Interference Case #1-5 (AM).......Shocking Audio Samples of Interference

[audiophile.]

AM IBOC Interference audio sample

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Here's some audio picked up off some good stuff, to demonstrate what the IBOC signal is doing to first adjacent channels. Take a listen, just shy of 6mb.


http://www.goobe.net/iboc/iboc_observ.mp3

 

[IBOCRocks]

AM IBOC Interference audio sample

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Here's some audio picked up off some good stuff, to demonstrate what the IBOC signal is doing to first adjacent channels. Take a listen, just shy of 6mb.


http://www.goobe.net/iboc/iboc_observ.mp3

I'm going to listen to more, but the first thing I obeserve is their example of 670 KLTT interfering with 680 in California. While they mention that the IBOC signal goes away, they don't mention that at the same time the analog drops from 50kw to 1.4kw!

I'd like to hear what that frequency sounds like with IBOC off, but at 50kw. Additionally (and I'm not knocking it) they say they're using a high-end Grundig with a beverage antenna...NOT an everyday setup. I bet the common car radio with it's commonly narrow bandwidth would have little problem. Just my $.02.

Update:

I've now listened to the whole thing. While it's pretty dramatic, I think that it was set up specifically (with stations specifically chosen) to be just that. I'm not downplaying the test, but I think it's akin to a pro-IBOC test where they use the cheapest, deafest clock radio they can find and say "see...no problem!!"

 

[SaynotoIB0C]

hmmmm...what I heard was unlistenable when Adjacent IBOC was on and was STILL UNLISTENABLE when the adjasent IBOC shut off.

 

[audiophile.]

hmmmm...what I heard was unlistenable when Adjacent IBOC was on and was STILL UNLISTENABLE when the adjasent IBOC shut off.

In a few cases that was true but most of them weren't that bad...

 

[autopaint]

And as has been pointed out, first adjacents are always out of market stations. I used to be able to hear WGY a 50 KW station in Albany on 810 Khz about 100 miles or so from me but since WNYC moved to 820 (neither runs IBOC you can't hear WGY at my QTH. Take that demo to the commisiona dn they will laugh you out of the building. No insult intended. No casual user has a beverage and no one that I know of regularly listens to first adjacent stations.

 

[audiophile.]

I think many of you forget these samples were taken at the time of the nightime switch over. If HD was on into nightime hours the effects would even more dramatic.

Also, did you forget about protected skywave?

 

[IBOCRocks]

I think many of you forget these samples were taken at the time of the nightime switch over. If HD was on into nightime hours the effects would even more dramatic.

Also, did you forget about protected skywave?

With all due respect, that's not true. If KLTT dropped from 50kw to 1.4kw and left the IBOC on, you wouldn't have heard it at night in that demonstration. And again, if they had used a common tabletop radio, I believe the interference wouldn't be nearly as bad as they heard using a high-bandwidth receiver with a beverage antenna-an antenna known for it's low noise and sensitivity.

In fact, if you listen carefully, it sounds like KLTT's IBOC was shut off first, then the analog was powered down. After the IBOC shuts down, you hear about 2 seconds of audio, then you hear a quick audio drop followed by the "rushing" sound of the radios AGC bringing up the California station.

It's my opinion at this point that the California station would not be audible at that time of day with or without IBOC. It may be the same thing at night as well...there is a big difference between 50kw and 1.4kw.

 

[Tom Wells]

Bravo for posting concrete real-world examples of the destructive effects on AM.
While it is easy to say that this is not representative of average modern listeners' conditions, it is also just as easy to buy a used AM car receiver fromthe 1960's on e-bay for 25 dollars with EVERY bit as much sensitivity and selectivity AND audio passband as this. This was the level of usability almost everyone *could* enjoy until IBOC.
The beverage antenna and remote location notwithstanding.....

 

[ElCheapo]

There is zero doubt that AM IBOC is detrimental to the hobby of DXing - that's really the only thing the demonstration proved to me.

Is that a decent justification for denying real world listeners in the local communities which these stations are licensed to the benefits of IBOC?

If it were up to me, the way AM radio is allocated would be reviewed and revised. If the I-A and I-B clears powered down and lost their protections, think of how many local stations could operate 24 hours a day - serving their local communities.

