Kudos KMCQ

I’ve been quick to criticize the bad clipped horrid audio of the vast majority of the Seattle area radio stations.

I thought I’d take a moment to make a positive comment about one exception.  104.5 FM, KMCQ, wonderfully clean audio.  Percussion instruments still sound like musical instruments instead of gated white-noise.

I’m not overly fond of the format, automated oldies, often of the slow dreary variety, but when they do get a good song on there it sounds good, so kudos to the engineering staff there!

Slightly Less Gloomy

It appears KZOK finally repaired whatever was causing the horrid audio, now it’s just back to the normal clipped and overly compressed audio those of us who live in the Seattle market are used to.

I’ve never really understood what it is with this region of the country, the obsession with being “loud” is extreme.  I understand the need on AM where the signal to noise ratio is bad unless you live next to the antenna, but on FM it makes no sense.

One notable exception is KMCQ, 104.5, one of the few stations in the Seattle market that isn’t badly clipped.  It’s nice to hear percussion instruments actually sound like the instrument instead of gated white noise.  Kudos…  I’m not real fond of the format, not that I have anything against oldies, but I don’t really care for the sedate, and I don’t like automation and the total lack of audience interaction, that’s just me, but I do appreciate good clean audio.

Some day I have to string up a shortwave antenna and see if I can receive anything beside computer hash.  The built-in antenna on my little SW receiver is completely useless in this house.

Radio Blog Blues

I apologize for the lack of posts here recently but truth be told, the state of radio is so depressing that I’ve lacked motivation.

Commercial Broadcasting in the Seattle area has consolidated into a handful of mostly right-wing mega-corporations that play nothing but bland automated crap or spew right-wing propaganda all day long, with the exception of one station that spews pseudo left wing propaganda that is so blatantly bogus that it’s an embarrassment to listen to.

KNDD used to be my favorite radio station for modern music but anymore, during the hours of the day it’s not automated, anytime they get a radio personality that actually has one, they’re rapidly replaced.  It’s as if they’ve cloned pig-vomit and sent a clone to every station in the Seattle market.

I don’t want to bash Mike Kaplan anymore. I’m sure he is doing the best he can.  However, either his aesthetics and mine are 180 degrees out of phase, or the upper management have clamped down on the budget so much that things like the Beach House, live talented original creative and funny radio personalities, and good website design are just out of reach now, but whatever it is, I don’t like it.

I like radio that actually involves and interacts with the audience, and even with the expanded play list, I still here the same song 2-4 times if I listen a whole day.  And maybe it’s just me, I mean I know I’m ADD’ish, but I get bored hearing the same song again and again all day long.

Jack-FM doesn’t play the same song twice in a day, but they play what they want, not want I want, so I find myself turning jack off quickly.  The station is the antithesis of audience involvement, completely automated, and I hate everything it stands for.

I used to like KZOK for older rock, and often still I’ll tune in and hear a favorite old song, but the sound quality is so atrocious that I can not stand it for more than about 30 seconds.

And KISW, which has remained true to it’s format for more than 30 years, now censors Show Biz Kids like everyone else.  Guess they’ve been castrated too.

Local content is almost non-existent in the Seattle market.  Want to find out what’s going on locally?  Forget radio, pick up a copy of Seattle Weekly or something.

So much for AM/FM broadcast in the Seattle market…

I think the FCC should go back to the old rules where no entity could own more than three stations in a market, one AM, one FM, and one television.  I also think they should go back to the old rule where at least 12 hours of every day must be local content and get rid of the 24×7 network crap stations.

I used to enjoy shortwave, but now all I get is computer hash from 1.7Mhz all the way to 30Mhz.  Not surprising in my house, but now if I take a portable and walk the neighborhood, it’s the same everywhere.  The FCC is obviously not enforcing part 15 when it comes to incidental radiation and that’s not an accident, it’s a way of reducing the exposure of US citizens to some less brain-dead brain-washed ideas from around the world.

So in a nutshell, that’s why I haven’t been posting much, general disgust with the broadcast scene in the Seattle market.

KZOK 102.5 FM Audio

Was wondering if anyone has knowledge of what happened to KZOK’s audio? It sounds like a 24 Kb/s MP3, which is to say horrid.  Pretty much anything over about 8Khz seems to be gone, but it sounds like there is a big peak just before it rolls off and everything sounds squished.  This has been going on for several weeks now.  I received no response to an inquiry I sent to CBS Radio.

Whatever it is, I sure hope it’s not permanent.

