problem in this area.
 
Am I understanding correctly that this is causing the "skipping" sound on SOME analog FM radios but not ALL analog FM radios?

Could it be doing something weird to the stereo pilot? I'm talking "out of me league" here, but I just wonder if some radios might be more sensitive to the stereo lock than others... trying to think of frequency drift, stereo pilot, , signal strength...

...On that thought, have you looked at the output from the transmitter on a scope when that part of the song is playing? I'm wondering if it might shed some light on this bizarre issue.
 
A Similar problem a few weeks ago on a less than optimal remote. Randy you might see if any of these apply or if there were other things in the program line.

Path is Automation to Omnia Processor, Processor out (Analog out-processed) to Barix mp3 encoder to internet to Barix mp3 decoder to transmitter. Analog Broadcast Tools components not included.

Pre Automation was Remote location Mac Computer with Skype, skype to automation computer.

Audio was from MP3 Rocket Program on a second PC.

Audio ripped to mp3 Rocket. MP3 Rocket player on a PC to Mac with Skype encoder to internet to Skype decoder then sent through an Omni One. Omnia one to Barix MP3 encoder to internet to MP3 Decoder Barix to transmitter. The levels of compression/decompression are excessive. To be able to do this remote (and it sounded good except for a portion of a song. Could this be attributed to the internet?

Look at the number of times the audio was crunched and uncrunched. It was on a portion of a single song. I gave it little concern given the path.
 
Randy Lahey said:
Thanks for the responses guys. No, it's not an HD station. It's just a regular FM...actually it's simulcast on AM as well. I'm not sure if this problem is affecting the AM too. The crappy thing is I can't really do any tests without playing it on the air.

My chain is as follows: Scott SS32 (playing an uncompressed WAV and not MP2) > Ward Beck R2k Radio series board > Arrianne Sequel Processor > Omnia 6 processor > 950 STL. It probably doesn't matter, but I want to give you all of the info I can, It's also running through a 25-seven delay, but the delay has been on "bypass" everytime this has happened.

I'm going to downlad it from Itunes and take it to work on Moday and see if I still have problems. The weirdest thing is how it affects some radios, but not others. It makes no sense.
Click to expand...

Is the 950 TL analog or "digital?"
 
Here's something that could explain the fact that not all radios break up during this song, if there is a phase error at the breakup points stereo radios would not hear it but monoral radios would. I've never heard a sharp phase breakup such as your example but it could happen.
 
Hi there!

Do you have the highpass filter turned on in your Omnia?

If not, turn it on and see if the problem goes away.

Some background on this thinking:

What I have been seeing on some radios (newer ones in particular) is a situation where PLL's (in the radio) will unlock on the deep low end on today's hit music.

I've not run into something so severe as what you have going on, but you never know! Typically I'll run across radios that go far enough off-channel on deep bass that it sounds like it is not quite tuned in. Maybe this is what is happening to you, and the mute circuit kicks in while it is off-frequency.

Radios with decent PLL's (and older ones still in good shape) will play just fine, while others sound absolutely horrible.

I'll second the suggestions of others. Watch the AFC indicator on your STL transmitter and receiver during the song as well. If the needle (or bargraph) moves around a lot during the intro, then you have found the culprit. If so, then a re-cap job is in order on the STL. If the STL passes, do the same thing on your exciter (read the AFC meter) and see if the needle wiggles any.

Good luck!

-Cornelius
 
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