The original purpose of clear channel stations was to provide service to areas of the country with no service at all. Today, that simply isn't a problem.

I take care of a sports talk station on a I-B channel. Is it fair that the local listeners of this station don't get ESPN Radio after dark just so two other stations can power up and serve the boonies where nobody is listening to them anyway? Is it fair that 26 stations have to go off the air to protect the huge and no longer necessary signals of 2?

 

[awj223]

There is zero doubt that AM IBOC is detrimental to the hobby of DXing - that's really the only thing the demonstration proved to me.

Is that a decent justification for denying real world listeners in the local communities which these stations are licensed to the benefits of IBOC?

I don't do a lot of DX listening. I'm not trying to catch rare signals. However, I do listen to skywave skip signals from 400-500 miles away several nights a week on average. This is not DXing. This is regular, predictable service that I use frequently, that IBOC on adjacents all night would ruin.

If it were up to me, the way AM radio is allocated would be reviewed and revised. If the I-A and I-B clears powered down and lost their protections, think of how many local stations could operate 24 hours a day - serving their local communities.

If it were up to me, the way frequencies that propagate long distances via skywave are assigned to stations intending to serve only local communities would be reviewed and revised. If AM were left to just the I-A and I-B clears and the locals moved to their own higher frequency band, think of how many local stations could operate 24 hours a day, serving their local communities - without clobbering each other's signals with skywave hash. Everyone wanting to listen to news, talk and sports over skywave gets what they want, and the local stations get what they want. The entire FM broadcast band takes up less spectrum than that allocated to a single cellular provider! Most cellular/PCS providers are sitting on enough spectrum to run the entire FM band, or all the Sirius and XM channels combined. Just open a new broadcast band!

The original purpose of clear channel stations was to provide service to areas of the country with no service at all. Today, that simply isn't a problem.

If every market is served well enough, why do we need MORE stations? Unless we're talking about the extremely rural areas, where it doesn't even make sense to build a weak transmitter to serve them. In these areas, you can hear dozens of stations at night on skywave. If all of them turn on the digital hash, chances are that NONE of these signals will be usable. You really expect someone to build local stations in areas like that? It probably wouldn't even sell enough ads to pay a single employee!

I take care of a sports talk station on a I-B channel. Is it fair that the local listeners of this station don't get ESPN Radio after dark just so two other stations can power up and serve the boonies where nobody is listening to them anyway? Is it fair that 26 stations have to go off the air to protect the huge and no longer necessary signals of 2?

If they're local to your station, they'll get their ESPN Radio at night. Why wouldn't they? I-B stations broadcast 24/7. Why anyone needs IBOC for ESPN Radio is beyond me. Just use the analog signal. Put the 26 on a new broadcast band and they won't have to sign off. The real mistake, though, was allowing those 26 to operate on AM in the first place.

Sports on IBOC would be a disaster. Can you say "processing delay"? Analog has many benefits, including:
1) It's instant. No processing delays.
2) It fades out, it doesn't drop out. One thing analog phones had that today's digital phones don't is a warning that the signal may cut out. With digital, it drops suddenly. This is okay for cellular networks because providers try to build them to have ubiquitous coverage. There aren't SUPPOSED to be fringe areas or dead spots. In radio, there WILL be fringe areas and dead spots, and unlike in TV, the receivers move. These conditions combined with digital broadcasting don't mix.
3) Can be received with passive components, so battery life on receivers is better. Digital processing eats up battery power.

 

[autopaint-1]

Sports on IBOC would be a disaster. Can you say "processing delay"? Analog has many benefits, including:
1) It's instant. No processing delays.
2) It fades out, it doesn't drop out. One thing analog phones had that today's digital phones don't is a warning that the signal may cut out. With digital, it drops suddenly. This is okay for cellular networks because providers try to build them to have ubiquitous coverage. There aren't SUPPOSED to be fringe areas or dead spots. In radio, there WILL be fringe areas and dead spots, and unlike in TV, the receivers move. These conditions combined with digital broadcasting don't mix.
3) Can be received with passive components, so battery life on receivers is better. Digital processing eats up battery power.