KNDD

Just returned from a visit to KNDD’s web site.   Got to say it matches the rest of the station, sterile, boring, devoid of the life it used to have.

Several years ago, 2006-2008ish…  It was exciting, the Beach House, Block Party Weekends, End Sessions with cutting edge musicians, a station with an air staff that wasn’t afraid to be bold, and fun, now it’s just blah.

The website has followed suit, it’s blah too.

I am glad to see the end has increased their play list, now at least it’s possible to listen to more than two hours without hearing the same song three times.

I’m thinking Seattle needs a new alternative station, one that gets cutting edge artists exposed, gravitates to high energy music, not the bordering on elevator music that is about 80% of the playlist these days.

Ultrawide Broadband

The rate at which data can be transmitted is a function of signal-to-noise ratio and bandwidth. Even with a signal significantly below the noise level, data can be transmitted at high speeds if enough spectrum is available.

Orthogonal frequency division multiplexing uses a large number of parallel narrow channels integrating the received signal over a relatively long period of time. Each channel carries only a low data rate but combining a large number of channels allows high data rates.

This form of modulation is very resistant to noise and multipath because of the long integration period of each carrier.  If you are driving and a carrier is momentarily interrupted, it does not cause a loss of information because it’s only a very small interruption in a relatively long integration time.

There is a limit to how long this interval can be and how narrow each carrier can be based upon the acceptable latency for an application.  For example, a two-way telephone conversation would need a low enough latency that the conversing parties would not notice the delay.  But radio or television could easily handle a delay of several seconds without problems.

Other than regulatory limits, the only limit to the number of carriers and total data capacity that can be transmitted is the speed of the digital signal processors and the bandwidth of the radio frequency amplifiers and antenna.  Fractal antennas and newer semi-conductors have extended these limits quite a bit.

This is going to continue to expand to provide faster wireless data rates as faster digital signal processors and better algorithms become available.

Single channel per carrier services are going to largely go away and ultra-wide broadband internet will occupy most of the spectrum with radio and television being largely replaced with audio and video over Internet Protocol across ultra-wide broadband networks.

Economies of spectrum, power, and infrastructure will fuel this conversion.  A public tired of having half a dozen mega-corporations owning all of the broadcast stations in a market and hungry for choice beyond what satellite operators offer as well as the superior quality that wider bandwidth will make available will also factor in.

Internet automobile receivers are already available.  These have the advantage of making a much larger amount of program sources available than even satellite services like Sirius.  The horrid licensing arrangements that the various record labels and artists unions impose on Internet broadcasters places some constraints on music being broadcast via this medium, but I think eventually enough artists will go Independent that these organizations will be forced to change their business model or die and become irrelevant.  Why should artists get less than 1% of sales and put up with very limited exposure just so labels can get rich?

Internet stations have a world-wide audience by the very nature of their operation, but at the same time they’re competing with a much larger number of stations than conventional broadcasters.  This will make very specialized program economically viable and more generalized programming less so.  Unfortunately, it also will continue to kill local markets and stations that cater to local markets.

Digital Radio

In the United States, iBiquity’s proprietary and bandwidth wasting HD-Radio is the only digital radio format approved by the FCC for digital radio broadcasting on AM and FM.

Outside the US, Digital Radio Mondaile (DRM) and Digital Multimedia Broadcasting (DMB) are widely used.  Both systems are open rather than proprietary. Manufacturers of receivers and transmitting equipment don’t have to pay license fees to enable their equipment to receive DRM or DMB which means the equipment is less expensive for consumers to buy.

Digital Radio Mondaile works in a 9Khz bandwidth rather than the 30Khz required by HD-Radio, which destroys two adjacent channels.  Thus it is possible to operate three DRM stations in the same spectrum as one HD-Radio could operate in while providing superior audio quality.

The main disadvantage is that you don’t have an analog signal, you need a DRM equipped receiver to receive a DRM signal.

The FCC should drop HD-Radio because of the adjacent channel interference issue and because it’s not proper to give a licensing monopoly to one company, and because it is not making efficient use of available spectrum.  The FCC should open up the market to DRM and DMB and let the chips fall where they may.

Because both DRM and DMB are going to use digital signal processors to decode them and only the software will be different, and because both are open standards, it would be trivial for a receiver manufacturer to offer receivers that can decode both. Because the additional license fees wouldn’t be built into the cost of the receiver, adoption would likely be more rapid.

If the real reason the FCC adopted iBiquity’s HD-Radio as “the standard” was to maintain compatibility with existing receivers, then the FCC would not have adopted the standard for television which obsoleted millions of televisions.