Why don't we have any CW stations? That is the simplest form of transmission. Radio stations aren't broadcasting specifically to cover local sports. At the network level where many stations receive their feeds from, the time it takes getting to and from the bird to the affiliate buildis in a delay. You can't tell me that some delays are allowed and others aren't. Television is all over the place. Off air analogue delivers a near instant picture, while digital is delayed and cable had another delay and satellite still another. We're focusing on nothing here. I'm curious as to what programs you listen to on a regular basis from a station located 400 miles from your location? Beleive me, if you do regularly listen to a station at that distance (and that would say to me that it isn't one of those 1 KW locals which many would have replace the big bad 50 KW clear channel operations which many in here complain about) you are one of the very few. Can't you hear that stations stream? Most larger stations do stream now and you wouldn't have to put up with the fading in and out.

 

[dbdigital]

AM IBOC Interference audio sample

--------------------------------------------------------------------------------

Here's some audio picked up off some good stuff, to demonstrate what the IBOC signal is doing to first adjacent channels. Take a listen, just shy of 6mb.


http://www.goobe.net/iboc/iboc_observ.mp3

Just as the NAB had sent bogus airchecks to members of Congress to demonstrate potential interference from LPFMs, I think this audio clip should be sent to both members of Congress and FCC Commissioners as a way of demonstrating the real-world intereference IBOC causes for analog AM.

IBOC is just not a viable solution for hybrid broadcasting on AM.

db

 

[autopaint-1]

"IBOC is just not a viable solution for hybrid broadcasting on AM."

Viable for whom, the dxer, the rural listener, the competition? I don't have any issues on the standard BCB. Of course I don't normally listen to stations on first adjacents.

 

[awj223]

Radio stations aren't broadcasting specifically to cover local sports. At the network level where many stations receive their feeds from, the time it takes getting to and from the bird to the affiliate buildis in a delay. You can't tell me that some delays are allowed and others aren't. Television is all over the place. Off air analogue delivers a near instant picture, while digital is delayed and cable had another delay and satellite still another. We're focusing on nothing here. I'm curious as to what programs you listen to on a regular basis from a station located 400 miles from your location?

This station is pretty good about delivering the audio almost instantaneously. I've been to games while listening to the station (which happens to be the flagship station for the broadcasts) and delays were less than 0.5 seconds. I care about delays because sometimes I don't like the TV announcers, so I mute the audio and turn on the radio. I refuse to subscribe to satellite because of the excessive delays. Cable TV and the radio are never more than 3/4 second out of sync. Satellite lags by 5-10 seconds or more.

What programs? I listen to baseball games, as well as the sports talk shows on that station which focus on my favorite team. On other stations I can get from skywave signals, I listen to news radio and talk programs. The talk programs I listen to are generally not syndicated and not available anywhere else.

Beleive me, if you do regularly listen to a station at that distance (and that would say to me that it isn't one of those 1 KW locals which many would have replace the big bad 50 KW clear channel operations which many in here complain about) you are one of the very few. Can't you hear that stations stream? Most larger stations do stream now and you wouldn't have to put up with the fading in and out.

These are big 50 kW stations, yes. Can I hear the streams? Not easily from the car. A lot of my listening happens in the car. Actually, I can hear streams from the car (which I've done a few times, but this requires lugging my laptop tethered to my cell phone, AND wiring the laptop to the car radio with an auxiliary input adapter) It's a pain in the *** and I've only done it a handful of times. Plus, the stream takes about 1-2 minutes to set up every single time (can't leave the laptop in the car while running errands, so this comes out to 1-2 minutes of my time every single stop I make), not including the amount of time it takes to boot the laptop. The streams are susceptible to getting dropped if I drive through a dead spot in the cellular network, requiring me to pull off the road so I can pull the laptop off the passenger seat and re-setup the stream (which takes another 30-60 seconds to rebuffer, and by then I've missed a chunk of the program).

I'll take fading signals over that anytime. Besides, the sports programs often aren't streamed on the station's website. I do have a subscription on the sports league's website so I can hear the games during the day, but again, I'll take fading skywave signals over lugging all that stuff with me anytime. These stations are much more likely to get me listening during times I can receive them over-the-air.

 

[ElCheapo]

I don't do a lot of DX listening. I'm not trying to catch rare signals. However, I do listen to skywave skip signals from 400-500 miles away several nights a week on average. This is not DXing. This is regular, predictable service that I use frequently, that IBOC on adjacents all night would ruin.