The FCC dictating one standard while the rest of the world uses another guarantees US citizens won’t have direct access to foreign broadcasts.  Instead, our information can be carefully filtered to comply with what the US government wants it’s citizens to see and hear.

For that reason alone, we should have a world standard, not one standard for North America, another for the rest of the world.  The 3x better use of spectrum favors DRM over HD-Radio as does the superior audio quality.  The lower cost to consumers favors DRM.

I’d like to encourage people to write to your congress critters to force the issue with the FCC.

KNDD – Mike Kaplan – Station Direction

KNDD has been running spots where Mike Kaplan is soliciting listener input.  I wish I could say I was optimistic about anything good happening because it seems to me it’s just gone downhill the last few years..  Now Harms is leaving.

I enjoyed about Lazlo’s time there because he went out of his way to get the audience involved in the station.  The Alki Beach House gave people a chance to get to know both artists and the on-air personalities face to face and it added a lot of excitement to the station.

DJ No-name was another person who was really good at getting the audience involved and creating community.

They seemed a lot less prone to censorship in those days, songs tended to have a better chance of being played unneutered. The emphasis on independent artists seemed stronger than today.

Automation used to be reserved for the wee early morning hours, which if there is any place for automation, that would be it.  These days, people have portable MP3 players, smart phones, mp3 players on their computers, etc.  If they want automatic music they can program their own selection to their specific tastes without commercials, so why should they want to listen to automation that is hit-n-miss as far as their musical taste is concerned, interrupted by commercials, and with audio quality that is generally crushed and inferior to what they can get from their player?

Which brings up another of my complaints, The End’s audio quality has also gone down hill in the last three years, at least that’s my perception.

And I know I’m old school but I really like it when the on-air personality can hit queues well, so well you sometimes can’t tell where one song ended and another begins, so well they never have dead air nor do they ever stomp on lyrics.  Harms was all that and he also knew the music, the artists, and was a good people person. I hate to see him go.

Since Mr. Kaplan is asking for input, let’s oblige him and give him some.  I’d really like to see KNND get the kind of audience involvement it used to have, the sense of no fear let’s do it-ness it used to have, and I know they’ve got a bunch of highly competent engineers that could restore the audio to what it used to be if they so desired, turn off that filter that drops everything below 80hz and stop clipping the highs to death, or maybe everyone’s gone deaf and doesn’t care:

Mike Kaplan, KNDD Program Director
mkaplan@entercom.com
206-577-2445

Hello world!

Shortly after Google ate Blogger.com, they discontinued FTP publishing which I relied on.

Hosting the blog on blogspot.com was not an option since it would take the domain off of my host and put it on Googles were I had no control and leave a bunch of broken links where people had linked to my blog.

The custom domain was also not an option since I have a lot of content besides the blogs that wouldn’t go there.

And at the time WordPress didn’t run well on our server and the most current version didn’t run at all.

I’ve just upgraded Eskimo’s server to Apache 2.4.3 running under CentOS 6.3 on an I7-2600 machine.  This platform provides decent response and can run the most current version of WordPress.

I used the Blogger import module to import my Blogs, at least those I wanted to keep.  It didn’t handle the sidebar so I’ve got a bit of work to do to get the old look and feel back but basically here we are.

 

Pirate Radio – How To Avoid Causing Interference

During my Jr. High and High School years I ran a number of bootleg radio stations ranging up to as much as 1Kw, but mostly in the 25-100 watt range on the AM broadcast bands.

I had a number of friends who also ran AM and FM pirate radio stations, one ran a pirate SW station.

I just ran across this article, “The Story of Bootleg Radio 1610“, and for anyone considering operating a pirate radio station, it’s an excellent example of what not to do.

In all of the years I ran a bootleg radio station, I only ran afoul of the FCC once, and that’s when my antenna broke and resonated in the 80 meter ham band and caused interference.

Prior to that occurrence I had run a pirate radio station in a major metropolitan area for more than half a decade. And I’m not talking occasional operation, I’m talking daily multi-hour operation, during the summer months 24 hour operation, with an average power level of around 100 watts.

The lesson here is simple, while any operation without a license that exceeds part 15 is illegal; the laws were written with a purpose of preventing interference and when you cause interference you’re much more likely to invoke enforcement than if you avoid causing any interference. Even if you are operating completely legally within the constraints of part 15, you still may not cause interference to licensed operations.

Avoiding causing interference is a function of being knowledgeable and exercising careful engineering to create a clean signal that does not interfere with any legitimate licensed service. The higher the power level you operate at, the cleaner your signal must be in order to avoid causing interference.

Avoiding interference to licensed service involves first doing a careful survey to find a frequency upon which you will not cause interference to legitimate services. The AM broadcasting band has become so crowded that this is a very difficult if not impossible undertaking in many locations and at night when ionospheric reflection transmits signals over the horizon by reflection off of the ionosphere.

You want to find a frequency that not only is it vacant, but where there are no nearby stations on the adjacent channels that might receive interference from your sidebands or in cases where the receivers selectivity is garbage.

A good example of what not to do was set by a friend of mine who operated a pirate AM station on 1570 Khz AM when a local broadcast station was operating on 1590 Khz. In addition to being close in frequency; there was no limiter employed so that overmodulation would create additional sideband components by clipping the audio waveform. Interference to the commercial broadcast station brought the FCC field engineer to his house.

Most of the precautions you would take to prevent interference also happen to be good for your signals strength and quality. RF power that is outside of the intended frequency spectrum is RF power not going towards your intended transmission.

With AM stations, most of the commercial kits are garbage having either entirely untuned and unmatched outputs that are inefficient and have high harmonic content, or at best very low-Q output circuits that are only broadly tuned and do not provide good harmonic suppression.

I would suggest either building your own gear or using commercial broadcast quality gear. If you build your own, take the time to design your transmitter, matching system, and antenna. Be sure your oscillator is stable and within 20 Hz of the selected frequency. I would really suggest aiming to get it spot on. Most commercial stations will be very close and if you can do likewise you’ll avoid generating an audible beat note.

Take care to put together a high quality low distortion audio chain that includes a compressor and limiter or optimize your modulation and avoid any negative modulation peaks of 100% or greater. While theoretically, your audio power has to be half the DC final input power for 100% modulation, in practice I like to have about twice the audio power as DC input power to insure that modulation is highly linear up to 100% and also to allow for unsymmetrical modulation where the positive peaks may be allowed to exceed 100% while limiting the negative peaks to less than 100%.

Design your transmitter to meet all the requirements that a commercial station would have to meet save for the power levels. Pay careful attention to suppressing harmonics and any other out-of-band radiation. Design the output section, antenna, any matching or antenna tuning, to use tuned circuits of as high-Q as possible within the constraints of providing the necessary bandwidth for the desired audio frequency response.

Call around to local AM stations and you’ll often find that they have surplus equipment, old compressor / limiters, mixing consoles, cart machines, turn tables, etc, that you can acquire free or very inexpensively if you get to know the engineers.

Once you’ve designed and built your equipment, take extensive measurements and monitor it closely to be sure that it’s operating as expected. Some things I would suggest, first, be absolutely sure you have a decent modulation limiter. Anytime you exceed 100% modulation on the negative portion of the waveform, it is clipped because you can’t have less than zero carrier signal; that clipping generates high order harmonics that cause sidebands far outside of your intended channel and will interfere with other stations above or below your operating frequency.

A simple and yet highly effective modulation monitor for AM signals is an oscilloscope setup as a trapezoid modulation monitor. To do this connect a sample of the transmitters RF signal to the normal vertical input, and put an audio signal on the horizontal input.

Here are some example images. Forgive my art work, I know it isn’t the best, but hopefully it will serve to demonstrate the concepts.

0% modulation trapezoidTo the right is an example of a display without modulation. Since there is no audio input you see only the RF carrier signal deflecting the beam vertically.

Only your sidebands actually carry information, the carrier signal serves only as a reference for their decoding. An unmodulated carrier is a complete waste of power.

You should strive to design your program content so that this (dead air) never happens. High average modulation will mask noise where your signal is weak providing a higher perceived signal strength.

50% modulation trapezoidTo the left is a trapezoid modulation pattern with approximately 50% modulation.

The vertical lines indicate the minimum and maximum transmitter power points of the modulation envelope.

The slanted lines should be straight. Any curvature represents non-linearity in your modulation system and audio distortion results.

Non-linearity reduces audio quality and produces high order harmonics that will cause adjacent channel interference.

100% modulation trapezoidTo the right is a trapezoid modulation pattern with approximately 100% modulation.

In practice, you’ll want to set your limiter so that your negative modulation never quite reaches 100%. The trapezoid never comes to a perfect triangle or goes beyond that point.

No limiter will limit completely precisely owing to variations in the audio waveform so you need to allow a small margin of safety.

Imperfect frequency response, linearity, or phase shift in the transmitters modulation system may cause peaks to overshoot slightly.