You are in the extreme minority. I've worked in a half dozen markets - both large and small - in programming and engineering. I've never seen any skywave listening reported in the Arb. I'm sure it happens occasionally, but I'm also sure it's extremely rare.

Sometimes, you've gotta think about the greater good.

People living in areas so remote that they can't receive any local stations have options now that didn't exist even 10 years ago. If I lived in the middle of nowhere, I'd be an XM subscriber. If I were a truck driver or someone who spent a lot of time on the open road at night, I'd be an XM subscriber.

Many of the 26 stations I cited earlier are in decent sized markets. My daytimer is in a market of about 250,000. It's ridiculous that the station has to sign off before 6PM some months to protect the mammoth coverage area of 1 station (the other I-B on the same frequency is west coast and doesn't effect our sign-off time.)

If the two 50,000 watt clears stayed at that same power and every other station on this frequency were allowed to stay on the air with 1,000 watts non-D at night, they could serve their local markets and the two clears could serve theirs with the same building penetration they've always enjoyed.

Personally, I could care less about AM IBOC - until they're ready to turn off the analog component entirely, I don't think it offers much benefit for AM. My hope is the skywave interference issue will cause the Commission to re-think the way AM is allocated in general.

I'm not holding my breath, but the people who own the I-A and I-B clears are also the biggest proponents of IBOC, so they may be somewhat flexible.

 

[Chuck]

I'm not holding my breath, but the people who own the I-A and I-B clears are also the biggest proponents of IBOC, so they may be somewhat flexible.

I'd think they'd be the LEAST flexible.

 

[ElCheapo]

I'd think they'd be the LEAST flexible.

Perhaps, but at some point they've gotta realize that a few dozen people listening to their giant signals a few states away aren't helping to pay their bills. It's the people in their local markets with Arbitron diaries that count.

If they feel IBOC will help them hold on to those local listeners, that will surely be their primary concern.

 

[awj223]

Many of the 26 stations I cited earlier are in decent sized markets. My daytimer is in a market of about 250,000. It's ridiculous that the station has to sign off before 6PM some months to protect the mammoth coverage area of 1 station (the other I-B on the same frequency is west coast and doesn't effect our sign-off time.)

If the two 50,000 watt clears stayed at that same power and every other station on this frequency were allowed to stay on the air with 1,000 watts non-D at night, they could serve their local markets and the two clears could serve theirs with the same building penetration they've always enjoyed.

So I ask again, why not allocate a new broadcast band, and allow these class-D stations to simulcast on the new band during the day, and operate exclusively on those frequencies at night? Give priority on the new band to the current class D AM owners, on the condition that one day they will vacate mediumwave entirely, which should clean up the band.

I see the FCC auctioning off large blocks of spectrum (25 MHz+). They just finished their AWS auction for mobile phone networks around 1700 MHz and 2100 MHz. Analog TV is shutting down, and each NTSC channel occupies 6 MHz. The entire FM band is 20 MHz. Just take three of those TV channels and you can have another FM! You could probably fit 2 to 3 times the number of stations in there depending on the level of compression. Those who want digital will have it, mediumwave listeners will have their skywave, and former class-D stations will have 24/7 operations.

 

[autopaint-1]

This is why you have congressional reps. Contact them and start a movement. If there's a call for a new band it will be granted. The X band has been closed by the commision and yet due to the call from a congressman, a new frequency has been made available for a station to serve an area which has been without a countywide local radio station.

 

[Chuck]

This is why you have congressional reps. Contact them and start a movement. If there's a call for a new band it will be granted. The X band has been closed by the commision and yet due to the call from a congressman, a new frequency has been made available for a station to serve an area which has been without a countywide local radio station.

The most logical first approach is to annex Channel 6 for FM radio. In some parts of the world that is their FM band. Receivers are already available that tune from about 72 MHz to 108 MHz.. That would really help unclog things.

A separate band for digital only broadcasts would also be a good idea. The problem is Congress likes to pay for some of their spending habits by auctioning off spectrum. Accommodating a few people who are interested in improving radio is not very high on their radar screen. Maybe a grass roots effort might work to get their attention. I hate to be cynical, but I doubt it.