125% modulation trapezoidTo left is an example of approximately 125% modulation.

Notice the line to the left of the trapezoid pattern. This represents the negative portion of the modulation envelope where the carrier has reached zero.

Also notice that at the other side of the trapezoid, the lines are no longer straight but taper off. This represents non-linearity in your transmitters output as it’s modulation capabilities are exceeded. This will also result in harmonics and adjacent channel interference but not as bad as going over 100% negative.

Note that if your transmitter is capable of exceeding 100% modulation on positive peaks cleanly then there is no harm in allowing positive modulation to exceed 100% and there is substantial advantage in doing so. Commercial broadcast stations are allowed to go up to 120% modulation on positive peaks.

This is why building your modulator to be capable of more than the theoretically required 50%, personal experience has taught me that it’s preferable to have about twice the audio power capability as DC input to the final, not that you will utilize all of this but it will insure your audio section is distortion free throughout the full range of modulation levels you might choose to utilize.

Commercial stations will often use clippers after the limiter followed by a low pass filter to remove any harmonics they generate but this really chews up the audio and makes it sound like crap so I don’t recommend it.

If you want to obtain good audio density I would make a number of recommendations, first a small amount of reverb injected into the audio chain, at a level where it is just barely audible, will provide additional density and cover noise.

Follow this with a good triband or multiband compressor. These break the audio into “bands” and compress each individually. This prevents things like a kick-drum or vocal cybalance from modulating the middle frequencies which are most noticable.

If you have the dollars, you can get a device called a peak inverter. Since you can’t exceed 100% negative modulation without extreme distortion and interference, but positive modulation can go arbitrarily high within the capabilities of your transmitter, a peak inverter will detect natural asymmetry in the audio waveform and switch the polarity such that the natural asymmetry is such that the peak is always greater in the positive direction. This allows you to modulate in excess of 100% without distorting the waveform of the audio source by taking advantage of any natural asymmetry in the waveform.

Lastly follow up by a fast asymmetrical limiter. I recommend setting the attack speed as fast as it goes, and the release speed as fast as you can get away with without the bass modulating the midrange. If you hear voices take on a chewed sound with bass notes, then the release time is too fast and the gain is following the bass waveform.

Set the limiter to limit the negative peaks a few percentage points shy of 100%, set the positive just shy of what your transmitter is capable of cleanly. If you see any rounding on the upper end of the trapezoid modulation pattern, you’re exceeding your transmitters capability. If you design your transmitter with a 2:1 audio to DC input you’ll never see this problem.

If you do these things you’ll have a loud, but clean, signal with good density that will mask noise to a large degree making the most of your coverage area.

Now assuming your transmitter, antenna tuning, and antenna are all designed well, your oscillator is stable and on frequency, you did a good survey before hand and found a truly unused channel with adjacent channels locally unused, your audio chain is clean, your modulation never exceeds 100% negative and positive doesn’t exceed your transmitters capability, you should have a professional sounding signal that won’t cause distortion and won’t sound amateurish (your program material may still be an issue).

Having done all of this work, I still recommend careful monitoring. You should have a good portable communications receiver capable of covering your operating frequeny and up to 30Mhz or so contiguously. I do not recommend getting the receiver too close to the transmitting antenna or you may fry your receivers front end.

Take your receiver about a block from your transmitting antenna while your transmitter is operating and modulated normally. Tune to the second adjancent channels to your transmitted channel. For example, if you are transmitting at 1000 Khz, then tune to 980 Khz and 1020 Khz and listen for any splatter from your station. If you hear splatter then something in your audio chain or the transmitter itelf is distorting your audio signal.

Then tune to harmonics of your transmitted signal, in the case of a 1Mhz transmission, tune to 2 Mhzs, 3 Mhz, 4 Mhz, etc. If you hear your signal, then your transmission isn’t clean and you either need to increase the quality of the tuned circuits in the transmitters output, antenna tuner, or the antenna itself, or possibly install a low pass filter between the transmitter and antenna.

If you’ve done everything to make sure your signal is clean, possibly even to the point of using a spectrum analyzer, and you still hear harmonics, there may be something non-linear object connected to something that receives your signal, rectifies it, and retransmits it. A good example might be metal gutters with a corroded joint. The gutter might play antenna and the corroded joint may act non-linearly distorting the signal and creating harmonics.

Not doing regular monitoring is the thing that allowed my broken antenna to resonate at 80 meters radiating a third harmonic of our transmitting frequency and drawing the attention of the FCC after six years of uneventful transmitting.